Testosterone Boosters/Natural Anabolics - A Natural Way to Boost Testosterone
What are Testosterone Boosters?
Testosterone boosters, or natural anabolics, are nutritional supplements which are purported to boost endogenous production of testosterone, or else, improve the bioavailability of testosterone already produced by the body. They are distinct from prohormones or off-the-shelf (OTS) steroids, which are compounds that are designed to mimic the actions of testosterone in the body by potentially leading to decreased natural testosterone production. Testosterone boosters are taken in with the aim to optimise your body's production and use of testosterone, rather than seeking to replace it.
This article will examine the role of testosterone boosting compounds in the bodybuilding market, looking at why athletes would consider taking them, as well as reviewing a number of ingredients commonly found in testosterone boosters and examining their efficacy with respect to increasing testosterone levels. Finally, we will look at a number of products found on the bodybuilding market and provide advice on readers to distinguish between the multitude of products so as to be better able to make an informed buying decision when purchasing dietary supplements.
Why would athletes take testosterone boosters?
The hormone testosterone is of prime importance for anyone seeking to increase their strength or muscle mass as it plays a very significant role in the acquisition of both. Indeed, men's higher testosterone levels are the main reason they are more muscular than women. Furthermore, higher testosterone levels are linked to greater burning of bodyfat, greater aggression, and increased sex drive. Clearly then, anything which could be seen to enhance the actions of testosterone in the body would be highly prized by athletes. For those athletes unwilling to take anabolic steroids or prohormones, testosterone boosting supplements which manage to enhance testosterone or increase the bioavailability of testosterone will be of considerable interest.
Testosterone boosters will often be stacked with similar sports supplements such as creatine, protein powders, fat burners and fish oils in an effort to help the natural athlete replicate some of the results achieved by drug users. A testosterone boosting supplement which works as advertised should allow for greater muscle mass and strength gains without any of the negative side effects of steroid use.
Ingredients Found in Testosterone Boosters
The number of ingredients purported to increase testosterone is longer than even an orang-utan's arms. Here we will look at some of the ones which have been marketed to bodybuilders over the years. Some you will have heard of and some may well be new, largely because they are so old but a thorough review necessitates covering as many ingredients as possible.
Boron - Boron is a trace mineral which was frequently found in many supplements in the 1980s and 90s, based on the belief it would increase testosterone levels. Post-menopausal women supplemented with boron showed increased blood levels of testosterone in one study1. However, it is a large stretch to suppose that once adequate boron status is reached, that supra-physiological amounts will lead to increased testosterone production. A more recent review2 of recent studies conducted into the effects of boron with male weight trainers showed no effect whatsoever on testosterone levels after the use of boron. Given the fact that most minerals are good for correcting deficiencies only, and the experience of millions of bodybuilders from the past, we can discount the idea of any anabolic properties attributable to boron.
Glandular Extracts - Glandular extracts such as dried bull's testicles were probably the first testosterone boosters marketed to athletes on the basis that bulls produce a vast amount of testosterone and if we could ingest their glandular extracts, we too could grow to superhuman proportions. Sadly, apart from getting strange looks from people, these extracts are worthless and better left on the bull. Thankfully (for the bulls' sakes) they are absent from the bodybuilding market today, although still marketed to the impressionable and the uninformed. If you see anyone claiming to have made great gains from these he will undoubtedly be full of bull! The reality is that there has never been a single study conducted showing benefits with the use of glandular.
Tribulus Terrestris - Tribulus Terrestris is the plant that kick-started the recent wave of natural testosterone boosters. It first came to prominence in the late 90s and was based on research conducted in Eastern Europe showing it elevated luteinizing hormone (LH) and testosterone by 72% and 40% respectively3. Unfortunately, the same study showed estradiol levels rising by 81%, and while the increase in testosterone and LH kept these values within normal bounds, the rise in estradiol placed it well beyond normal measurements seen in healthy males. This raises the possibility that the body is up-regulating aromatization to help counter the increased testosterone and LH produced by tribulus ingestion. This suggests taking the tribulus with an anti-estrogen such as 6-OXO may be a good idea.
However, a number of other studies have been unable to replicate the results of the original tribulus study. There have been criticisms made of many tribulus products containing insufficient amounts of the potent tribulus terrestris extract, as opposed to the raw plant material, as well as most studies being funded by the manufacturer.
