Four new sesquiterpenoid derivatives from the heartwood of Mansonia gage.

Four new sesquiterpenoid derivatives named mansonones N (1), O (2), P (3), and Q (4) were isolated from a dichloromethane extract of the heartwood of Mansonia gagei, a plant used in folk medicine in Thailand. Their structures were resolved on the basis of spectrometric data interpretation and the single-crystal X-ray analysis of 1 and 2

Cyclic tetrapeptides from marine bacteria associated with the seaweed Diginea sp.and the sponge Halisarca ectofibrosa

A Pseudomonas sp. was cultured which was associated with the Japanese seaweed Diginea sp. Crude extracts prepared from this bacterial culture were found to inhibit the growth of other marine bacterial strains. From this bacterial culture, two new peptides cyclo-[phenylalanyl-prolyl-leucyl-prolyl] (3) and cyclo-[isoleucyl-prolyl-leucyl-alanyl] (4) have been isolated together with two known peptides (1) and (2). The crude extract from a culture of Pseudoalteromonas sp. associated with the Thai sponge Halisarca ectofibrosa was found to inhibit the growth of Bacillus subtilis and Vibrio anguillarum. Isolation studies yielded a fraction containing two peptides that were identified as cyclo-[phenylalanyl-leucyl] (5) and cyclo-[leucyl-isoleucyl] (6) by means of LC-MS and 2D NMR data. Absolute stereochemistry was confirmed by the synthesis of cyclo-[l-phenylalanyl-l-leucyl]. Peptides (1)-(3) were also isolated from this bacterial strain. None of the individual peptides isolated in this study showed antibiotic activity