Antibacterial 5α-Spirostane Saponins from the Fruit of Cordyline manners-suttoniae.

Antibacterial-activity-guided fractionation of a dichloromethane extract from the fruit of Cordyline manners-suttoniae and subsequent structure-activity investigations resulted in the identification of 10 new (1-10) and one known (11) 5α-spirostane saponin. The structures of the new compounds were established by 1D and 2D NMR analyses. The absolute configurations of the isolated compounds were determined by X-ray diffraction analysis or chemical derivatizations. The most active compound, suttonigenin F (6), inhibited the Gram-positive bacteria Staphylococcus aureus with MIC75 values that were comparable to those of the antibiotic chloramphenicol. Structure-activity relationships were also obtained from the assessment of antibacterial and cytotoxic activities of the isolated saponins.

Potent Antibacterial Prenylated Acetophenones from the Australian Endemic Plant Acronychia crassipetala.

Acronychia crassipetala is an endemic plant species in Australia. Its phytochemistry and therapeutic properties are underexplored. The hexane extract of the fruit A. crassipetala T. G. Hartley was found to inhibit the growth of the Gram-positive bacteria Staphylococcus aureus. Following bio-activity guided fractionation, two prenylated acetophenones, crassipetalonol A (1) and crassipetalone A (2), were isolated. Their structures were determined mainly by NMR and MS spectroscopic analyses. This is the first record of the isolation and structural characterisation of secondary metabolites from the species A. crassipetala. Their antibacterial and cytotoxic assessments indicated that the known compound (2) had more potent antibacterial activity than the antibiotic chloramphenicol, while the new compound (1) showed moderate cytotoxicity.