Abstract

One of the main objectives for an aesthetic surgery patient seeking consultation is a desire to look younger and reverse the appearance of aging. Most of these patients also use topical creams in addition to undergoing surgical procedures. Over-the-counter (OTC) anti-aging products are a billion-dollar industry to which even young patients who wish to prevent the aging process contribute.

Many OTC products advertise dramatic results, but there have been relatively little scientific data to support these claims. We reviewed the literature on ingredients commonly found in OTC anti-aging creams. We conclude that although many different compounds are marketed as anti-aging products, studies proving their efficacy are limited. Vitamin C and alpha-hydroxy acids have been the most extensively researched products, and their anti-aging capabilities have been demonstrated in the literature. There have also been some promising studies on vitamin A and vitamin B derivatives. Moisturizers have been shown to increase skin hydration and improve the overall appearance of skin. Studies also indicate that pentapeptides can be effective in decreasing facial wrinkles and roughness. However, botanicals, which have become popular over the last few years, require significantly more research to formulate any positive conclusions for their topical application. As aesthetic surgeons, it behooves us to educate ourselves on the most common ingredients found in topical anti-aging products and their efficacy.

The authors have no financial interest in and receive no compensation from the manufacturers of any of the products mentioned in this article.

Learning Objectives:

The reader is presumed to have knowledge of the basic concepts of skin aging. After studying this article, the participant should be able to:

  1. Summarize the causes of skin aging.

  2. Discuss the commonly used anti-aging compounds

  3. Distinguish which products have been proven through double-blinded placebo-controlled studies to have anti-aging effects.

Physicians may earn 1 AMA PRA Category 1 credit by successfully completing the examination based on material covered in this article. The examination begins on page 413. ASAPS members can also complete this CME examination online by logging onto the ASAPS Members-Only Web site (http://www.surgery.org/members) and clicking on “Clinical Education” in the menu bar.

A common reason for patient consultation in a plastic surgery office is aging of the skin. There are two processes that lead to aging: the intrinsic chronologic aging of the skin, which is largely genetic, and environmentally induced aging.1 Environmental exposure to ultraviolet (UV) radiation, smoking, wind, and chemical exposure result in roughness, fine lines, sagging, irregular pigmentation, and decreased skin elasticity.1 Cumulative exposure to UV irradiation is one of leading causes of these skin changes. On a cellular level, UV degrades collagen and alters skin connective tissue. Many of these alterations in the extracellular matrix are mediated by matrix metalloproteinases that degrade fibrillar collagen (type I and III).2,3 However, the primary mechanism by which UV irradiation damages skin cells is by the photochemical generation of reactive oxygen species (ROS)—superoxide anion, peroxide, and singlet oxygen—that damage nucleic acids, lipids, and proteins, including collagen.3,4 This cumulative collagen damage disrupts the structural integrity of skin and contributes to wrinkle formation.

The skin protects itself with naturally occurring antioxidants, such as vitamins A, C, and E, squalene, and coenzyme Q-10, which donate electrons and neutralize the ROS.5,6 These natural antioxidants become depleted with age and UV exposure.7 UV radiation also forms thymine dimers—an inappropriate bond between two thymine bases in the DNA. These nucleic acid errors are excised and repaired, but if cumulative damage allows for the replication of a dimer, carcinogenesis results.

In 2000, according to Time magazine, Americans spent more than $2 billion on OTC anti-aging products.8,9 Many OTC products boast dramatic results using various combinations of ingredients to produce the desired youthful effects. To participate in a patient's quest for slowing down the visible signs of aging, it behooves the plastic surgeon to educate him- or herself about the most common ingredients found in OTC cosmetics and their efficacy.

Vitamins

Vitamin A/retinols

Vitamin A is a naturally occurring antioxidant in the skin. The biologically active form of vitamin A is all-trans retinoic acid or tretinoin (Retin-A). Retinoic acid aids in epidermal proliferation, keratinization, and peeling. It also modifies keratin synthesis, fibroblastic proliferation, and collagen metabolism.10 Topical application of retinoic acid has been widely proven to improve global appearance, fine and coarse wrinkling, roughness, pigmentation, and sallowness in many studies.11,12 However, retinoic acid is a prescription formulation that can be irritating to the skin and is not used in OTC cosmetics. Only less potent forms of vitamin A are available for nonprescription use: retinol, retinaldehyde, and retinyl palmitate, which is the ester of retinol combined with palmitic acid. All vitamin A derivatives are converted to their biologically active form, retinoic acid, in the skin.13

A few experimental studies have investigated OTC vitamin A derivatives as anti-aging alternatives. In 2000, Varani et al14 found that retinol was effective in improving the extracellular matrix of aging skin. They applied 1% retinol for 7 days on volunteers over 80 years of age. Histologic study of skin samples revealed increased fibroblast growth and collagen synthesis with decreased matrix-degrading matrix metalloproteinases as compared with untreated individuals.

Some studies on retinyl esters have been promising. In 1998, Creidi et al15 applied 0.5% retinaldehyde to the skin of volunteers for 18 weeks. They used optical profilometry to determine quantitative calculations of skin texture, wrinkling, roughness, and other surface irregularities. With these measurements, they found a significant reduction of wrinkles and surface roughness of the crow's feet area. Vitamin A esters also appear to be protective against the carcinogenic effect of UV radiation. In 2003, Antille et al16 reported that application of retinyl palmitate on the buttocks of young adult men exposed to UVB rays inhibited the formation of thymine dimers equivalent to that of SPF 20. However, retinyl palmitate has not yet been proven to be an effective anti-aging agent. The studies on vitamin A derivatives are promising, but there have been few large-scale double-blinded placebo-controlled trials investigating the clinical benefits of any of the OTC vitamin A products.

Vitamin B

There has been minimal investigation of the B vitamins as anti-aging ingredients, but a few studies have been encouraging. In a study in which a group of middle-aged women applied topical niacinamide B3 daily to one side of their face and compared it to the other side as a control for 12 weeks, there were significant improvements in fine lines and wrinkles, hyperpigmented spots, red blotchiness, and skin yellowing. There was also quantitative improvement in elasticity.17 Nicotinamide, another vitamin B analog, has been shown in in-vitro culture to increase the synthesis of ceramide, a compound that decreases with aging.18 However, the clinical relevance of this analog has not been established.

