Limonoids from the leaves of Soymida febrifuga and their insect antifeedant activities.

Three new phragmalin-type limonoids (1-3) were isolated from the leaves of Soymida febrifuga together with thirteen known limonoids. The structures of these compounds were established on the basis of spectroscopic data. All these isolates were evaluated for their anti-feedant activities in tobacco caterpillar (Spodoptera litura) and castor semilooper (Achaea janata) using a no-choice laboratory bioassay. Among the tested, compounds 9 and 15 demonstrated the potent anti-feedant index (76.46 µg/cm(2), 66.61 µg/cm(2) against A. janata, and 61.69 µg/cm(2), 51.93 µg/cm(2)against S. litura).

Cytotoxic sesquiterpenes from Hedychium spicatum: isolation, structure elucidation and structure-activity relationship studies.

Phytochemical investigation of chloroform extract from rhizomes of Hedychium spicatum resulted in the isolation of six new sesquiterpenes (1-6) along with fifteen known compounds (7-21). Their structures were elucidated on the basis of the extensive spectroscopic analyses (IR, Mass and NMR) and by comparison of the data with those reported in the literature. Further, cytotoxic activities of all the isolates were evaluated by determining their inhibitory effects against A-549, B-16, Hela, HT-29, NCI-H460, PC-3, IEC-6 and L-6 cancer cell lines. Results indicated that compounds 1 and 3 may serve as an important natural lead compounds for future development as they showed potent cytotoxic activity against Hela cell lines with an IC50 value of 0.3 µg/mL and 1.80 µg/mL, respectively.

Practical and efficient approach to the synthesis of guineensine.

A total synthesis of guineensine, a secondary metabolite of the Piperaceae family, has been executed in 12 steps with an overall yield of 27%. Key steps in the synthesis featured novel application of a Julia-Kocienski olefination reaction which effectively constructed alkenamide skeleton. This contributes a unique approach to the synthesis of the piperamide alkaloids.