Modulatory potential of clocimum oil mouse skin papillomagenesis and the xenobiotic detoxication system

The present study was designed to elucidate the mechanistic inhibitory effi cacy of clocimum (an eugenol rich variety of Ocimum gratissimum; Labiatae) oil on murine skin papillomagensis. Topical application of clocimum oil (50 mu l/animal/day) during peri-initiation stage (1 week before and 2 weeks a fter initiation) of 7,12-dimelhylbenz[a]anthracene (DIMBA)-induced papillom agenesis and/or during the tumour promotion stage reduced (P < 0.05) the (i ) tumour burden to 5.00, 4.41 and 4.50 (positive control value 5.27); (ii) cumulative number of papillomas to 85, 75 and 72 (positive control value : 95); and (iii) percent incidence of mice bearing papillomas to 94, 89 and 8 8, respectively (positive control value 94). Significant (P < 0.01) elevati on in the hepatic levels of glutathione S-transferase (GST), sulfhydryl (-S H) and cytochrome b(5) (Cyt. b(5)) was observed by the respective topical t reatment of clocimum oil. Even in the skin tissue of the mouse, the topical treatment of clocimum oil enhanced (P < 0.05) the -SH content. The results suggest the modest chemopreventive potential of clocimum oil against the m urine skin papillomagenesis, and such effects may be partly due to the modu lated xenobiotic detoxication system enzymes. (C) 1999 Elsevier Science Ltd . All rights reserved.