The mutagenic and antimutagenic effects of the traditional phytoestrogen-rich herbs, Pueraria mirifica and Pueraria lobata

Pueraria mirifica is a Thai phytoestrogen-rich herb traditionally used for the treatment of menopausal symptoms. Pueraria lobata is also a phytoestrogen-rich herb traditionally used in Japan, Korea and China for the treatment of hypertension and alcoholism. We evaluated the mutagenic and antimutagenic activity of the two plant extracts using the Ames test preincubation method plus or minus the rat liver mixture S9 for metabolic activation using Salmonella typhimurium strains TA98 and TA100 as indicator strains. The cytotoxicity of the two extracts to the two S. typhimurium indicators was evaluated before the mutagenic and antimutagenic tests. Both extracts at a final concentration of 2.5, 5, 10, or 20 mg/plate exhibited only mild cytotoxic effects. The plant extracts at the concentrations of 2.5, 5 and 10 mg/plate in the presence and absence of the S9 mixture were negative in the mutagenic Ames test. In contrast, both extracts were positive in the antimutagenic Ames test towards either one or both of the tested mutagens 2-(2-furyl)-3-(5-nitro-2-furyl)-acrylamide and benzo(a)pyrene. The absence of mutagenic and the presence of anti-mutagenic activities of the two plant extracts were confirmed in rec-assays and further supported by a micronucleus test where both plant extracts at doses up to 300 mg/kg body weight (equivalent to 16 g/kg body weight plant tuberous powder) failed to exhibit significant micronucleus formation in rats. The tests confirmed the non-mutagenic but reasonably antimutagenic activities of the two plant extracts, supporting their current use as safe dietary supplements and cosmetics.

Retroviral reverse transcriptase inhibitory activity in Thai herbs and spices: screening with Moloney murine leukemia viral enzyme.

Fifty-seven Thai herbs and spices were examined for their retroviral reverse transcriptase inhibitory activity. All herbs and spices were extracted with hot-water and methanol. Reverse transcriptase inhibitory activity of the extracts was determined by using Moloney Murine Leukemia Virus reverse transcriptase (M-MuLV-RT) reacted with 3H-dTTP and radioactivity measured with a scintillation counter. Eighty-one per cent (46/57) of hot-water extracts and 54% (31/57) of methanol extracts showed inhibitory activities. At a concentration of 125 micrograms/ml, 13% (6/46) of hot-water extracts, namely Eugenia caryophyllus Bullock et Harrison, Phyllanthus urinaria Linn., Terminalia belerica Roxb., Nelumbo nucifera Gaertn., Psidium guajava Linn. and Lawsonia inermis Linn., had a relative inhibitory ratio (IR) over 50%. They showed ratios of 100%, 91%, 75%, 74%, 61% and 60%, respectively. For methanol extracts, only 10% (3/31) had IR values over 50%. They were T. belerica, E. caryophyllus and N. nucifera which exhibited IR values of 83%, 54% and 54%, respectively.