A new sterol, named testusterol (1), and five known compounds
(2-6) were isolated from the n-hexane and dichloromethane
extracts of the sponge species Xestospongia testudinaria. Their
chemical structures were elucidated based on extensive spectro
scopic analyses (1D, 2D NMR, ESIMS and HRESIMS) and comparison
with published data. The results of in vitro test (utilizing brine
shrimp Artemia salina LEACH) showed that three extracts ethanol,
dichloromethane, and ethanol/water, significantly inhibited Artemia
salina with LC50 values ranging from 6.09 to 16.83µg/mL.
Remarkably, the new compound 1 exhibited potent inhibition
against both Gram-positive (Staphyloccocus aureus, Bacillus subtilis,
Lactobacillus fermentum), and Gram-negative (Escherichia coli,
Salmonella enterica, Pseudomonas aeruginosa) bacteria species, with
IC50 values of less than 12.0nM and MIC ranging from 4.70 to
75.23nM as determined by the broth-microdilution assay