Scientific Name(s): Pueraria mirifica Airy Shaw et. Suvatabhandu.
Common Name(s): Kwao Keur, Kwao Krua, Kwao Kruea, White Kwao Krua
The plant species P. mirifica (pueraria) belongs to the Fabaceae, or bean, subfamily, and its tuberous roots contain several phytoestrogens.Manonai 2007 P. mirifica is a woody vine commonly found in forests throughout ThailandMalaivijitnond 2006 with 28 cultivars presently documented. The tuberous root varies in size depending on soil condition, but may weigh as much as 100 kg. The plant's palmate-type leaves are simple or ovate and contain 3 leaflets in 1 petiole. The blue-to-purple flowers are composed of 5 petals and bloom from February to March.
The plant species is rich in phytoestrogens, and postmenopausal women in Thailand have consumed it for more than 100 years citing its beneficial estrogen effects.Manonai 2008 In traditional Thai medicine, it is common to use P. mirifica as a skin moisturizer, to improve regrowth of hair, to improve body flexibility and sexual performance, and to firm and enlarge the breasts.Malaivijitnond 2006 Commercial products containing pueraria are continually introduced into the world marketSookvanichsilp 2008 and have become popular in Thailand, Korea, and Japan.Malaivijitnond 2006 Most commercial products are available as topical rejuvenating, antiaging, or skin-lightening creams or gels, as beauty soaps, or as capsules or tablets for increasing appetite, enlarging breasts, modulating hair growth or regrowth, and other rejuvenating purposes.Sookvanichsilp 2008, Malaivijitnond 2006, Chansakaow 2000, Liang 2000, Roufs 2007, Yagi 2007, Tehara 2006, Liu 2005, Konoike 2006, Ishiwatari 2003 Since 1999, domestic and global demand for the raw materials from P. mirifica roots or tubers has increased, resulting in intense harvesting of the plant from the forests of Thailand.Cherdshewasart 2007
Isoflavones, coumestans, and lignans are the 3 main classes of phytoestrogens. The tuberous roots of P. mirifica primarily contain the active component miroestrol and its derivative, deoxymiroestrol.Chansakaow 2000 The tuberous roots of P. mirifica also contain daidzin, daidzein, genistin, genistein, puerarinIngham 1986 mirificoumestan, kwakhurinIngham 1986, Tahara 1987 coumestrolIngham 1988 mirificin, and 2 steroids, estrone and estriol.Sookvanichsilp 2008, Ingham 1986, Ingham 1989, Chansakaow 2000 The manufacture and synthesis of miroestrol is documented.Corey 1993, Ishikawa 2006 Deoxymiroestrol was isolated and identified as the most active phytoestrogen of the plant.Cherdshewasart 2004, Sookvanichsilp 2008, Ishikawa 2001
Thin-layer chromatography analysis has documented varying amounts of phytoestrogens collected from P. mirifica in different locations in Thailand.Malaivijitnond 2006, Cherdshewasart 2007 One of the challenges of large-scale manufacturing of P. mirifica for drugs and cosmetics is resolving these variations in lots.
