Antioxidant properties and inhibitory effect of ethanolic extract of Struchium sparganophora (Ewuro Odo) leaf on α--amylase and α--glucosidase activities

Evaluation of chemical composition, in vitro antioxidant, and antidiabetic activities of solvent extracts of Irvingia gabonensis leaves

Irvingia gabonensis commonly referred to as wild mango or ogbono is a tropical plant with both nutritional and medicinal uses. The present study was designed to evaluate the chemical composition, in vitro antioxidant activity, and inhibitory activity of carbohydrate hydrolyzing enzymes related to diabetes by different extracts of the plant. From the results of the study, Total Phenolic Content (TPC) was highest in the aqueous and ethanol extracts (367.30 ± 00 mg/100g GAE) compared to the chloroform and n-hexane extracts whereas the Total Flavonoid Content (TFC) was highest (230.69 ± 0.18 mg/100g QE) in the ethanol extract. Analysis of the in vitro antioxidant activity showed that the ethanol extract also possessed the highest 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity (IC₅₀: 21.42 ± 0.05 μg/ml) and hydroxyl radical scavenging activity (81.43 ± 0.11%) compared to other solvent extracts. The aqueous extract had the highest (23.91 ± 0.04 mM Fe++ equivalent) ferric antioxidant reducing power (FRAP). However, the antioxidant activity of the extracts was significantly lower than that of the reference compounds used for the study (butylated hydroxytoluene and Gallic acid). In vitro antidiabetic activity of the extracts was measured based on inhibition of α-amylase and α-glucosidase. The aqueous extract had the highest α-amylase and α-glucosidase inhibitory activity followed by the ethanol extract compared to the chloroform and n-hexane extracts. The inhibitory activity of the aqueous extract against both enzymes was higher compared to the reference compound Acarbose. Gas Chromatography-Mass Spectrometry analysis of the extracts revealed the presence of chemical constituents including fatty acids, vitamin, phytosterols, aromatic compounds, glycosides. The interaction of these compounds with α-amylase and α-glucosidase was evaluated in silico by molecular docking. Phytosterols namely, campesterol, stimasterol and γ-sitosterol had the best binding affinities to α-amylase and α-glucosidase. In conclusion, the results of this study revealed that the aqueous and ethanol extracts of Irvingia gabonensis had the highest phenolic content, antioxidant activity, and in vitro antidiabetic activity. These results offer a scientific explanation for the mode of preparation and traditional use of the plant in the treatment of diabetes.

Hypoglycemic, antidyslipidemic, and antioxidant activities of methanol extract of Struchium sparganophora leaves in alloxan-induced oxidative stress-mediated diabetes in rats

Background

Diabetes mellitus is clinically underlined by hyperglycemia and dyslipidemia. In view of this, the current study assessed the glycemic and lipidemic control potentials of methanol extract of Sruchium sparganophora leaves (SPA) in the alloxan-induced diabetic model using male Wistar rats. Experimental diabetes was induced through a single intraperitoneal injection of 120 mg/kg freshly prepared alloxan. Thirty-six rats were randomly assigned into six groups of normoglycemic control, untreated diabetic group, and diabetic treated with (i) metformin (12 mg), (ii) metformin 12 mg + SPA 300 mg/kg, (iii) SPA 300 mg/kg, and (iv) SPA 600 mg/kg per os twice at 9.00 and 18.00 h daily for 10 days. Fasting blood glucose (FBG) level and markers of dyslipidemia, and oxidative stress markers were determined.

Results

SPA at selected doses decreased fasting blood glucose which was significantly (p < 0.05) raised by alloxan. Increase in plasma total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and triglyceride (TG) concentrations and decrease in HDL-cholesterol (HDL-C) concentration (p < 0.05) caused by alloxan were significantly moderated by SPA at selected doses. Glutathione-s-transferase (GST), superoxide dismutase (SOD), and catalase (CAT) activities reduced by alloxan (p < 0.05) in both the liver and pancreas were reversed by SPA 300 and 600, and its combination with metformin. Decreased reduced glutathione (GSH) concentration in alloxan diabetic rats was also reversed by the extract, while the level of malondialdehyde (MDA) exacerbated by alloxan (p < 0.05) in the tissues was decreased by the extracts.

Conclusion

Struchium sparganophora possesses considerable antihyperglycemic, antidyslipidemic, and antioxidant potentials without compromising organ functionality.

Screening of antidiabetic and antioxidant activities of medicinal plants

Diabetes is a common metabolic disorder characterized by abnormally increased plasma glucose levels. Postprandial hyperglycemia plays an essential role in development of type-2 diabetes. Inhibitors of carbohydrate-hydrolyzing enzymes (such as α-glucosidase and α-amylase) offer an effective strategy to regulate/prevent hyperglycemia by controlling starch breakdown. Natural α-amylase and α-glucosidase inhibitors, as well as antioxidants from plant-based sources, offer a source of dietary ingredients that affect human physiological function in order to treat diabetes. Several research studies have investigated the effectiveness of plant-based inhibitors of α-amylase and α-glucosidase, as well as their antioxidant activity. The aim of this review is to summarize the antidiabetic and antioxidant properties of several medicinal plants around the world. Half inhibitory concentration (IC50, for enzyme suppression) and half effective concentration (EC50, for antioxidant activity) values of less than 500 μg/mL were defined as the most potent plant-based inhibitors (in vitro) and are expected to provide interesting candidates for herbal treatment of diabetes, as foods, supplements, or refined drugs.