the invention is predicated on the discovery that uv - damaged rna fragments , when applied to living skin cells , increase the survival rate of the treated cells , compared with untreated cells , when the cells are subsequently exposed to uv radiation . in particular , it has been noted that the damaged rna generated from treatment of whole rna with uv radiation offers treated cells considerable protection from the cytotoxic effects of uvb radiation . the level of protection provided is greater than that provided by unirradiated rna . the rna used in the invention can be from any source and can be of any type . for example , it may be obtained from plant , animal , or microbial sources , and may be messenger rna ( mrna ), transfer rna ( trna ), mitochondrial rna ( mtrna ), viral rna , or synthetic rna . in a preferred embodiment , whole rna is irradiated with uvc ( wavelength of about 254 nm ) for a period of at least about 3 minutes , and preferably for at least 5 minutes . other uv wavelengths can also be used in irradiating the rna , but the dosage of will be higher . in a particularly preferred embodiment , the rna employed is substantially pure , i . e ., at least about 90 % free of non - rna material . the uv treatment results in a fragmentation of the rna . fragments prepared as described above were applied to plated epidermal skin cells at an amount of about 1 μ / ml , with unirradiated rna used as a control , and then the plates exposed to uvb radiation at a level of from 0 to 75 mj at 15 mj intervals . after an overnight incubation , the cells treated with the irradiated rna were found to have protected the skin cells from the damaging effects of uv radiation . although unirradiated rna also provide some apparent measure of protection , the protection provided by the irradiated rna is significantly higher . the fragments of the present invention can be incorporated into a variety of cosmetic or pharmaceutical products . for example , fragments can be added as a sunscreen component to makeup compositions , such as lipsticks , eyeshadows , foundations , or any other type of composition intended to be worn on the skin outdoors , e . g ., a moisturizer or lip balm , where uv protection is desirable . the fragments are also useful as an active component of sunscreen compositions . the fragments are water soluble , and can be routinely incorporated into the formulation of interest in any manner known in the art . in a preferred embodiment , the fragments , when used in purified form , are added in an amount of from about 0 . 001 - 5 %, preferably about 0 . 5 - 3 %, by weight of the total composition . the fragments of the invention can also be used in combination with other sun protection materials . thus , in another embodiment , the fragments are combined with one or more other sunscreens of any type . the second sunscreen may be of the physical barrier type , e . g ., titanium dioxide or zinc oxide , or the chemical type , e . g ., benzophenones ; para - amino benzoic acid ( paba ) and its derivative ; phenyl or homomenthyl salicylate ; or cinnamates . the combination is useful in any situation in which the fragments alone could be used , e . g ., in a makeup formulation , a sunscreen formulation or self - tanning formulation . the additional sunscreen can be incorporated into the formulation in amount determined in accordance with its usual usage . in a further embodiment , the fragments are also combined with antioxidants or free - radical scavengers , which provide supplementary protection against uv - induced skin damage . examples of such materials include vitamin e and derivatives thereof , vitamin c and derivatives thereof , green tea extract , proanthocyanidins , β - carotene and the like . in an additional embodiment , the rna fragments are also useful in prevention of photoaging . as noted above , repeated and / or prolonged exposure to the sun &# 39 ; s uv radiation contributes substantially to premature decline in the quality and quantity of elastin and collagen in the skin . these changes are manifested externally by typical signs of aging , such as deep lines and wrinkles , loss of elasticity , skin dryness and unevenness , and increased frequency of blotches or pigmented spots . the uv - protection provided by the fragments of the invention can also provide the desired protection against photoaging . thus , in addition to the use as a sunscreen in the products noted above , the fragments alone can be used to prevent photoaging when used in a variety of skin products , such as those described above . in this regard , the irradiated fragments can also be combined with other anti - aging or skin - enhancing agents . for this purpose , the fragments can be combined with one or more of the following products : alpha - or beta - hydroxy acids , such as lactic acid , glycolic acid , citric acid , alpha - hydroxyoctanoic acid , alpha - hydroxydecanoic acid , alpha - hydroxylauric acid , tartaric acid , glucouronic acid , galactouronic acid , alpha - hydroxybutyric acid , alpha - hydroxyisobutyric acid , malic acid , mandelic acid , pyruvic acid , and tartronic acid , and salicylic acid ; retinoids , such as retinol , retinyl acetate , retinyl palmitate , retinyl butyrate , retinyl oleate , retinyl linoleate , and retinoic acid ; dhea and derivatives thereof . twenty micrograms of messenger rna ( mrna ) purchased from sigma is solubilized in one ml of pbs . the solubilized rna is split into two 0 . 5 ml aliquots , each of which is placed into a 35 mm petri dish . one aliquot is irradiated with uvc at 254 nm for a period of five minutes , while the other sample remains unexposed to uv radiation . each sample is then further diluted by adjusting the volume to 10 ml in 10 % dmem , to yield a final concentration of 1 μ / ml . the stock solutions are then added either neat , or are further diluted to yield final concentrations of 0 . 1 , 0 . 5 or 1 μg / ml per ml . hacat skin cells ( transformed human keratinocytes ) are seeded into two 96 well plates , and allowed to reach approximately 75 % confluence prior to treatment . the prepared rna solutions are added to individual wells , and incubated overnight , humidified , at 37 ° c ., and 5 % carbon dioxide . plates are then rinsed three times with 180 μl pbs , and are irrigated with 100 μl pbs during irradiation . plates are irradiated with uvb , from 0 to 75 mj / cm 2 at 15 mj intervals . following irradiation , pbs is aspirated , and the mrna solution is added as described above . after an overnight incubation at 37 ° c ., plates are assayed for cell viability using the neutral red dye uptake assay . tables 1a and 2a show the results obtained using unirradiated ( 1 ) and irradiated ( 2 ) mrna as protectant , the results being expressed as percentage survival after irradiation . tables 1b and 2b shows the percentage change in survival rate for each treatment relative to the unirradiated control . table 1a______________________________________averageabsorbancemj uvb 0 15 30 45 60 75______________________________________control 0 . 495 0 . 485 0 . 448 0 . 391 0 . 315 0 . 262 . 1 μg / ml 0 . 573 0 . 524 0 . 483 0 . 412 0 . 352 0 . 287 . 5 μg / ml 0 . 575 0 . 509 0 . 490 0 . 435 0 . 380 0 . 2931 μg / ml 0 . 598 0 . 549 0 . 509 0 . 441 0 . 359 0 . 292______________________________________ table 1b______________________________________ % changemj uvb 0 15 30 45 60 75______________________________________control . 1 μg / ml 15 . 6 8 . 0 7 . 6 5 . 4 11 . 7 9 . 8 . 5 μg / ml 16 . 1 4 . 9 9 . 3 11 . 3 20 . 4 12 . 11 μg / ml 20 . 6 13 . 2 13 . 5 12 . 7 14 . 0 11 . 6______________________________________ table 2a______________________________________averageabsorbancemj uvb 0 15 30 45 60 75______________________________________control 0 . 413 0 . 353 0 . 358 0 . 273 0 . 238 0 . 238 . 1 μg / ml 0 . 473 0 . 408 0 . 344 0 . 304 0 . 301 0 . 268 . 5 μg / ml 0 . 467 0 . 480 0 . 456 0 . 396 0 . 379 0 . 2601 μg / ml 0 . 468 0 . 444 0 . 511 0 . 398 0 . 355 0 . 301______________________________________ table 2b______________________________________ % changemj uvb 0 15 30 45 60 75______________________________________control . 1 μg / ml 14 . 7 15 . 5 - 4 . 0 11 . 0 26 . 7 12 . 9 . 5 μg / ml 13 . 2 35 . 9 27 . 4 44 . 9 59 . 5 9 . 41 μg / ml 13 . 5 25 . 5 42 . 6 45 . 4 49 . 1 26 . 8______________________________________ these results show a significant difference in survival rate of the cells treated with irradiated rna fragments as compared with the cells treated only with unirradiated rna , and therefore , demonstrate the protective effect of the irradiated rna fragments . the following is an example of a formulation containing rna fragments of the invention : ______________________________________material weight % ______________________________________stearic acid 2 . 4glyceryl monostearate 2 . 2butyl paraben 0 . 1mineral oil / lanolin alcohol ( amerchol ) 9 . 5petrolatum / lanolin alcohol 2 . 0sesame oil 4 . 3propyl paraben 0 . 1deionized water qstriethanolamine 99 % 0 . 82methyl paraben 0 . 3trisodium edta 0 . 1propylene glycol 4 . 3purified mrna 0 . 001______________________________________
the present invention relates to a protection - effective amount of uv - damaged rna fragments , in combination with a cosmetically or pharmaceutically acceptable carrier . the compositions are useful in the prevention of skin damage to uv radiation and in preventing photoaging .