Drug – bio-affecting and body treating compositions – Topical sun or radiation screening – or tanning preparations
Reexamination Certificate
2000-06-23
2002-09-24
Dodson, Shelley A. (Department: 1616)
Drug, bio-affecting and body treating compositions
Topical sun or radiation screening, or tanning preparations
C424S060000, C424S400000, C424S401000, C514S294000, C514S415000, C514S456000, C514S457000, C514S685000
Reexamination Certificate
active
06455032
ABSTRACT:
This invention relates in one aspect to compositions which are applied to the skin after ultra violet (UV) radiation exposure, particularly following exposure to the sun. Such compositions may be referred to as after-sun compositions. In another aspect the invention relates to compositions for oral administration which protect against UV induced skin damage. In another aspect the invention relates to methods for protecting the skin from UV induced immunosuppression and UV induced skin damage, such as that resulting from exposure to the sun.
Exposure of the skin to ultraviolet radiation causes both critical damage to the epidermal DNA, which may have long-term irreversible consequences if remaining unrepaired, and may lead to a specific impairment of the T lymphocyte immune system.
In chronically UV-exposed skin, damage to DNA culminates in carcinogenesis, the most common tumour in man being the basal cell carcinoma (BCC), followed by squamous cell carcinoma (SCC), and more rarely malignant melanoma. For example, approximately two-thirds of the Australian population suffer from non-melanoma skin cancer at some time in their lives, the proportion increasing with decreasing latitude, and leading the world. Australia also has the world's highest incidence of melanoma.
The immuosuppression caused by UV exposure appears to be a prerequisite for non-melanoma and melanoma cancer promotion. It is mediated by a number of mechanisms, such as the formation of epidermal cis-urocanic acid in UV-irradiated skin, the persistence of pyrimidine dimers in epidermal DNA, and the upregulation of inflammatory eicosanoids like PGE2. It is understood that photoimmunosuppression permits the initiated tumour cell to evade recognition and rejection by normal immunological mechanisms, to remain latent for extended periods, and to eventually proliferate into a tumour.
Immunocompromised patients, whether genetically (xeroderma pigmentosum) or pharmacologically (organ transplant recipients) [see Boyle et al (1984)
Lancet,
31 March, 702-705 and Kinlen et al (1994) Invest Dermatol,
Br. J. Med.
ii 1461-1466], have a higher incidence of skin cancer. Also sun-exposed skin areas on humans are immunologically impaired compared with non-exposed skin [O'Dell et al (1980)
Arch. Dermatol.,
116, 559-561], and the level of immunological responsiveness of skin cancer patients is reduced compared with non-skin cancer patients [Yoshikawa et al,
Invest. Dermatol.,
95:530-536 (1990)]. The immune deficiency following UV exposure is now known to result from a deficiency in Th1 cell activity, whereas Th2 responses remain active [Ullrich, S. E. (1996)
Photochem. Photobiol.
64, 254-258].
The chronic exposure of the skin to solar radiation is well documented as the cause of the photoageing phenomenon, such as thickening of skin, drying of skin, increased skin pigmentation, skin spots and skin lesions.
UV exposure, such as chronic solar UV radiation causes the well known effects of reddening of the skin with accompanying inflammation, known as erythema. This is often referred to as “sunburn” which is painful, often itchy, and generally results in a subsequent peeling of the skin which has been subject to chronic solar irradiation.
Erythema is particularly prevalent in light skinned individuals and children. Chronic erythema may predispose individuals to skin disorders, such as skin cancers in later life. Depending on an individual's skin colouration, erythema may result in as little as 20 minutes exposure to the sun.
