Phenolic content, acute toxicity of Ajuga iva extracts and assessment of their antioxidant and carbohydrate digestive enzyme inhibitory effects

The management of blood glucose level is the hallmark in the treatment of type 2 diabetes, and this may be achieved through the inhibition of the digestive enzymes involved in carbohydrate metabolism. The aim of this work is the investigation of phenolic compounds content, antioxidant activity and for the first time, the in vitro anti-hyperglycemic potential of aerial part of Ajuga iva Schreber extracts through the inhibition of digestive enzymes (α-amylase and α-glucosidase), responsible of the digestion of poly and oligosaccharides. Test for total phenolic content showed that the methanol extract has the highest polyphenolic and flavonoid concentrations with (65.3 mg GAEs/g extract and 132.6 mg REs/g extract). The methanol extract has also exhibited the higher antioxidant activity compared to the aqueous extract in different tests with (IC50 = 0.187 ± 0.016 mg/mL; 62.19 ± 0.45 mg TE/g extract; 89.12 ± 0.23 mg AAE/g extract) in DPPH, ABTS and FRAP tests, respectively. Ajuga iva extracts exhibited a remarkable inhibitory activity against key digestive enzymes linked to type 2 diabetes, with a more potent inhibitory effect against α-glucosidase and a considerable inhibition against α-amylase. The results indicated also that the tested extracts are non-toxic with an LD50 higher than 2 g/kg in female Swiss mice. These results suggested that the phenolic compounds in A. iva extracts maybe behind the antioxidant and antidiabetic activities. However, further investigations regarding the bioactive compounds and their mechanisms of action are required for developing new natural drugs against diabetes-related hyperglycemia.