Inhibition of Dimethylbenz(a)anthracene (DMBA) - Croton Oil-Induced Mouse Skin Tumorigenesis by Gmelina arborea with Potential Anti-Inflammatory Activity

In traditional Indian medicine, the plant Gmelina arborea Linn. (GA) is described to have the ability to relieve edema. The present study evaluates the anticancer property of GA stem bark against 7,12-dimethylbenz(a) anthracene (DMBA)-croton oil-induced skin tumorigenesis along with the evaluation of anti-inflammatory activity. The observed inhibition of inflammation in carrageenan-induced (41.8%) and formalin-induced (34.07%) models may be due to inhibition of prostaglandins (PGs). Skin papilloma was induced by a single topical application of DMBA (470 nmol/200 mu L acetone), followed by repeated application of croton oil (1% in 200 mu L acetone). Low-concentration GA (GALC; 5% in 200 mu L distilled water) and high-concentration GA (GAHC; 10% in 200 mu L distilled water) were applied topically 30 min before croton oil application. The GALC and GAHC groups showed 85.7% and 57.14% tumor incidence, respectively. The number of papillomas per mouse was observed to be significantly (p <= 0.01) reduced in the treated groups. The onset of papilloma development was delayed considerably from 6 (control) to 12 wk (GAHC). Thus, results from the study give insights into the anticancer efficacy of Gmelina arborea, which may be due to prevention of inflammation-mediated tumor promotion by inhibiting PGs.