With an increasing awareness of the dangers of UV exposure to skin, “sun blocks” or sunscreens have been available for a number of years. Sunscreens are applied to the skin prior to sun exposure. Typically sunscreen compositions contain UVA-type sunscreen agents and/or UVB-type sunscreen agents. Typical UVA-type sunscreen agents include certain benzophenones and dibenzylmethanes. Typical UVB-type sunscreen agents include substituted para-aminobenzoates, alkyl esters of para-methoxycinnamate and/or various esters of salicylic acid. Generally sunscreening agents are used in amounts effective to provide the desired level of protection from erythema caused by UVA and/or UVB radiation. Examples of many known sun screening agents are described in WO 96/14826 which is incorporated herein by reference.
Sun screening compositions may contain physical sun screening agents such as red petrolatum, or titanium dioxide, such as in amounts from 2-5% by weight of the total composition. Precipitated silica, kaolin, talc, chalk and the like may also be used in such compositions.
A diverse range of compounds have been proposed as UV absorbers for use in sunscreen compositions. Amongst this enormous class of sunscreen agents flavonoid compounds, including isoflavone compounds, have been mentioned. The applicant's investigations indicate that isoflavone compounds show poor UV absorbing capacity, contributing as little as 1.5 units sun protection factor (SPF) to sunscreen compositions.
Concerns have arisen with regard to the light stability of various UV absorbers, potential toxic effects of compounds over long term exposure, complexity and cost of formulations, and overall effectiveness of sunscreen compositions. Sunscreen compositions require specific application to the skin prior to UV exposure. Failure to apply sunscreen, inadequate application to the skin, and/or loss of sunscreen from the skin all have the potential to lead to UV damage to the skin.
Currently available sunscreens are not all efficacious in protecting skin from UV exposure, such that immune deficiency of skin and the potentially serious consequences which may ensue remain unaddressed.
It has surprisingly been found by the applicant that certain isoflavone compounds when applied to the skin subsequent to UV exposure or for oral administration prior to or following UV exposure, in the form of an after-sun composition, protect the skin from UV induced immunosuppression and UV induced skin damage. It has also been found that extracts of soy and clover protect skin from UV induced immunosuppression and UV induced skin damage.
In accordance with one aspect of the present invention there is provided a composition for application to the skin following UV exposure or for oral administration prior to or following UV exposure, which composition comprises a compound of the general Formula (I)
in which
Z is H,
R
1
is H, or R
A
CO where R
A
is C
1-10
alkyl or an amino acid,
R
2
is H, OH, or OR
B
where R
B
is an amino acid or COR
A
where R
A
is as previously defined,
W is H, A is H or OH, and B is selected from
W is H, and A and B taken together form a six membered ring selected from
W, A and B taken with the groups with which they are associated comprise
W and A taken together with the groups with which they are associated comprise
and B is
wherein
R
3
is H, COR
A
where R
A
is as previously defined, CO
2
R
C
where R
C
is C
1-10
alkyl, or COR
B
where R
B
is as previously defined,
R
4
is H, COR
D
where R
D
is H, OH, C
1-10
alkyl or an amino acid, CO
2
R
C
where R
C
is as previously defined, COR
E
where R
E
is H, C
1-10
alkyl or an amino acid, COOH, COR
C
where R
C
is as previously defined, or CONHR
E
where R
E
is as previously defined,
R
5
is H, CO
2
R
C
where R
C
is as previously defined, or COR
C
OR
E
where R
C
and R are as previously defined, and where the two R
5
groups are attached to the same group they are the same or different,
R
6
is H or hydroxy C
1-10
alkyl,
X is preferably O, but may be N or S, and
Y is
where
R
7
is H, or C
1-10
alkyl,
in association with a dermatologically acceptable or pharmaceutically acceptable carrier.
Preferably the compounds of the Formula (I) are selected from:
wherein
R
7′
is H or CH
3
R
8
is COR where R
D
is as previously defined, or H,
R
9
CO
2
R
C
or COR
E
where R
C
and R
E
are as previously defined,
R
10
is COR
C
or COR
C
OR
E
where R
C
and R
E
are as previously defined,
R
11
is H or OH,
R
12
is H, COOH, C
Husband Alan James
Kelly Graham Edmund
Dodson Shelley A.
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Novogen Research Pty. Ltd.
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