A new vitamin B choline analog, called 2-dimethylaminoethanol (DMAE), has recently been investigated. In 2005, a randomized clinical study by Grossman19 found that application of 3% DMAE facial gel for 16 weeks resulted in improvement of coarse wrinkles, under-eye dark circles, nasolabial folds, sagging neck skin, and neck firmness. These effects did not regress during a 2-week cessation of application. Studies measuring cutaneous tensile strength by subjecting treated and untreated skin to suction distension have found that DMAE-treated skin has increased firmness.20

Vitamin C

Vitamin C is a water-soluble antioxidant and the most plentiful antioxidant in the skin.6,21 Its biologically active form, L-ascorbic acid, an alpha-hydroxy acid, is a cofactor for collagen synthesis and is naturally found in fruits, vegetables, and tea.2224 Vitamin C is one of the most well-studied vitamins in anti-aging and has been proven effective in multiple studies. Reports comparing the clinical appearance of mild to moderately photodamaged facial skin after a 3-month application of 10% topical vitamin C (Cellex-C; Cellex-C International, Toronto, Ontario, Canada) to the hemi-face found statistically significant improvement compared with the untreated hemi-face with respect to surface texture, fine wrinkling, tactile roughness, coarse rhytids, skin laxity, and sallowness.25

Many groups have used optical profilometry to demonstrate significant improvements in skin texture, wrinkling, and roughness with vitamin C treatment.25,26 Histologic proof that vitamin C improves skin has also been published. In 2002, Fitzpatrick and Rostan27 applied 10% vitamin C to the cheek of volunteers and compared it with the opposite untreated cheek. At 12 weeks, biopsy specimens revealed an increase in the Grenz zone collagen (the connective tissue immediately beneath the epidermis) and increased gene expression of type I collagen in the skin. There have even been significant changes noted with lower concentrations of vitamin C. In another randomized double-blinded placebo-controlled study, 5% vitamin C applied to one forearm of volunteers and placebo to the other forearm for 6 months resulted in increased expression of collagen I, collagen III, and tissue inhibitor of matrix metalloproteinase on the treated side I.28 Similar studies with 5% vitamin C also found an increase in elastic fibers and more uniform distribution of type I collagen bundles.29 In 2004, Sauermann et al30 investigated the epidermal-dermal junction and depth of dermal papilla in volunteers of all ages and found that as people age, the papillae and its nutritive capillary decrease in density. They then applied topical 3% vitamin C on the forearm of volunteers and saw that there was an increase in the dermal papillae with new vessel formation after 1 month of treatment, compared with the opposite forearm where placebo was applied. These studies suggest that vitamin C increases the integrity of the extracellular matrix in the skin. On the basis of the large body of evidence supporting its anti-aging effects, topical vitamin C has proven to be an effective ingredient in OTC formulations.

Vitamin E

Vitamin E is a lipophilic antioxidant that occurs naturally in the skin. Vitamin E scavenges free radicals, preventing their ability to damage the lipid cell membrane. Forms of vitamin E that may be seen on cosmetic labels are tocopherols and tocotrienols. There have been no clinically applicable human studies demonstrating an anti-aging benefit of topical vitamin E. In in-vitro cultures, some antioxidant effects have been noted. In 2002, Chung et al31 found that human dermal fibroblasts treated with vitamin E show decreased expression of human macrophage metalloelastase in response to UVB radiation. In 1999, Jones et al32 reported that a vitamin E analog suppressed UVR-induced oxidative stress in human skin fibroblasts in vitro.32

The combination of antioxidant vitamins appears to be synergistic. On a molecular level, vitamin C helps regenerate vitamin E from its oxidized form, thus enhancing its antioxidant capacity.6,33 Application of topical 1% vitamin E and 15% vitamin C for 4 days before irradiation with a solar simulator was shown to decrease thymine dimer and sunburn cell formation in pigs.34,35 Sunburn cells are keratinocytes undergoing apoptosis—a protective mechanism controlled by tumor suppressor gene p53 to eliminate cells at risk of malignant transformation—and an indicator of UV cellular damage.36 Although vitamin E appears to be protective, more clinical studies need to be performed on humans before any conclusions can be made about vitamin E as an anti-aging compound.

Antioxidants

Other lipophilic antioxidants found in the skin are co-enzyme Q-10 and squalene. These antioxidants have been found to decrease with age and irradiation and have therefore been investigated as anti-aging products.3739 Both ubiquinone and idebenone, a synthetic derivative of coenzyme Q-10, have been used as an antioxidant replacement, but studies have shown that topical application does not increase their concentrations in the skin.38 There have also been no human clinical studies studying the efficacy of coenzyme Q-10 or squalene as a photoprotective anti-aging agent, and a porcine skin study showed that 1% ubiquinone and 1% idebenone applied topically to pig skin daily for 4 days had no photoprotective effect.35

Alpha lipoic acid (ALA) is an antioxidant that is not naturally found in the skin but has been used as an additive in cosmetic creams.4042 ALA is a potent reactive oxygen scavenger and has been found to repair oxidative damage in vitro.43 In an animal study, 0.5% ALA was applied to the skin of rats and found to increase collagen synthesis in the dermis and epidermis.44 In a randomized, placebo-controlled double-blind study performed by Beitner45 in 2003, 5% alpha-lipoic acid was applied twice daily to the cheek of volunteers for 12 weeks. Laser profilometry showed 50% decreased skin roughness compared with 40% on the placebo, which had carrier cream of 0.3% coenzyme Q-10 and .03% acetyl-L-carnitine. Although this difference was not statistically significant, clinical self-assessment by patients reported subjective improvement with the ALA-containing cream.

Alpha-hydroxyl acids

Alpha-hydroxyl acids (AHAs) may be seen on cosmetic product labels as glycolic acid, lactic acid, malic acid, citric acid, alpha-hydroxyethanoic acid, alpha-hydroxyoctanoic acid, alpha-hydroxycaprylic acid, hydroxycaprylic acid, and hydroxyl fruit acids. Many alpha-hydroxyl acids occur naturally in foods. Glycolic acid is present in sugar cane, lactic acid is present in sour milk and tomato juice, malic acid is found in apples, tartaric acid is found in grapes and wine, citric acid occurs in citrus fruits, and ascorbic acid, as mentioned above, is widely found in fruits, vegetables, berries, and tea.22 The most commonly used alpha-hydroxyl acids in cosmetics are glycolic acid and lactic acid. The Food and Drug Administration limits OTC AHAs to less than 10% concentration. Mild peels of 10% to 40% can be used in salons by trained professionals. Peels with more than 40% AHA concentration can be used only by medical doctors.

Alpha hydroxyl acids thin the stratum corneum by reducing corneocyte (the dead layer of surface skin cells) cohesion and speeding up the normal process of skin cell regeneration and exfoliation.4648 At higher concentrations of 25%, AHAs can cause increased epidermal or papillary dermis thickness, increased acid mucopolysaccharides, improved quality of elastic fibers, and increased collagen density.49 They also can promote increased gene expression of collagen and hyaluronic acid in the dermis and epidermis.50,51 These findings have been reproduced in many studies and in different species of animals.5255

The degree of exfoliation is directly proportional to the duration of application, and higher concentrations of acids have more potent anti-aging effects.22 A study comparing 5% versus 12% lactic acid found that application of 12% lactic acid twice daily for 3 months resulted in increased epidermal and dermal firmness and thickness with clinically improved skin smoothness and appearance of lines and wrinkles. With 5% lactic acid, there were similar clinical and epidermal changes but no modulation of the dermis.

However, the clinical changes induced by lower concentrations of alpha-hydroxyl acids still significantly improve the appearance of photodamaged skin without causing as much irritation. In 1996, Stiller et al56 performed a double-blind vehicle-controlled randomized clinical trial in which 8% glycolic acid or 8% L-lactic acid creams were applied twice daily to the face and outer forearms for 22 weeks. A significant percentage of patients had at least one grade of facial improvement (scale 0 to 9) in photodamage compared with placebo. On the forearms, treatment with glycolic acid cream or L-lactic acid cream ameliorated the overall severity of photodamage, as demonstrated by decreasing sallowness, mottled hyperpigmentation, and roughness. Extensive clinical studies have proven alpha hydroxyl acids to be an effective anti-aging compound.