Today, tribulus remains a central ingredient of many testosterone boosting supplements and many bodybuilders swear to its effectiveness, often citing increased libido while taking tribulus containing products. It has been suggested this could be related to effects on dopamine rather than testosterone, with increased dopamine being noted to increase libido. Indeed, animal studies have shown loss of muscular co-ordination in sheep consistent with neurological disease such as Parkinson's4. Although it should not be a concern for bodybuilders using tribulus for a short period of time, prolonged use is not advised. Dosages used in clinical studies where a positive effect has been shown have ranged between 750mg-1500mg daily. As already stated, it is recommended to take this in combination with an anti-estrogen, and the user should ensure it is with tribulus terrestris extract and not just the plant material.
Tribulus terrestris plant only contains trace amounts of protodioscin (the active steroidal sapogenin / saponin responsible for stimulating LH in men), so consuming the whole plant is useless. Tribulus must be standardized for at least 10% protodioscin in order to be effective. Many supplement companies will sell a tribulus product containing 2% protodioscin or less so try to ensure when buying tribulus you only buy a product with a high amount of protodioscin.
Zinc - Zinc is a trace mineral which like boron has been advocated for many years as important for boosting testosterone production. There is some research to support this contention. Zinc is an essential factor in the production of testosterone by men, and a deficiency in Zinc has been linked to low testosterone levels5. Further research has shown zinc to be beneficial in athletes in preventing the decline in testosterone triggered by exhaustive exercise.6
Supplementing with zinc is therefore something athletes should consider especially if they are unaware of their own zinc status, which is likely. As athletes will deplete their body of minerals and vitamins at a faster rate than the sedentary population, supplemental zinc can certainly have its place.
However, it should be noted that once optimal Zinc status has been attained, there is no evidence to show that increasing zinc levels beyond the point at which the deficiency is corrected will do anything to increase testosterone production further. That is, taking zinc can well allow you to go from low to normal testosterone, but not from normal to high levels. Intakes of 15-30mg should be sufficient to cover athletes' needs.
Divanil - Divanil is a lignan found in stinging nettle root and is a relative newcomer to the testosterone boosting category and has a number of impressive user reports to merit further analysis. There is a relative lack of research into divanil but we do have research supporting the theory that divanil can bind to sex hormone binding globulin factor (SHGB) which in turn will lead to an increase in free testosterone.7 8 Anecdotal feedback from bodybuilders taking either divanil or divanil containing products such as Activate Xtreme, suggests it can raise libido, increase aggression and improve strength, as well as increasing muscle mass and decreasing bodyfat. Dosages vary but most people tend to take this product as part of a formula such as the aforementioned Activate Xtreme.
Icariin - Icariin is a flavonol derived from epimedium extract, more commonly known as Horny goat weed. Icariin has been shown in a number of studies to act as a PDE5 inhibitor 9 10 11 in a similar fashion to impotency drugs such as Viagra and Cialis. This accounts for its presence in many formulas designed to boost sexual drive and performance. It also has been shown to act as a testosterone mimetic12 and to boost libido via this route. Given the popularity of supplements featuring it, and the quantity of research behind it, Icariin has become a staple of many bodybuilders' supplement programs either as part of a formula or by itself.
Basella Alba - Basella alba is related to spinach and often used as a food in cooking in East Asia. Recently it has attracted the interest of bodybuilders in its potential to hopefully impart Popeye-like characteristics, if they are able to consume enough. Research shows it has the ability to increase bodyweight significantly, as well as increase seminal weight, due to its ability to significantly increase production of testosterone13 14. Basella alba is found increasingly often in testosterone booster products as a result of the interest sparked by research. To date there is no standalone Basella alba product so this is the only route for bodybuilders interested in trying this compound.
Dicyclopentanone - Dicyclopentanone is a relatively new compound to the market with some research conducted in Russia backing its status as a legal muscle building product, showing an absence of androgenic properties and a high anabolic/androgenic ratio15. Given the relative paucity of research behind it most people will have to experiment with this item to test its effectiveness.
Forskolin - Forskolin has been postulated to enhance testosterone in the body through its ability to enhance 3,5 cyclic adenosine monophosphate (cAMP) levels. By enhancing cAMP levels, higher LH levels can lead to higher testosterone levels in users of forskolin. The theory is backed up by studies showing the use of forskolin led to higher testosterone levels, increased lean body mass and lowered body fat in subjects using forskolin16 17. Forskolin is found in a number of bodybuilding supplements so those interested in taking this have no lack of option in trying it. Forskolin has also been shown to upregulate aromatase, suggesting further research on forskolin as it is becoming a debated ingredient.
