Thin-layer chromatography–contact bioautography as a tool for bioassay-guided isolation of anti-Streptococcus mutanscompounds fromPinus merkusiiheartwood

Abstract

In this study, thin-layer chromatography‒contact bioautography (TLC‒CB) was used for the bioassay-guided isolation of antibacterial compounds against Streptococcus mutans from ethanolic extract of Pinus merkusii heartwood. In the TLC‒CB technique, clear inhibition zones at two major spots on the TLC plate were observed against S. mutans. The major separated anti-S. mutans compounds were isolated by a preparative TLC plate (silica gel) with the mobile phase composed of n-hexane and ethyl acetate (7:3 v/v). The isolated components were identified as dehydroabietic acid and resin acids. Resin acids were further purified by a pentafluorophenyl (PFP) high-performance liquid chromatography (HPLC) column using water and methanol as eluents. Isopimaric acid and abietic acid were obtained. The antibacterial properties of dehydroabietic acid, isopimaric acid, and abietic acid against four strains of S. mutans were evaluated using broth microdilution method. The results revealed that the isolated substances exhibite...