IngredientsBulbine natalensis Baker is a succulent medicinal plant native to southern Africa and belongs to the family Asphodelaceae. Its accepted synonym in current botanical literature is Bulbine latifolia (L.f.) Spreng., and it is a predominant species within the genus Bulbine. There are approximately 90 species in the genus Bulbine, found mainly in the southern and western provinces of South Africa and in Australia.
Indigenous people of South Africa refer to B. natalensis by several vernacular names: ibhucu in Zulu, ingcelwane in Xhosa, and rooiwortel in Afrikaans.
Bulbine natalensis Baker is a native succulent herb that is regarded as precious, highly valued, and extensively used throughout the continent for medicinal purposes. The plant grows quickly and thrives in shale and sandstone-based soils and on well-drained sites. It is an aloe-like, succulent plant characterized by rosette-shaped leaves and yellow spiked, star-shaped flowers.
Extracts of B. natalensis are available commercially in capsules, tablets, bulk powders, and liquid form, and the ingredient is sometimes combined with other testosterone boosters or added to protein powders. In traditional contexts, traditional herbalists and healers — referred to as iNyanga or iSangoma in South Africa — prepare various decoctions, infusions, or tinctures from Bulbine species as natural remedies. Leaves and roots are used in varying forms, including decoctions, infusions, and lotions, when used to manage skin diseases.
Traditionally, the leaves, roots, and rhizomes of Bulbine species are used to treat a wide range of conditions by different ethnic groups of South Africa, ranging from skin disorders, gastrointestinal and respiratory conditions to parasitic infections. People of African descent primarily use Bulbine plants to treat wounds, sunburns, scars, rashes, and other skin conditions, though after the 19th century, their ethnomedicinal uses broadened among rural communities to cover mouth ulcers, diarrhoea, stomach ailments, and other conditions.
B. natalensis is traditionally used to treat different skin diseases; it attracted significant attention through its ability to treat multiple skin conditions, such as eczema and ringworm. The genus Bulbine (Asphodelaceae) is spread across Southern Africa and Australia and has been traditionally used for various medicinal applications such as treating skin diseases, burns, diarrhoea, and sexually transmitted diseases.
Scientific evaluations from various researchers have substantiated the use of B. natalensis in the traditional context for the enhancement of male sexual disorders, cure of wounds, rashes, itches, ringworm, diabetes, rheumatism, cracked lips and herpes, diarrhea, and paroxysms, among other conditions.
The roots of B. natalensis are used to treat vomiting, diarrhoea, convulsions, and venereal disease. The plant is particularly valued and extensively used for treating male impotency, owing to a reputed aphrodisiac and invigorating effect.
Traditional herbalists in South Africa prepare various decoctions, infusions, or tinctures from Bulbine species as natural remedies for herpes, cracked lips, rashes, ringworm, burns, and wounds. Though most wound-healing claims of Bulbine species carry ethnobotanical significance in traditional medicine, they often lack ethnopharmacological explanations and scientific depth in the literature for plausible evidence of their dermatological relevance.
Phytochemical investigations have revealed a wide range of bioactive constituents in B. natalensis, including anthraquinones, triterpenes, sterols, fatty acids, and phenolic compounds. Phytochemical screening of the aqueous extract of the stem has revealed the presence of saponins, cardiac glycosides, tannins, alkaloids, and anthraquinones.
Anthraquinones feature as the primary class of compounds in Bulbine species, with a specific abundance in a subclass known as phenylanthraquinones. Knipholone, a phenylanthraquinone, has been reported as the marker compound for Bulbine species. Other compound classes include isofuranonaphthoquinones, flavonoids, phenolics, and triterpenes.
The rhizomes of Bulbine natalensis have furnished six previously unreported anthraquinone derivatives, together with eight known specialized metabolites, with structures determined by interpretation of 1D and 2D NMR and HRESIMS data. Additional isolated compounds include 8-C-glycosyl aloesol, bulbnatalonoside E, bulbnatalonoside C, bulbnatalonoside D, bulbnatalonoside B, bulbnatalonoside A, knipholone, bulbine-knipholone, 6′-methylknipholone, and bulbnatalone.
