Xanthones from Tovomita pyrifolium

The wood of Tovomita pyrifolium (Guttiferae) contains the novel tovopyrifolins A [1,6-dihydroxy-7-methoxy-5-prenyl-6′,6′-dimethylpyrano (2′,3′:3,2)xanthone], B (1,5-dihydroxy-3,4-dimethoxyxanthone) and C (1,3,5-trihydroxy-2-methoxyxanthone) and also the known tovophyllins A and B [structure revised to 1,6-dihydroxy-5-prenyl-6′, 6′-dimethylpyrano(2′,3′:3,2)-6″,6″-dimethylpyrano(2″,3″:7,8)xanthone].     

A pyrano-isoflavone from seeds of Milletia thonningii

Extraction of the seeds of Milletia thonningii gave alpinumisoflavone, its monomethyl and dimethyl derivatives, robustic acid and a new pyrano-isoflavone. The structure of the latter was established by chemical transformation and spectroscopic means.     

Abiesin,a biflavonoid of abies webbiana

Abiesin, a new biflavonoid, has been isolated from the leaves of Abies webbiana and identified as 5,3″,7″- trihydroxy-7,4′,4?-trimethoxy-(3′,6″)-biflavone.     

Lactones,flavonoids and benzophenones from Garcinia conrauana and Garcinia mannii

Two novel lactones have been isolated from the stem barks of Garcinia conrauana and G. mannii. The major component of the bark of G. conrauana was identified as 3-(3$\text{,}\text{?}$ 3″-dimethylallyl)-conrauanalactone [4-hydroxy-3-(3″, 3″-dimethylallyl)-6-pentadecylpyran- 2-one] by comparison of spectral data of the isolated compound and two methylethers with that obtained for the previously isolated conrauanalactone. A minor component of the bark of G. mannii was tentatively identified as 3-α-hydroxy-5-(heptadec-8′-enyl)-tetrahydro- furan-2-one on the basis of spectral data from the isolated compound and its monoacetate. The distributions of biflavonoids and related compounds and benzophenones in the stem bark, heartwood, seeds and leaves of the two species are reported.     

A new method for oligo(ADP-ribose) fractionation according to chain length

A new method was developed to separate mono- and oligo-(ADP-ribose) with chain lengths below 11 ADP-ribose units by size difference of one ADP-ribose residue. The separation was performed on a DEAE-cellulose column by elution with a NaCl gradient (0–0.3 $\text{M}$) in the presence of 7 $\text{M}$ urea at pH 7.6. Using this method, the chain length distribution of oligo(ADP-ribose) molecules attached to histones by incubation of isolated nuclei with radioactive NAD was determined. The average chain length estimated from this distribution coincided exactly with the value obtained by the phosphodiesterase digestion method, suggesting that the oligomers were synthesized directly on histones and not elongated from pre-existing ADP-ribose.     

Two new C-methylated flavonoids from Myrica gale

From the leaves of Myrica gale 2′,4′-dihydroxy-6′-methoxy-3′,5′-dimethylchalcone has been isolated. The fruits yielded 2′-hydroxy-4′,6′-dimethoxy-3′-methyldihydrochalcone. The constitutions were deduced from spectroscopic data and confirmed by synthesis.     

A substituted 1,2-diarylethane from Cymbidium giganteum

In addition to sitosterol and taraxerone, a new substituted 1,2-diarylethane, gigantol has been isolated from Cymbidium giganteum and characterized as 1-(3′-hydroxy-5′-methoxyphenyl-2-(4″-hydroxy-5″-methoxyphenyl)ethane on the basis of physicochemical data and through synthesis of its derivative.     

C-glycosylflavones from Oryza sativa

Eight flavone C-glycosides isolated from rice plant were found to act as probing stimulants for planthoppers. They have been identified as the known compounds schaftoside, neoschaftoside, carlinoside, isoorientin 2″-glucoside and the new constituents neocarlinoside (6-C-β-D-glucopyranosyl-8-C-β-L-arabinopyranosylluteolin), isoscoparin 2″-glucoside (chrysoeriol 6-C-β-D-(2-O-β-D-glucopyranosyl)glucopyranoside) and its 6?-p-coumaric and ferulic acid esters.     

青蕨植物化学成分的研究

从青蕨根部的乙酸乙酯提取物中分离得到4个化合物。通过化学及波谱分析鉴定其结构为：saucerneol D(1),dehydrogoniothalamin(2),1-acetoxyl-2-piperonyl-6-[6-methoxyl-piperonyl]3,7-dioxabicyclo-[3,3,0]-octane(3) and 5,5′-dihydroxy-3-methoxy-6,8,3″,3″-tetramethylpyran-(3′,4′)flavone-7-O-[β—D—apiofuranosyl-(1→6)]-β-D-glucopyranoside(4)。其中化合物(4)为新化合物,化合物(1)为首次从该属植物中分离得到。     

Evaluation of 3-(4′-(4″-fluorophenyl)-6′-phenylpyrimidin-2′-yl)-2-phenylthiazolidin-4-one for in vivo modulation of biomarkers of chemoprevention in the 7,12-dimethylbenz[a]anthracene-induced hamster buccal pouch carcinogenesis

A new bis heterocycle comprising both bioactive 2-aminopyrimidine and thiazolidin-4-one nuclei namely 3-(4′-(4″-fluorophenyl)-6′-phenylpyrimidin-2′-yl)-2-phenylthiazolidin-4-one 3 was synthesized, characterized with the help of melting point, elemental analysis, FT-IR, MS, one-dimensional NMR (¹H, ¹³C) spectra and we evaluated the chemopreventive potential of 3-(4′-(4″-fluorophenyl)-6′-phenylpyrimidin-2′-yl)-2-phenylthiazolidin-4-one based on in vivo inhibitory effects on 7,12-dimethylbenz[a]anthracene (DMBA)-induced hamster buccal pouch carcinogenesis. Administration of 3 effectively suppressed oral carcinogenesis initiated with DMBA as revealed by the reduced incidence of neoplasms. Lipid peroxidation, glutathione (GSH) content, and the activities of glutathione peroxidase (GPx), glutathione S-transferase (GST) were used to biomonitor the chemopreventive potential of 3. Lipid peroxidation was found to be significantly decreased, whereas GSH, GPx, GST, and GGT were elevated in the oral mucosa of tumor-bearing animals. Our data suggest that 3 may exert its chemopreventive effects in the oral mucosa by modulation of lipid peroxidation and enhancing the levels of GSH, GPx, and GST.