Dioscorea root extract benefit and side effects by Ray Sahelian, M.D. research studies
June 17 2015

Diosgenin is a steroidal saponin, which is extracted from the root of Wild Yam (Dioscorea villosa) and other species.
Dioscorea is a genus of flowering plants, and some Dioscorea species are known and used as a source for the steroidal sapogenin diosgenin. Diosgenin is found in several Dioscorea species and one Heterosmilax species, namely D. zingiberensis, D. septemloba, D. collettii and H. yunnanensis.

Liver protection
Int Immunopharmacol. 2014. Protective effects of the total saponins from Dioscorea nipponica Makino against carbon tetrachloride-induced liver injury in mice through suppression of apoptosis and inflammation.

For a list of herbs used in Chinese medicine, see Chinese Herbs.

Dioscorea research studies
Antioxidant activity of dioscorea and dehydroepiandrosterone (DHEA) in older humans.
Life Sci. 1996.
Araghiniknam M, Chung S, Nelson-White T, Eskelson C, Watson RR.
Arizona Prevention Center, University of Arizona, School of Medicine, Tucson
Dioscorea is a yam steroid extract used in commercial steroid synthesis and consumed by people. DHEA is a steroid which declines with age, but without known activity. This study was designed to determine whether dioscorea supplementation could increase serum dehydroepiandrosterone sulfate (DHEAS) in humans and modulate lipid levels in older people. The subjects were selected volunteers aged 65-82 years. The serum DHEAS level, lipid peroxidation and lipid profile were assessed. Three weeks of dioscorea supplementation had no affect on serum DHEAS level. However DHEA intake of 85 mg/day increased serum DHEA levels 100.3%. DHEA and dioscorea significantly reduced serum lipid peroxidation, lowered serum triglycerides, phospholipid and increased HDL levels. Both DHEA and the steroid yam extract, dioscorea, have significant activities as antioxidant to modify serum lipid levels.

Toxicology Int. 2014. Protective effects of dioscorea alata L. In aniline exposure-induced spleen toxicity in rats: a biochemical study.

Dioscorea alata (water yam) (Chinese yam)
Chinese yam (Dioscorea alata cv. Tainung No. 2) feeding exhibited antioxidative effects in hyperhomocysteinemia rats.
J Agric Food Chem. 2004.
Antioxidative effects of Dioscorea alata (D. alata) were investigated in hyperhomocysteinemia (HHcy) induced by methionine (Met) oral feeding (1 (g/kg of BW)/day). These results indicated that HHcy induced by Met could be reversed by Dioscorea alata feeding. Dioscorea alata feeding exhibited its antioxidative effects in HHcy including alleviating PA, lipid peroxidation, and oxidative stress, but did not induce activity of antioxidant enzymes which had already adaptively increased by HHcy.

Both dioscorin, the tuber storage protein of yam (Dioscorea alata cv. Tainong No. 1), and its peptic hydrolysates exhibited angiotensin converting enzyme inhibitory activities.
J Agric Food Chem. 2002.
Dioscorin, the tuber storage protein of yam, was purified to homogeneity by DE-52 ion-exchange chromatography. This purified dioscorin was shown by spectrophotometric methods to inhibit angiotensin converting enzyme (ACE) in a dose-dependent manner (12.5-750 microg, respectively, 20-62% inhibitions) using N-[3-(2-furyl)acryloyl]-Phe-Gly-Gly (FAPGG) as substrates. The 50% inhibition (IC(50)) of ACE activity was 6 microM dioscorin (250 microg corresponding to 7.81 nmol) compared to that of 0.00781 microM (0.0095 nmol) for captopril. The commercial bovine serum albumin and casein (bovine milk) showed less ACE inhibitory activity. The use of qualitative TLC also showed dioscorin as ACE inhibitors. Dioscorin showed mixed noncompetitive inhibitions against ACE; when 31.25 microg of dioscorin (0.8 microM) was added, the apparent inhibition constant (K(i)) was 2.738 microM. Pepsin was used for dioscorin hydrolysis at 37 degrees C for different times. It was found that the ACE inhibitory activity was increased from 51% to about 75% during 32 h hydrolysis. The smaller peptides were increased with increasing pepsin hydrolytic times. Dioscorin and its hydrolysates might be a potential for hypertension control when people consume yam tuber.

