Two new limonoids isolated from the fuits of Melia toosendan

In the present study, two new limonoids, 1, 7-dihydroxyl-3-acetoxyl-12-ethoxylnimbolinin (1) and 1-tigloyloxy-3-acetoxyl-7-hydroxyl-12-ethoxylnimbolinin (2), together with other four known limonoids (3-6), were isolated from the fruits of Melia toosendan. Their structures were elucidated by means of extensive spectroscopic analyses (NMR and ESI-MS) and comparisons with the data reported in the literature. The isolated compounds were evaluated for their antibacterial activities. Compound 4 exhibited significant antibacterial activity against an oral pathogen, Porphyromonas gingivalis ATCC 33277, with an MIC value of 15.2 gmL-1. Compound 2 was also active against P. gingivalis ATCC 33277, with an MIC value of 31.25 gm-1. In conlcusion, our resutls indicate that these compounds may provide a basis for future development of novel antibiotics.