Botanicals

Plant polyphenols are responsible for the intrinsic antioxidant properties found in botanicals. Polyphenols can be divided into several classes of chemicals: anthocyanins, bioflavonoids, proanthocyanidins, catechins, hydroxycinnamic acids, and hydroxybenzoic acids.57 Various plants used in anti-aging creams contain these compounds. Anthocyanins are found in red wine and berries; bioflavonoids are found in citrus fruits, soybeans, red wine, Ginkgo biloba, and many other vegetables; proanthocyanidins are found in coca, red wine, grape seed extract, green tea, and black tea; catechins are found in tea, chocolate, apples, pears, grapes, and red wine; hydroxycinnamic acids are found in coffee and red wine; and hydroxybenzoic acids are found in fruits, nuts, tea, and red wine.57

Bioflavonoids are antioxidant, anticancer, and antiinflammatory.5860 Bioflavonoids also inhibit UV-induced matrix metalloproteinases, which cause connective tissue damage to the skin.2,61 Anthocyanins, a group of flavonoids present in many common vegetables, have been shown to decrease UVB-induced DNA fragmentation and reactive oxygen species in human keratinocytes, thereby decreasing cancer formation.62,63 Proanthocyanidins are believed to inhibit production of free radicals and inflammatory pathways, such as histamine, serine protease, prostaglandins, and leukotrienes.64 There have been many in-vitro cell culture and animal experiments investigating the photoprotective potential of commonly used botanicals, but relatively few randomized placebo-controlled human clinical studies have been conducted. Several representative findings are summarized in the Table. Given the limited data, it is not yet possible to formulate any conclusions on the efficacy of botanicals.

Table

Photoprotective potential of commonly used botanicals

Compound Findings 
Grape seed extract 
 Rat Grape seed extract injected subcutaneously decreased inflammation (dec IL-TFN, PGE2) in injured ears and paws.65 
 Human beings Grape seed extract accelerated human healing.65,66 
 Human keratinocytes Keratinocytes cultured in grape seed proanthocyanidins showed dose-dependent decrease in UVB-induced oxidative stress pathways.67 
Tree bark 
 Hairless mice Pycnogenol (Pinus puinaster) bark extract applied after solar-simulated UV radiation to dorsal skin decreased tumor formation, erythema, and edema.68 
 Human keratinocytes Keratinocytes cultured with pycnogenol showed downregulation of antiinflammatory genes.69,70 
 Human beings Witch hazel (Hamamelis virginiana) bark extract applied to irradiated skin for 3 days resulted in decrease in erythema.71 
Soy extract 
 Hairless mice Topical application of genistein (soy extract) 60 minutes before UVB resulted in complete blockage of UVB-induced acute skin burns, dose-dependent inhibition of skin carcinogenesis >90%, and inhibition of photodamage (epidermal hyperplasia and reactive acanthuses) after UVB exposure twice weekly for 4 weeks.72 
  Ten percent bifidobacterium-fermented soy extract (BE) applied topically for 6 weeks increased hyaluronic acid content, hydration.73 
 Human fibroblasts Fibroblasts treated in vitro with soy extract showed increased expression of collagen and hyaluronan.74 
 Human beings Genistein applied to dorsal skin 60 min before UVB radiation blocked erythema and discomfort.72 
  Soy extract emulsion applied topically for 2 weeks showed increased dermal papillae density.74 
Milk thistle 
 Hairless mice Silbinin (milk thistle extract) applied topically 30 minutes before or immediately after UV exposure decreased number of apoptotic sunburn cells, thymine formation, and compounds responsible for oxidative stress.7477 
  Silbinin applied topically 30 minutes before or immediately after UV exposure decreased tumor formation and markers of cell proliferation and apoptosis.78 
Green tea 
 Mouse Topical application of EGCG (-)-epigallocatechin-3-gallate (green tea polyphenol) for 10 days before UVB decreased depletion of antioxidant enzymes79 
  Topical application of EGCG resulted in reduced UVA-induced skin roughness and sagging, as well as increased collagen secretion.80 
 Rat keratinocytes Keratinocytes cultured in tea decreased lipid peroxidation production and decreased apoptosis.81 
 Human dermal fibroblasts Topical application of EGCG has decreased UVA- and UVB-induced collagenase synthesis in dermal fibroblasts.80 
 Human beings Topical application decreased UVB-induced inflammation and myeloperoxidase activity in skin and decreased pyrimidine fibers.82 
  Topical application decreased UVA-induced erythema, sunburn cells, and injury to epidermal Langerhan cells.83 
Ginkgo biloba 
 Mouse G biloba extract applied topically to dorsal skin inhibited croton oil-induced edema (down-regulation of COX-2) induction.84 
  G biloba extract applied topically to mouse skin increased antioxideant activity (superoxide dismutase & zinc) after UV irradiation.85 
Algae/seaweed extract 
 Human keratinocytes Keratinocytes cultured with algae (Phaeodactylum tricornutum) extract showed decreased oxidative protein damage when exposed to UVA and UVB.86 
 Human stratum corneum cells Cells cultured with algae (P tricornutum) extract showed decreased oxidative protein damage when exposed to UV skin cell cultures.87 
 Human skin fibroblasts Fibroblasts cultured with algal extract showed decreased UVA-induced superoxide dismutase activity.88 
Aloe vera 
 Rat Topical application to dermal rat wounds showed increased biosynthesis and turnover of collagen, and accumulation of glycosaminoglycans resulting in scars of greater tensile strength.8991 
  Aloe vera applied to second-degree burns showed decreased inflammation measured by capillary permeability and leukocyte adhesion.92 
 Rat keratinocytes Keratinocytes irradiated and cultured in aloe extract and the supernatant injected into rats showed decreased IL-10 and suppressed, delayed hypersensitivity, suggesting an antiinflammatory effect.93 
 Hairless dogs Topical application for 50 days showed normalization of hyperpigmentation and dermal connective tissue organization.94 
 Pig skin Topical application had no effect on erythema or apoptotic sunburn cell formation with UV irradiation.35 
 Human fibroblasts Fibroblasts cultured in kinetin passaged multiple times had decreased morphologic alterations.95 
Compound Findings 
Grape seed extract 
 Rat Grape seed extract injected subcutaneously decreased inflammation (dec IL-TFN, PGE2) in injured ears and paws.65 
 Human beings Grape seed extract accelerated human healing.65,66 
 Human keratinocytes Keratinocytes cultured in grape seed proanthocyanidins showed dose-dependent decrease in UVB-induced oxidative stress pathways.67 
Tree bark 
 Hairless mice Pycnogenol (Pinus puinaster) bark extract applied after solar-simulated UV radiation to dorsal skin decreased tumor formation, erythema, and edema.68 
 Human keratinocytes Keratinocytes cultured with pycnogenol showed downregulation of antiinflammatory genes.69,70 
 Human beings Witch hazel (Hamamelis virginiana) bark extract applied to irradiated skin for 3 days resulted in decrease in erythema.71 
Soy extract 
 Hairless mice Topical application of genistein (soy extract) 60 minutes before UVB resulted in complete blockage of UVB-induced acute skin burns, dose-dependent inhibition of skin carcinogenesis >90%, and inhibition of photodamage (epidermal hyperplasia and reactive acanthuses) after UVB exposure twice weekly for 4 weeks.72 
  Ten percent bifidobacterium-fermented soy extract (BE) applied topically for 6 weeks increased hyaluronic acid content, hydration.73 
 Human fibroblasts Fibroblasts treated in vitro with soy extract showed increased expression of collagen and hyaluronan.74 
 Human beings Genistein applied to dorsal skin 60 min before UVB radiation blocked erythema and discomfort.72 
  Soy extract emulsion applied topically for 2 weeks showed increased dermal papillae density.74 
Milk thistle 
 Hairless mice Silbinin (milk thistle extract) applied topically 30 minutes before or immediately after UV exposure decreased number of apoptotic sunburn cells, thymine formation, and compounds responsible for oxidative stress.7477 
  Silbinin applied topically 30 minutes before or immediately after UV exposure decreased tumor formation and markers of cell proliferation and apoptosis.78 
Green tea 
 Mouse Topical application of EGCG (-)-epigallocatechin-3-gallate (green tea polyphenol) for 10 days before UVB decreased depletion of antioxidant enzymes79 
  Topical application of EGCG resulted in reduced UVA-induced skin roughness and sagging, as well as increased collagen secretion.80 
 Rat keratinocytes Keratinocytes cultured in tea decreased lipid peroxidation production and decreased apoptosis.81 
 Human dermal fibroblasts Topical application of EGCG has decreased UVA- and UVB-induced collagenase synthesis in dermal fibroblasts.80 
 Human beings Topical application decreased UVB-induced inflammation and myeloperoxidase activity in skin and decreased pyrimidine fibers.82 
  Topical application decreased UVA-induced erythema, sunburn cells, and injury to epidermal Langerhan cells.83 
Ginkgo biloba 
 Mouse G biloba extract applied topically to dorsal skin inhibited croton oil-induced edema (down-regulation of COX-2) induction.84 
  G biloba extract applied topically to mouse skin increased antioxideant activity (superoxide dismutase & zinc) after UV irradiation.85 
Algae/seaweed extract 
 Human keratinocytes Keratinocytes cultured with algae (Phaeodactylum tricornutum) extract showed decreased oxidative protein damage when exposed to UVA and UVB.86 
 Human stratum corneum cells Cells cultured with algae (P tricornutum) extract showed decreased oxidative protein damage when exposed to UV skin cell cultures.87 
 Human skin fibroblasts Fibroblasts cultured with algal extract showed decreased UVA-induced superoxide dismutase activity.88 
Aloe vera 
 Rat Topical application to dermal rat wounds showed increased biosynthesis and turnover of collagen, and accumulation of glycosaminoglycans resulting in scars of greater tensile strength.8991 
  Aloe vera applied to second-degree burns showed decreased inflammation measured by capillary permeability and leukocyte adhesion.92 
 Rat keratinocytes Keratinocytes irradiated and cultured in aloe extract and the supernatant injected into rats showed decreased IL-10 and suppressed, delayed hypersensitivity, suggesting an antiinflammatory effect.93 
 Hairless dogs Topical application for 50 days showed normalization of hyperpigmentation and dermal connective tissue organization.94 
 Pig skin Topical application had no effect on erythema or apoptotic sunburn cell formation with UV irradiation.35 
 Human fibroblasts Fibroblasts cultured in kinetin passaged multiple times had decreased morphologic alterations.95 