Avena Sativa - Avena sativa, better known as wild oat, has been around for a considerable length of time on the bodybuilding scene. It has been shown to increase free testosterone levels by enhancing LH levels. A 1986 study with volunteers who expressed interest in improving their sexual response showed men experienced a 22% increase in genital sensation and women a 15% increase after using avena sativa. A follow up study showed men experienced increased sex drive, enhanced erections and more pleasure during sex when taking avena sativa. Avena sativa is often found in conjunction with tribulus as they appear to work via similar mechanisms, and can be found in many bodybuilding formulas.
Eurycoma Longifolia (Longjack) - Longjack, or Tongkat Ali as it is also known, has been studied extensively and long been prescribed as an aphrodisiac in the far east where it came to prominence. Studies have demonstrated its efficacy in acting as an aphrodisiac several times. 18 19 There is no peer-reviewed research on this herb on humans to date but anecdotal feedback and its widespread use in the Far East for centuries suggests it does seem to aid in improving sexual vigour and performance, although there is not much, if anything, noted about its effects on athletic performance.
Yohimbe - Yohimbe, or its pharmaceutical form, Yohimbine HCl, is one of the oldest and most well known aphrodisiacs. It owes its reputation in large part to its abilities as a vasodilator, widening blood vessels and thereby increasing blood flow to sexual organs. It has also been widely touted as a novel supplement to aid with the burning of stubborn, hard to remove, bodyfat, especially lower bodyfat. It is recommended to use with a low carbohydrate diet if used as a dieting aid20. As a testosterone booster though there is nothing to suggest it acts as anything more than an impotency aid.
Arachidonic Acid - Arachidonic acid is a semi-essential fatty acid and has been around in various forms on the supplement market for a while now and studied extensively for its mooted testosterone enhancing qualities. Numerous animal studies have indicated that arachidonic acid will elevate testosterone, leading to its inclusion in a number of supplements.21 22 There is also research showing positive effects of arachidonic acid on anaerobic capacity in resistance training males23. On the downside, arachidonic acid has also been shown to have a pro-inflammatory effect so users ought to bear this in mind when considering its use. Currently, the US company Molecular Nutrition own the patent on this fatty acid but they have licensed its use to a number of supplement companies who have chosen to add arachidonic acid to their products so there are many options available for those interested in trying this product out.
Vitex Agnus Castus - Better known as vitex, this is a flower found in the Mediterranean. It has been around for a while and there is some research supporting its use as a testosterone boosting ingredient. One study shows that high doses of vitex lowered prolactin levels24 in men. Reducing prolactin is associated with increasing male sexual libido significantly, and is how prescription drugs such as Bromocriptine and Cabergoline exert their well known pro-sexual effects. However, another study showed that use of Vitex in combination with a dopamine agonist (Bromocriptine) lowered testosterone levels25. This may indicate that elevation of libido (which is commonly seen with both Bromocriptine and vitex) is an unreliable guide to whether testosterone is being elevated. It could be the case that dopaminergic stimulation is responsible for the increased libido seen with vitex, as opposed to increased testosterone release. For those interested in using vitex agnus castus to boost sexual performance and libido a number of options exist on the bodybuilding market.
Chrysin – Chrysin is a naturally occurring flavone, which came to prominence in a blaze of hype marketed under the tagline of Flavone X, back in the 1990s in the magazine Musclemedia 2000. It was widely used as an anti-aromatase (estrogen lowering) product but research has failed to supports its claims to reduce estrogen or raise testosterone.26 27 28 This absence of research supporting its use as a testosterone booster is disappointing for sure, and led to it falling in popularity as a supplement to enhance muscle mass. However, it has recently been promoted more in libido enhancing products and for this purpose there is some research supporting its role29. It has also been shown to demonstrate anxiety reducing effects30, and this possible role in reducing stress could also act as a libido enhancer, since stress is widely recognised as having a disastrous effect on libido.
