Screening of antibacterial compounds in Salvia officinalis L. tincture using thin-layer chromatography-direct bioautography and liquid chromatography-tandem mass spectrometry techniques

Abstract

Thin-layer chromatography-direct bioautography (TLC-DB) followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used for screening and tentative identification of the antibacterial constituents of Salvia officinalis L. ethanol extract. Seven bacterial strains were used as test organisms, both pathogenic and nonpathogenic, that is, Staphylococcus aureus, methicillin-resistant S. aureus (MRSA), Staphylococcus epidermidis, Micrococcus luteus, Bacillus subtilis, luminescence gene-tagged Pseudomonas syringae pv. maculicola, and naturally luminescent marine bacterium Aliivibrio fischeri. Eight fractions with the widest antimicrobial spectrum were detected using TLC-DB, isolated by semi-preparative TLC, and subjected to LC-MS/MS analyses. Finally, five bioactive components were tentatively identified, based on their fragmentation pattern, such as salvigenin, cirsimaritin, rosmanol, carnosic acid, and 12-O-methyl carnosic acid.