Steroidal Sapogenins
syn. diosgenin and analogs
syn. 25R-spirostanes
Description:
Steroidal sapogenins (also known as steroidal glycosides) are a group of natural steroid-like molecules widely found in plants. These compounds share the same basic 4-ring carbon skeleton as human steroid hormones such as progesterone, testosterone, estrogen, and cortisol. Because of this, sapogenins are used as starting materials in the synthesis of virtually all steroid medications including synthetic estrogens, progestins, corticosteroids, and anabolic/androgenic steroids.492 A small number of steroidal sapogenins have also been shown to exhibit weak hormonal activity during in-vitro and in-vivo animal studies (usually estrogenic), although such properties are generally poorly characterized and understood.
In nature, sapogenins are commonly attached to sugars to form a series of soap-like molecules called saponins. Saponins have been shown to possess a wide range of biological activity in mammals.493,494 For example, some bind with cholesterol in the bile, inhibiting its reabsorption (reducing serum cholesterol levels). This may potentially allow some to offer a cardio-protective effect. Others have been shown to possess blood thinning, cancer fighting, liver protecting, blood sugar lowering, immune system modulating, neuroprotective, anti-inflammatory, and antioxidant properties. The beneficial properties of saponins are the subject of ongoing research.
Saponins are only partially hydrolyzed to free sapogenins and component sugars during the digestive process.495 The disassociation of the steroidal sapogenin from its sugar attachment may, therefore, increase or decrease some or all of its various individual biological activities. In some cases, the biological effect may be entirely dependent on retention of the intact saponin molecule.496 We, therefore, cannot automatically ascribe the beneficial/therapeutic properties of a saponin to its base sapogenin. Each sapogenin must be individually studied, and its properties determined.
Diosgenin (25R-spirost-5-ene-3 β‚-ol) is the most widely known and studied steroidal sapogenin. It has been shown to exhibit bile acid and cholesterol lowering effects, and may have antioxidant and anti-carcinogenic (cancer fighting) properties.497,498 It also appears to exert weak steroid (estrogenic) activity in humans,499 and has been used as a natural medicine to help alleviate the symptoms of low estrogen associated with menopause.500 Diosgenin, extracted from the Mexican yam, was the first sapogenin widely used to manufacture steroid drugs. This sapogenin (as well as its source materials such as smilax and Mexican yam) has also been widely sold as a sport nutrition product due to this association. No anabolic action has ever been documented in human studies with diosgenin, however, and it appears unlikely to offer direct ergogenic value.
Several other steroidal sapogenins are also available on the sports nutrition market. What is known of these compounds is summarized below. In most cases these compounds have been linked by their manufacturers to a single Russian study from 1976, which reported strong anabolic (without androgenic) activity in rats given 6-keto derivatives of diosgenin, agigenin, and alliogenin.501 Although an exact identification of all commercial sapogenins cannot be made due to errors in labeling, it is clear that most (if not all) were never directly mentioned in this original Russian paper. Furthermore, none have been examined in human exercise studies, and clear anabolic, androgenic, or ergogenic effects have not yet been deomonstrated.
25(R)-spirost-4-ene-3,6β-diol
This compound is a 4-ene, 6-hydroxyl derivative of diosgenin. At present, the properties of this compound in humans are unknown.
25(R)-spirost-4-ene-3β-ol-6-one
Of the listed saponins, this would be the closest (structurally) to a 6-keto derivative of diosgenin. The exact properties of this compound in humans are unknown. Note that 6-keto diosgenin itself is not possible to synthesize, as its 5-ene group occupies a bond necessary for 6-ketone reduction.
25(R)-5α-spirostan-3β‚6α-diol
The compound 25(R)-5alpha-spirostan-3 β‚6α-diol is a derivative of a sapogenin known as agigenin. It is also commonly referred to as 6alpha-hydroxydiosgenin. The exact properties of this specific sapogenin in humans are unknown.
25(R)-5α-spirostan-3,6-dione
This is a “dione” version of the sapogenin listed above. The exact properties of this compound in humans are also unknown.
Promoted Benefits:
Steroidal sapogenins are promoted to exert anabolic steroid-like activity, increasing muscle mass and strength.
Clinical Studies:
The use of steroidal sapogenins as sport supplements is supported by in-vitro data only. These supplements have a Clinical Support Rating of 1 (1/5).
One in-vitro study demonstrated dioscin (the saponin form of the sapogenin diosgenin) to increase growth hormone secretion when incubated with rat pituitary cells.502 It is unknown if this effect is retained in diosgenin, or if this compound has growth hormone stimulating or ergogenic effect in exercising humans.
The most commonly cited study on steroidal sapogenins (referenced earlier) was published in 1976, and reported anabolic activity in rats given 6-keto derivatives of the sapogenins agigenin, diosgenin and alliogenin.503 The most active sapogenin in this study (a 6-keto derivative of alliogenin) produced a significant increase in the weight of rat muscle and organ tissue (heart, liver, and kidney). No significant androgenic effect was seen. It is unknown if this translates into a potential anabolic effect in humans.
Further research is needed to determine if any of the individual steroidal sapogenins have ergogenic effects in humans.
Empirical Evidence:
Steroidal sapogenins are not readily available as stand-alone nutritional supplements. In virtually all sports nutrition products that contain them, they are complexed with other potential ergogenic compounds. This means that even an anecdotal assessment of their individual anabolic or performance-enhancing properties is very difficult to make. Many researchers in the field (including myself) are reserved about the potential anabolic action of these steroid-like plant compounds, but do recommend further research. An Empirical Evidence Rating is presently unavailable for steroidal sapogenins.
Effective Dosage:
Effective dosages for these supplement compounds have not been established.
Side Effects / Safety:
Diosgenin appears to be well tolerated, with few side effects reported.504 None of the other cited sapogenins has been the subject of peer-reviewed human safety evaluations.
