Antimicrobial, antioxidant, -amylase and -glucosidase inhibitory activities of a chemically characterized essential oil from Lavandula angustifolia Mill.,: in vitro and in silico investigations

Lavandula angustifolia is a medicinal plant widely known by its medicinal virtues against various pathogenesis, including diabetes, cancer and infectious diseases. In this study we aimed to explore the volatile profile of L. angustifolia essential oil (EO) as well as its in vitro and in silico antimicrobial, antioxidant and antidiabetic effects. The chemical constituents were investigated through Gas Chromatography-Mass Spectrometry (GC/MS) analysis. Three complementary antioxidant tests, namely DPPH, FRAP and inhibition of lipid peroxidation assays were used to reveal the antioxidant ability of L. angustifolia EO. The antidiabetic effect of this oil was determined using alpha-amylase and alpha-glucosidase enzymes. Molecular docking and ADMET analysis were used to confirm the experimental effects. The antibacterial and antifungal activities of L. angustifolia EO were evaluated against a range of Gram-positive and Gram-negative bacteria, and yeasts, including Bacillus cereus, Micrococcus luteus, Staphylococcus aureus, Salmonella enterica, Escherichia coli, Klebsiella aerogenes, Candida albicans, and Candida tropicalis using the disc-diffusion and broth-microdilution assays. GC-MS analysis revealed a plethora of chemical components, where linalool (28.94%), linalyl acetate (19.95%) and caryophyllene (6.46%) are the major constituents. The L. angustifolia EO demonstrated promising antioxidant properties against DPPH, FRAP and lipid peroxidation. Moreover, this oil exhibits significant antidiabetic activity against alpha-amylase and alpha-glucosidase enzymes (p < 0.05). Results demonstrated significant action against all tested microorganisms, with inhibition zones ranging from 19.1 +/- 1.0 to 13.4 +/- 0.9 mm for bacteria and from 24.10 +/- 0.9 to 19.05 +/- 1.03 mm for fungi. Moreover, low values of minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and minimum fungicidal concentration (MFC) varying from 0.125 to 1.0% (v/v) for bacteria and from 0.25 to 2.0% (v/v) for fungi were attained. Analysis of the MBC/MIC and MFC/MIC ratios suggested the presence of a bactericidal and fungicidal mechanism. In light of these findings, L. angustifolia EO could be used as a natural source for the development of novel and effective antimicrobial, antioxidant and antidiabetic agents.