Karela is a single-herb formulation prepared from the fruit extract of Karela (Momordica charantia). Karela has insulin-secretagogue activity and is recommended in the management of prediabetes and type 2 diabetes. Karela increases glucose uptake in the liver, muscles, and fat cells. Karela enhances insulin sensitivity and is thus useful in the management of prediabetes and type 2 diabetes. Karela possesses potent free radical scavenging and iron-chelating activities, thereby showing potent antioxidant effect. Momordicosides present in Karela enhance fatty acid oxidation.
Pharmacological Actions
1. Prediabetes
Consumption of Karela as whole fruit, extract, or dried powder is known to reduce blood sugar levels. Karela juice and extract can stimulate peripheral glucose uptake and regulate the amount of glucose uptake by the gut. Karela has the potential to become a component of the diet or a dietary supplement for patients with prediabetic conditions.
2. Antidiabetic activity
Karela has been found to reduce blood glucose and lipids under diabetic conditions, protect B cells, enhance insulin sensitivity, and reduce oxidative stress. Karela stimulates glucose uptake in the liver, muscles, and fat cells.
A study indicates that Karela extract lowers blood glucose by depressing its synthesis, on one hand through the depression of the key gluconeogenic enzymes, glucose-6-phosphatase, and fructose-1,6 bisphosphatase, and on the other by enhancing glucose oxidation by the shunt pathway through activation of its principal enzyme glucose-6 phosphate dehydrogenase.
Karela extract has significant repairing effects on HIT-T15 cells against superoxide anion radicals, which did not correlate to Karela extract's superoxide dismutase (SOD) activity. A study hypothesized that the different fractions of Karela extract may make different contributions to its cell-repairing activity and its ability to stimulate insulin secretion.
Another study demonstrates that Karela increases glucose utilization in the liver, which contributes to its hypoglycemic action.
Karela extract is found to significantly reduce the levels of blood glucose, glycosylated hemoglobin, lactate dehydrogenase, glucose-6-phosphatase, fructose-1,6-bisphosphatase, and glycogen phosphorylase; concomitantly increase the levels of hemoglobin and glycogen; and activate hexokinase and glycogen synthase. These results clearly show the antidiabetic properties of Karela
Four cucurbitane glycosides-momordicosides Q, R, S, and T-and stereochemistry-established karaviloside XI were isolated from M charantia to study their antidiabetic properties. These compounds and their aglycones exhibit a number of biological effects beneficial in the management of diabetes and obesity. In both, L6 myotubes 3T3-L1 adipocytes, stimulate GLUT4 translocation to the cell membrane, an essential step for inducible glucose entry into cells. This is associated with increased activity of AMP-activated protein kinase (AMPK), a key pathway mediating glucose uptake and fatty acid oxidation. Furthermore, momordicoside(s) enhances fatty acid oxidation and glucose disposal during glucose tolerance tests in both insulin-sensitive and insulin-resistant mice. These findings indicate that cucurbitane triterpenoids, the characteristic constituents of Karela, may provide a lead as a class of therapeutics for diabetes and obesity.
Another study shows that Karela extract is effective in ameliorating the high-fat diet-induced hyperglycemia and hyperleptinemia and decreases the levels of blood glycated hemoglobin (HbA1c) and free fatty acid, whereas it increases the adipose peroxisome proliferator-activated receptor (PPAR)-7
and liver PPAR-a mRNA level. Additionally, e Karela is found to significantly decrease the nic weights of epididymal white adipose tissue and ,6- visceral fat and decrease the adipose leptin and resisting mRNA level. It is suggested that at least a 1 portion of these effects could be through PPAR-y mediated pathways, resulting in lowering the glucose level and improving insulin resistance, partly through PPAR-a-mediated pathways to improve plasma lipid profiles. This demonstrates that Karela extract can influence dual PPAR-a/PPAR-y expression, and the mediated gene expression is effective in ameliorating insulin resistance and visceral obesity?
In a study, Karela extract was orally mulate administered to overweight rats to assess the effect of the extract on the body weight of rats. Five weeks of treatment not only showed a significant decrease in the body weight of rats, but also a significant decrease in blood glucose, total cholesterol, and low-density lipoprotein cholesterol levels. However, there was an increase in the high globin, density lipoprotein cholesterol level in the serum."
3. Antihyperlipidemic activity
Karela extract has been shown to have, besides its hypoglycemic property, strong hypolipidemic action on diabetic hypertriglyceridemia and hypercholesterolemia."
4. Antioxidant activity
A study revealed that treatment with Karela extracts significantly decreases the levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and alkaline phosphatase (ALP) in hyperammonemic rats by reversing the oxidant-antioxidant imbalance in ammonium chloride-induced hyperammonemia. It is suggested that Karela extract offers protection against hyperammonemia by preserving the structural integrity of the hepatocellular membrane against the damage caused by ammonium chloride. This shows the potent antioxidant activity of the Karela extract, 10
In another study, the Karela extract is shown to possess potent diphenylpicrylhydrazyl radical scavenging activity and iron-chelating activity, thereby exhibiting potent antioxidant activity
A study showed that Karela extract causes a significant increase in hepatic antioxidant enzymes such as SOD, catalase (CAT), and glutathione peroxidase (GPx) activities. The strongest increase (about 9-fold) is observed in GPx activity, while about 2-fold to 5-fold increases were observed in SOD and CAT activities. Karela extract also exhibits a hepatoprotective effect. In addition, about 50% increase is also noted with hepatic cytosolic glutathione & TM-L S-transferases. On the other hand, treatment with Karela significantly reduces both ethoxyresorufin O-deethylase and methoxyresorufin O-deethylase activities in liver microsomes, which are known to be catalyzed by CYP1A isoforms. These results suggest that Karela extract possesses antioxidant activity
Indications
- Prediabetes
- Type 2 diabetes
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