Quantitative estrogenic activity of white kwao krua Pueraria mitifica from various parts of Thailand in ovariectomized rats

To quantify the estrogenic activity of White Kwao Krua (WKK: Pueraria mirifica) collected from 25 provinces throughout Thailand, the vaginal cytology assay in ovariectomized rats was used as an indicator. Rats were fed with WKK at the doses of 10, 100, 1,000 mg/kgBW/day suspended in 0.7 ml of distilled water, and compared to rats fed with 0.7 ml distilled water only and injected with a single dose of 17β- estradiol. The treatment schedule was separated into 3 periods: pre-treatment, treatment and post¬-treatment. The duration for each period was 14 days. From this study, it was found that the first day of appearance of cornified cells after 100 mg/kgBW/day of WKK treatment and the durations of occurrence of cornified cell during 1,000 mg/kgBW/dayof WKK treatment could be used as an indicator to rank the estrogenic activity of WKK. The estrogenic activity of WKK was a dose dependent. WKK at 10 mg/kgBW/day could not stimulate the vaginal cell and the vaginal cornification in rats treated with 1,000 mg/kgBW/day of WKK was occurred faster and longer than that of rats treated with 100 mg/kgBW/day. Changes of vaginal cells after WKK treatment were agreed with the increase of uterus weight. It was found that WKK collected from Kanchanaburi was the most potent in term of induction of vaginal cornification. The proliferation of vaginal epithelium was faster (4 days after 100 mg/kgBW/day of WKK treatment) and longest (for 18 days during 1,000 mg/kgBW/day of WKK treatment). The estrogenic activity of WKK collected from Kanchanaburi at dosage of 1,000 mg/kgBW/day was equated to that of 17β- estradiol at the dose of 200 µg /100gBW/day. When the estrogenic activity was related to the regions, WKK collected from the central part showed the highest estrogenic activity. The body weight of rats in the control group was significantly increased throughout the study period, however, the body weight gain was decreased in rats fed with WKK, in a dose-dependent manner. The histological examination of rats liver treated with 1,000 mg/kgBW/day of WKK showed no signs of abnormality, it may conclude that WKK collected from the 25 provinces has considerably safe for human use. This study should be a practical guide to search for plant materials or set up a plantation of P. mirifica with high estrogenic activity to serve the market demand.