**5. Antidiabetic (Hypoglycemic) activity**

Diabetes mellitus is known as a metabolic disease that is the fastest growing diseases in the world, and is characterized by hyperglycemia resulting from defects in insulin secretion and insulin action [55]. Drugs obtained from the plants used all over the world to treat diabetes. Bitter melon is used to treat many diseases with good medicinal values, but more emphasis is given to its anti-diabetic properties. As an antidiabetic drug, bitter melon has been widely used in different countries for thousands of years is suggested as a remedy for the treatment of diabetes [56].

It contains active compounds, including charantin that reduce blood sugar levels. In addition, bitter melon contains lectin which also reduce blood glucose level that is a major factor of hypoglycemic effect [57]. Some other compounds present in bitter melon such as steroids, inorganic, triterpene, proteid, lipid and phenolic compounds also offer anti-diabetic properties. The aqueous extract of bitter melon fruits is reported to stimulate insulin secretion of β cells in pancreatic islets isolated from obese-hyperglycemic mice [23, 24, 57]. Antidiabetic mechanism of bitter melon extracts is suggested to enhance insulin secretion by the islets of Langerhans, reducing glycogenesis in liver tissue, enhancing peripheral glucose utilization and increasing serum protein levels [23, 24, 57].

Oral administration of the aqueous extract *M. charantia* fruits are observed to lower blood glucose level in diabetic rats [24]; they are shown to stimulate insulin secretion of β cells in pancreatic islets isolated from obese-hyperglycemic mice [24]. They are also indicated to play a role in the renewal of β cells in diabetic rats or recovery of destroyed β cells [24]. *M. charantia* fruit juice is examined to reduce blood glucose levels in diabetic rats due to enhancing insulin secretion by the islets of Langerhans, reducing glycogenesis in liver tissue, enhancing peripheral glucose utilization and increasing serum protein levels [23, 24, 57].

## **6. Antihyperlipidemic activity and weight loss**

Hyperlipidemia is a major health problem and associated with diabetes due to increase in morbidity and mortality. High blood lipid concentration is associated with cerebrovascular disease, ischemic heart diseases, and atherosclerosis. *M. charantia* is proved to have an antihyperlipidemic effect. A component of *M. charantia*, metformin, and other components such as alkaloids, flavonoids, saponins, tannins, and triterpenes have suggested to lower total cholesterol level in diabetic rats. Moreover, bitter melon has been described to repair damaged β-cells, resulting in increasing the levels of insulin and its sensitivity [23, 56, 57]; by enhancing the release and synthesis of thyroid hormones and adiponectin, and also by inhibiting the activity of glucosidase that inhibits the absorption of glucose. The action of AMPK (adenosine-5-monophosphate kinase) is shown to be increased by bitter melon consumption that is associated with fat release from fatty tissues and glucose uptake and thus resulting in weight loss [23, 24]. Diabetic rats that are treated with *M. charantia* extract are also exhibited significant reduction of blood lipid levels [23, 24]. Bitter melon has also shown to reduce the cholesterol and trigliceride levels by increasing Apo-A-1 (Apo lipoprotein A-1) which is basic protein component compulsory for HDL synthesis [23, 24]. Recently, it is observed that bitter melon has ability to reduce body weight and the accumulation of high fat due to its anti-hyperlipidemic activity [24].

*Bitter Melon: A Multifunctional Medicinal Plant with Powerful Bioactive Compounds DOI: http://dx.doi.org/10.5772/intechopen.98812*
