  Neopetrosia exigua has received great attention in natural product chemistry.
The diversity of N. exigua constituents has been demonstrated by the continued
discovery of novel bioactive metabolites such as antimicrobial metabolites. In
this study, in order to localise the active component of N. exigua biomass
according to the polarity, a sequential gradient partition with different
solvents (nhexane, carbon tetrachloride, dichloromethane, n-butanol, and water)
was performed to obtain fractions containing metabolites distributed according
to their polarity. The antimicrobial activities of N. exigua fractions were
then evaluated using disc diffusion and microdilution methods (influence on the
growth curve, Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal
Concentration (MBC)). The results showed that the active metabolites were
present in n-hexane, CH2Cl2, nBuOH, and water fractions. n-hexane, CH2Cl2, and
n-BuOH fractions were the most effective fractions. Among microbes tested,
Staphylococcus aureus was the most susceptible microbe evaluated. The obtained
results are considered sufficient for further study to isolate the compounds
represent the antimicrobial activity.