Maca Extract – Maca, also known as Lepidium meyenii, is a plant widely used as a herbal tonic in South America which was said to be fed to Inca warriors before battle to make them ferocious and made them very virile, to such an extent that women had to be protected from them!31 Doubtless that story is overblown, and given the fact that these tribes also frequently indulged in the use of cocoa leaf (used to make cocaine), perhaps other factors were more important in this story. Trials conducted in the modern day have shown that maca can increase libido as well as improve seminal volume in men.32 33 Widely eaten to this day in modern day Peru, maca has not been shown to increase testosterone levels in any research to date. Indeed, one small trial showed that while it increased libido in most men, it actually decreased testosterone levels in more men than it increased testosterone.34
Instead, it is often regarded as a 'superfood', containing a high level of a number of nutrients which makes it useful as a general food staple. Although maca cannot hurt and it is cheap enough, its ability to do more than increase libido is in doubt, hence it is mainly found nowadays in products that promote themselves as sexual enhancers rather than testosterone boosters.
Fadogia Stem Extract – Fadogia is a very new product to the testosterone boosting scene, and there are not that many reports from users on this compound although it has attracted a significant degree of interest. It has proven difficult to source for some time but products containing fadogia are starting to appear on the bodybuilding supplement market now. There is some research supporting its ability to increase testosterone levels,35 however this research was with fadogia stem extract and not fadogia plant extract or the fadogia plant material itself. This is very important, since in the same way tribulus plant material will do nothing for users, fadogia stem extract is what is needed to enhance testosterone activity. Users should look for a Fadogia stem extract with at least 10% active steroidal sapogenins.
Fenugreek – Fenugreek is cultivated worldwide and frequently found as an ingredient in curries. It has been shown to stimulate appetite, which is not surprising to anyone who has eaten too many curries but there is no research, beyond some supplement company sponsored trials showing it does anything useful for athletes. With so many effective testosterone boosters out there we would leave fenugreek on the shelf for now, until further research supports its usage.
6-Bromoandrostenedione – Commonly known as 6-bromodione in the supplement industry, this is found as either 6-alpha-bromodione, or 6-beta-bromodione. 6 alpha-bromodione is a competitive inhibitor of aromatase enzymes,36 which basically means it works by way of binding to the active binding site of the aromatase enzyme resulting in prevention of interaction with androgens. This is good for rapid binding and short term aromatase control, but unfortunately a competitive inhibitor will eventually let go of the enzyme and allow it to do feminizing things to male hormones. 6 beta-bromodione is a suicide inhibitor of the aromatase enzyme.
Together the two will provide for a powerful one-two punch to reduce estrogen and increase test as well but there is some concern over 6-bromodione owing to the fact that in the words of supplement guru Patrick Arnold (who probably has more experience with these types of products than anyone else) "other 6-alpha halogenated androstenes (6-alpha fluoro, 6-alpha chloro) have anabolic androgenic activity. I strongly suspect the 6-alpha bromo would too, since in the 4-halo series of testosterones all 3 halogen substitutions are effective... so you would want to stay away from 6-alpha-bromoandrostenedione if your goal is HPTA recovery." This basically suggests the possibility that rather than being a natural testosterone booster working with your body to elevate testosterone, 6-bromodione has the potential to lower your body's natural testosterone levels after the product is discontinued.
This covers most of the popular ingredients found in testosterone boosters today, although supplement companies are always looking to add anything that sounds new to help their latest products sell, often stacking testosterone boosting compounds with others designed to reduce estrogen, or offer some synergistic activity to enhance overall product effectiveness. We therefore now examine some of the best of current crop of testosterone boosting products on the market and offer readers practical advice on how to best take them.
Popular Products Available Today
Activate Xtreme – Driven Sports' Activate Xtreme is a popular testosterone boosting product with a significant following in the US. Containing divanil, basella alba, and icariin, it is dosed at 4 capsules a day for a month's supply. Users frequently report improved muscle gain, enhanced recovery, heightened libido, as well as reduced bodyfat so this makes it a very popular product. Typically, users take this for 4-6 weeks followed by 2-4 weeks off.
Vitrix – Vitrix is the best selling testosterone booster from Nutrex Research and has proven to be a best seller for many years. Containing high grade tribulus terrestris, avena sativa, vitex and longjack, it is most frequently used as a libido enhancer. The dosage is 6 capsules a day, making a 180 capsule bottle last 30 days.
