Research
Lipoic Acid, Vitamins A, E Research:
Stability study of lipoic acid in the presence of vitamins A and E in o/w emulsions for cosmetic application.
Author: Segall A, Sosa M, Alami A, Enero C, Hormaechea F, Pizzorno MT, Bregni C, Serrao R.
Author affiliation: Department of Pharmaceutical Technology, School of Pharmacy and Biochemistry, University of Buenos Aires. Junin 956, 1113 Buenos Aires.
Publication date & source: 2004.09, J Cosmet Sci., 55(5):449-61
The effectiveness of any cosmetic product containing a functional ingredient is determined by the skin delivery of the active molecule, which is influenced by the type of carrier and the molecule itself. Furthermore, the functional ingredient should be stable in the formulation. The purpose of this paper is to study the stability of lipoic acid in the presence of vitamins A (as palmitate) and E (as acetate) in semisolids for cosmetic use. The systems formulated were studied in regard to their aspect, pH, stability under centrifugation, and rheological behavior. The chemical analyses of lipoic acid and vitamins A and E were carried out by HPLC after studying the specificity of the method employed in each case. The quantitation of the active principles was performed by HPLC with C18 (5 microm) columns. The mobile phase was methanol for the vitamins, with spectrophotometric detection at 325 nm for vitamin A and 230 nm for vitamin E. The mobile phase for lipoic acid was methanol:water (80:20) and phosphoric acid at pH 3.0, with spectrophotometric detection at 332 nm. All systems were stable to centrifugation, and no significant modification of rheological behavior was observed in relation to the base emulsion used as control. The chemical studies performed indicated that although lipoic acid is not very stable in these formulations, the presence of vitamin A favors its chemical stability.
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More research on Alpha Lipoic Acid
Randomized, placebo-controlled, double blind study on the clinical efficacy of a cream containing 5% alpha-lipoic acid related to photoageing of facial skin.
Author: Beitner H
Author affiliation: Department of Dermatology, Karolinska Hospital, 17176 Stockholm, Sweden.
Publication date & source: 2003.10, Br J Dermatol, 149(4):841-9
BACKGROUND: alpha-lipoic acid (LA) or the reduced form dihydrolipoate (DHLA) is a potent scavenger with
anti-inflammatory properties. Previous uncontrolled studies with topical treatment with 5% LA-containing
creams indicate a beneficial effect on photoageing skin. OBJECTIVE: The purpose of this study was to investigate whether a cream containing 5% LA showed any advantages concerning a number of the criteria associated with ageing of the facial skin, compared with an identical cream lacking LA.
MATERIAL AND METHODS: Thirty-three women, mean age 54.4 years, were included in this controlled study. After randomization half the face was treated twice daily for 12 weeks with the LA cream and the other half with the control cream. The following methods of assessment were used: self-evaluation by the test subjects, clinical evaluation, photographic evaluation and laser profilometry. Profilometry was performed before the start of treatment and at the end. RESULTS: All four methods of assessment showed a statistically significant improvement on the LA-treated half of the face. Laser profilometry, the most objective method used, showed an average decrease in skin roughness of 50.8% (44.9-54.0) on the LA-treated side, compared with 40.7% (32.4-48.7) on the placebo-treated half of the face P < 0.001 (Wilcoxon matched pairs test).
CONCLUSIONS: It is indicated that 12 weeks of treatment with a cream containing 5% LA improves clinical characteristics related to photoageing of facial skin.
Alpha lipoic acid (ALA) protects proteins against the hydroxyl free radical-induced alterations: rationale
for its geriatric topical application.
Author: Perricone N, Nagy K, Horvath F, Dajko G, Uray I, Zs -Nagy I.
Author affiliation: Department of Dermatology, Yale School of Medicine, New Haven, CT, USA.