Chrysophanol, 10,7′-bichrysophanol, and bulbine-knipholone are other examples of active anthraquinones isolated from B. natalensis that have been explored for different biological activities.
Research has identified the presence of sterols including stigmasterol, sitosterol, and ergosterol in B. natalensis, which have been investigated for antifungal activity. The root and underground stems of B. natalensis showed higher quantities of total phenolics, total flavonoids, and total proanthocyanidin content compared to the leaves.
The bioactive compounds of B. natalensis are known to modulate key biological pathways associated with oxidative stress, inflammation, and hormonal regulation.
In the context of androgenic effects, the elevated testosterone content observed in animal studies may result from an increase in testicular cholesterol concentration, since cholesterol is the starting material for androgen biosynthesis. A minimum level of blood androgen is required for the maintenance of body shape, muscle mass and strength, normal sexual desire, and other functions. The increase in testosterone by the extract is therefore considered indicative of the androgenic and anabolizing potential of the plant.
Regarding cytochrome P450 interactions, a methanolic extract of B. natalensis was found to activate the pregnane X receptor (PXR) (EC50 6.2 ± 0.6 µg/ml) in HepG2 cells, resulting in increased mRNA expression of CYP3A4 (2.40 ± 0.01 fold) and CYP2C9 (3.37 ± 0.3 fold) at 30 µg/ml, which was reflected in increased activities of the two enzymes. Among the constituents of B. natalensis, knipholone was the most potent PXR activator (EC50 0.3 ± 0.1 µM), and was the most effective in increasing the expression of CYP3A4 (8.47 ± 2.5 fold) and CYP2C9 (2.64 ± 0.3 fold) at 10 µM.
Anthraquinones, especially knipholone, activate the aryl hydrocarbon receptor (AhR), influencing CYP enzyme expression. B. natalensis significantly induces CYP1A2 and CYP2B6 activity in a dose-dependent manner; clinical relevance on drug interactions and safety requires further investigation. Both water and methanolic extracts of B. natalensis, as well as knipholone, bulbine-knipholone, and 6′-O-methylknipholone, dose-dependently increased mRNA expression encoded by CYP2B6, CYP1A2, and ABCB1 genes.
The most extensively studied area of activity for B. natalensis is its effect on male reproductive hormones and sexual behaviour in rodents. The phytochemical constituents of the aqueous extract of Bulbine natalensis stem and its effect on male rat sexual behaviour were evaluated over 7 days. Phytochemical screening revealed the presence of saponins, cardiac glycoside, tannins, alkaloids, and anthraquinones. Administration of the extract at doses of 25 and 50 mg/kg body weight resulted in a significant increase (p < 0.05) in mount frequency, intromission frequency, ejaculatory latency, ejaculation frequency, serum testosterone and luteinizing hormone concentrations, computed indices of sexual behaviour, erection, quick flips, long flips, and total penile reflexes, whereas mount latency, intromission latency, and post-ejaculatory interval were significantly decreased.
Aqueous extract of Bulbine natalensis stem at 25, 50, and 100 mg/kg body weight was investigated for anabolic and androgenic effects in 60 male Wistar rats grouped into four groups for 14 days. All doses of the extract increased the testicular-body weight ratio as well as alkaline phosphatase activity, glycogen, sialic acid, protein, and cholesterol content of the testes, except at the 100 mg/kg dose, which compared well with controls for glycogen and cholesterol.
It was found that all doses increased the testicular-body weight ratio and related parameters, although 100 mg/kg body weight negatively affected testicular and testosterone concentrations as well as hormones such as serum follicle-stimulating and luteinizing hormones. A dosage of 50 mg/kg body weight showed the best androgenic and anabolic activities, supporting the use of the plant to treat male sexual dysfunction.
