Aim: This study was designed for isolating and characterizing antiplasmodial compounds from marine octocoral-associated bacteria.
Materials and methods: The organic extract of the Bacillus sp. was subjected to purification using several chromatography techniques guided by bioassays to yield three isocoumarin derivatives (1-3). Chemical structures of the compounds were elucidated on the basis of HRMS spectra and NMR spectroscopy. The antiplasmodial activity of the isolated compounds was evaluated in vitro against the chloroquine-resistant Plasmodium falciparum strain W2.
Results: Isolated compounds were identified as bacilosarcin A (1), AI77-F (2), and AI77-H (3). Bacilosarcin A (1) displayed a low micromolar activity (IC(50) = 2.2 μM) against P. falciparum while compounds 2 and 3 showed no activity.
Conclusions: Bacilosarcin A was found to be responsible for the antiplasmodial activity observed in the crude extract obtained from the Bacillus sp.
Keywords: Bacillus; Leptogorgia alba; Plasmodium falciparum; bacilosarcin A; isocoumarins; marine bacteria; octocorals.