Effects of "Chinese yam" on hepato-nephrotoxicity of acetaminophen in rats.
Acta Pharmacol Sin. 2002.
To study the effect of yam in Taiwan, which is a commonly used Chinese medicine, on hepato-nephro-toxicity in rats. Crude water extract of yam (Dioscorea alata), was used to treat rats with an acute toxicity induced by acetaminophen (APAP) challenge. The pharmacological and biochemical studies showed the extract of yam had the effect of kidney secureness and liver fortification. The pathologic sections showed good improvements in renal tubular degranulation changes, necrosis and disintegration. The extract of yam also possessed a good protection against the inflammation of central vein and necrosis of liver tissue. The liver and kidneys are originated from the same source. Pathologically, deficiency of the life essence in the kidney may lead to the blood deficiency in the liver. The results showed that the yam could prevent the damages of the liver and kidneys, thus preserving their functions. This could b e the reason why the yam was commonly used in traditional Chinese medicine, as seen in Liuwei Dihuang Wan be used in the case of deficiency of liver-yin and kidney-yin.Antifungal properties of yam (Dioscorea alata) peel extract.

Folia Microbiol (Praha). 1996.
The extraction of natural antifungal compounds from the peels of yam (Dioscorea alata) and the effect of these compounds on both the vegetative and reproductive structures of some yam not pathogens were studied. Four prominent antifungal components were obtained; one of the components was fully characterized and identified as beta-sitosterol. The antifungal activity of the compounds toward the germination of spores of two yam pathogens showed an inhibition of less than 57% at a concentration of 50 mg/L while inhibition on the elongation of germ-tubes of Fusarium moniliforme was as high as 82% at the same concentration. However, the ED50 for inhibition of germ-tube elongation in the yam compounds for the same organism was below 32 mg/L. The role of the yam compounds at high concentrations in disease resistance is discussed.

Nutritional assessment of yam (Dioscorea alata) tubers.
Plant Foods Hum Nutr. 1994.
The nutrient and antinutrient components of tubers from seven cultivars of Dioscorea alata were determined. The average crude protein content of D. alata tubers was 7.4%. Starch (75-84%) was the predominant fraction of the tuber dry matter. Significant differences in crude protein and starch contents were observed among cultivars. Vitamin C content of the yam tubers ranged from 13 to 24 mg/100 g fresh weight. The results showed yams to be reasonably good sources of minerals. Phytic acid contents of the yams were low, with values ranging from 58 to 198 mg/100 g dry matter. Total oxalate levels in yam tubers were found to be in the range of 486-781 mg/100 g dry matter, but may not constitute a nutritional concern since 50-75% of the oxalates were in the water-soluble form. The overall results are suggestive of the nutritional superiority of yams compared to other tropical root crops.

Dioscorea batatas
Yam (Dioscorea batatas) tuber mucilage exhibited antioxidant activities in vitro.
Planta Med. 2002.
The yam (Dioscorea batatas Decne) tuber mucilage (YTM) was extracted and partially purified by SDS and heating treatments. These results suggest that mucilage of yam tuber might play roles as antiradicals and antioxidants.

Antioxidant activities of dioscorin, the storage protein of yam (Dioscorea batatas Decne) tuber.
J Agric Food Chem. 2001.
Dioscorin, the storage protein of yam (Dioscorea batatas Decne) tuber (which is different from dioscorine found in tubers of Dioscorea hirsuta), was purified. It is suggested that 32 kDa dioscorin, the storage protein of yam tuber, may play a role as antioxidant in tubers and may be beneficial for health when people take it as a food additive or consume yam tubers.

Dioscorin, the major tuber storage protein of yam (Dioscorea batatas decne) with carbonic anhydrase and trypsin inhibitor activities.
J Agric Food Chem. 1999.
Dioscorin, the tuber storage protein of yam (Dioscorea batatas Decne), was purified successively.

Dioscorea bulbifera
[Anticancer effects of various fractions extracted from Dioscorea bulbifera on mice bearing HepA]
Zhongguo Zhong Yao Za Zhi. 2004.
To investigate the anti-cancer activities and the possible mechanism of Chinese herb Dioscrea bulbifera. The herb was extracted sequentially with petroleum ether, ethanol and water. The anticancer screen were carried out in vivo with HepA in mice. The inhibitory effects on the formation of ascites volume and HepA cell viability in ascites were found in those extracted fractions except water fraction, the petroleum ether fraction being the strongest. Life span of mice bearing HepA ascites was prolonged after exposed to 100 mg x kg(-1) petroleum ether fraction and shortened after exposed to water fraction significantly. Besides, abnormal microstructure on HepA cells surface was found and it was supposed to be potential effect against viability of HepA which was convinced with the regeneration of HepA cells from ascites in mice exposed to petroleum ether fraction. Anticancer active compounds are mainly extracted by petroleum ether from hydrophobic constituents of Dioscrea bulbifera and the anticancer effects were related to direct toxicity on tumor cell.

