Drug – bio-affecting and body treating compositions – Topical sun or radiation screening – or tanning preparations
Patent
1999-02-05
2000-11-21
Dodson, Shelley A.
Drug, bio-affecting and body treating compositions
Topical sun or radiation screening, or tanning preparations
424400, 424401, 514354, 514355, 514356, 514734, 514844, 514847, 514886, 514887, A61K 742, A61K 740, A61K 700, A61K 3105, A61K 31455
Patent
active
061498963
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
It is generally agreed that DNA damage and repair play a major role in the fate of living cells in terms of viability, mutagenesis and carcinogenesis, and aging. Skin cells are subject to continuous assaults by solar radiation, of which UVB is responsible for sunburns and skin cancer, while UVA is tanning. Both ranges of UV light are known to produce specific photoproducts, such as thymine dimers and the 6-4 photoproduct, and UVA has been shown to affect DNA strand breaks, in addition to formation of photoproducts, particularly as a result of attacks by reactive oxygen species.
The mechanism of excision repair, the major repair mechanism of damaged DNA, has been discovered in 1963 by Riklis (1964, 1965),(1),(2), Setlow and Carrier(3), (1964), and Boyce and Howard-Flanders (1964)(4). Since then, the generality of this repair pathway, as predicted by Riklis, was confirmed for many types of healthy cells and for different types of radiations, such as ultraviolet and ionizing radiations. Other modes of repair have been identified, including postreplication repair and strand break repair by ligation, and thus DNA damage and repair have become a most important event in cellular biology.
In 1981, Riklis(1)(2) had shown the possibility of enhancing DNA repair by the radioprotective compound WR-2721. He later showed the possibility of enhancing DNA repair by other chemical compounds, such as the vitamin nicotinamide.
The fact that ultraviolet assault on cells results in the formation of photoproducts is long known. In 1960 Beukers and Berends(5) identified thymine dimers (T<>T) as the product of irradiation of frozen thymine solutions with short UV radiation. In 1961 Wacker(6) identified T=T as the major photoproduct of UVC radiation which is responsible for cell death. It being the substrate of repair by photoreactivation was shown in 1962 by Rupert.
In 1963, as mentioned, thymine dimer was shown to be excised from DNA during the process of excision repair (Riklis(1)(2) Setlow & Carrier(3) Boyce & Howard-Flanders(4)). Other photoproducts have also been identified by various authors (Wang(7), Riklis(8) et al). A unique photoproduct was discovered by Riklis in DNA irradiated in a dry state, and a year later this product was found in spores and named the "spore product" (Setlow & Carrier(3)).
The excision repair pathways exist in normal healthy cells of mammals, plants and bacteria. Mutant bacteria exist which are deficient in repair, and in parallel there are human diseases which are manifested in extreme sensitivity to sun light (xeroderma pigmentosum) or to ionizing radiation (ataxia telangiectasia) and are deficient in cell ability to repair DNA.
FIELD OF INVENTION
The invention relates to cosmetic suncare compositions comprising in combination nor-dihydroguiaretic acid (NDGA), a known antioxidant with anti-inflammatory properties and niacinamide, optionally with BHT and propyl gallate. These include compositions in the form of post-exposure soothing creams, milks and ointments for soothing sunburns, which deep inside the skin cells enhance the repair of DNA from damages incurred during exposure to the sun. In addition, sunscreen preparations containing this combination of repair enhancers and antioxidants, reduce the degree of sunburn while acting towards enhancing repair from the instant damage. The small molecular weight of the compounds comprising EDNAR, "Enhanced DNA Repair", ensures penetration into skin cells and activity at the damage-sites in DNA.
The achievement of enhancing DNA repair by compounds which are of natural origin, NDGA and niacinamide, in an antioxidant environment is a breakthrough in suncare products which act not only as filters of UV radiation but provide further protection by an efficient repair of damages. These compounds, in cosmetic preparations, greatly improve the efficacy of such preparations by providing extra protection against UV light.
The discovery of DNA excision repair, showing that gaps may be formed in DNA and are filled by enzymatic
REFERENCES:
patent: 4975272 (1990-12-01), Voyt
patent: 5545399 (1996-08-01), Lee et al.
Oren-Riklis, legal representative by Liatt
Riklis, deceased Emanuel
Riklis, legal representative by Eitan
Riklis, legal representative by Eran
Riklis, legal representative by Ruth
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