Publication date & source: 1999.07, Arch Gerontol Geriatr., 29(1):45-56
The well known OH* free radical scavenging properties of alpha-lipoic acid (ALA) cannot be easily utilized
for biological experiments, because the compound is practically insoluble in water. We elaborated a simple method of preparing its Na-salt (Na-ALA) which proved to be water soluble. It has been demonstrated by ESR spin trapping experiments with DMPO, using the Fenton reaction as the source of OH* free radicals that Na-ALA maintains its OH* free radical scavenging ability: it reacts nearly an order of magnitude faster with these radicals than the spin trap itself. It was tested in two different systems to determine whether Na-ALA was able to protect bovine serum albumin (BSA) against the OH* free radical-induced polymerization and protein oxidation. (i) OH* free radicals were generated by Fenton reaction in the presence of BSA. This protein is polymerized by these radicals shown by the loss of its water solubility; Na-ALA exerted a considerable protective effect against this type of protein damage. (ii) BSA oxidation was induced by Co-gamma irradiation of 80 krad, resulting in a strong increase in the protein carbonyl content. Na-ALA inhibited this carbonyl formation very efficiently. The data suggest that the interaction of the OH radical with Na-ALA takes place on the disulfide group, yielding thiosulfinate or thiosulfonate. The results indicate that the geriatric topical application of Na-ALA may have an established rationale.
Vitamin A Research:
Vitamin A exerts a photoprotective action in skin by absorbing ultraviolet B radiation.
Author: Antille C; Tran C; Sorg O; Carraux P; Didierjean L; Saurat JH
Author affiliation: Department of Dermatology, University Hospital, Geneva, Switzerland.
Publication date & source: 2003, J Invest Dermatol, 121(5):1163-7
Retinyl esters, a storage form of vitamin A, concentrate in the epidermis, and absorb ultraviolet radiation
with a maximum at 325 nm. We wondered whether these absorbing properties of retinyl esters might have a biologically relevant filter activity. We first used an in vitro model to assess the photoprotective properties of retinyl palmitate. We then applied topical retinyl palmitate on the back of hairless mice before exposing them to 1 J per cm2 ultraviolet B, and assayed the levels of thymine dimers produced in epidermal DNA 2 h following ultraviolet B exposure. Finally, we applied topical retinyl palmitate or a sunscreen on the buttocks of human volunteers before exposing them to four minimal erythema doses of ultraviolet B; we assayed the levels of thymine dimers produced 2 h following ultraviolet B exposure, and determined the intensity of erythema 24 h after ultraviolet B. In vitro, retinyl palmitate was shown to be as efficient as the commercial filter octylmethoxycinnamate in preventing ultraviolet-induced fluorescence or photobleaching of fluorescent markers. The formation of thymine dimers in mouse epidermis was significantly inhibited by topical retinyl palmitate. In human subjects, topical retinyl palmitate was as efficient as a sun protection factor 20 sunscreen in preventing sunburn erythema as well as the formation of thymine dimers. These results demonstrate that epidermal retinyl esters have a biologically relevant filter activity and suggest, besides their pleomorphic biologic actions, a new role for vitamin A that concentrates in the epidermis.
Vitamin E Skin Research:
Free Radic Biol Med. 2004 Feb 15;36(4):456-63.
Vitamin E delivery to human skin: studies using deuterated alpha-tocopherol measured by APCI LC-MS.
Vaule H, Leonard SW, Traber MG.
Department of Nutrition and Food Management, Oregon State University, Corvallis, OR 97331, USA.
Enrichment of skin surface lipids with deuterium-labeled alpha-tocopherol was compared with plasma
enrichment to evaluate kinetics of the delivery of vitamin E to skin surface lipids. For 7 d, subjects
consumed 75 mg each of RRR-alpha-[5-(C2H3)]- (d3) and all rac-alpha-[5,7-(C2H3)2]- (d6) tocopheryl acetates with breakfast. Blood was drawn and skin lipids were collected daily for 2 weeks, then every other day for 2 weeks. A liquid chromatography-mass spectrometry atmospheric pressure chemical ionization method for quantification of deuterium labeled (d3, d6, d9-alpha-tocopherols) and unlabeled (d0-) alpha- and gamma-tocopherols was developed. Tocopherols were quantified at their m/z [M-1] using single ion recording. alpha-Tocopherol detection was linear from 1 to 100 pmol with a detection limit of 40 pg (93 fmol). Detection of gamma-tocopherol was twice as sensitive due to greater ionization efficiency. Though d3- and d6-alpha-tocopherols appeared in plasma within 24 h of the first dose, d3-alpha-tocopherol was not detected in skin surface lipids until approximately 1 week. Plasma percentage d3 peaked at day 8, while skin surface lipid percentage d3 increased on average until day 19. Apparently skin employs a mechanism to deliver alpha-tocopherol into skin via lipid secretions.
