Mineral Composition, in vitro Inhibitory Effects of α-Amylase, α-Glucosidase, β-Galactosidase Enzymes and Antibacterial Activity of Ajuga Iva Subsp. Pseudoiva (DC.) Bric.

Abstract

In this study, we investigated the mineral composition, in vitro antidiabetic activity, and antibacterial potential of the aerial part of Ajuga iva. The mineral content of the plant powder was quantified using Inductively Coupled Plasma Atomic Emission Spectrometry. Then, three aqueous extracts were prepared: decocted, infused, and macerated and five organic: methanolic, ethyl acetate, chloroformic, and petroleum ether obtained by Soxhlet, and methanolic macerated extract. The in vitro hypoglycemic effect of the extracts was evaluated on α-amylase, α-glucosidase, and β-galactosidase, then the antibacterial activity was studied by the disk diffusion method, the minimum inhibitory concentrations (MICs) and bactericidal concentrations (MBCs) against six pathogenic bacteria, and finally, the correlation between the chemical composition and the inhibitory activities of different extracts on three enzymes was evaluated using Principal Component Analysis (PCA). The results obtained revealed that iron (112.00 mg/l) is the main mineral element, followed by potassium (44.071 mg/l) and sodium (16.572 mg/l). The results of in vitro antidiabetic activity showed that ethyl acetate extract presented the highest inhibitory activities against α-amylase and α-glucosidase with IC50 equal to 1475.67±94.21µg/ml and 140.50±32.25µg/ml respectively, while methanolic macerated extract showed high inhibitory activity against β-galactosidase. The results of the PCA analysis showed that the in vitro antidiabetic activity shows a linear relationship with the content of polyphenols, flavonoids, and tannins in Ajuga iva extracts. The study of the antibacterial effect showed that the five organic extracts have an inhibitory effect towards the microorganisms tested with zones of inhibition vary between 7 and 14 mm, except for Staphylococcus aureus that presented resistance to the five extracts. Furthermore, the MICs obtained range from 1.56 to 50 mg/ml, and the MBCs vary from 50 to 200 mg/ml. These results indicate that polar organic extracts of Ajuga iva have significant antidiabetic and antibacterial activities.