Method of filtering UV- light

Details Method of filtering UV- light Method of filtering UV- light

2001-06-25

2003-09-09

Criares, Theodore J. (Department: 1617)

Drug, bio-affecting and body treating compositions

Preparations characterized by special physical form

Cosmetic, antiperspirant, dentifrice

C514S778000, C516S105000

Reexamination Certificate

active

06616935

ABSTRACT:

This is the U.S. national phase of International Application No. PCT/EP99/09292 filed Nov. 30, 1999, the entire disclosure of which is incorporated herein by reference.
The present invention relates to the use of water-insoluble linear poly-&agr;-glucan as UV filter, and to a sun protection product comprising water-insoluble linear poly-&agr;-glucan which has been produced biotechnologically.
Known UV filters are e.g. pigments, such as titanium dioxide and zinc oxide as such or in the form of “micronized particles”.
From a cosmetics viewpoint, these pigments have the disadvantage that they whiten, i.e. make the skin appear white in color.
As a compromise for reducing the whitening to a tolerable degree and nevertheless achieving an acceptable UV protection, these pigments are usually used in sun protection products with a comparatively small particle size between 10 and 100 nm (A. Schrader, M. Rohr “Auffalligkeiten bei der Entwicklung und Prüfung von mikropigmenthaltigen Sonnenschutzformulierungen” [Unusual features in the development and testing of sun protection formulations containing micropigments] SÖFW Journal, 124, pages 478-487, 8/98).
In addition, titanium dioxide is to be viewed critically from a health viewpoint. In a study using titanium dioxide which had been extracted from sun protection products, it was observed upon irradiation with sunlight that titanium dioxide is able to catalyze photooxidation and damages bacterial DNA (CTFA/TRN Volume 12, No. 3, page 5 (1998) with reference to FEBS Letters, 418, 87-90, 1997).
A light-protecting action is also known for individual polysaccharides. For example, a light-protecting action has been described for poly-&bgr;-1,3-glucans (H. Eggensperger, M. Wilker, “Multiaktiv wirksame Polysaccharide Teil I-Pilzextrakte und Teil II-Pflanzliche Polysaccharide” [Multiactive polysaccharides part I-fungus extracts and part II-vegetable polysaccharides] in SÖFW Journal, 123, August 97, pages 542-546 and 12/97, pages 838-842). Poly-&bgr;-1,3-glucans which can be obtained from yeasts have a linear structure with a small proportion of &bgr;-1,6 branching.
It has also been proposed to use glycogen (a highly branched poly-1,4-&agr;-glucan with branching in the 6-position) obtained biotechnologically or from marine molluscs for sun protection products (M. Pauly, G. Pauly “New Polysaccharides Interest in Care Cosmetology” IN-COSMETICS 1997, Conference Proceedings, pages 417-444, Verlag fur chemische Industrie, H. Ziolkowsky GmbH, 1998).
EP-B-0 487 000 proposes the use of a cosmetic composition in the form of an emulsion having 15 to 40% by weight of an enzymatically debranched starch in sun protection products, where the enzymatically degraded starch is a linear poly-1,4-&agr;-glucan having 15 to 65 anhydroglucose units. However, there is no reference to a potential light protection action of the enzymatically debranched starch used therein; instead, it is used as an emulsifying auxiliary.
In view of the risks of intensive UV exposure, there is a growing need for suitable UV filters, preferably those which can reflect UV radiation, which not only offer reliable protection, but also do not impair the external appearance and are thus also suitable for daily use.
Surprisingly, it has been found that water-insoluble linear poly-&agr;-glucan has a very good UV protective function, and upon application appears transparent and does not whiten.
The present invention thus relates to the use of water-insoluble linear poly-&agr;-glucan as UV filter having an action which protects against UV radiation.
In a particularly preferred embodiment, the present invention relates to a sun protection product which comprises, as UV filter, water-insoluble linear poly-&agr;-glucan which has been produced biotechnologically, in particular biocatalytically.
In principle, the water-insoluble linear poly-&agr;-glucan can be added to any cosmetic or medicinal preparation for which a UV protecting action is desired. In particular, it is suitable for use in decorative cosmetics in order at the same time to impart to these a UV protecting action and to prevent, for example, skin aging as a result of intensive daily solar irradiation.
A preferred field of application is also sun protection products. The invention is described in more detail below using sun protection products as an example. However, it goes without saying that these statements are not limited to sun protection products, but can be applied directly to other fields of application for which UV protection is desired, such as the above-mentioned cosmetics.
Sun protection products containing water-insoluble linear poly-&agr;-glucan prepared according to the invention can ensure excellent UV protection and appear transparent even when the concentrations of poly-&agr;-glucan are high.
For the sun protection products or cosmetics prepared according to the invention by adding water-insoluble linear poly-&agr;-glucans as UV filters, recourse may be made to the formulations and additives customary for such products. Particularly preferred bases for formulations are emulsions, such as, for example, W/O or O/W emulsions, aqueous or fat-containing gels, hydrogels, oils, emulsifier-free emulsions, wax-oil bases etc.
Examples of application forms are creams, compact creams, lotions, milks, masks, sprays, fluids, powders, ointments, ointment bases etc.
The sun protection products or cosmetics prepared according to the invention can, in addition to the water-insoluble linear poly-&agr;-glucan, also comprise further, known UV filters.
The proportion of poly-&agr;-glucan depends on the base used and is usually from about 0.5 to about 20% by weight, preferably about 2 to about 15% by weight, based on the total weight of the product. For many applications, an amount of about 10% by weight or less often suffices.
An amount of less than 0.5% by weight is of no importance for UV protection. If required, an amount greater than 20% by weight can also be used, for example amounts up to 70% by weight are incorporated for “sun protection cream compacts”.
It goes without saying that the amount depends heavily on the composition of the respective product. If the product comprises further UV filters or if the base of the product is colored or pigmented per se, such as, for example, pigmented O/W or W/O emulsions, such that the UV permeability is reduced from the outset, smaller amounts of poly-&agr;-glucan may be sufficient. For UV-permeable bases, e.g. transparent bases, such as nonpigmented emulsions, gels or oils, larger amounts of poly-&agr;-glucan are advantageously added.
The required amount can, however, be determined directly from case to case by a person skilled in the art using a few routine experiments.
For the purposes of the present invention, water-insoluble linear poly-&agr;-glucans are polysaccharides built up from glucans as monomeric building blocks such that the individual building blocks are always linked together in the same way. Each basic unit or building block defined in this way has exactly two linkages, each to one other monomer. The only exceptions to this are the two base units which form the start and the end of the polysaccharide. These have only one linkage to a further monomer and form the end-groups of the linear polyglucan.
If the base unit has three or more linkages, then this is referred to as branching. In this context, the number of hydroxyl groups per 100 base units which are not involved in constructing the linear polymer backbone and form the branches gives the “degree of branching”.
According to the invention, the linear water-insoluble poly-&agr;-glucans have a degree of branching of at most 8%, i.e. they have a maximum of 8 branches and 100 base units. The degree of branching is preferably less than 4% and in particular at most 2.5%.
Particular preference is given to poly-&agr;-glucans whose degree of branching in the 6-position is less than 4%, preferably at most 2% and in particular at most 0.5%, and is preferably in each case at most 2% and in particular 1% in the other posi

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