Uses and Pharmacology
Some of the isoflavonoids in P. mirifica had antioxidant activity similar to that of alpha tocopherol or vitamin E.Cherdshewasart 2008P. mirifica decreased neuronal cell death in a time- and dose-dependent manner against neurotoxic agents in an Alzheimer disease model in vitro.Sucontphunt 2007, Sawatsri 2004 Mechanism of action may be associated with an effect on synaptic density by inducing synaptophysin expression via estrogen receptor.Chindewa 2008
Spinasterol, an active cytotoxic component of P. mirifica, was active against certain gynecological cancer cell lines and activates estrogen receptors ER-alpha and ER-beta. The ethanol extract had antiproliferative effects on breast cancer cell lines MCF-7, ZR-75-1, MDA-MB-231, SK-BR-3, and Hs578T. Another component, known as PE-D, affected the growth in a dose-dependent and time-dependent manner on some breast cancer cell lines (MCF-7, MDAMB-231), and on the growth of ovarian (2774) and cervical cancer cells (HeLa).Baek 2003, Jeon 2005 The estrogenic effect of some components in P. mirifica has been compared with estradiol, a major estrogen in humans.Jeon 2005, Cherdshewasart 2008 The rank order of phytoestrogen potency is: deoxymiroestrol; miroestrol; 8-prenylnaringenin; coumestrol; genistein/equol; daidzein; resveratrol.Matsumura 2005P. mirifica also had an estrogenic effect on a human HepG2 hepatoma cell line that contained an estrogen receptor and a luciferase reporter gene; this evidence indicates that metabolic activation of P. mirifica promotes estrogenic activity.Lee 2002 Another study also documents that estrogenic activity may result from metabolic activation of liver enzymes.Cherdshewasart 2008
The proposed mechanism of action involves strong competitive binding of the plant's phytoestrogens to ER-alpha and/or synthesis suppressor of ER-alpha.Cherdshewasart 2007
Pretreatment of rats with P. mirifica (1,000 mg/kg body weight per day tuberous root powder) resulted in decreased virulence of rat mammary tumor development from 7,12-dimethylbenz(a)anthracene (7,12-DMBA). Histopathological analysis of the mammary tumor tissues revealed lower ER-alpha, ER-beta, and ER-alpha/ER-beta profile.Cherdshewasart 2007
Cognitive improvements were reported in ovariectomized rats administered P. mirifica extract and pure puerarin, with the researchers suggesting potential applications in cognitive decline due to ageing.Anukulthanakorn 2016
The active ingredients from the root of P. mirifica had lethal properties during various growth cycles against the yellow fever mosquito (Aedes aegypti) and other mosquito species with disease-spreading abilities.Lapcharoen 2005
In rabbits, P. mirifica improved endothelial function through a nitric oxide pathway, decreased contractile responses to norepinephrine, and increased responses to estradiol. The plant caused no changes in lipid profile or liver enzymes.Wattanapitayakul 2005 In male and female gonadectomized rats, P. mirifica had estrogen-like activity and affected accessory sex organs. It increased luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in both sexes.Malaivijitnond 2004 The mechanism of action involved direct stimulation of the accessory sex organs and suppression of the hypothalamic-pituitary-gonadal axis. Overall activity was more potent in female rats than in male rats. Studies in mice found that P. mirifica does not affect male fertility or the hypothalamus-pituitary-testis axis.Jaroenporn 2006 The testis, epididymis, and seminal vesicle all had normal histopathology in P. mirifica -treated male mice.
P. mirifica may greatly alter the length of menstrual cycles and suppress ovulation by reducing serum levels of gonadotropins. The length of the menstrual cycle increased in monkeys treated with P. mirifica 10 and 100 mg/day of root extract and disappeared completely in monkeys treated with root extract 1,000 mg/day. Serum FSH, LH, estradiol, progesterone, and immunoreactive-irinhibin were lower in a dose-dependent manner during treatment. During the posttreatment period, only monkeys treated with P. mirifica 10 and 100 mg/day of extract recovered from the changes in menstrual cycle length and hormone levels.Trisomboon 2005 Other studies document similar activity for the P. mirifica 1,000 mg/day dose of Trisomboon 2004 root extract and the direct correlation in dose with gonadotrophin levels.Trisomboon 2006
The plant had a dose-dependent estrogenic effect on rat vaginal cornification.Cherdshewasart 2007P. mirifica phytoestrogens at a dose of root extract 1,000 mg/day decreased serum parathyroid hormone and calcium levels in aged menopausal monkeys and, thus, may be beneficial in treating bone loss caused by estrogen deficiency.Trisomboon 2004P. mirifica had an estrogenic action in aged menopausal monkeys by changing the sexual skin area around the perineum to the base of the tail to a reddish pigmentation.Trisomboon 2006 FSH may be a candidate marker for the study of P. mirifica's estrogenic effects in female monkeys if changes in urinary hormones are used as an indicator.Trisomboon2007, Trisomboon 2007