ZMA – Basically this product is a combination of zinc, discussed above, and magnesium. The combination of both together should meet an athlete's nutritional needs for these essential nutrients, ensuring testosterone levels are optimised, as well as promoting restful sleeping patterns. At 3 capsules daily, a bottle of 90 capsules will last 30 days.
Animal Stak – Developed by Universal Nutrition's Animal division, it complements the rest of the Animal range, being a product designed for the hardcore lifter. Containing longjack, avena sativa and tribulus, this is more of a complete health product rather than a pure testosterone booster. Dosage is one pack a day, making a 44 pack bottle last 44 days.
Tribuloid – Tribuloid by Goliath Labs contains a slew of ingredients including tribulus, longjack, zinc and avena sativa, making it a good choice for someone wanting to try multiple testosterone boosting ingredients at once. Dosage is 2 capsules a day, making a 30 day supply.
Anabol-5 – Another product by Nutrex, this has dicyclopentanone at its core, which is difficult to find so makes for a good choice for athletes wanting to try it out. In addition, it has a number of other ingredients which should enhance its functions as a lean mass gaining product. The recommended dose is 4 capsules daily, meaning a bottle lasts 30 days.
Bioforge – The manufacturers, Biotivia, are a relative newcomer to the field of testosterone enhancement, being better known for their resveratrol products, but Bioforge is a research driven formula combining forskolin, icariin, zinc and indole-3-carbinol to produce a product designed to enhance testosterone and amplify fat burning. One bottle last 30 days, taking 3 capsules daily.
Reversitol – Reversitol is a 6-bromo based product made by iForce Nutrition, also containing other ingredients to boost the formula. One bottle will last 30 days, taking 2 capsules a day.
Halodrol Liquigels – Gaspari Nutrition's Halodrol Liquigels contains at its core, arachidonic acid and is one of the few products out there containing this ingredient, stacked here with a variety of others to try to enhance testosterone activity. At 3 capsules a day, one box will last 20 days. This product should not be confused with the prohormone H-Drol which has now been discontinued by Gaspari.
It is hoped that readers now have an idea about the uses and applications of testosterone boosters as well as an understanding about how they work and which product is best suited for them. With so many on the market, it is wise to try them one at a time and the user can then assess for themselves how well they respond to them. Compared to the products available even ten years ago, this field has advanced significantly and today a number of products offer valid alternatives to the natural bodybuilder wishing to avoid the use of illegal drugs but still wanting something to enhance muscle size, strength, and libido in a natural manner.
- Nielsen FH, et al. Effect of dietary boron on mineral, estrogen, and testosterone metabolism in postmenopausal women (1987)
- Nancy R. Green1 and Arny A. Ferrando
- Milanov, S., E. Maleeva, M. Tashkov. Tribestan effect on the concentration of some hormones in the serum of healthy subjects (1981)
- Bourke CA. Hepatopathy in sheep associated with Tribulus terrestris. Aust Vet J. 1983 Jun;60(6):189.
- Prasad, Mantzoros, Beck, Hess and Brewer Zinc status and serum testosterone levels of healthy adults (1996)
- Kilic M, Baltaci AK, Gunay M, Gokbel H, Okudan N, Cicioglu I The effect of exhaustion exercise on thyroid hormones and testosterone levels of elite athletes receiving oral zinc. (2006)
- Schottner M, Gansser D, Spiteller G. Interaction of lignans with human sex hormone binding globulin (SHBG).
- Schottner M, Gansser D, Spiteller G. Lignans from the roots of Urtica dioica and their metabolites bind to human sex hormone binding globulin (SHBG).
- Jiang Z, Hu B, Wang J, Tang Q, Tan Y, Xiang J, Liu J. Effect of icariin on cyclic GMP levels and on the mRNA expression of cGMP-binding cGMP-specific phosphodiesterase (PDE5) in penile cavernosum. Journal of the Huazhong University of Science and Technology. 2006
- Ning H, Xin ZC, Lin G, Banie L, Lue TF, Lin CS. Effects of icariin on phosphodiesterase-5 activity in vitro and cyclic guanosine monophosphate level in cavernous smooth muscle cells. Urology. 2006
- Dell'agli M, Galli GV, Dal Cero E, Belluti F, Matera R, Zironi E, Pagliuca G, Bosisio E. Potent Inhibition of Human Phosphodiesterase-5 by Icariin Derivatives. Journal of Natural Products. 2008
- Zhang ZB, Yang QT. The testosterone mimetic properties of icariin. Asian Journal of Andrology. 2006
- Moundipa FP, Kamtchouing P, Koueta N, Tantchou J, Foyang NP, Mbiapo FP, Effects of aqueous extracts of Hibiscus macranthus and Basella alba in mature rat testis function.