Publication Types: Clinical Trial
PMID: 14975448 [PubMed - indexed for MEDLINE]
Green Tea Research
Double-blinded, placebo-controlled trial of green tea extracts in the clinical and histologic appearance of
photoaging skin.
Author: Chiu AE, Chan JL, Kern DG, Kohler S, Rehmus WE, Kimball AB
Author affiliation: Department of Dermatology, Emory University, USA.
Publication date & source: 2005.07, Dermatol Surg., 31(7 Pt 2):855-60
Publication type: Clinical Trial; Randomized Controlled Trial
BACKGROUND: Green tea extracts have gained popularity as ingredients in topical skin care preparations to
treat aging skin. Green tea polyphenolic compounds have significant antioxidant and anti-inflammatory activities, and studies suggest that these extracts help mediate ultraviolet radiation damage.
OBJECTIVE: To evaluate the effects of a combination regimen of topical and oral green tea supplementation on the clinical and histologic characteristics of photoaging.
METHODS: Forty women with moderate photoaging were randomized to either a combination regimen of 10% green tea cream and 300 mg twice-daily green tea oral supplementation or a placebo regimen for 8 weeks. RESULTS: No significant differences in clinical grading were found between the green tea-treated and placebo groups, other than higher subjective scores of irritation in the green tea-treated group. Histologic grading of skin biopsies did show significant improvement in the elastic tissue content of treated specimens (p<.05).
CONCLUSION: Participants treated with a combination regimen of topical and oral green tea showed histologic improvement in elastic tissue content. Green tea polyphenols have been postulated to protect human skin from the cutaneous
signs of photoaging, but clinically significant changes could not be detected. Longer supplementation may be required for clinically observable improvements.
Skin photoprotection by green tea: antioxidant and immunomodulatory effects.
Author: Katiyar SK
Author affiliation: Department of Dermatology, University of Alabama at Birmingham, Birmingham, AL 35294, USA. skatiyar@uab.edu
Publication date & source: 2003.09, Curr Drug Targets Immune Endocr Metabol Disord., 3(3):234-42.
Publication type: Review; Review, Tutorial
Because of a characteristic aroma and health benefits, green tea is consumed worldwide as a popular beverage. The epicatechin derivatives, commonly called polyphenols, present in green tea possess antioxidant, anti-inflammatory and anti-carcinogenic properties. The major and most highly chemopreventive constituent in green tea responsible for the biochemical or pharmacological effects is (-)-epigallocatechin-3-gallate (EGCG). Epidemiological, clinical and biological studies have implicated that solar ultraviolet (UV) light is a complete carcinogen and repeated exposure can lead to the development of various skin disorders including melanoma and nonmelanoma skin cancers. We and others have shown that topical treatment or oral consumption of green tea polyphenols (GTP) inhibit chemical carcinogen- or UV radiation-induced skin carcinogenesis in different laboratory animal models. Topical treatment of GTP and EGCG or oral consumption of GTP resulted in prevention of UVB-induced inflammatory responses, immunosuppression and oxidative stress, which are the biomarkers of several skin disease states. Topical application of GTP and EGCG prior to exposure of UVB protects against UVB-induced local as well as systemic immune suppression in laboratory animals, which was associated with the inhibition of UVB-induced infiltration of inflammatory leukocytes. Prevention of UVB-induced suppression of immune responses by EGCG was also associated with the reduction in immunosuppressive cytokine interleukin (IL)-10 production at UV irradiated skin and draining lymph nodes, whereas IL-12 production was significantly enhanced in draining lymph nodes. Antioxidant and anti-inflammatory effects of green tea were also observed in human skin. Treatment of EGCG to human skin resulted in the inhibition of UVB-induced erythema, oxidative stress and infiltration of inflammatory leukocytes. We also showed that treatment of GTP to human skin prevents UVB-induced cyclobutane pyrimidine dimers formation, which are considered to be mediators of UVB-induced immune suppression and skin cancer induction. The in vitro and in vivo animal and human studies suggest that green tea polyphenols are photoprotective in nature, and can be used as pharmacological agents for the prevention of solar UVB light-induced skin disorders including photoaging, melanoma and nonmelanoma skin cancers after more clinical trials in humans.
