4-Hydroxyisoleucine: A Potential New Treatment for Type 2 Diabetes Mellitus.

4-Hydroxyisoleucine (4-HIL) is a compound found in Trigonella foenum-graecum (fenugreek) seeds, which have been used as part of traditional medicine to treat diabetes mellitus. The synthesis of 4-HIL on a large scale is possible using fermentation methods (artificial synthesis) involving the isolation of the L-isoleucine dioxygenase gene from Bacillus thuringiensis, which can yield a greater quantity of 4-HIL than that produced with conventional methods (82 % attained with fermentation methods vs. 0.6-39 % attained with conventional methods). In studies of rats and humans, T. foenum-graecum improved laboratory parameters associated with renal dysfunction and dyslipidemia, increased levels of antioxidants and hormones that are altered in patients with type 2 diabetes mellitus (T2DM), and decreased fasting blood glucose, 2-h postprandial plasma glucose, and glycated hemoglobin. Similarly, in in vitro and preclinical studies, 4-HIL decreased glucose levels, hepatic glucose production, glucose/insulin ratios, indicators of hepatic damage, triglycerides, and total cholesterol, and increased utilization of glucose and levels of high-density lipoprotein cholesterol. Studies in humans are needed to determine whether 4-HIL is safer and more effective than current medications for the treatment of T2DM.