lnhibition of croton oil-induced inflammatory and tumor promoting activity in mice skin by henna (Lawsonia inermis)

Henna (Lawsonia inermis) inhibited inflammatory responses triggered by croton oil in mice ears and skin. Topical application of 0.5 or 1 mg henna extract (HE) to mice ears prior to application of 0.8 mg croton oil inhibited edema significantly (P < 0.02). The average weight of inflammated ear punches decreased by 64 and 87 %. Application of HE (5 or 10 mg) reduced, significantly (P < 0.05), Hyperplasia and leukocytes infiltration induced in the skin by application of croton oil (8 mg). Since tumor promotion is closely related to inflammation, the antitumor promoting activity of HE was investigated in two-stage model of skin carcinogenesis in mice. Twice weekly application of 5 and 10 mg HE prior to application of 8 mg croton oil on the shaved back skin prevented 40 and 50 % papilloma formation, respectively. HE, also, reduced, significantly (P < 0.001), the average number of papillomas per mouse and delayed their appearance. The anti-tumor promoting activity of henna could be ascribed to its anti-inflammatory potential.