Moisturizers

Skin hydration is important for the overall appearance of the skin. Dryness can cause the skin to appear discolored, flaky, and rough. The stratum corneum (SC) contains corneocytes held together by a lipid bilayer. Lipid membranes in the stratum corneum comprised of cholesterol, free fatty acids (the most abundant being linoleic acid), and ceramides restrict transepidermal water loss (TEWL) and maintain the skin barrier.96 Corneocytes contain water-soluble molecules called natural moisturizing factors that allow the skin to bind water.97 It is the combined action of binding water and preventing water loss that maintains skin hydration and allows the stratum corneum to be soft and flexible.

Moisturizers contain occlusives, humectants, and emolients.98,99 Occlusives prevent transepidermal water loss and are comprised of oils or fats such as petroleum, lanolin, mineral oil, vegetable oil, or waxes.96,100 Humectants are low-molecular-weight substances that attract water. Natural moisturizing factors are naturally occurring humectants. Common humectants used in moisturizers are glycerin, propylene glycol, and urea.96 Emollients have no hydrating properties, but they are often used in moisturizers to act as a filler between desquamating corneocytes to allow for a smoother skin surface.

There have been only a limited number of studies on moisturizers published in the literature. Petrolatum—the most commonly used occlusive substance—is able to decrease water loss from the skin by about 50% but does not produce any increase in hydration.101,102 In the epidermis of aged individuals, there is about a 30% decrease in stratum corneum lipid content and significantly delayed barrier recovery.103 Therefore many of the investigations of moisturizers have involved topical application and replacement of stratum corneum lipids. In a mouse model, all three lipid components (fatty acids, cholesterol, and ceramide) were necessary for normal barrier repair.104 Betz et al105 investigated the hydrating power of liposomes—vesicles with a phospholipid bilayer membrane identical to natural cell membranes—in 2005. They found that a liposome made from egg phospholipids applied to the forearm increased skin water content 1.5-fold after 30 minutes and that daily application maintained this level of hydration.

Glycerin (glycerol) and propylene glycol are commonly used humectants. However, there have been few clinical studies demonstrating their hydrating effects. The best clinical study investigating the hydrating and protective effects by glycerol was performed by Gloor and Gehring106 in 2001. Topical application of 85% glycerol emulsion for 3 weeks in volunteers with normal skin resulted in significant reduction in TEWL measured by three different machines. All other studies in the literature on humectants involved experiments on individuals with atopic dermatitis or looked at barrier repair with skin injury. In a study in which glycerol was applied for 3 days to tape-stripped and sodium lauryl sulphate–damaged skin, faster barrier repair and greater stratum corneum hydration was seen in glycerol-treated sites.107 However, the results in the literature are inconsistent. In a study looking at topical application of 20% glycerin to the skin of patients with atopic dermatitis, there was no difference in TEWL compared with placebo.108 Unfortunately, most of the research on humectants involves subjects with preexisting dry skin conditions with altered stratum corneum, and the findings may not be applicable to the hydration of normal skin.

An anti-aging compound that has recently been investigated for its hydrating properties is the vitamin B analog nicotinamide, which was discussed previously. In 2005, Soma et al109 compared topical application of 2% nicotinamide cream with white petrolatum to patients with atopic dermatitis for 4 weeks. They found that both substances increased stratum corneum hydration, but nicotinamide application was significantly more effective and resulted in a higher desquamation index and decreased transepidermal water loss. On a molecular level, human keratinocytes incubated with nicotinamide showed increased biosynthesis of ceramide, glucosylceramide and sphingomyelin, all stratum corneum lipids crucial to the skin water barrier.110

Pentapeptides

In 1993, Katayama et al111 found that a subfragment pentapeptide of type I collagen lysine-threonine-threonine-lysine-serine significantly increased production of type I collagen, type III collagen, and fibronectin in human lung and dermal fibroblasts in a dose and time dependent manner. To make this peptide more lipophilic and increase its ability to penetrate skin, Lintner112 linked it to palmitic acid and patented the pentapeptide known as palmitoyl-lysine-threonine-threonine-lysine-serine (pal-KTTS). This is the compound that is currently used in OTC pentapeptide-based creams.

