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Clinically proven
to reduce oxidative stress.
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SKIN CANCER AND PHOTOAGING OF THE SKIN
Topical activity of ascorbic acid: from in vitro optimization to in vivo efficacy.
Raschke T, Koop U, Dusing HJ, Filbry A, Sauermann K, Jaspers S, Wenck H, Wittern KP. Skin Pharmacol Physiol. 2004 Jul-Aug;17(4):200-6
We present here a new cosmetic formula system containing 3% ascorbic acid based on an optimized oil-in-water (O/W) emulsion. This formulation demonstrated a good long-term stability of the active ingredient and also of the emulsion itself. It could be deduced from in vitro release studies that this O/W emulsion enabled a better release of the hydrophilic active agent than an alternative W/O emulsion. By measuring the ultraweak photon emission, which is a well-established parameter for the oxidative stress in the skin, the high in vivo antioxidant capacity of 3% ascorbic acid was demonstrated after 1 week of product application. This placebo-controlled study also proved that ascorbic acid in an O/W cream reduced oxidative stress in human skin significantly better than the derivative sodium ascorbyl-2-phosphate, a more stable vitamin C replacement commonly used in cosmetic formulations. With increasing age, the number of papillae in the epidermal-dermal junction zone in human skin are reduced. This implies a possible consequence of reduced mechanical resistance of the skin and impaired supply of the epidermis with nutrients. In a 1-month placebo-controlled study on 25 human volunteers, a significant increase in the number of dermal papillae after application of the 3% ascorbic acid cream was demonstrated, using a confocal laser scanning microscope. Fine lines and wrinkles are a characteristic sign of aged and especially photo-aged skin. Application of 3% ascorbic acid in a 12-week placebo-controlled usage study indicated a significant reduction of facial wrinkles. Altogether, 3% ascorbic acid in a cosmetic O/W emulsion has been shown to be appropriately stable and to enable a good release of the active agent in vitro as a precondition for a high efficacy in vivo. Application in vivo resulted in a significant reduction of oxidative stress in the skin, an improvement of the epidermal-dermal microstructure and a reduction of fine lines and wrinkles in aged skin. These results were received within a relatively short period of time of product application.
Toward mechanism-based antioxidant interventions: lessons from natural antioxidants.
Kagan VE, Kisin ER, Kawai K, Serinkan BF, Osipov AN, Serbinova EA, Wolinsky I, Shvedova AA. Ann N Y Acad Sci. 2002 Apr;959:188-98.
It is generally accepted that one of the major and important contributions to skin aging, skin disorders, and skin diseases results from reactive oxygen species. More than other tissues, the skin is exposed to numerous environmental chemical and physical agents, such as ultraviolet light, causing oxidative stress. Accelerated cutaneous UV-induced aging, photo aging, is only one of the harmful effects of continual oxygen radical production in the skin. Interestingly, our ELISA assays of 8-oxo-2'-deoxyguanosine in skin of young and old Balb/c mice showed that cumene hydroperoxide-induced accumulation of the biomarker of oxidative DNA damage in skin of 32-week-old mice occurred independently of their vitamin E status, while no accumulation of oxo8-dG was detectable in the skin of young animals. This suggests that vitamin E is not the major protector of skin against cumene hydroperoxide-induced oxidative stress. Production and accumulation of apoptotic cells is one of the characteristic features of skin damage by oxidative stress that, in the absence of effective scavenging by macrophages, dramatically enhances oxidative damage and inflammatory response. In our model experiments, we demonstrated that Cu-OOH induces significant oxidative stress in phospholipids of normal human epidermal keratinocytes (NHEK) whose characteristic feature is an early and profound oxidation of phosphatidylserine (PS), likely related to PS externalization. Since externalized PS is a signal for recognition of apoptotic cells by macrophage scavenger receptors, PS oxidation may be translatable into elimination of thus damaged NHEKs. Experiments are now underway to determine whether inhibition of PS oxidation by antioxidants may interfere with important signaling functions of oxidative stress in eliminating apoptotic cells.
Immediate effects of UV radiation on the skin; modification by an antioxidant complex containing carotenoids.
Cesarini JP, Michel L, Maurette JM, Adhoute H, Bejot M. Photodermatol Photoimmunol Photomed. 2003 Aug;19(4):182-9
BACKGROUND/AIMS: The ultraviolet (UV) portion of sunlight is involved in the induction and development of skin cancers against which a limited photoprotection may be provided by reduced time of exposure, clothing, and sunscreen applications. The concept of an effective, safe, systemic photoprotection will circumvent many of the shortcomings. The UV-induced oxidative stress is a cause of DNA damage and a few publications have shown, in humans, minimal benefits, if any, of the oral intake of antioxidant complex, contrasting with the large literature showing beneficial effects in vitro or in animal models. METHODS: We investigated, in 25 healthy individuals, the capacity of an antioxidant complex (AOC) - vitamins (lycopene, beta-carotene, alpha-tocopherol), selenium - to reduce UV-induced damages. The AOC was a |
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