In a 24-week randomized, double-blind, placebo-controlled trial of 51 postmenopausal women, oral P. mirifica exhibited estrogenicity on vaginal tissue, alleviated vaginal dryness symptoms and dyspareunia, improved signs of vaginal atrophy, and restored atrophic vaginal epithelium.Manonai 2007 In another clinical trial of 51 postmenopausal women 46 to 60 years of age, P. mirifica tuberous root had an estrogen-like effect on bone turnover rate at a dose of 20, 30, and 50 mg/day for a 24-week period.Manonai 2008 Phase 1 to 3 trials in Thailand compared the estrogenic effect of P. mirifica to conjugated equine estrogen in relieving climacteric symptoms in perimenopausal women.Lamlertkittikul 2004, Chandeying 2007
A small (n=52) clinical study evaluated oral P. mirifica at 25 and 50 mg over 6 months in relieving menopausal symptoms, and reported efficacy for both doses. The researchers suggest 1 mg of P. mirifica is equivalent to 0.52 to 0.75 mcg of ethinyl estradiol.Virojchaiwong 2011
Similar to findings in monkeys,Jaroenporn 2014 a randomized clinical study (n=82) reported P. mirifica gel to be effective in improving signs of vaginal atrophy and restoring vaginal epithelium at 6 and 12 weeks, but to a lesser extent than conjugated estrogen cream.Suwanvesh 2017
In small clinical trials, the administration of P. mirifica crude extract improved hot flushes, frustration, sleep disorder, skin dryness, high blood cholesterol, amenorrhea, and other menopause-related symptoms in women. There was no change in blood cells or liver and renal function.Hosoyama 2007, Muangman 2001
In sex-hormone–deficient male rats, treatment with P. mirifica root powder completely inhibited bone loss in long bones and axial bones. At higher doses, it increased bone density without affecting accessory sex organs.Urasopon 2007 In a similar study, P. mirifica completely inhibited bone loss in long bones and axial bones in estrogen-deficient female rats.Urasopon 2008 However, the highest dose of P. mirifica root powder (1,000 mg/kg body weight per day) caused an undesired adverse reaction of increased uterine weight.
In postmenopausal osteoporotic monkeys oral administration of P. mirifica improved both bone quality and quantity.Kittivanichkul 2016
Commercial products are available as topical creams, gels, and soaps, or in oral capsule and tablet dosage forms.Sookvanichsilp 2008, Malaivijitnond 2006, Chansakaow 2000, Liang 2000, Roufs 2007, Yagi 2007, Tehara 2006, Liu 2005, Konoike 2006, Ishiwatari 2003 Some clinical studies used 200 to 400 mg extract from root or tuber orally per day. Commercial manufacturers suggest a dosage of 250 mg of active ingredients from the root orally every morning and evening. For topical products, manufacturers suggest a twice-daily topical application to the breast area for 3 to 5 minutes until fully absorbed.
A small (n= 52) clinical study evaluated oral P. mirifica at 25 and 50 mg over 6 months in relieving menopausal symptoms, and reported efficacy for both doses. The researchers suggest 1 mg of P. mirifica is equivalent to 0.52 to 0.75 mcg of ethinyl estradiol.Virojchaiwong 2011
Pregnancy / Lactation
Avoid use during pregnancy and lactation because of the lack of clinical data and the plant's phytoestrogen activity.
Phytoestrogens have estrogen-like effects. Theoretically, drug interactions may occur with the following:
Corticosteroids (eg, prednisone)
May increase pharmacologic and toxicologic effects.
Hydantoins (eg, phenytoin)
May affect concentration of these medications.
Thyroid hormones (eg, levothyroxine)
May decrease serum free thyroxine concentrations.
Increased triglyceride levels may occur.Manonai 2008
Because of the estrogen-like effect of P. mirifica, use with caution in patients with asthma, diabetes mellitus, epilepsy, migraine, or systemic lupus erythematosus. Also use with caution in patients with abnormal triglyceridesManonai 2008 or hypercalcemia.Manonai 2008, Urasopon 2007, Urasopon 2008
High doses of P. mirifica caused general and genotoxicity in animals.Saenphet 2005 Rats treated with aqueous and ethanolic root extracts of P. mirifica had significantly lower body weight gain and lower packed red cell volume; the plant also had mutagenic activity.Sanchanta 2005 A root extract dosage of 100 mg/kg had adverse effects on mating efficiency and reproduction in female mice.Jaroenporn 2007 No estrogen hormone activities were found in egg and chicken meat tissue or rats.Tubcharoen 2003, Tubcharoen 2003 The median lethal dose for oral consumption of P. mirifica root powder in mice was 2,000 mg/kg body weight per day.Cherdshewasart 2003
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