A new bilobalide isomer and two cis-coumaroylated flavonol glycosides from Ginkgo biloba leaves.

A new bilobalide isomer (1), together with two flavonol glycosides (2, 3), have been isolated and elucidated from the extract of Ginkgo biloba leaves. Significantly, 1 was a new sesquiterpene lactone with two lactone ring groups, both 2 and 3 were two flavonol glycosides with a same cis-coumaroylated fragment. Their chemical structures were elucidated by NMR and MS spectroscopic date and the absolute configuration of 1 was specific established by Cu-Kα X-ray crystallographic analyses. However, 1-3 showed no obvious anti-platelet aggregation activity.

Lineariifolianoids M-O, three rare sesquiterpene lactone dimers inhibiting NO production from Inula lineariifolia.

Three rare squiterpene lactone dimers lineariifolianoids M-O (1-3) were isolated from Inula lineariifolia for the first time. Their structures and absolute configuration were established on the basis of by NMR and MS spectroscopic data and X-ray crystallography. Furthermore, those three compounds exhibited significant inhibitory activity against LPS-induced NO production in RAW 264.7 macrophages with IC50 values of 1.421, 1.087 and 1.243 µM, respectively.

Serine palmitoyltransferase, a key enzyme for de novo synthesis of sphingolipids, is essential for male gametophyte development in Arabidopsis.

Sphingolipids are important signaling molecules involved in various cellular activities. De novo sphingolipid synthesis is initiated by a rate-limiting enzyme, serine palmitoyltransferase (SPT), a heterodimer consisting of LONG-CHAIN BASE1 (LCB1) and LCB2 subunits. A mutation in the Arabidopsis thaliana LCB1 gene, lcb1-1, was found to cause embryo lethality. However, the underpinning molecular and cellular mechanisms remain largely unclear. Here, we report the identification of the fumonisin B(1) resistant11-2 (fbr11-2) mutant, an allele of lcb1-1. The fbr11-2 mutation, most likely an allele stronger than lcb1-1, was transmitted only through female gametophytes and caused the formation of abortive microspores. During the second pollen mitosis, fbr11-2 initiated apoptotic cell death in binucleated microspores characteristic of nuclear DNA fragmentation, followed by cytoplasm shrinkage and organelle degeneration at the trinucleated stage. In addition, a double mutant with T-DNA insertions in two homologous LCB2 genes showed a phenotype similar to fbr11-2. Consistent with these observations, the FBR11/LCB1 expression was confined in microspores during microgametogenesis. These results suggest that SPT-modulated programmed cell death plays an important role in the regulation of male gametophyte development.