Drug – bio-affecting and body treating compositions – Topical sun or radiation screening – or tanning preparations
Reexamination Certificate
2000-05-19
2002-06-25
Dees, Jose′ G. (Department: 1616)
Drug, bio-affecting and body treating compositions
Topical sun or radiation screening, or tanning preparations
C424S401000, C514S456000, C514S944000
Reexamination Certificate
active
06409996
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a composition that contains one or more flavonoids, a method of obtaining such composition, and the use thereof as UV-absorbing agent, i.e., for producing a sunscreen product.
2. The Prior Art
In the art of sunscreen production it has been found that flavonoids may be used in order to enhance absorption of UV-radiation.
The abstract of Japanese document JP-55-111411-A discloses the use of flavonol in cosmetics for the purpose of protecting against sunburn.
Another effort to use a flavonoid as a sun protecting agent is disclosed in Japanese patent abstract JP-63-96120A, which describes an anti-suntan cosmetic including i.a. a flavone derivative and/or a coumarine. Unfortunately, coumarines are known to be skin irritating and are generally an unwanted substance in products for dermatological use.
It is furthermore known from the article “Orange Peel Wax”, Cosmetics & Toiletries magazine vol. 109, august 1994, that the wax extracted from oranges comprises flavonoids, carotenoids and unsaturated monoesters, and that these compounds have strong UV-absorptive properties.
The sun emits UV-radiation having wavelengths in the area of 200 nm to 400 nm. This area is commonly subdivided into 3 different bands designated UV-A (320 nm-400 nm), UV-B (290 nm-320 nm) and UV-C (200 nm-290 nm) respectively. Most of the UV-radiance reaching the earth is UV-A (about 90%). UV-B is only represented by about 10% of the UV-radiance but, due to its high energy level, it causes about 98% of the erythema of humans, while UV-C, having the highest energy level, is nearly totally blocked by the ozone in the atmosphere.
Modern research into the causes of skin cancer indicates that this UV-radiance, and particularly UV-B, may cause long term damage to skin cells, e.g., in terms of damage to cell DNA, eventually resulting in skin cancer.
Thus, many prior art sunscreen products aim to protect primarily against UV-B. Wearing a sunscreen product, people tend to expose A) themselves to direct sunlight for extended periods of time, counting on the protection offered by the sunscreen. However, long term influence by UV-A may cause accelerated aging of the skin and is also recognized as eventually causing skin cancer.
This problem is partly addressed in PCT application WO 96/18382 which discloses a cosmetic and/or dermatological composition for preventing harmful effects on human skin due to UV-radiation. The composition comprises one or more flavonoids or their glucosides and preferably also both a cinnamon acid derivative and an anti oxidizing agent such as vitamin E. The flavonoids can, according to WO 96/18382, be obtained as various plant extracts, and are preferably flavonones, e.g., naringin and hesperidin.
PCT application WO 96/18379 discloses a cosmetic and/or dermatological composition for preventing oxidative damaging of hair and skin such as stinging or sensible skin. The composition is essentially the same as disclosed in WO 96/18382 and comprises one or more flavonoid components optionally combined with a cinnamon acid derivative and an anti oxidizing agent.
The documents WO 96/18382 and WO 96/18379 furthermore suggest the use of additional UV-B absorbing components in order to obtain a higher absorption in the UV-B-range.
However, the suggested compositions comprising mainly flavanones such as naringin and hesperidin combined with cinnamon acid derivatives and/or further UV-B absorbers has proven to more or less entirely block the UV-radiation in the UV-B range, but not to provide an adequate protection of the skin in i.a. the UV-A range, and the provided absorption profiles seem merely arbitrarily selected.
As many people sunbathe in order to tan their skin and UV-radiance plays an important role in the tanning process, it is thus desirable to provide a sunscreen product enabling both tanning and at the same time offering substantial protection of the skin cells. However, as indicated above, the prior art documents do not provide a UV-absorbing composition having such a satisfactory profile for both protecting human skin cells and at the same time allowing the skin to tan.
There thus remains a need for a composition having a optimized UV-absorption profile, so as to block and/or absorb essentially the most damaging wavelengths in a carefully balanced way while still allowing the skin to tan and furthermore without subjecting the skin to unwanted substances.
Therefore it is an object of the present invention to overcome the shortcomings of in particular the above mentioned prior art and to provide such an optimized UV-absorbing composition.
SUMMARY OF THE INVENTION
This object is obtained by the composition according to the invention characterized in that it includes at least one flavonone and at least one flavone and having an UV-absorbency at 282 nm in water where the flavanone(s) accounts for 75-98% of the flavonoids absorbency, and where the flavone(s) accounts for 2-25% of the flavonoids UV-absorbency at 282 nm in the composition.
This first aspect of the invention is based on the recognition that flavanones are particularly effective as UV-B-filters and flavones are particularly effective as UV-A-filters, and the recognition that a particularly advantageous composition of flavanones and flavones exists, where said composition of flavonoids has an absorbency profile in terms of UV-radiation at specific wavelengths, which profile matches the degradation profile of human skin cell DNA, in terms of the composition having the most intense absorbency at the wavelengths where the DNA is most vulnerable.
It has thus for the first time been realized that by matching the profile of human skin cell DNA degradation as a function of UV-wavelengths with a substantially inverse absorption profile, it is possible to exactly filter out the most damaging wavelengths and at the same time allow the skin to tan.
It has furthermore surprisingly been found that this criterion is met by a composition comprising at least one flavanone and at least one flavone, in which composition the flavanone part preferably represents about 75-98% of the flavonoids UV-absorbency in water at 282 nm, and the flavone part preferably represents about 2-25% of the flavonoids UV-absorbency in water at 282 nm.
The term “flavonoids UV-absorbency” designates the total amount of UV-absorbency caused by the flavonoids in the composition.
Preferably the flavanones account for 78-90% of the absorbency and the flavones account for 2-10% of the flavonoids absorbency in water at 282 nm, and more preferably the flavanones account for 80-85% of the absorbency and the flavones account for 3-5% of the flavonoids absorbency in water at 282 nm.
The further 10-17% absorbency may be provided by the same and/or other substances, e.g., carotenoids; however, this further absorbency is preferably provided substantially by other flavonoids, and even more preferably substantially by flavanones, flavanoles and/or flavones.
According to a preferred embodiment of the composition according to the invention the composition comprises at least one flavanone and at least one flavone, where said flavanone(s) accounts for 75-98% of the flavonoids absorbency, and where said flavone(s) accounts for 2-25% of the flavonoids UV-absorbency at 282 nm in an aqueous solution of the composition.
This particularly advantageous ratio between flavanone and flavone is obtained when the respective absorbency at 282 nm for flavanone and flavone is as disclosed above.
It is furthermore, preferable if the ratio between flavanones and flavones in dry weight (solids content) is around between 50:1 to 2:1, more preferable around 30:1 to 5:1 and even more preferable around 25:1 to 10:1, and in particular around 20:1.
It has even further been recognized that the above disclosed objective may be accomplished by a composition of flavanoids and particularly defined as comprising at least one flavanone and at least one flavone, which composition is characterized in that the flavonoids have a UV-absorption profile
Dees Jose′ G.
Dykema Gossett PLLC
Flavone Sunproducts A/S
Lamm Marina
LandOfFree
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