The compound received a significant amount of attention after effective anti-aging results were presented at the 20th World Congress of Dermatology in Paris, France in 2002. In vivo studies of cultured explanted human skin incubated with pal-KTTS showed a dose-dependent increase in collagen IV and glycosaminoglycan synthesis.112 In a double-blind, placebo-controlled study in which .005% (50-ppm) pal-KTTS was applied to the right eye area of female volunteers twice a day for 28 days, optic profilometry revealed a quantitative decrease in wrinkle depth, wrinkle density, and skin rugosity by 18%, 37%, and 21% respectively.112 Another study in which 25 volunteers were treated with twice-daily applications of 3% Matrixyl (Sederma, Paris, France) (a commercial product containing 100-ppm pal-KTTS) to the half-face for 6 months also revealed significant decreases in wrinkle depth, roughness, wrinkle volume, and main lines density by 21.6%, 16.4%, 24.4%, and 46.8% compared with placebo.113 Similar results were confirmed in 2005 by Robinson et al,114 who used the same concentration of pal-KTTS (3 ppm) to treat 93 women in a 12-week, double-blind, placebo-controlled, split-face randomized clinical study.

When compared with a commercially available cream containing 5% vitamin C in 10 volunteers who applied either cream on a half-face twice daily for 6 months, wrinkle depth, roughness, wrinkle volume, and main lines density decreased significantly more on the half-face treated with Matrixyl as compared with the half-face treated with vitamin C.113 When compared with 0.07% retinol applied twice daily, at 2 months there appeared to be a slightly greater decrease in main wrinkle depth and volume with Matrixyl, but at 4 months, retinol was more effective in all categories. None of these differences were statistically significant.113 Nevertheless, there appears to be an overwhelming body of evidence that pal-KTTS is effective in decreasing facial wrinkles and roughness.

Conclusion

Although many different compounds are marketed as anti-aging products, there are few studies proving their efficacy. Vitamin C, alpha-hydroxyl acids, and pentapeptides have been the most extensively researched compounds, and their anti-aging capabilities have been replicated in the literature. There have also been some promising studies on vitamin A and vitamin B derivatives. Other newer botanicals require more research to formulate conclusions that can be extended to their topical application. Moisturizers have been shown to increase skin hydration and improve the overall appearance of skin.

Despite the limited body of evidence, patients continue to use a variety of OTC products. However, for many patients, OTC remedies alone may not be sufficient to produce the desired effects, and prescription-strength medications or surgical procedures may be necessary.

References

1
Gendler
EC
Analysis and treatment of the aging face
Dermatol Clin
 
1997
;
5
:
561
567
.
2
Hantke
B
Lahmann
C
Venzke
K
Fischer
T
Kocourek
A
Windsor
LJ
et al
Influence of flavonoids and vitamins on the MMP- and TIMP-expression of human dermal fibroblasts after UVA irradiation
Photochem Photobiol Sci
 
2002
;
1
:
826
833
.
3
Fisher
GJ
Choi
HC
Bata-Csorgo
Z
Shao
Y
Datta
S
Wang
ZQ
et al
Ultraviolet irradiation increases matrix metalloproteinase-8 protein in human skin in vivo
J Invest Dermatol
 
2001
;
117
:
219
226
.
4
Harman
D
Free radicals in aging
Mol Cell Biochem
 
1998
;
84
:
55
61
.
5
Pinnell
SR
Cutaneous photodamage, oxidative stress, and topical antioxidant protection
J Am Acad Dermatol
 
2003
;
48
:
1
19
.
6
Farris
PK
Topical vitamin C: A useful agent for treating photoaging and other dermatologic conditions
Dermatol Surg
 
2005
;
31
:
814
818
.
7
Sander
CS
Chang
H
Salzmann
S
Müller
CS
Ekanayake-Mudiyanselage
S
Elsner
P
et al
Photoaging is associated with protein oxidation in human skin in vivo
J Invest Dermatol
 
2002
;
118
:
618
625
.
8
Gorman
C
Face-lift in a jar?
Time
 
2000
;
14
:
48
52
.
9
Chiu
A
Kimball
AB
Topical vitamins, minerals and botanical ingredients as modulators of environmental and chronological skin damage
Br J Dermatol
 
2003
;
49
:
681
691
.
10
Torras
H
Retinoids in aging
Clin Dermatol
 
1996
;
14
:
207
215
.
11
Kang
S
Voorhees
JJ
Photoaging therapy with topical tretinoin: an evidence-based analysis
J Am Acad Dermatol
 
1998
;
39
Pt 3
:
S55
S61
.
12
Nyirady
J
Bergfeld
W
Ellis
C
Levine
N
Savin
R
Shavin
J
et al
Tretinoin cream 0.02% for the treatment of photodamaged facial skin: a review of 2 double-blind clinical studies
Cutis
 
2001
;
68
:
135
142
.
13
Kockaert
M
Neumann
M
Systemic and topical drugs for aging skin
J Drugs Dermatol
 
2003
;
2
:
435
441
.
14
Varani
J
Warner
RL
Gharaee-Kermani
M
Phan
SH
Kang
S
Chung
JH
et al
Vitamin A antagonizes decreased cell growth and elevated collagen-degrading matrix metalloproteinase and stimulates collagen accumulation in naturally aged human skin
J Invest Dermatol
 
2000
;
114
:
480
486
.
15
Creidi
P
Vienne
MP
Ochonisky
S
Lauze
C
Turlier
V
Lagarde
JM
et al
Profilometric evaluation of photodamage after topical retinaldehyde and retinoic acid treatment
J Am Acad Dermatol
 
1998
;
39
:
960
965
.
16
Antille
C
Tran
C
Sorg
O
Carraux
P
Didierjean
L
Saurat
JH
Vitamin A exerts a photoprotective action in skin by absorbing ultraviolet B radiation
J Invest Dermatol
 
2003
;
121
:
1163
1167
.
17
Bissett
DL
Oblong
JE
Berge
CA
Niacinamide: A B vitamin that improves aging facial skin appearance
Dermatol Surg
 
2005
;
31
part 2
:
860
865
.
18
Tanno
O
Ota
Y
Kitamura
N
Katsube
T
Inoue
S
Nicotinamide increases biosynthesis of ceramides as well as other stratum corneum lipids to improve the epidermal permeability barrier
Br J Dermatol
 
2000
;
143
:
524
531
.
19
Grossman
R
The role of dimethylaminoethanol in cosmetic dermatology
Am J Clin Dermatol
 
2005
;
6
:
39
47
.
20
Uhoda
I
Faska
N
Robert
C
Cauwenbergh
G
Piérard
GE
Split face study on the cutaneous tensile effect of 2-dimethylaminoethanol (deanol) gel
Skin Res Technol
 
2002
;
8
:
164
167
.
21
Shindo
Y
Witt
E
Hans
D
Epstein
W
Packer
L
Enzymic and non-enzymic antioxidants in epidermis and dermis of human skin
J Invest Dermatol
 
1994
;
102
:
122
124
.
22
Van Scott
E
Ditre
CM
Yu
RJ
Alpha-hydroxyacids in the treatment of signs of photoaging
Clin Dermatol
 
1996
;
14
:
217
226
.
23
Phillips
CL
Combs
SB
Pinnell
SR
Effects of ascorbic acid on proliferation and collagen synthesis in relation to the donor age of human dermal fibroblasts
J Invest Dermatol
 
1994
;
103
:
228
232
.
24
Colven
RM
Pinnell
SR
Topical Vitamin C in aging
Clin Dermatol
 
