IngredientsButea superba Roxb. is a creeping leguminous plant classified within the family Fabaceae (Leguminosae), primarily found in Thailand and Southeast Asia. The species epithet superba was assigned by the Scottish botanist William Roxburgh. Locally it is known as "Kwao Krua Daeng" (Red Kwao Krua) in Thai. The plant belongs to the same genus as Butea monosperma (flame of the forest), though it is a distinct species. The plant is also traditionally used in India, where it is called lataa-palaash.
It is a perennial, woody vine or climbing shrub that can grow up to 10 meters long, using other trees for support. The plant is characterised by its trifoliate leaves, bright orange-red flowers, and stout, twisted stems. The large, fleshy, tuberous root is the source of the active phytochemicals used in traditional remedies and modern supplements. Unlike many medicinal plants, this vining woody perennial can live for many years, with stems reaching 20 cm or more in diameter, growing from massive, spindle-shaped tubers that resemble yam roots.
The plant thrives in the deciduous forests of mainland Southeast Asia, extending across Thailand, Vietnam, India, and China. It is commonly found in Thai deciduous forests.
Butea superba is a vine that grows in India, China, Vietnam, and Thailand; the roots (tubers) are used as medicine. Modern commercial preparations include dried root powder in capsule form, standardized ethanolic or aqueous extracts (sometimes standardized to specific flavonoid content such as 4% butein), and topical liquid extracts. Traditional remedies involved decocting the roots into teas or tinctures, believed to invigorate energy and promote youthful stamina. Historically, it was brewed into tonics or decoctions aimed at improving sexual performance, enhancing stamina, and promoting general geriatric wellness.
Its underground tuberous roots have been used in Thai folklore medicines for over 100 years. Red Kwao Krua or Kwao Krua Dang herbs are a group of leguminous plants which have been used for centuries as traditional herbal medicines in Thailand. Butea superba is a Thai medicinal plant that has been used as a folk medicine to improve physical and mental conditions and to prevent impaired sexual performance in middle-aged or elderly males. One of the earliest documented references to the plant in a Thai-language medicinal text was recorded by Suntara in 1931, noting its use as a rejuvenating agent and to increase sexual performance in men. The tuberous roots of this plant have been used for centuries as a folk medicine not only to improve physical and mental conditions but also to prevent impaired sexual performance in middle-aged or elderly males.
In traditional Thai healthcare, Butea superba has been used to address male reproductive challenges, such as erectile dysfunction, declining potency, and age-related decline in vitality. Butea superba has been utilised as a rejuvenative tonic in traditional Thai and Southeast Asian practices for generations. Historically, texts describe its use as a "great stimulant" by warriors to boost physical strength and stamina, leading to its reputation as a general tonic for overall well-being.
Less common traditional uses include remedies for diarrhea, fever, and painful urination. Beyond its celebrated role in men's health, Butea superba has been utilised as a general tonic to improve overall well-being, support cardiovascular health, and boost physical endurance. Healers sometimes prescribed it for its anti-inflammatory and rejuvenating properties, recommending it to those recovering from illness or fatigue.
In Indian ethnomedicine (where it is known as lataa-palaash), traditional applications extended further. A spoonful of paste made from the root was given to women to facilitate easier childbirth. Moreover, the root was combined with other botanical ingredients like Nyctanthes and Woodfordia floribunda to create a paste applied to treat poisonous animal bites.
The Thai FDA has approved many traditional recipes that are comprised of B. superba as a major ingredient with limited claims for tonic purposes. One case report described hyperandrogenemia that occurred in a male who took capsules containing Butea superba tuber for several weeks. Consequently, dietary supplements that contain any parts of this plant are not permitted for human use by Korean authorities.
The tuberous root is the primary source of bioactive phytochemicals. The potential effects of Butea superba are attributed to phytochemicals concentrated in its tuberous roots. Researchers have identified several classes of active compounds, including flavonoids, flavonoid glycosides, and sterol compounds. Specific components include butrin, isobutrin, and phytosterols like β-sitosterol, campesterol, and stigmasterol.
A flavonoid (3,7,3′-trihydroxy-4′-methoxyflavone) and a flavonoid glycoside (3,3′-dihydroxy-4′-methoxyflavone-7-O-β-D-glucopyranoside) were isolated from the tuber root of Butea superba Roxb. The structures were determined on the basis of spectral analysis, including 2D-NMR techniques. These two compounds have been specifically implicated in phosphodiesterase-inhibitory activity (see Mechanisms of Action below).