The results of the anabolic/androgenic study indicate anabolic and androgenic activities of Bulbine natalensis stem in male rat testes, with the 50 mg/kg body weight dose exhibiting the highest anabolizing and androgenic activities.
The effects of oral administration of aqueous extract of B. natalensis stem at daily doses of 25, 50, and 100 mg/kg body weight on reproductive function of Wistar rats were evaluated. The indices of mating and fertility success as well as quantal frequency increased after 7 days of treatment in all dose groups except the 100 mg/kg group. The number of litters was not statistically different (P > 0.05) from the control.
Evidence is currently limited to animal (rodent) studies. There are no published human clinical trials investigating the effects of B. natalensis on testosterone levels or sexual function outcomes. Notably, the testosterone-enhancing effects observed in animal studies were not seen at higher doses (100 mg/kg), where some parameters worsened — a critical point for safety. The dose-dependent biphasic response observed in rodents (pro-androgenic at moderate doses, adverse at high doses) makes direct extrapolation to humans premature.
In an experimental setting, research demonstrated a wound-healing effect of B. natalensis and B. frutescens leaf gels, specifically an increase in tensile strength by increasing fibroplasia, collagen deposition, and maturation. Traditionally, Bulbine leaves are used by several ethnic groups in South Africa to treat dermatological conditions including wounds, which has led to the development of Bulbine-containing cosmetic products.
Although empirical evidence relating to the traditional dermatological uses of Bulbine species is well-documented, it primarily focuses on wound healing. Efforts have been made to scientifically validate the traditional use of Bulbine species for wound healing; however, studies involving all five Bulbine species commonly used in South Africa are lacking.
Evidence for wound-healing effects is predominantly preclinical (in vitro and animal models). Most wound-healing claims of Bulbine species carry ethnobotanical significance in traditional medicine, but seem rather superficial and often lack ethnopharmacological explanations and scientific depth in the literature for plausible evidence of their dermatological relevance. No peer-reviewed human clinical trials specifically assessing wound healing with B. natalensis were identified in available literature.
Among isolated compounds from B. natalensis rhizomes, one anthraquinone derivative was found to be a moderate inhibitor (IC50 0.02 ÎĽM) against methicillin-resistant Staphylococcus aureus (MRSA). B. natalensis possesses anti-inflammatory and broad-spectrum antimicrobial properties, as reported in pharmacological screening.
Antimicrobial evidence is restricted to in vitro laboratory studies. No clinical trials on infectious disease outcomes have been conducted in humans. These findings are considered preliminary and hypothesis-generating only.
Bulbine natalensis is recommended in South African traditional medicine to treat diabetes, but its modes of action were previously unknown. A study assessed the phenolic acid profiles, mineral composition, and in vitro functional effects of B. natalensis to better understand its glucose-lowering capabilities. Antioxidant capacity was assessed by potassium ferricyanide reducing power and DPPH radical scavenging assays, and inhibition of alpha-amylase, alpha-glucosidase, pancreatic lipase, and DPP4 was evaluated by standard enzyme assays.
The use of B. natalensis for the management of diabetes has been reported ethnobotanically, but as of the 2020 review by Musara and colleagues, no study had yet been conducted specifically on the antidiabetic activity of this plant. Subsequent work has examined in vitro enzyme inhibition, but no controlled clinical trials in diabetic humans have been published. Evidence remains preliminary and confined to in vitro models.
Recent studies have demonstrated antioxidant and anti-inflammatory activities of B. natalensis, supporting its relevance in both traditional and modern medicine. The methanolic extracts of B. natalensis leaves, underground stems, and roots possess significant phytochemical content, in conjunction with antioxidant and antibacterial activities. These findings are primarily in vitro and preclinical; no human clinical trials isolating anti-inflammatory or antioxidant endpoints have been identified.
The only published human clinical trial directly involving B. natalensis assessed safety rather than efficacy. As the first step in a series of experiments designed to assess in vivo effects of Bulbine natalensis (ProLensis™) supplementation, investigators performed a placebo-controlled, double-blind clinical trial to assess the short-term safety of this ingredient.