1996
;
14
:
227
234
.
25
Traikovich
SS
Use of topical ascorbic acid and its effects on photodamaged skin topography
Arch Otolaryngol Head Neck Surg
 
1999
;
125
:
1091
1098
.
26
Rubino
C
Farace
F
Dessy
LA
Sanna
MP
Mazzarello
V
A prospective study of anti-aging topical therapies using a quantitative method of assessment
Plast Reconstr Surg
 
2005
;
115
:
1156
1162
.
27
Fitzpatrick
RE
Rostan
EF
Double-blind, half-face study comparing topical Vitamin C and vehicle for rejuvenation of photodamage
Dermatol Surg
 
2002
;
28
:
231
236
.
28
Nusgens
BV
Humbert
P
Rougier
A
Colige
AC
Haftek
M
Lambert
CA
et al
Topically applied vitamin C enhances the mRNA level of collagens I and III, their processing enzymes and tissue inhibitor of matrix metalloproteinase I in the human dermis
J Invest Dermatol
 
2001
;
116
:
853
859
.
29
Humbert
PG
Haftek
M
Creidi
P
Lapiere
C
Nusgens
B
Richard
A
et al
Topical ascorbic acid on photoaged skin. Clinical, topographical and ultrastructural evaluation: double-blind study vs placebo
Exp Dermatol
 
2003
;
12
:
237
244
.
30
Sauermann
K
Jaspers
S
Koop
U
Wenck
H
Topically applied Vitamin C increases the density of dermal papillae in aged human skin
BMC Dermatology
 
2004
;
4
:
13
31
Chung
JH
Seo
JY
Lee
MK
Eun
HC
Lee
JH
Kang
S
et al
Ultraviolet modulation of human macrophage metalloelastase in human skin in vivo
J Invest Dermatol
 
2002
;
119
:
507
512
.
32
Jones
SA
McArdle
F
Jack
CI
Jackson
MJ
Effect of antioxidant supplementation on the adaptive response of human skin fibroblasts to UV-induced oxidative stress
Redox Rep
 
1999
;
4
:
291
299
.
33
Thiele
JJ
Hsieh
SN
Ekanayake-Mudiyanselage
S
Vitamin E: critical review of its current use in cosmetic and clinical dermatology
Dermatol Surg
 
2005
;
31
:
805
813
.
34
Lin
JY
Selim
MA
Shea
CR
Grichnik
JM
Omar
MM
Monteiro-Riviere
NA
et al
UV photoprotection by combination topical antioxidants vitamin C and vitamin E
J Am Acad Dermatol
 
2003
;
48
:
866
874
.
35
Tournas
JA
Lin
FH
Burch
JA
Selim
MA
Monteiro-Riviere
NA
Zielinski
JE
et al
Ubiquinone, idebenone, and kinetin provide ineffective photoprotection to skin when compared to a topical antioxidant combination of Vitamins C and E with ferulic acid
J Invest Dermatol
 
2006
;
126
:
1185
1187
.
36
Murphy
G
Young
AR
Wulf
HC
Kulms
D
Schwarz
T
The molecular determinants of sunburn cell formation
Exp Dermatol
 
2001
;
10
:
155
160
.
37
Lenaz
G
Bovina
C
D'Aurelio
M
Fato
R
Formiggini
G
Genova
ML
et al
Role of mitochondria in oxidative stress and aging
Ann N Y Acad Sci
 
2002
;
59
:
99
213
.
38
Passi
S
De Pita
O
Puddu
P
Littarru
GP
Lipophilic antioxidants in human sebum and aging
Free Radical Research
 
2002
;
36
:
471
477
.
39
Podda
M
Traber
MG
Weber
C
Yan
LJ
Packer
L
UV-irradiation depletes antioxidants and causes oxidative damage in a model of human skin
Free Radic Biol Med
 
1998
;
24
:
55
65
.
40
Dar
A
Shaviv
NJ
Hermann
R
Niebch
G
Borbe
HO
Fieger-Busches
H
Enantioselective pharmacokinetics and bioavailability of different racemic alpha-lipoic acid formulations in healthy volunteers
Eur J Pharm Sci
 
1996
;
4
:
167
174
.
41
Selim
MA
Monteiro-Riviere
NA
Grichnik
JM
Pinnell
SR
Alpha-lipoic acid is ineffective as a topical antioxidant for photoprotection of skin
J Invest Dermatol
 
2004
;
123
:
996
998
.
42
Podda
M
Tritschler
HJ
Ulrich
H
Packer
L
Alpha-lipoic acid supplementation prevents symptoms of vitamin E deficiency
Biochem Biophys Res Commun
 
1994
;
204
:
98
104
.
43
Biewenga
GP
Haenen
GR
Bast
A
The pharmacology of the antioxidant lipoic acid
Gen Pharmacol
 
1997
;
29
:
315
331
.
44
Han
B
Nimni
ME
Transdermal delivery of amino acids and antioxidants enhance collagen synthesis: in vivo and in vitro studies
Connect Tissue Res
 
2005
;
46
:
251
257
.
45
Beitner
H
Randomized, placebo-controlled, double blind study on the clinical efficacy of a cream containing 5% alpha-lipoic acid related to photoageing of facial skin
Br J Dermatol
 
2003
;
149
:
841
849
.
46
Scheinberg
RS
Alpha-hydroxy acids for skin rejuvenation
WJM
 
1994
;
160
:
366
367
.
47
Fartasch
M
Teal
J
Menon
GK
Mode of action of glycolic acid on human stratum corneum: ultrastructural and functional evaluation of the epidermal barrier
Arch Dermatol Res
 
1997
;
289
:
404
409
.
48
Berardesca
E
Distante
F
Vignoli
GP
Oresajo
C
Green
B
Alpha hydroxyacids modulate stratum corneum barrier function
Br J Dermatol
 
1997
;
137
:
934
938
.
49
Ditre
CM
Griffin
TD
Murphy
GF
Sueki
H
Telegan
B
Johnson
WC
et al
Effects of alpha-hydroxy acids on photoaged skin: a pilot clinical histologic and ultrastructural
J Am Acad Dermatol
 
1996
;
34
Pt 1
:
187
195
.
50
Bernstein
EF
Lee
J
Brown
DB
Yu
R
Van Scott
E
Glycolic acid treatment increases type I collagen mRNA and hyaluronic acid content of human skin
Dermatol Surg
 
2001
;
27
:
429
433
.
51
Okano
Y
Abe
Y
Masaki
H
Santhanam
U
Ichihashi
M
Funasaka
Y
Biological effects of glycolic acid on dermal matrix metabolism mediated by dermal fibroblasts and epidermal keratinocytes
Exp Dermatol
 
2003
;
12
suppl 2
:
57
63
.
52
Kim
SJ
Park
JH
Kim
DH
Won
YH
Maibach
HI
Increased in vivo collagen synthesis and in vitro cell proliferative effect of glycolic acid
Dermatol Surg
 
1998
;
24
:
1054
1058
.
53
Hood
HL
Kraeling
MEK
Robl
MG
Bronaugh
RL
The effects of an alpha hydroxyl acid (gycolic acid) on hairless guinea pig skin permeability
Food Chemical Toxicol
 
1999
;
37
:
1105
1111
.
54
Moon
SE
Park
SB
Ahn
MT
Youn
JI
The effect of glycolic acid on photoaged albino hairless mouse skin
Dermatol Surg
 