Experimental pathological study of subacute intoxication by Dioscorea bulbifera
Fa Yi Xue Za Zhi. 2003.
To study the pathological change and the toxic mechanism of Dioscorea bulbifera in mice. Sixty ICR mice were randomly assigned to four groups poisoned respectively with 200% Dioscorea bulbifera L of 1/4 LD50, 1/10LD50, 1/30LD50 and a control group treated with distilled water by oral administration. All animals were pathologically examined with LM and some of them were examined with TEM when the mice died during the experiment or the survival mice were sacrificed after thirty days. The pathological changes showed fatty change and the increasing glycogen of liver cells; degeneration and necrosis of the epithelia of uriniferous tubules. The serum BUN and ALT of the experimental groups mice were higher than that of control group. Enzyme histochemical staining showed the decreasing activity of G-6-P and SDH in the liver cells in the experimental groups. The experiment suggests that the target organs were liver and kidney. The toxic mechanism of Dioscorea bublifera L was the damage of the mitochondrional and endoplasmic reticulum membrane directly. As a result, the activity of the SDH and G-6-P decreased, the metabolism was affected.

Antitumor-promoting constituents from Dioscorea bulbifera in JB6 mouse epidermal cells.
Biol Pharm Bull. 20023.
An antitumor-promoting effect was found in the extracts/ingredients of a plant used as a traditional medicine in mainland China, using the neoplastic transformation assay of mouse epidermal JB6 cell lines. The ethyl acetate soluble fraction of 75% ethanol extract of the rhizomes of Dioscorea bulbifera showed an inhibitory effect against the tumor promotion of JB6 (Cl 22 and Cl 41) cells induced by a promoter, 12-O-tetradecanoylphorbol-13-acetate (TPA). Further investigation on the constituents of the EtOAc fraction from the rhizomes revealed the chemical structure to be kaempferol-3,5-dimethyl ether (1), caryatin (2), (+)-catechin (3), myricetin (4), quercetin-3-O-galactopyranoside (5), myricetin-3-O-galactopyranoside (6), myricetin-3-O-glucopyranoside (7) and diosbulbin B (8). Constituent antitumor-promoting activities were also examined in the same way. Compounds 1-7, characterized as flavonoids with the two hydroxyl groups at C-7 and C-4', showed the most potent inhibitory effect, but there seemed to be differences in the inhibitory effect between flavonol aglycones and flavonol glycosides. Compared with epicatechin, catechin exhibited much stronger inhibitory activity which suggested that chemical stereo structures of compounds affect the efficiency of inhibition. Compound 8 showed moderate activity. The constituents with antitumor-promoting activity from this plant are reported for the first time.

Dioscorea dumetorum
Pharmacological evaluation of Dioscorea dumetorum tuber used in traditional antidiabetic therapy.
J Ethnopharmacol. 1986.
This study was undertaken to confirm or otherwise disprove the alleged effectiveness of Dioscorea dumetorum tuber in the traditional treatment of clinical diabetes mellitus. Hydroalcoholic extracts of the tuber were fractionated by precipitation or solvent partition and the various extracts or fractions subjected to phytochemical and pharmacological tests. Whereas the alkaloid-containing fraction was hyperglycaemic in fasting normal mice, the whole extract and the fractions containing steroidal derivatives evinced significant hypoglycaemic activities in fasting normal mice or rabbits and in fasting alloxan-diabetic rabbits. The hypoglycaemic action of the glycosidic portion in particular was prompt and potent, in normal as well as in severely alloxan-diabetic rabbits suggesting thereby the possibility of obtaining an agent that could act in conditions of even severe insulin lack.