After giving informed consent and being cleared for participation by passing a screening physical and EKG, 36 apparently healthy men (mean age 29.4 ± 7.7 years, height 177.2 ± 5.2 cm, weight 82.2 ± 10.7 kg) consumed 4 capsules of ProLensis™ (325 mg in the morning, 325 mg six hours later) or a matched placebo every day for 28 days. Clinical chemistry panels (renal, hepatic, and hematological biomarkers) and general markers of health (heart rate, blood pressure, EKG) were assessed before and after 28 days of supplementation.
In 27 of 29 variables, no differences were noted between groups. Alkaline phosphatase (ALP) increased marginally in the ProLensis™ group (+2.0 IU/L, +3%) compared to a parallel decrease in the placebo group (-2.4 IU/L, -3.8%); P < 0.04. Creatinine decreased slightly in the ProLensis™ group (-0.08 mg/dL, -7.4%) compared to no change in the placebo group (P < 0.003).
The investigators considered the observed differences in ALP and creatinine not clinically relevant, given that all values for both groups fell well within normative clinical limits (typical values for ALP range from 20 to 140 IU/L; typical values for creatinine range from 0.6 to 1.3 mg/dL for men and 0.5 to 1.1 mg/dL for women).
The authors concluded that, within the confines of the current experimental design (subject demographics, dose, and duration of use), these preliminary data suggest that ProLensis™ is as safe as placebo with respect to the hemodynamic, hepatic, renal, and hematologic biomarkers assessed. Future studies should seek to clarify extraction methods and bioactives, investigate potential efficacy, and confirm these safety data to strengthen the total body of evidence.
Important limitation: This study was supported in part by a research grant from Sports Nutrition Research, Ltd., indicating potential industry funding conflict. The trial was also brief (28 days), enrolled only 36 men, and did not include efficacy outcomes (such as testosterone levels or sexual function endpoints). It should be considered preliminary.
In the only human study conducted with Bulbine natalensis, it was consumed at a dosage of 325 mg twice daily. This equates to a total daily dose of 650 mg using the standardized commercial preparation ProLensis™.
Animal studies demonstrated that low to moderate doses of Bulbine natalensis extract (25–50 mg/kg body weight) significantly enhance libido, increase testosterone and luteinizing hormone levels, and improve sexual performance in male rats. A dosage of 50 mg/kg body weight was established as optimal in rat studies.
Rat studies investigating the interaction of Bulbine natalensis with testosterone note that 50 mg/kg (of a 10:1 extraction) appears to be the optimal dosage; based on body surface area conversions, this correlates into an estimated human dose of 8 mg/kg, or approximately 550 mg for a 150 lb person, 730 mg for a 200 lb person, and 900 mg for a 250 lb person. These doses are currently only estimates, and they are within the range seen in the only industry-funded trial, which used 650 mg. Doses would be 10-fold higher if the raw plant is used without any particular extraction process.
Bulbine natalensis is not approved by the FDA for any conditions; therefore, there is no official dose, and users and supplement manufacturers have established unofficial doses based on trial and error.
The effects of aqueous extract of Bulbine natalensis Baker stem at 25, 50, and 100 mg/kg body weight for 14 days on the functional indices of the liver and kidney were evaluated. The extract did not significantly alter total protein, sodium, potassium, chloride, calcium, magnesium, uric acid, and creatinine levels. However, the 50 and 100 mg/kg doses reduced the liver- and kidney-body weight ratios by the end of the experimental period. The extract increased the activities of liver gamma-glutamyl transferase (GGT), alkaline phosphatase (ALP), alanine and aspartate aminotransferase (ALT and AST), and total bilirubin, globulin, and urea.
The extract produced higher effects on the liver functional indices (39%) than the kidney parameters (21%). Histological examination revealed slight distortions in the architecture of the liver lobules as well as proximal and convoluted tubules of the kidney. The alterations produced in some of the functional indices as well as in the hepatorenal architecture may adversely affect normal hepatic and renal functions. The parameter-specific effect of the extract suggests selective toxicity.
