Phytochemical study of bioactive constituents from Satureja montana L. Growing in Egypt and their antimicrobial and antioxidant activities

Abstract

Objective: This work aimed to investigate the lipid constituents and flavonoidal compounds of Satureja montana, in addition to evaluation of different extracts and/or isolated compounds as antimicrobials and antioxidants. Methods: The volatile and lipid constituents were extracted with n-hexane by partition from hydroalcoholic extract of S. montana L. aerial parts, after then were fractionated to unsaponifiable matters and fatty acid methyl esters which were identified by gas–liquid chromatography and/or gas chromatography–mass spectrometry. The phenolic constituents were isolated from the ethyl acetate fraction of the aqueous methanolic extract of the aerial parts of the plant. The antimicrobial activity of different extracts and the isolated compounds was evaluated against Gram-positive, Gramnegative bacteria, yeast, and fungus using a modified Kirby-Bauer disc diffusion method. Results: The identified compounds are luteolin-7-rhamnoside-4’-O-β-glucopyranoside (1), quercetin-3-O-α-L-rhamnopyranoside (2), quercetin- 7-O-glucopyranoside (3), luteolin-7-O-glucopyranoside (4), 5-hydroxy-6,7,8,4’-tetramethoxy flavone (5), gallic acid (6), 2,3-hexahydroxydiphenoyl 1-galloyl glucopyranoside (7), and quercetin (8). The structure of all isolated compounds was established using different chromatographic and spectroscopic measurements (PC, thin-layer chromatography, ultraviolet [UV], 1D, 2D-nuclear magnetic resonance, and MS). Compound-2 showed the highest antibacterial activity against all the tested microorganisms. Hydroalcoholic extract exhibited high antioxidant activity (87.7%). On the other hand, hexane fraction showed a low antioxidant activity (46.4%), in addition to the compound-8 showed the highest antioxidant activity (96.27%) in 2,2-diphenyl-1-picrylhydrazyl assay. Conclusion: It can be concluded that the hydroalcoholic extract of S. montana showed significant antimicrobial and antioxidant activity.