1999
;
25
:
179
182
.
55
Kim
TH
Choi
EH
Kang
YC
Lee
SH
Ahn
SK
The effects of topical alpha-hydroxyacids on the normal skin barrier of hairless mice
Br J Dermatol
 
2001
;
144
:
267
273
.
56
Stiller
MJ
Bartolone
J
Stern
R
Smith
S
Kollias
N
Gillies
R
et al
Topical 8% glycolic acid and 8% L-lactic acid creams for the treatment of photodamaged skin. A double-blind vehicle-controlled clinical trial
Arch Dermatol
 
1996
;
132
:
631
636
.
57
Manach
C
Williamson
G
Morand
C
Scalbert
A
Remesy
C
Bioavailability and bioefficacy of polyphenols in humans. I. Review of 97 bioavailability studies
Am J Clin Nutr
 
2005
;
81
suppl
:
230S
242S
.
58
Maia Campos
PM
Gianeti
MD
Kanashiro
A
Lucisano-Valim
YM
Gaspar
LR
In vitro antioxidant and in vivo photoprotective effects of an association of bioflavonoids with liposoluble viatmins
Photochem Photobiol
 
2006
;
82
:
683
688
.
59
Middleton
E
Kandaswami
C
Effects of flavonoids on immune and inflammatory cell functions
Biochem Pharmacol
 
1992
;
43
:
1167
1179
.
60
Widyarini
S
Husband
AJ
Reeve
VE
Protective effect of the isoflavonoid equol against hairless mouse skin carcinogenesis induced by UV radiation alone or with a chemical carcinogen
Photochem Photobiol
 
2005
;
81
:
32
37
.
61
Moon
H
Chung
JH
The effect of 2?,4?,7?-trihydroxyisoflavone on ultraviolet-induced matrix metaalloproteinases-1 expression in human skin fibroblasts
FEBS Lett
 
2006
;
580
:
769
774
.
62
Cimino
F
Ambra
R
Canali
R
Saija
A
Virgili
F
Effect of Cyanidin-3-O-glucoside on UVB-induced response in human keratinocytes
J Agric Food Chem
 
2006
;
54
:
4041
4047
.
63
Tarozzi
A
Marchesi
A
Hrelia
S
Angeloni
C
Andrisano
V
Fiori
J
et al
Protective effects of cyaniding-3-O-beta-glycopyranoside against UVA-induced oxidative stress in human keratinocytes
Photochem Photobiol
 
2005
;
81
:
623
629
.
64
Shi
J
Yu
J
Pohorly
JE
Kakuda
Y
Polyphenolics in grape seeds—biochemistry and functionality
J Med Food
 
2003
;
6
:
291
299
.
65
Li
WG
Zhang
XY
Wu
YJ
Tian
X
Anti-inflammatory effect and mechanism of proanthocyanidins from grape seeds
Acta Pharmacol Sin
 
2001
;
22
:
1117
1120
.
66
Khanna
S
Venojarvi
M
Roy
S
Sharma
N
Trikha
P
Bagchi
D
et al
Dermal wound healing properties of redox-active grape seed proanthocyanidins
Free Radic Biol Med
 
2002
;
33
:
1089
1096
.
67
Mantena
SK
Katiyar
SK
Grape seed proanthocyanidins inhibit UV-radiation-induced oxidative stress and activation of MAPK and NF-kappaB signaling in human epidermal keratinocytes
Free Radic Biol Med
 
2006
;
40
:
1603
1614
.
68
Sime
S
Reeve
VE
Protection from inflammation, immunosuppression and carcinogenesis induced by UV radiation in mice by Topical pycnogenol
Photochem Photobiol
 
2004
;
79
:
193
198
.
69
Rihn
B
Saliou
C
Bottin
MC
Keith
G
Packer
L
From ancient remedies to modern therapeutics: pine bark uses in skin disorders revisited
Phytother Res
 
2001
;
15
:
76
78
.
70
Rohdewald
P
A review of the French maritime pine bark extract (Pycnogenol) a herbal medication with a diverse clinical pharmacology
Int J Clin Pharmacol Ther
 
2002
;
40
:
158
168
.
71
Deters
A
Dauer
A
Schnetz
E
Fartasch
M
Hensel
A
High molecular compounds (polysaccharides and proanthocyanidins) from Hamamelis virginiana bark: influence on human skin keratinocyte proliferation and differentiation and influence on irritated skin
Phytochemistry
 
2001
;
58
:
949
958
.
72
Wei
H
Saladi
R
Lu
Y
et al
Isoflavone genistein: Photoprotection and clinical implications in dermatology
J Nutr
 
2003
;
133
11 Suppl 1
:
3811S
3819S
.
73
Miyazaki
K
Hanamizu
T
Sone
T
Chiba
K
Kinoshita
T
Yoshikawa
S
Topical application of Bifidobacterium-fermented soy milk extract containing genistein and daidzein improved rheological and physiological properties of skin
J Cosmet Sci
 
2004
;
55
:
473
479
.
74
Sudel
KM
Venzke
K
Mielke
H
Breitenbach
U
Mundt
C
Jaspers
S
et al
Novel aspects of intrinsic and extrinsic aging of human skin: beneficial effects of soy extract
Photochem Photobiol
 
2005
;
81
:
581
587
.
75
Singh
RP
Agarwal
R
Mechanisms and preclinical efficacy of silibinin in preventing skin cancer
Eur J Cancer
 
2005
;
41
:
1969
-1679
76
Dhanalakshmi
S
Mallikarjuna
GU
Singh
RP
Agarwal
R
Silibinin prevents ultraviolet radiation-caused skin damages in SKH-1 hairless mice via a decrease in thymine dimer positive cells and an up-regulation of p53-p21/Cip1 in epidermis
Carcinogenesis
 
2004
;
25
:
1459
1465
.
77
Katiyar
SK
Treatment of silymarin, a plant flavonoid, prevents ultraviolet light-induced immune suppression and oxidative stress in mouse skin
Int J Oncol
 
2002
;
21
:
1213
1222
.
78
Mallikarjuna
G
Dhanalakshmi
S
Singh
RP
Agarwal
C
Agarwal
R
Silbinin protects against photocarcinogenesis via modulation of cell cycle regulators, mitogen-activated protein kinases, and Akt signaling
Cancer Res
 
2004
;
64
:
6349
6356
.
79
Vayalil
PK
Elmets
CA
Katiyar
SK
Treatment of green tea polyphenols in hydrophilic cream prevents UVB-induced oxidation of lipids and proteins, depletion of antioxidant enzymes and phosphorylation of MAPK proteins in SKH-1 hairless mouse skin
Carcinogenesis
 
2003
;
24
:
927
936
.
80
Kim
J
Hwang
JS
Cho
YK
Han
Y
Jeon
YJ
Yang
KH
Protective effects of (-)-epigallocatechin-3-gallate on UVA-and UVB-induced skin damage
Skin Pharmacol Appl Skin Physiol
 
2001
;
14
:
11
19
.
81
Fu
YC
Jin
XP
Wei
SM
Lin
HF
Kacew
S
Ultraviolet radiation and reactive oxygen generation as inducers of keratinocyte apoptosis: protective role of tea polyphenols
J Toxicol Environ Health A
 
2000
;
61
:
177
188
.
82
Katiyar
SK
Perez
A
Mukhtar
H
Green tea polyphenol treatment to human skin prevents formation of ultraviolet light B-induced pyrimidine dimers in DNA
Clin Cancer Res
 
