Dichapetalin-type triterpenoids and lignans from the aerial parts of Phyllanthus acutissima.

Chemical investigation of the aerial parts of Phyllanthus acutissima resulted in the isolation of five new dichapetalin-type triterpenoids, acutissimatriterpenes A-E ( 1- 5), and two new lignans, acutissimalignans A ( 6) and B ( 7), along with two known lignans and three known ellagic acid derivatives. The structures of 1- 7 were determined mainly on the basis of spectroscopic methods. The compounds obtained were evaluated for cytotoxic and anti-HIV-1 activities.

Suppression by Curcuma comosa Roxb. of pro-inflammatory cytokine secretion in phorbol-12-myristate-13-acetate stimulated human mononuclear cells.

Curcuma comosa Roxb. is a medicinal plant that has traditionally been used in Thailand for treatment of inflammation in postpartum uterine bleeding. The purpose of this study was to evaluate its anti-inflammatory effects using peripheral blood mononuclear cells (PBMC) and human pro-monocytic cell line (U937). Pretreatment with hexane or ethanol extract or two diarylhepatanoids (5-hydroxy-7-(4-hydroxyphenyl)-1-phenyl-(1E)-1-heptene and 7-(3,4-dihydroxyphenyl)-5-hydroxy-1-phenyl-(1E)-1-heptene) of C. comosa significantly decreased the release of pro-inflammatory cytokines, tumor necrosis factor alpha (TNF-alpha) and interleukin-1beta, from phorbol-12-myristate-13-acetate (PMA)-stimulated PBMC and U937 cells. In PMA-stimulated U937 cells, the two C. comosa diarylhepatanoids reduced the expression of TNF-alpha and suppressed expression of IkappaB kinase and activation of nuclear factor kappa B. These results indicated that C. comosa and its diarylheptanoids have anti-inflammatory properties which could be exploited for clinical use.

Cytotoxic and anti-HIV-1 caged xanthones from the resin and fruits of Garcinia hanburyi.

Three new caged xanthones, 7-methoxydesoxymorellin (1), 2-isoprenylforbesione (2) and 8,8a-epoxymorellic acid (3), together with nine known caged xanthones were isolated from the EtOAc extracts of resin and fruits of Garcinia hanburyi. The structures were determined by spectroscopic methods. Most of the isolated compounds showed significant cytotoxicities against a panel of mammalian cancer cell lines. Compound 3, together with the known compounds desoxymorellin, morellic acid, gambogic acid, hanburin, forbesione and dihydroisomorellin, exhibited anti-HIV-1 activity in the reverse transcriptase (RT) assay while the known compounds desoxygambogenin and dihydroisomorellin were found moderately active in the syncytium assay. This work represents the first report on the anti-HIV-1 activities of caged xanthones.

Cytotoxic styryl-lactones from the leaves and twigs of Polyalthia crassa.

Four new styryl-lactones, crassalactones A-D (1-4), were isolated from a cytotoxic ethyl acetate-soluble extract of the leaves and twigs of Polyalthia crassa, together with seven known compounds, (+)-3-acetylaltholactone, (+)-altholactone, aristolactam AII, cinnamic acid, (+)-goniofufurone, (+)-goniopypyrone, and (+)-howiinol A. Their structures were determined on the basis of spectroscopic methods. The absolute configuration of 1-3 was established by chemical conversions. Single-crystal X-ray analysis and the Mosher ester method were used to confirm the absolute stereochemistry of 4. Cytotoxic evaluation against several mammalian cancer cell lines was performed on all new isolates, aristolactam AII, and the modified (+)-tricinnamate derivative 11 obtained from 1.

Cytotoxic arylnaphthalide lignan glycosides from the aerial parts of Phyllanthus taxodiifolius.

The arylnaphthalide lignan glycosides, taxodiifoloside, cleistanthoside A, cleistanthin A and cleistanthin A methyl ether, together with a triterpene, glochidone, have been isolated from the aerial parts of Phyllanthus taxodiifolius. The structures were established using spectral and chemical methods. Compounds and, as well as the derivatives and exhibited potent cytotoxic activities with GI50 values in the range of 10(-7)-10(-9) M in five cultured mammalian cancer cell lines while the new compound showed moderate activity (GI50 in the order of 10(-6) M). Compounds and were inactive in all tested cell lines.

Corymine potentiates NMDA-induced currents in Xenopus oocytes expressing NR1a/NR2B glutamate receptors.

Previous studies demonstrated that corymine, an indole alkaloid isolated from the leaves of Hunter zeylanica, dose-dependently inhibited strychnine-sensitive glycine-induced currents. However, it is unclear whether this alkaloid can modulate the function of the N-methyl-D-aspartate (NMDA) receptor on which glycine acts as a co-agonist via strychnine-insensitive glycine binding sites. This study aimed to evaluate the effects of corymine on NR1a/NR2B NMDA receptors expressed in Xenopus oocytes using the two-electrode voltage clamp technique. Corymine significantly potentitated the NMDA-induced currents recorded from oocytes on days 3 and 4 after cRNA injection but it showed no effect when the current was recorded on days 5 and 6. The potentiating effect of corymine on NMDA-induced currents was induced in the presence of a low concentration of glycine (< or =0.1 microM). Spermine significantly enhanced the potentiating effect of corymine observed in the oocytes on days 3 and 4, while the NMDA-receptor antagonist 2-amino-5-phosphonopentanone (AP5) and the NMDA-channel blocker 5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine (MK-801) reversed the effect of corymine. On the other hand, the nonspecific chloride channel blocker 4,4-di-isothiocyano stilbene-2,2-disulfonoc acid (DIDS) had no effect on the corymine potentiation of NMDA currents. There was no good correlation between corymine- and spermine-induced potentiation of the NMDA-current response in Xenopus oocytes. These results suggest that corymine potentiates the NMDA-induced currents by interacting with a site different from the spermine binding site.

Cytotoxic coumarins from Mammea harmandii.

Two new naturally occurring coumarins, isomesuol (1) and mammearin A (2), together with nine known Mammea coumarins 3-11 were isolated from the EtOAc extract of the leaves and twigs of Mammea harmandii. Coumarins 1, 3 and 4 showed cytotoxicity against a panel of mammalian cancer cell lines. Their structures were determined by spectroscopic methods. The assignments of 13C-NMR signals of isomesuol (1), which was isolated for the first time as a natural product, have been revised.