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Ten new carbazole alkaloids, claulansines A−J (1−10), and seven known analogues (11−17) were isolated from the stems of Clausena lansium. Their structures were established on the basis of extensive spectroscopic analyses, and their absolute configurations were determined by CD experiments and computational methods. Screening results indicated that compounds 1, 6, 8−10, 13, 14, and 17 showed selective neuroprotective effects at the concentration of 10 μM.

The methanol fraction of an ethanolic extract from the roots of Polygala tenuifolia Willd. showed antagonistic action on neurotoxicity induced by glutamate and serum deficiency in PC12 cells. Bioassay-guided fractionation led to the isolation of six new triterpenoid saponins, onjisaponins V - Z, and Vg ( 1 - 6), together with ten known saponins ( 7 - 16). The structures of 1 - 6 were elucidated by spectroscopic and chemical methods. Screening results indicated that compounds 1 - 16 showed neuroprotective effects against serum deficiency and glutamate at the concentration of 10 (-5) mol/L.

Three novel sesquiterpenoid-based meroterpenoids of psidials A-C (1-3) have been isolated from the leaves of Psidium guajava L. Their complete structures were elucidated by spectral and chemical methods, and that of 1 was confirmed by single-crystal X-ray diffraction analysis. Psidial B (2) and C (3) represented the new skeleton of the 3,5-diformylbenzyl phloroglucinol-coupled sesquiterpenoid. A possible biosynthetic pathway for 2-3 was postulated. 2-3 showed activity to enzyme PTP1B in 10 µM.Psidium guajaVa L, a shrub or small tree, is grown throughout the tropics and subtropics and is known for its edible fruits. Its leaves are used in folk medicine as an antiinflammatory and hemostatic agent, and for treating pulmonary diseases, coughs, vomiting, and diarrhea. 1 Previous investigations on the leaves of Psidium guajaVa L have led to the isolation of several triterpenoids, 2 flavonoids, 3 tannins, 4 and carotenoids. 5

Aim: The aim of this study was to investigate the cognition-enhancing activity and underlying mechanisms of a triterpenoid saponin (polygalasaponin XXXII, PGS32) isolated from the roots of Polygala tenuifolia Willd. Methods: The Morris water maze was used to evaluate the spatial learning and memory of mice. To detect the basic properties of synaptic transmission and long-term potentiation (LTP) in the dentate gyrus of rats, electrophysiological recordings were made of evoked potentials. Western blotting analysis and immunofluorescence assays were used to determine the phosphorylation of extracellular signal-regulated kinase (ERK), cAMP response element-binding protein (CREB), synapsin I and the expression of brain derived neurotrophic factor (BDNF). Results: When administered at 0.125, 0.5, or 2 mg/kg, PGS32 could significantly prevent scopolamine-induced cognitive impairments in mice. Intracerebroventricular (icv) administration of PGS32 greatly enhanced basic synaptic transmission in the dentate gyrus of rats and induced LTP. In primary hippocampal neurons, as well as in the hippocampus of maze-trained mice, PGS32 activated the mitogen-activated protein (MAP) kinase cascade by promoting phosphorylation of ERK, CREB and synapsin I. The expression of BDNF was also greatly enhanced in the hippocampus. Conclusion: Our findings suggest that PGS32 can improve hippocampus-dependent learning and memory, possibly through improvement of synaptic transmission, activation of the MAP kinase cascade and enhancement of the level of BDNF. Therefore, PGS32 shows promise as a potential cognition-enhancing therapeutic drug.

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Twelve new dihydroagarofuran sesquiterpene polyol esters, triptersinines A-L (1-12), and eight known sesquiterpene pyridine alkaloids were isolated from the leaves of Tripterygium wilfordii. Their structures were elucidated on the basis of spectroscopic analyses, including UV, IR, and NMR experiments ((1)H-(1)H COSY, NOESY, HSQC, and HMBC). Furthermore, in an in vitro bioassay, compounds 1, 9, 11, 13, 14, and 18 showed moderate inhibitory effects on nitric oxide production in LPS-induced macrophages at 5 μM; all compounds were inactive when tested against five human cancer cell lines (IC(50) values >1 μM).

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