Antidiabetic Actions of Ethanol Extract of Camellia sinensis Leaf Ameliorates Insulin Secretion, Inhibits the DPP-IV Enzyme, Improves Glucose Tolerance, and Increases Active GLP-1 (7-36) Levels in High-Fat-Diet-Fed Rats

Novel Approaches for the Management of Type 2 Diabetes Mellitus: An Update

Diabetes mellitus is an irreversible, chronic metabolic disorder indicated by hyperglycemia. It is now considered a worldwide pandemic. T2DM, a spectrum of diseases initially caused by tissue insulin resistance and slowly developing to a state characterized by absolute loss of secretory action of the β cells of the pancreas, is thought to be caused by reduced insulin secretion, resistance to tissue activities of insulin, or a combination of both. Insulin secretagogues, biguanides, insulin sensitizers, alpha-glucosidase inhibitors, incretin mimetics, amylin antagonists, and sodium-glucose co-transporter-2 (SGLT2) inhibitors are the main medications used to treat T2DM. Several of these medication's traditional dosage forms have some disadvantages, including frequent dosing, a brief half-life, and limited absorption. Hence, attempts have been made to develop new drug delivery systems for oral antidiabetics to ameliorate the difficulties associated with conventional dosage forms. In comparison to traditional treatments, this review examines the utilization of various innovative therapies (such as microparticles, nanoparticles, liposomes, niosomes, phytosomes, and transdermal drug delivery systems) to improve the distribution of various oral hypoglycemic medications. In this review, we have also discussed some new promising candidates that have been approved recently by the US Food and Drug Administration for the treatment of T2DM, like semaglutide, tirzepatide, and ertugliflozin. They are used as a single therapy and also as combination therapy with drugs like metformin and sitagliptin.

Evaluation of acute oral toxicity, anti-diabetic and antioxidant effects of Aloe vera flowers extract

ETHNOPHARMACOLOGICAL RELEVANCE

Aloe vera (L.) Burm.f. is widely used in various traditional systems of medicine worldwide. Since over 5000 years ago, several cultures have used A. vera extract medicinally for conditions ranging from diabetes to eczema. It has been shown to reduce the symptoms of diabetes by enhancing insulin secretion and protecting pancreatic islets.

AIM OF THE WORK

This research study aimed to investigate the in-vitro antioxidant effect, the acute oral toxicity, and the possible pharmacological in-vivo anti-diabetic activity with histological examination of the pancreas of the standardized deep red A. vera flowers methanolic extracts (AVFME).

MATERIALS AND METHODS

The liquid-liquid extraction procedure and TLC technique were used to investigate chemical composition. Total phenolics and flavonoids in AVFME were quantified by Folin-Ciocalteu and AlCl₃ colorimetric methods, respectively. The present study involved evaluating the in-vitro antioxidant effect of AVFME using ascorbic acid as the reference standard, an acute oral toxicity study by using thirty-six albino rats and different concentrations of AVFME (200 mg/kg, 2, 4, 8 and 10 g/kg b.w.). Furthermore, the in-vivo anti-diabetic study was performed on alloxan-induced diabetes in rats (120 mg/kg, I.P.) and two doses of AVFME (200 and 500 mg/kg b.w., orally) were used as compared to glibenclamide (5 mg/kg, orally) as a standard hypoglycemic sulfonylurea medication. A histological examination of the pancreas was performed.

RESULTS

AVFME resulted in the highest phenolic content of 150.44 ± 4.62 mg gallic acid equivalent per gram (GAE/g) along with flavonoid content of 70.38 ± 0.97 mg of quercetin equivalent per gram (QE/g). An in-vitro study revealed that the antioxidant effect of AVFME was strong as ascorbic acid. The results of the in-vivo studies showed that the AVFME didn't cause any apparent toxicity signs or death in all groups at different doses which proves the safety of this extract with a wide therapeutic index. The antidiabetic activity of AVFME demonstrated a considerable drop in blood glucose levels as glibenclamide, without severe hypoglycemia or significant weight gain which is considered an advantage of AVFME over glibenclamide use. The histopathological study of pancreatic tissues confirmed the protective effect of AVFME on the pancreatic beta-cells. The extract is proposed to have antidiabetic activity through inhibition of α-amylase, α-glucosidase, and dipeptidyl peptidase IV (DPP-IV). Molecular docking studies were conducted to understand possible molecular interactions with these enzymes.

CONCLUSION

AVFME represents a promising alternative source of active constituents against diabetes mellitus (DM) based on its oral safety, antioxidant, anti-hyperglycemic activities, and pancreatic protective effects. These data revealed the antihyperglycemic activity of AVFME is mediated by pancreatic protective effects while significantly enhancing insulin secretion through increasing functioning beta cells. This suggests that AVFME has the potential as a novel antidiabetic therapy or a dietary supplement for the treatment of type 2 diabetes (T2DM).

Potential Hypoglycemic and Antilipidemic Activity of Polyphenols from Passiflora ligularis (Granadilla)

The consumption of fruits or by-products from plants of the Passifloraceae family has been associated with multiple health and nutritional benefits, due to their phenolic compound content. Likewise, the effects of polyphenols from Camellia sinensis (green tea) have been explored and are considered a reference for different biological actions of these bioactive substances. This study compared the hypoglycemic and antilipemic activity of polyphenol-rich extracts of Passiflora ligularis Juss (passion fruit) and Camellia sinensis (green tea) given to a group of Wistar rats induced to be overweight. The individuals were subjected to three doses of supplementation of both sources of polyphenols in the drinking water. An additional group without polyphenol supplementation served as a control group. Water consumption, weight gain, glycemia, cholesterol, serum triglycerides and percentage of fecal ethereal extracts were analyzed. Although Passiflora ligularis Juss had five times less polyphenol content than Camellia sinensis, rats fed doses of 2.5 and 3.0 g/L Passiflora ligularis Juss showed reduced glycemia by 16%, suggesting an antiglycemic activity similar to that of Camellia sinensis. On the other hand, higher doses of polyphenols from Passiflora ligularis Juss and Camellia sinensis significantly reduced triglyceride levels (p = 0.05) by more than 17% compared to the unsupplemented control group. The polyphenol-rich extracts produced effective inhibitory activity of lipemic metabolites with a reduction in the percentage of fecal lipids (p < 0.05), with no side effects on liver tissue. The 3.0 g/L dose produced the best result on signs of metabolic syndrome associated with excess weight. Polyphenols extracted from fresh Colombian passion fruit showed the potential to decrease metabolic syndrome risk factors in a murine model.