Chemical constituents and antibacterial activity of rhizomes from globba schomburgkii hook.f.

Abstract

Globba schomburgkii Hook.f. rhizomes were extracted with dichloromethane and fractionated using column chromatography to obtain 10 fractions (FA-FJ). The most active fractions, FE and FG, were further fractionated to give seven and thirteen sub-fractions, respectively. The fractions and sub-fractions were tested for antibacterial activity using 96-well plate microdilution method. The antibacterial activity of several sub-fractions (such as FE.B, FE.C, FE.D, FG.D, FG.G, and FG.H) were higher than that of the crude extract. Chemical compositions of all fractions and sub-fractions were analyzed by gas chromatography hyphenated with mass spectrometry (GC-MS), revealing 167 compounds identified according to match between the experimental MS and retention index data and that from the NIST17 library. The major volatile compounds were identified as γ-bicyclohomofarnesal and (E)-15,16-dinorlabda-8(17),11-dien-13-one (P2). Some of the compounds such as (E)-labda-8(17),12-diene-15,16-dial, methyl isocostate, zederone, alantolactone, and 8α,11‑elemadiol have been reported to be biologically active. Lastly, two pure compounds isolated by column chromatography were characterized by 1H, 13C, COSY, HSQC and HMBC NMR techniques as petasol (P1) and P2.