Pueraria mirifica Airy Shaw & Suvatabandhu is an indigenous herb of Thailand, known in Thai as “Kwao Kreu” or “Kwao Kreu Kao” (White Kwao Kreu), It belongs to the Family Leguminosae, subfamily Papilionoideae or the soy, bean & pea subfamily. The plants are commonly found in abundant in the forests in the north, the west and the northeast of Thailand at the altitude of 300-800 meters above sea level. Active principles in this plant are found in the tuberous root, which looks like a chain of round-shaped bulbs of various sizes connected to the next one via small root throughout the entire length of the root. The shape and size of the tuberous root are diverse depending on the environment in which it exists.
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 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.
Health benefit of phytoestrogens is at least two folds. Firstly, as stated earlier, Pueraria mirifica contains various kinds of phytoestrogens, e.g., miroestrol, deoxymiroestrol, genistein, daidzein, daidzin, genistin, coumestrol, etc. These phytoestrogens can bind to the estrogen receptors like estrogen does with different degrees of affinity giving different estrogenic potency. When Pueraria is taken, its phytoestrogens would go around the body through blood circulation and bind estrogen receptors present in various organs. This would help restore normal function of the body once slow down due to the aging process. Hence, phytoestrogens from Pueraria mirifica can correct estrogen insufficiency in the body and relieve the post-menopausal symptoms.
Secondly, there is evidence to support that phytoestrogen consumption contributes to lower risks of cardiovascular disease and that phytoestrogens may even prevent cardiovascular-related diseases. In a study, it was proven that phytoestrogens in soybeans could decrease the level of LDL cholesterol and increase the level of HDL cholesterol in the blood; therefore, reducing the risk of cardiovascular diseases. Moreover, it was reported that subjects who consumed soy at least three times daily had a decrease in the levels of total cholesterol, LDL cholesterol and triglyceride.
The dietary supplement dose of Pueraria mirifica recommended by the physician for its estrogenic effect in this case is 100 mg per day.
When Pueraria mirifica is taken as a dietary supplement, its phytoestrogen constituents will naturally alleviate symptoms occurring as a result of the aging process and a deficiency in estrogen levels, e.g., sagging breasts, wrinkled skin, bone loss, gray hair, etc. These aging signs and symptoms will, to a certain extent, be reversed.
When applied topically to the skin, Pueraria mirifica will be beneficial to that respective part of the body. With regard to the safety and efficacy of dermal preparations of Pueraria mirifica extract, standard dermal toxicity tests were performed in various animal species as well as in humans, and no toxicity was observed. Moreover, the efficacy of breast cream was recently evaluated in a large group of human volunteers.
Medicinal Plant Research Institute,
Dept. of Medical Sciences,
Ministry of Public Health, Thailand.
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