Combined effects of clofibrate and diosgenin on cholesterol metabolism in rats

Therapeutic potential and research progress of diosgenin for lipid metabolism diseases

Diosgenin, a steroidal saponin, is a natural product found in many plants. Diosgenin has a wide range of pharmacological activities, and has been used to treat cancer, nervous system diseases, inflammation, and infections. Numerous studies have shown that diosgenin has potential therapeutic value for lipid metabolism diseases via various pathways and mechanisms, such as controlling lipid synthesis, absorption, and inhibition of oxidative stress. These mechanisms and pathways have provided ideas for researchers to develop related drugs. In this review, we focus on data from animal and clinical studies, summarizing the toxicity of diosgenin, its pharmacological mechanism, recent research advances, and the related mechanisms of diosgenin as a drug for the treatment of lipid metabolism, especially in obesity, hyperlipidemia, nonalcoholic fatty liver disease, atherosclerosis, and diabetes. This systematic review will briefly describe the advantages of diosgenin as a potential therapeutic drug and seek to enhance our understanding of the pharmacological mechanism, recipe-construction, and the development of novel therapeutics against lipid metabolism diseases.

Hypoglycemic effects of steroidal sapogenins isolated from Jamaican bitter yam, Dioscorea polygonoides

In this study, three steroidal sapogenins (Delta3 diosgenin, diosgenin, and pennogenin) and the phytosterols, stigmasterol and beta-sitosterol were isolated from Jamaican bitter yam, Dioscorea polygonoides. Their effects on fasting blood glucose and intestinal amylase and ATPases in streptozotocin-induced diabetic rats were studied. The diabetic rats (fed supplemented and unsupplemented diets) lost weight significantly compared to the normal group. There was a significant increase in the activity of alpha-amylase in the proximal region of the small intestinal mucosa of diabetic rats fed sapogenin extract or commercial diosgenin. However, this did not result in increased fasting blood glucose. Instead, supplementation of the diet with bitter yam sapogenin extract significantly decreased fasting blood glucose compared to the diabetic group. Supplementation of the diet with bitter yam sapogenin extract or commercial diosgenin significantly reduced Na+-K+-ATPase activity in all three regions compared to the diabetic control group. Commercial diosgenin supplementation resulted in a significant increase in Ca2+ ATPase activity in proximal region compared to the diabetic control and bitter yam sapogenin extract groups. The effect of bitter yam sapogenin extract or commercial diosgenin on intestinal Na+-K+-ATPase activity could account for their hypoglycemic properties. However, there was adverse effect on the body weight.

Evaluation of the lipid-lowering activity of AY-25,712 in rats

The effect of AY-25,712 (2-methyl-2-phenyl-3(2H)-furanone-5-carboxylic acid) on serum lipids, hepatic lipogenesis and biliary cholesterol was investigated in male rats. Based on one-week treatment, the minimal effective dose of AY-25,712 which lowered serum triglycerides was 1 mg/kg/day, and LDL-cholesterol, 5 mg/kg/day. Nicotinic acid produced a similar lipid-lowering profile albeit at 5 times higher doses. AY-25,712 at doses of 2 mg/kg/day and higher significantly increased the ratio of HDL to total cholesterol. Unlike clofibrate, AY-25,712 did not increase liver weight or liver mitochondrial alpha-glycerophosphate dehydrogenase, nor increase biliary cholesterol levels in rats fed a diet containing 2% cholesterol and 0.5% cholic acid. AY-25,712 lowered serum cholesterol, triglycerides and phospholipids in rats rendered hyperlipidemic with Triton WR-1339 and decreased the elevated serum triglycerides in streptozotocin-diabetic rats. [14C]Acetate incorporation into cholesterol by liver homogenate was suppressed in rats given AY-25,712 p.o. for 1 week. The results show that AY-25,712 is a potent LDL-cholesterol- and triglyceride-lowering agent in rats, and that its lipid-lowering profile differs from that of clofibrate but resembles that of nicotinic acid.

Studies on the disposition of diosgenin in rats, dogs, monkeys and man

Rats, dogs and squirrel monkeys were given a single oral dose of [4-(14)C]diosgenin. Virtually all of the radioactivity was excreted in the feces. All of the absorbed radioactivity was eliminated via the bile. The percent of dose absorbed decreased with increasing dose. The amount of radioactivity in livers of rats given [4-(14)C]diosgenin was less than that after [4-(14)C]cholesterol, but more than after [4-(14)C]beta-sitosterol. Absorbed radioactivity in rats distributed into tissues, most notably the liver, adrenals, and walls of the gastrointestinal tract. No serum diosgenin was detected after a single large dose to rats and dogs. After multiple doses (100 mg/kg/day for 4 weeks) of diosgenin to dogs, up to 15 micrograms/ml of unchanged diosgenin was found in serum. Serum from human subjects receiving 3 g/day of diosgenin for 4 weeks contained less than 1 microgram/ml of unchanged drug. After a single dose of [14C]diosgenin, several metabolites were detected in the bile of rats and dogs; the pattern of metabolites was dissimilar in the two species. No diosgenin or 7-hydroxydiosgenin was found. One of the major biliary metabolites was diosgenin monohydroxylated in the F ring, but the location of the hydroxyl group was different in the two species. Although rat caecal contents were capable of reducing diosgenin to smilagenin in vitro, no smilagenin was present in the feces of rats given chow supplemented with diosgenin. It was concluded that diosgenin is poorly absorbed in the species tested, and that the amount which is absorbed undergoes extensive biotransformation.