A pterocarpan (3-hydroxy-9-methoxypterocarpan, medicarpin) and four isoflavones — 7-hydroxy-4′-methoxy-isoflavone (formononetin), 7,4′-dimethoxyisoflavone, 5,4′-dihydroxy-7-methoxy-isoflavone (prunetin), and 7-hydroxy-6,4′-dimethoxyisoflavone — were isolated from the tuber roots of Butea superba Roxb. Researchers have also isolated isoflavones such as daidzein and genistein from Butea superba.
The roots of B. superba contain flavonoids, tannins, alkaloids, glycosides, and phenols. A new bioactive flavonol glycoside was isolated from the stems: 3,5,7,3′,4′-pentahydroxy-8-methoxy-flavonol-3-O-β-D-xylopyranosyl(1→2)-α-L-rhamnopyranoside. Additionally, medicarpin isolated from the extracts of Butea superba Roxb. has been reported to improve bone resorption and osteoclastogenesis in preclinical studies.
Phytosterols including β-sitosterol, campesterol, and stigmasterol have been identified in the root. These sterols are structurally similar to cholesterol and are present throughout the Fabaceae family; their individual contribution to Butea superba's biological effects has not been fully characterised in dedicated studies.
The most extensively investigated biochemical mechanism relates to cyclic nucleotide phosphodiesterase (PDE) inhibition. A flavonoid and a flavonoid glycoside were isolated from the tuber root of Butea superba Roxb., with structures determined by spectral analysis including 2D-NMR techniques. These compounds showed higher inhibitory effects on cAMP phosphodiesterase than caffeine and theophylline. Inhibition of cAMP phosphodiesterase is directly relevant to corpus cavernosal vasodilation, as elevated cyclic nucleotide levels promote smooth muscle relaxation and blood flow.
Some studies suggest the extract may also act as a mild inhibitor of the enzyme cAMP phosphodiesterase, further promoting penile blood flow. The roots contain flavonoids, tannins, alkaloids, glycosides, and phenols; these phytochemicals, especially flavonol and flavonoid glycoside, isolated from Red Kwao Krua function as phytoandrogens, with similar effects as testosterone.
Orally administered Butea superba tubers have an androgenic effect on the reproductive organs of intact and ovariectomized rats, and exhibit anti-estrogenic activity on LH secretion in ovariectomized rats. The phytochemicals in Butea superba contain flavonoids that exhibit androgenic and antiestrogen effects, in contrast to the closely related Pueraria mirifica (White Kwao Krua), whose phytochemicals are predominantly phytoestrogenic isoflavonoids. No changes in serum testosterone, LH, and FSH levels were observed in any of the intact rats treated with BS, but a significant increase in seminal vesicle weight was observed only in the high-dose (250 mg/kg) group. Researchers concluded that B. superba needs endogenous testosterone to work synergistically to stimulate the accessory sex organs of intact animals.
The proposed mechanisms center on improving blood flow and influencing hormone function. Flavonoids are antioxidants that may support cardiovascular health and improve circulation by increasing nitric oxide production. This enhanced release promotes vasodilation (the widening of blood vessels), which is critical for healthy erectile function.
In the context of cognitive research, olfactory bulbectomy (OBX) in mice down-regulated phosphorylation of synaptic plasticity–related signalling proteins including NMDA receptor, AMPA receptor, calmodulin-dependent kinase II, and cyclic AMP-responsive element-binding protein. OBX also reduced choline acetyltransferase in the hippocampus. Butea superba extract and tacrine reversed these neurochemical alterations. Moreover, B. superba inhibited ex vivo activity of acetylcholinesterase in the brain.
One study evaluated the estrogenic and antiestrogenic activities of native and in vitro hepatic metabolized tuberous extracts of wild Butea superba collected from 23 out of the 76 provinces in Thailand by yeast estrogen screening (YES), using the human estrogen receptors hERα and hERβ. Six pure compounds isolated from B. superba were tested and exhibited a maximum relative potency compared to 17β-estradiol of 15.5% and 5.27% in the hERα and hERβ assays, respectively. This activity is markedly weaker than phytoestrogens found in Pueraria mirifica.
The primary and most-cited human clinical study is the randomized double-blind trial by Cherdshewasart and Nimsakul (2003), published in the Asian Journal of Andrology. The aim was to study the effect of Butea superba on erectile dysfunction (ED) in Thai males. A 3-month randomized double-blind clinical trial was carried out in volunteers with ED, aged 30 to approximately 70 years, to evaluate the therapeutic effect of the crude preparation of Butea superba tubers on ED. There was a significant upgrading in 4 of the 5 descriptive evaluations of the IIEF-5 questionnaire. Estimation of the sexual record indicated that 82.4% of the patients exhibited noticeable improvement. Haematology and blood chemistry analysis revealed no apparent change. The plant preparation appears to improve the erectile function in ED patients without apparent toxicity.