2000
;
6
:
3864
3869
.
83
Elmets
CA
Singh
D
Tubesing
K
Matsui
M
Katiyar
S
Mukhtar
H
Cutaneous photoprotection from ultraviolet injury by green tea polylphenols
J Am Acad Dermatol
 
2001
;
44
:
425
432
.
84
Kwak
WJ
Han
CK
Son
KH
Chang
HW
Kang
SS
Park
BK
et al
Effects of Ginkgetin from Ginkgo biloba leaves on cyclooxygenases and in vivo skin inflammation
Planta Med
 
2002
;
68
:
316
321
.
85
Aricioglu
A
Bozkurt
M
Balabanli
B
Kilinç
M
Nazaroglu
NK
Türközkan
N
Changes in zinc levels and superoxide dismutase activities in the skin of acute, ultraviolet-B-irradiated mice after treatment with ginkgo biloba extract
Biol Trace Elem Res
 
2001
;
80
:
175
179
.
86
Bulteau
AL
Moreau
M
Saunois
A
Nizard
C
Friguet
B
Algae extract-mediated stimulation and protection of proteasome activity within human keratinocytes exposed to UVA and UVB irradiation
Antioxidant Redox Signaling
 
2006
;
8
1–2
:
136
143
.
87
Nizard
C
Poggioli
S
Heusele
C
Bulteau
AL
Moreau
M
Saunois
A
et al
Algae extract protection effect on oxidized protein level in human stratum corneum
Ann NY Acad Sci
 
2004
;
1019
:
219
222
.
88
Lyons
NM
O'Brien
NM
Modulatory effects of an algal extract containing astaxanthin on UVA-irradiated cells in culture
J Dermatol Sci
 
2002
;
30
:
73
84
.
89
Chithra
P
Sajithlal
GB
Chandrakasan
G
Influence of aloe vera on collagen characteristics in healing dermal wounds in rats
Mol Cell Biochem
 
1998
;
181
:
71
76
.
90
Chithra
P
Sajithlal
GB
Chandrakasan
G
Influence of aloe vera on the glycosaminoglycans in the matrix of healing dermal wounds in rats
J Ethnopharmacol
 
1998
;
59
:
179
186
.
91
Heggers
JP
Kucukcelebi
A
Listengarten
D
Stabenau
J
Ko
F
Broemeling
LD
et al
Beneficial effect of aloe on wound healing in an excisional wound model
J Altern Compement Med
 
1996
;
2
:
271
277
.
92
Somboonwong
J
Thanamittramanee
S
Jariyapongskul
A
Patumraj
S
Therapeutic effects of aloe vera on cutaneous microcirculation and wound healing in second degree burn model in rats
J Med Assoc Thai
 
2000
;
83
:
417
445
.
93
Byeon
SW
Pelley
RP
Ullrich
SE
Waller
TA
Bucana
CD
Strickland
FM
Aloe barbadensis extracts reduce the production of interleukin-10 after exposure to ultraviolet radiation
J Invest Dermatol
 
1998
;
110
:
811
817
.
94
Kimura
T
Doi
K
Depigmentation and rejuvenation effects of kinetin on the aged skin of hairless descendants of Mexican hairless dogs
Rejuvenation Res
 
2004
;
7
:
32
39
.
95
Rattan
SI
Clark
BF
Kinetin delays the onset of ageing characteristics in human fibroblasts
Biochem Biophys Res Commun
 
1994
;
201
:
665
672
.
96
Loden
M
Role of topical emollients and moisturizers in the treatment of dry skin barrier disorders
Am J Clin Dermatol
 
2003
;
4
:
771
788
.
97
Kraft
JN
Lynde
CW
Moisturizers: what they are and a practical approach to product selection
Skin Therapy Lett
 
2005
;
10
:
1
8
.
98
Glaser
DA
Anti-aging products and cosmeceuticals
Facial Plat Surg Clin N Am
 
2003
;
11
:
219
227
.
99
Madison
KC
Barrier function of the skin: “la raison d'etre” of the epidermis
J Invest Dermatol
 
2003
;
121
:
231
241
.
100
Glaser
DA
Anti-aging products and cosmeceuticals
Facial Plast Surg Clin N Am
 
2004
;
12
:
363
372
.
101
Loden
M
The increase in skin hydration after application of emollients with different amounts of lipids
Acta Derm Venereol
 
1992
;
72
:
327
331
.
102
Petersen
E
N. The hydrating effect of a cream and white petrolatum measured by opthothermal infrared spectrometry in vivo
Acta Derm Venerol
 
1991
;
71
:
373
376
.
103
Ghadially
R
Brown
BE
Sequeira-Martin
SM
Feingold
KR
Elias
PM
The aged epidermal permeability barrier
J Clin Invest
 
1995
;
95
:
2281
2290
.
104
Man
MQ
Feingold
KR
Elias
PM
Exogenous lipids influence permeability barrier recovery in acetone-treated murine skin
Arch Dermatol
 
1993
;
129
:
728
738
.
105
Betz
G
Aeppli
A
Menshutina
N
Leuenberger
H
In vivo comparison of various liposome formulations for cosmetic application
Int J Pharmaceutics
 
2005
;
296
:
44
54
.
106
Gloor
M
Gehring
W
Increase in hydration and protective function of horny layer by glycerol and a W/O emulsion: are these effects maintained during long term use?
Contact Dermatitis
 
2001
;
44
:
123
125
.
107
Fluhr
JW
Gloor
M
Lehmann
L
Lazzerini
S
Distante
F
Berardesca
E
Glycerol accelerates recovery of barrier function in vivo
Acta Derm Venereol
 
1999
;
79
:
418
421
.
108
Loden
M
Andersson
AC
Andersson
C
Instrumental and dermatologist evaluation of the effect of glycerine and urea on dry skin in atopic dermatitis
Skin Res Technol
 
2001
;
7
:
209
213
.
109
Soma
Y
Kashima
M
Imaizumi
A
Takahama
H
Kawakami
T
Mizoguchi
M
Moisturizing effects of topical nicotinamide on atopic dry skin
Int J Dermatol
 
2005
;
44
:
197
202
.
110
Tanno
O
Ota
Y
Kitamura
N
Katsube
T
Inoue
S
Nicotinamide increases biosynthesis of ceramides as well as other stratum corneum lipids to improve the epidermal permeability barrier
Br J Dermatol
 
2000
;
143
:
524
531
.
111
Katayama
K
Armendariz-Borunda
J
Raghow
R
Kang
AH
Seyer
JM
A pentapeptide from type 1 procollagen promotes extracellular matrix production
J Biol Chem
 
1993
;
268
:
9941
9944
.
112
Lintner
K
.
Cosmetic or dermopharmaceutical use of peptides for healing, hydrating and improving skin appearances during natural or induced ageing (heliodermia, pollution)
.
US Patent 6620419
,
2003
.
113
Matrixyl
The messenger peptide for dermal matrix repairs
Available at: http://web.winltd.com/winspa/matrixyl_blue.pdf
Last accessed July 3, 2007.
114
Robinson
LR
Fitzgerald
NC
Doughty
DG
Dawes
NC
Berge
CA
Bissett
DL
Topical palmitoyl pentapeptide provides improvement in photoaged human facial skin
Int J Cosmetic Sci
 
2005
;
27
:
155
160
.