Bitter Melon and Diabetes Mellitus

Bitter melon (Momordica charantia) has traditionally been used in the management of diabetes in many countries and territories. However, standardized information on the use of this vegetable as an antidiabetic drug is still very limited. Many animal studies and clinical trials have showed the remarkable effect of bitter melon on diabetes. The research results showed that bitter melon could enhance insulin sensitivity, repair damaged pancreas islet β-cells and stimulate insulin secretion. What’s more, bitter melon could reduce hyperglycemia by regulating intestinal flora, inhibiting glucosidase and amylase, scavenging free radicals, enhancing the activity of AMP-activated protein kinase (AMPK) and increasing expression of peroxisome proliferator-activated receptors (PPARs). In addition, it could also act as the glucagon-like peptide 1 receptor (GLP-1 R) agonist and the 11-hydroxysteroid dehydrogenase type 1 (11β-HSD1) inhibitor to exert hypoglycemic effects. Therefore, we will discuss the hypoglycemic mechanisms of crude extracts and different phyto-metabolites derived from bitter melon in the paper.Abbreviations:AEBM, aqueous extract of bitter melon; AGEs, total advanced glycation end products; Akt, protein kinase B; ALT, alanine aminotransferase; ALX, alloxan; AMPK, adenosine monophosphate-activated protein kinase; aPKC, atypical protein kinase C; AST, aspartate aminotransferase; AUC, areas under the curve; β-CD, β-cyclodextrin; BCAAs, branched-chain amino acids; BM, bitter melon; BMI, body mass index; BMJ, bitter melon juice; BMP, bitter melon powder; BW, body weight; DBP, diastolic blood pressure; DM, diabetes mellitus; Erk1/2, extracellular signal-regulated kinase 1/2; FBG, fasting plasma glucose; FP, fermented polysaccharide; FPG, fasting plasma glucose; GLP-1R, glucagon-like peptide 1 receptor; GLUT4, glucose transporter 4; GSK-3, glycogen synthase kinase-3; HbA1c, glycated hemoglobin A1c; HDL, high-density lipoprotein; HFD, high-fat diet; IKK, IkB kinase; IL, interleukin; IRS, insulin receptor substrate; JNK, c-Jun N-terminal kinase; LDL, low-density lipoprotein; M, male; MC, Momordica charantia; polysaccharide; MCS, Momordica charantia saponin; MDA, malondialdehyde; MET, metformin; NA, nicotinamide; NF-κB, nuclear factor κB; PDK-1, phosphoinositide-dependent protein kinase-1; PI3-K, phosphoinositide 3-kinase; PIP3, phosphatidylinositol (3,4,5)-trisphosphate; PPAR, peroxisome proliferator-activated receptor; PPG, post-prandial plasma glucose level; PTP, phosphatase; SBP, systolic blood pressure; SCFAs, short-chain fatty acids; SOCS-3, suppressor of cytokine signaling-3; SOD, superoxide dismutase; STZ, streptozotocin; TC, total cholesterol; TG, triglyceride; TNF-α, tumor necrosis factor-α; TPC, total phenolic content; TTC, total triterpene content; UACR, urine albumin-to-creatinine ratio; WC, waist circumference; 11β-HSD1, 11-hydroxysteroid dehydrogenase type 1.