A second key study was published in BJU International by Cortés-González et al. (2009/2010). An open-label study was carried out among 32 men with organic ED to evaluate the IIEF-5 response to B. superba, a 'natural health' product (100 mg), compared to 50 mg of sildenafil. After a 1-week wash-out, responders to BS received either 100 mg starch or 100 mg of another batch of BS (double-blind). Of the patients in the BS group, 27 (84%) responded positively, compared with 26 (81%) in the sildenafil group. When assessing the score alone, 12 (38%) had a better score after taking BS, compared to seven (22%) after sildenafil, and eight (25%) had the same score. The results were surprising and could not be repeated in the double-blind part of the study, where no effect was confirmed for Butea superba. This failure to replicate in the double-blind arm substantially weakens the conclusions of that study.
A subsequent systematic review of botanical drugs for erectile dysfunction, published in Frontiers in Pharmacology (2023), assessed both studies critically. In two studies on B. superba, the result of one open-label study showed that B. superba did not improve ED over the sildenafil group. It is worth noting that in this study, 100 mg of B. superba extract was given 1–2 hours before each sexual encounter. However, in another study, B. superba was given with a larger dose regularly per day. In most studies, the experimental drug or placebo was given 1–3 times daily, rather than just before sexual intercourse. The reviewers also noted methodological concerns: researchers believed that a PDE5-inhibitor may have been blended in the B. superba capsule used in that trial. Furthermore, this study was not randomized, double-blind, or placebo-controlled. Only 33 patients aged 42–78 years took B. superba.
Evidence strength: Preliminary. Two small human studies, one with serious methodological concerns including possible product adulteration. No large-scale randomised placebo-controlled trials have been conducted.
Research by Mizuki et al. (2014), published in the Journal of Pharmacological Sciences, investigated cognitive and emotional deficits in olfactory bulbectomized (OBX) mice, an animal model of dementia and depression. This study investigated the effects of an alcoholic extract of Butea superba (BS) on cognitive deficits and depression-related behaviour using OBX mice. OBX mice were treated daily with BS (100 and 300 mg/kg, p.o.) or reference drugs, tacrine (2.5 mg/kg, i.p.) and imipramine (10 mg/kg, i.p.) from day 3 after OBX. BS and tacrine reversed neurochemical alterations, and moreover, BS inhibited ex vivo activity of acetylcholinesterase in the brain.
A 2021 study published in Evidence-Based Complementary and Alternative Medicine (PMC) examined scopolamine-induced cognitive impairment in aged male rats. The study aimed to investigate cognitive and memory dysfunction amelioration of B. superba ethanolic extract (BSE), a possible mechanism of action, and its toxicity. The results from the Y-maze test, novel object recognition test, and passive avoidance test exhibited that the administration of BSE at 50 mg/kg (BSL) and 200 mg/kg (BSH) could ameliorate scopolamine-induced cognitive impairment in all behavioural testing. Moreover, BSE could prevent the cognitive deficit in a dose-dependent manner in a passive avoidance test. Furthermore, BSE inhibited acetylcholinesterase's (AChE) ex vivo activity in the cerebral cortex and hippocampus. The same study found that BSE had free radical scavenging activities in DPPH and FRAP antioxidant assays. Furthermore, male rats treated with BSE at 200 mg/kg/day for two weeks could significantly increase serum testosterone compared with control.
Evidence strength: Preclinical only. All cognitive research has been conducted in rodent models. No human clinical trials on cognitive function have been reported.
A study published in the Journal of Ethnopharmacology (2014) examined the antidepressant-like effect of Butea superba in mice. Ethnopharmacologically, Butea superba is a Thai medicinal plant that has been used as a folk medicine to improve physical and mental conditions. Researchers had previously reported that the plant extract could improve cognitive deficits and depression-like behaviour in olfactory bulbectomized mice, an animal model of dementia and depression. This study examined the effect of BS on depression-like behaviour in mice subjected to unpredictable chronic mild stress (UCMS) to clarify the antidepressant-like activity of BS and its molecular mechanism. UCMS mice were administered BS daily (300 mg of dried herb weight/kg, p.o.) or a reference drug, imipramine (10 mg/kg, i.p.), 1 week after starting the UCMS procedure. The study found antidepressant-like activity linked to hippocampal neurogenesis and synaptic plasticity-related signalling.
Evidence strength: Preclinical only. All antidepressant research has been conducted in rodent models. No human clinical evidence exists in this area.
Research on long-term treatment of Butea superba on sperm motility and concentration was studied because Butea superba has been used to enhance sexual performance in men with unknown long-term effects on spermatozoa. This study aimed to investigate effects of chronic treatment of B. superba on sperm motility and concentration in rats and mice in correlation with testicular damage. Adult male rats and mice were orally administered distilled water or B. superba alcoholic extract (0.01, 0.1, or 1.0 mg/kg BW/day) for 6 months. The results showed that long-term treatment with B. superba extract significantly increased the sperm concentration and delayed the decreased motility with time.