This pattern of findings is an indication that the extract is not completely "safe" as an oral remedy, according to the investigators.
The aqueous extract of B. natalensis stems was reported to be safe at doses of 25 and 50 mg/kg body weight for female rats during the organogenic period of pregnancy, while signs of negative effects on reproductive functions were observed with 100 mg/kg body weight of either male or female rats.
In rats, a watery extract of Bulbine natalensis stem increased blood levels of cholesterol and triglycerides and decreased levels of HDL cholesterol. In addition, all doses of 14-day repeated consumption increased serum concentrations of cholesterol and triacylglycerols.
Systemic toxicity was also observed on the white blood cell count in animal studies, suggesting animals may be predisposed to atherosclerosis.
Most evidence comes from animal studies, with limited short-term human data. Repeated oral administration of Bulbine natalensis extract in animal studies, especially at moderate to high doses (50–100 mg/kg), led to significant changes in liver and kidney function markers, including increased liver enzymes (ALT, AST, GGT, ALP), higher total bilirubin and urea, and mild structural changes in the liver and kidney tissues.
In the single available human trial, preliminary data suggest that ProLensis™ is as safe as placebo with respect to the hemodynamic, hepatic, renal, and hematologic biomarkers assessed at a dose of 650 mg/day for 28 days — but the study was not powered for safety conclusions nor designed to evaluate long-term effects.
Research into herb-drug interactions has identified a meaningful mechanistic concern. In a CYP inhibition assay, the methanolic extract as well as the anthraquinones strongly inhibited the catalytic activity of CYP2C9, while inhibition of CYP3A4 was weak. These results suggest that consumption of B. natalensis may pose a potential risk for herb-drug interaction (HDI) if taken with conventional medications that are substrates of CYP3A4 and CYP2C9, and may contribute to unanticipated adverse reactions or therapeutic failures.
B. natalensis significantly induces CYP1A2 and CYP2B6 activity in a dose-dependent manner. Both water and methanolic extracts increase P-glycoprotein (P-gp) mRNA expression, suggesting additional herb-drug interaction potential. These findings suggest that B. natalensis may affect normal homeostasis of select CYPs with subsequent risks for HDIs when concomitantly ingested with conventional medications that are substrates of CYP2B6 and CYP1A2. However, more in-depth translational studies are required to validate the clinical relevance of these findings.
Adverse effects have been reported on both the liver and kidneys with the same dosages seen to increase testosterone. Safety concerns include potential organ damage, which necessitates caution when considering supplementation. The field as a whole lacks long-term human safety data, efficacy data from controlled human trials, and standardized characterization of commercial extracts. The herb-drug interaction risk through CYP modulation is mechanistically plausible but has not yet been confirmed in clinical pharmacokinetic studies in humans.
Health conditions that Bulbine natalensis may help support.
Bulbine natalensis is a South African plant traditionally used as a male aphrodisiac. Preclinical animal studies (rat models) demonstrate significant increases in serum testosterone and LH, along with improvements in reproductive tissue weight and sperm quality. It is considered a rapidly emerging ingredient in andropause and testosterone support formulations, though human clinical trial data remain limited.
Bulbine natalensis is a Southern African succulent herb used in traditional Zulu and Xhosa medicine as an aphrodisiac. Animal studies show dose-dependent testosterone increases and aphrodisiac activity. No human RCTs exist; evidence is preclinical but mechanistically consistent, though dose-dependent toxicity concerns have been noted.
Bulbine natalensis is a South African perennial herb traditionally used as an aphrodisiac and prosexual agent. Rat studies show significant dose-dependent testosterone increases. A short-term placebo-controlled clinical safety study in healthy men was conducted, though large-scale human efficacy trials for testosterone are still limited. Systematic reviews (Clemesha et al.) list it among compounds with non-conflicting testosterone-increase data.
Body systems that Bulbine natalensis may help support.
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