Background: Plants are the source of important products with nutritional and therapeutic value. Topical or oral administration of some plant extracts has been shown to reduce photodamage. Cacao bean and cola nut are popular edible plants that contain polyphenols and xanthine derivatives. These plant extracts possess protective effects against UV-induced erythema when taken orally, and an H(2)O(2)-scavenging effect.
Methods: Plant extracts containing xanthine derivatives and three xanthine derivatives were topically applied to the dorsal skin of hairless mice, and the mice were exposed to a resemblance of solar ultraviolet irradiation at a dose of 13.0 J/cm(2) (UVA) for 15 weeks, five times a week on weekdays. After the final irradiation, histological, and analytical studies were performed.
Results: Topical application of plant extracts (cacao beans, cola nuts) and caffeine, theobromine, and theophylline markedly prevented photodamage including wrinkle formation and histological alterations. A significant increase in total hydroxyproline content caused by UV irradiation was observed. In contrast, topical application of plant extracts and xanthine derivatives reduced total hydroxyproline and pepsin-resistant hydroxyproline content in comparison with that of the control (vehicle, UV-irradiation group). Moreover, naphthol AS-D chloroacetate esterase staining and diaminobenzidine staining suggested that leukocytes including neutrophils increased in the UV-exposed skin. In contrast, weak staining was observed in skin treated with xanthine derivatives.
Conclusion: Topical application of plant extracts and xanthine derivatives suppressed wrinkle formation, dermal connective alteration, and collagen accumulation. It is suggested that xanthine derivatives prevented neutrophil infiltration caused by UV-irradiation.