Cancer chemoprevention of chemically induced tumours by
Picroliv, an
iridoid glycoside mixture purified from Picrorhiza kurroa, was studied on
20-methylcholanthrene (20-MC)-induced
sarcoma model and 7,12-dimethylbenz[a]
anthracene (DMBA)-initiated
papilloma formation in BALB/c mice. Administration of
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 animals 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 exhibited anti-tumour-promoting activity on a two-stage
carcinogenesis test on mouse skin using DMBA as an initiator and
croton oil as a promoter. Topical application of
Picroliv (1 and 5 mg/mouse) 30 minutes prior to that of
croton oil application resulted in a 50 and 60% reduction in the number of animals that developed
papillomas, and 48 and 64% reduction in the number of
papillomas per mouse. There was also a delay in the onset of first skin tumour in the group of animals treated with
Picroliv.
Oral administration of
Picroliv (150 mg/kg, p.o.) prior to DMBA application delayed the onset of
papillomas and the percent of mice (60%) with tumours indicates that
Picroliv inhibited the tumour initiation induced by DMBA.
Picroliv administration was also found to increase the life span of transplanted Dalton's
Lymphoma Ascites (DLA) and Ehrlich
Ascites Carcinoma (EAC) harboring mice and reduced the volume of transplanted solid tumours.