Dioscorea villosa
The effects of sustained delivery of diosgenin on the adrenal gland of female rats.
Biomed Sci Instrum. 2003.
University of Mississippi Medical Center, Jackson, MS
Diosgenin has been reported to have tremendous medical applications. In addition, as an herbal extract it appears to be free of any major adverse effects. Recently, Wild Yam has been used to minimize post-menopausal symptoms and is sold unregulated over the counter at a variety of pharmacy and health food stores. The specific objectives of this study were to continuously deliver diosgenin to adult ovariectomized female rats for 45 days and follow changes in body weight, organ weight and histopathological changes in the adrenal gland. Adult female Sprague Dawley rats were divided into three equal groups (n = 54, 250-300 gm BW). Rats in group I served as the control group, animals in group II were ovariectomized and animals in group II were ovariectomized, and supplemented with tricalcium phosphate (TCP) drug delivery system loaded with 500 mg diosgenin. The results indicated that ovariectomized animals had a significant increase in body weight and spleen weights. Slight increases in wet adrenal weights were observed in the ovariectomized group compared to the control animals. Histopathological evaluation of the adrenal gland revealed an increase in the cortical and medullary adrenal areas of the ovariectomized group and a significant decrease in these areas in the diosgenin treated animals. The information is considered important because reduction in adrenal mass may poses a potential for major endocrine complications.

Effects of wild yam extract on menopausal symptoms, lipids and sex hormones in healthy menopausal women.
Climacteric. 2001 Jun.
Baker Medical Research Institute, St Kilda Central, Melbourne Victoria, Australia.
Many women seek alternatives to hormonal therapies for the management of menopausal symptoms. Among the treatments currently popular are extracts of wild yam (Dioscorea villosa), which are applied topically in the form of a cream. These preparations are known to contain steroidal saponins, including diosgenin, which has been claimed to influence endogenous steroidogenesis. However, there have been no studies of the safety or efficacy of these preparations in the management of menopausal symptoms. We therefore conducted a double-blind, placebo-controlled, cross-over study of the effects of a wild yam cream in 23 healthy women suffering from troublesome symptoms of the menopause. After a 4-week baseline period, each woman was given active cream and matching placebo for 3 months in random order. Diaries were completed over the baseline period and for 1 week each month thereafter, and blood and saliva samples were collected at baseline and at 3 and 6 months, for measurement of lipids and hormones. This study suggests that short-term treatment with topical wild yam extract in women suffering from menopausal symptoms is free of side-effects, but appears to have little effect on menopausal symptoms. It emphasizes the importance of careful study of treatments for menopausal symptoms if women are to be adequately informed about the choices available to them.

Dioscorea panthaica
Steroidal saponins from Dioscorea panthaica and their cytotoxic activity.
Pharmazie. 2004.
A new steroidal saponin, dioscoreside E (1), and a known compound, protodioscin (2), were isolated from an ethanol extract of the rhizomes of Dioscorea panthaica. Compounds 1 and 2 showed cytotoxic activity against a panel of tumor cell lines.

Dioscorea tokoro
Methanol extract of Dioscoreae Rhizoma inhibits pro-inflammatory cytokines and mediators in the synoviocytes of rheumatoid arthritis.
Int Immunopharmacol. 2004.
Dioscoreae Rhizoma (MDR), the root of Dioscorea tokoro MAKINO, has been used for the treatment of arthritis, muscular pain and urinary diseases in oriental medicine. The present work evaluates a methanol extract of Dioscoreae Rhizoma. MDR did not show any cytotoxic effect on mouse lung fibroblast cells (mLFCs) or human fibroblast-like synovial cells (hFLSCs). However, it significantly reduced the proliferation of hFLSCs stimulated by interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha). MDR significantly inhibited the production of TNF-alpha and IL-1beta as well as down-regulating the expression of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) in IL-1beta- and TNF-alpha-stimulated hFLSCs. MDR also effectively reduced the level of reactive oxygen species (ROS) in these cells. Taken together, these findings provide evidence that MDR may be a candidate for the treatment of rheumatoid arthritis (RA).

Rehmannia Endurance - With Dioscorea
Planetary Formulas
Planetary Formulas Rehmannia Endurance is based on the classic Chinese tonifer Rehmannia Six: Liu Wei Di Huang Wan, one of the most strengthening tonics of Chinese herbalism. Traditionally it was used for those who are tired and run down from overwork and inadequate rest due to a fast paced-lifestyle.

Supplement Facts:
Calcium 128 mg
Rehmannia Root 320 mg
Poria Cocos Sclerotium 160 mg
Tree Peony Root Bark 160 mg
Dioscorea Root 160 mg
Alisma Rhizome 160 mg
He Shou Wu Root (Fo Ti) 80 mg
Chrysanthemum Flower 64 mg
Ligustrum Seed 64 mg
Saw Palmetto Berry 48 mg
Lycii Fruit Extract 40 mg also known as goji berry and available as a supplement.
Cornus Fruit 18 mg

A number of diocorea species have been researched including:
dioscorea bulbifera
compositae dioscorea
D batatas
dioscorea opposita