Protective effect of Picroliv, the active constituent of Picrorhiza kurroa, against chemical carcinogenesis in mice

Cancer chemoprevention of chemically induced tumours by Picroliv, an iridoi d glycoside mixture purified from Picrorhiza kurroa, was studied on 20-meth ylcholan-threne (20-MC)-induced sarcoma model and 7,12-dimethylbenz[a]anthr acene (DMBA)-initiated papilloma formation in BALB/c mice. Administration o f Picroliv (100 and 200 mg/kg, p.o) inhibited the sarcoma development by 47 and 53% as estimated on day 200 after 20-MC administration. Control animal s started dying of tumour burden 76 days after 20-MC administration and all animals were dead by day 170, while 60 and 66% of the animals survived in the Picroliv treated group, 100 and 200 mg/kg, respectively. Picroliv exhib ited anti-tumour-promoting activity on a two-stage carcinogenesis test on m ouse skin using DMBA as an initiator and croton oil as a promoter. Topical application of Picroliv (I and 5 mg/mouse) 30 minutes prior to that of crot on oil application resulted in a 50 and 60% reduction in the number of anim als that developed papillomas, and 48 and 64% reduction in the number of pa pillomas per mouse. There was also a delay in the onset of first skin tumou r in the group of animals treated with Picroliv. Oral administration of Pic roliv (150 mg/kg, p.o.) prior to DMBA application delayed the onset of papi llomas and the percent of mice (60%) with tumours indicates that Picroliv i nhibited the tumour initiation induced by DMBA. Picroliv administration was also found to increase the life span of transplanted Dalton's Lymphoma Asc ites (DLA) and Ehrlich Ascites Carcinoma (EAC) harboring mice and reduced t he volume of transplanted solid tumours. (C) 2001 Wiley-Liss, Inc.