In a study on male mice, the isoflavones daidzein and genistein (isolated from Butea superba) improved sperm number, motility, cholesterol, and testosterone levels.
Evidence strength: Preclinical only. No human trials have evaluated sperm parameters as a primary endpoint.
A flavonol glycoside isolated from the stems of Butea superba showed antimicrobial activity against plant pathogenic fungi including Trichoderma viride, Aspergillus fumigatus, A. niger, and gram-positive bacteria including Streptococcus pyogenes, Staphylococcus aureus, and Bacillus subtilis, as well as gram-negative bacteria Escherichia coli, Proteus vulgaris, Klebsiella pneumoniae, and Pseudomonas aeruginosa.
Evidence strength: In vitro only. No human trials exist for this application.
Formononetin and prunetin isolated from the tuber roots of Butea superba Roxb. showed moderate cytotoxic activity on KB cell lines with IC₅₀ values of 37.3 ± 2.5 μM and 71.1 ± 0.8 μM, and on BC cell lines with IC₅₀ values of 32.7 ± 1.5 μM and 47.3 ± 0.3 μM, respectively.
Evidence strength: In vitro only. No human or animal cancer models have been studied for Butea superba as an anticancer agent.
The following dosages are reported directly from published studies and should not be construed as recommended doses:
In the 3-month randomized double-blind clinical trial, haematology and blood chemistry analysis revealed no apparent change, and the plant preparation appeared to improve erectile function without apparent toxicity. Side effects observed in the Cortés-González (2009) open-label comparison study included flare-up in 7 (22%) of BS-treated patients (vs. 10 [31%] with sildenafil), headache in 2 (6%), dizziness in 3 (9%), blurred vision in 3 (9%), palpitations in 3 (9%), dyspepsia in 5 (16%), back pain in 6 (19%), and skin rash in 2 (6%).
At higher doses in rats, adverse effects found included an increase in spleen relative weight and increased serum levels of alkaline phosphatase (ALP) and aspartate aminotransferase (AST) at 150 mg/kg BW/day. At 200 mg/kg BW/day, rats showed significant decreases and increases in blood neutrophil and eosinophil levels, respectively, and a decrease in serum creatinine levels. Serum hormonal analysis revealed a dose-dependent decrease in testosterone, but not LH, in rats treated with 150 and 200 mg/kg BW/day. Subchronic treatment at high doses exhibited adverse effects to blood chemistry, haematology, and blood testosterone level. The results should initiate awareness of the possible adverse risk of over-dose consumption of B. superba products for the treatment of erectile dysfunction in mature males.
Hormonal disruption is currently being investigated because it may initiate a biphasic response in the human body, causing disturbance of endocrine function and/or hormonal replacement action. Butea superba has demonstrated androgenic and anti-estrogenic activities in female rats and the potential to affect the pituitary-testicular axis and sex organs in male rats. One human case report described hyperandrogenemia in a male who took capsules containing Butea superba tuber for several weeks.
The herb's mutagenic and antimutagenic properties were examined, revealing no mutagenic effects in bacterial strains; however, high doses could cause acute micronucleus formation, indicating potential genotoxicity. Reproductive toxicity was not observed in male rats even at the highest dose tested.
One study evaluated estrogenic and antiestrogenic activities of tuberous extracts of wild Butea superba collected from 23 Thai provinces. Six pure compounds tested exhibited a maximum relative potency compared to 17β-estradiol of 15.5% and 5.27% in the hERα and hERβ assays, respectively, suggesting some capacity for estrogen receptor interaction that could be relevant in sex hormone-dependent conditions, though at substantially lower potency than dedicated phytoestrogens.
In the Cortés-González comparison study, researchers believed that PDE5-inhibitors may have been blended in the B. superba capsule used, raising a documented concern about the integrity of commercially available preparations. This issue underscores the importance of sourcing standardised, verified products and is an active concern cited in peer-reviewed literature.
When taken by mouth, Butea superba is possibly safe when taken in appropriate doses for up to 3 months. Safety data beyond 3 months in humans are absent from the current peer-reviewed literature.
Health conditions that Butea superba may help support.
Butea superba is a Thai medicinal herb (red kwao krua) used traditionally in Thailand to enhance male sexual vitality and libido. Clinical studies in Thailand, including a small RCT, found it improved erectile function scores. It contains cAMP phosphodiesterase inhibitors and phytoandrogens.
Body systems that Butea superba may help support.
Go back