- Wolf-Bernhard Schill, Thomas K. Monsees Effects of Basella alba and Hibiscus macranthus extracts on testosterone production of bull Leydig cells
- Mel'nikova TA, Mel'nik SI - Anabolic activity of some dicyclopentanone derivatives
- Michael P. Godard, Brad A. Johnson and Scott R. Richmond - Body Composition and Hormonal Adaptations Associated with Forskolin Consumption in Overweight and Obese Men
- Badmaev, V., Majeed, M., Conte, A. A., Parker, JE. 2002, Diterpene forskolin (Coleus forskohlii Benth.): a possible new compound for reduction of body weight by increasing lean body mass.
- H. H. Ang , S. Ikeda , E. K. Gan - Evaluation of the potency activity of aphrodisiac in Eurycoma longifolia Jack
- Ang, H H : Cheang, H S : Yusof, A P - Effects of Eurycoma longifolia Jack (Tongkat Ali) on the initiation of sexual performance of inexperienced castrated male rats.
- Lyle Mcdonald, The Stubborn Fat Loss Solution (2008)
- Romanelli F. ; Valenca M ; Conte D. ; Isidori A. ; Negro-vilar A . Arachidonic acid and its metabolites effects on testosterone production by rat Leydig cells
- C Gupta and A S Goldman - The arachidonic acid cascade is involved in the masculinizing action of testosterone on embryonic external genitalia in mice
- Roberts MD, Iosia M, Kerksick CM, Taylor LW, Campbell B, Wilborn CD, Harvey T, Cooke M, Rasmussen C, Greenwood M, Wilson R, Jitomir J, Willoughby D, Kreider RB - Effects of arachidonic acid supplementation on training adaptations in resistance-trained males
- Merz, PG; Gorkow C, Schrödter A, Rietbrock S, Sieder C, Loew D, Dericks-Tan JS, Taubert HD (1996). "The effects of a special Agnus castus extract (BP1095E1) on prolactin secretion in healthy male subjects
- Nasri S, Oryan S, Rohani AH, Amin GR - The effects of Vitex agnus castus extract and its interaction with dopaminergic system on LH and testosterone in male mice.
- Saarinen N, Joshi SC, Ahotupa M, Li X, Ammälä J, Mäkelä S, Santti R. (2001). "No evidence for the in vivo activity of aromatase-inhibiting flavonoids"
- Int J Sport Nutr Exerc Metab. (2000). "Effects of anabolic precursors on serum testosterone concentrations and adaptations to resistance training in young men".
- Gambelunghe C, Rossi R, Sommavilla M, Ferranti C, Rossi R, Ciculi C, Gizzi S, Micheletti A, Rufini S - Effects of chrysin on urinary testosterone levels in human males.
- Dhawan K, Kumar S, Sharma A - Beneficial effects of chrysin and benzoflavone on virility in 2-year-old male rats.
- Wolfman C, Viola H, Paladini A, Dajas F, Medina JH. Possible anxiolytic effects of chrysin, a central benzodiazepine receptor ligand isolated from Passiflora coerulea. Pharmacol Biochem Behav. 1994 Jan
- Downie, Andrew. "On a Remote Path to Cures" New York Times. January 1, 2008.
- Gonzales, GF.; Cordova A., Vega K., Chung A., Villena A., Gonez C. & Castillo S. (2002). "Effect of Lepidium meyenii (maca) on sexual desire and its absent relationship with serum testosterone levels in adult healthy men
- Gonzales, GF; Cordova A., Gonzales C., Chung A., Vega K. & Villena A. (2001). "Lepidium meyenii (maca) improved semen parameters in adult men"
- Yakubu MT, Akanji MA, Oladiji AT. Aphrodisiac potentials of the aqueous extract of Fadogia agrestis (Schweinf. Ex Hiern) stem in male albino rats.
- Osawa Y, Osawa Y, Coon MJ. Stereochemistry of the functional group determines the mechanism of aromatase inhibition by 6-bromoandrostenedione.