White Kwao Krua (Pueraria mirifica)

White Kwao Krua (Pueraria mirifica)

Pueraria mirifica is Thailand’s endemic species found mainly in the northern and western part of Thailand and has local name as “White Kwao Krua”. The Thai vine herbal plant is grown in association with the moderate-size trees ranking from timber wood to bamboo in the deciduous rain forest. White Kwao Krua (Pueraria Mirifica) has long been used in Thailand in folk medicine and medicinal purposes. The enlarge underground tuber accumulate “phytoestrogens” comprising isoflavone. The compounds that make Pueraria mirifica different from any other phytoestrogen- containing plants in the Family Leguminosae are Miroestrol and Deoxymiroestrol, which possess highest estrogenic activity among the known phytoestrogens due to structural similarity to estradiol. Miroestrol was actually the first compound isolated from this plant by a group of German chemists in 1940, but the plant had been mistakenly reported then as Butea superba. It was later on classified as a new plant called Pueraria mirifica Airy Shaw et Suvatabhandu. The isolation and identification of deoxymiroestrol from the root of Pueraria mirifica has just been reported in the February 2000 issue of the Journal of Natural Products. The authors proposed that since deoxymiroestrol is easily oxidized to miroestrol, deoxymiroestrol, not the previously reported miroestrol, is more likely to be the actual chemical constituent of Pueraria mirifica. However, it is very likely that the two phytoestrogens coexist in the root of this plant. AS shown below, the chemical structures of the two compounds are very similar to that of estradiol, the main human estrogen.

In addition to miroestrol and deoxymiroestrol, Pueraria mirifica also contains other chemicals that belong to isoflavone and coumestran groups of phytoestrogens, e.g., Genistein, Daidzein, Daidzin, Genistin, and Coumestrol that are usually found in soybeans. (Table). However, the estrogenic activity of Miroestrol and Deoxymiroestrol is much more potent than that of soy isoflavones.

Table : Chromene, Isoflavonoid and coumestran derivatives in Pueraria mirifica
Chromene