Further polyoxypregnanes from Marsdenia tenacissima.

Two new polyoxypregnanes, designated marstenacigenins A and B, along with a known compound, dresgenin, were isolated from the mild acid hydrolysate of the ethanol extract of the stems of Marsdenia tenacissima. Their structures were deduced by a combination of 1D and 2D NMR spectroscopic techniques as 12 beta-cinnamoyl-dihydrosarcostin and 12 beta,20-dibenzoyldihydrosarcostin, respectively.

Inhibitory effect of green tea extract on the carcinogenesis induced by asbestos plus benzo(a)pyrene in rat.

In this experiment lung carcinoma was induced by crocidolite plus benzo(a)pyrene in rat. From the cancer models, we observed that the incidence (16.0%) of lung carcinomas was lower, and the survival time (376 days) of the first case of carcinoma and the mean survival time (758 days) of the rats with carcinoma were higher in the group of rats drinking 2% green tea extract for life than in the positive group (without drinking green tea extract). The mortality ratio (0.5047) was smaller in the experimental group than in the positive control group, and the survival curve of the experimental group significantly raised up, in comparison with the positive group.

Saikosaponin derivatives from Bupleurum wenchuanense.

From the roots of Bupleurum wenchuanense 14 derivatives of saikosaponin were isolated and identified as 2"-O-beta-D-xylopyranosylsaikosaponin b2, 3",6"-O O-diacetylsaikosaponin b2, 2"-O-beta-D-glucopyranosylsaikosaponin b2, saikosaponin b2, 6"-O-acetylsaikosaponin b2, saikosaponin d, 2"-O-acetylsaikosaponin d, 3"-O-acetylsaikosaponin d,6"-O-acetylsaikosaponin d, 16-epichikusaikoside, prosaikogenin G, saikosaponin a,2"-O-acetylsaikosaponin a and 3"-O-acetylsaikosaponin a. The first two compounds are new derivatives of saikosaponin and this is the first isolation of prosaikogenin G from a plant. Their complete 1H and 13C NMR assignments were made by using a combination of 2D NMR techniques (DQF-COSY, HOHAHA, ROESY, HETCOR, HMQC and HMBC). Some of the compounds showed cytotoxic activity against the P-388 cell line.

Mg(2+)-deprivation enhances and Mg(2+)-supplementation diminishes the embryotoxic and teratogenic effects of Ni2+, Co2+, Zn2+, and Cd2+ for frog embryos in the FETAX assay.

The influence of Mg2+ on the embryotoxicity and teratogenicity of Ni2+, Co2+, Zn2+, and Cd2+ for Xenopus embryos was studied by an adaptation of the FETAX protocol. In seven assays, 25 groups of embryos were grown from 5 to 101 hours post-fertilization in FETAX media that contained five graded MgCl2 concentrations (0, 6.2, 62, 620, or 6,200 mumol per L), with or without added NiCl2 (56 mumol per L), CoCl2 (1,800 mumol per L), ZnCl2 (300 mumol per L), or CdCl2 (18 mumol per L). In FETAX assays performed with the standard Mg2+ concentration (620 mumol per L), the incidence of malformations in control embryos averaged 5.4 (SD +/- 1.3) percent; the incidence of malformations in the controls was increased at low Mg2+ concentrations (32 +/- 7 percent at 62 mumol per L; 100 percent at greater than or equal to 6.2 mumol per L). The specified additions of Ni2+, Co2+, Zn2+, or Cd2+ caused death in < 10 under standard conditions (620 mumol Mg2+ per L). Mg(2+)-deprivation greatly enhanced and Mg(2+)-supplementation significantly reduced the incidence and severity of the teratogenic and embryotoxic effects of Ni2+, Co2+, Zn2+, and Cd2+ (p < 0.0001 by analysis of variance [ANOVA]). To explain these findings, the authors speculate that Mg2+ competes with the other divalent metal ions for a carrier mechanism involved in metal absorption or cellular uptake, or for binding to critical molecular targets.

[Studies on the chemical components of Viscum coloratum. VIII. Isolation and structure of 3-beta-D-glucopyranosyloxy-butanol-2].

From the ethanol extract of Viscum coloratum (Kom.) Nakai, a glucoside of aliphatic diol and three other glucosides were isolated. Based on chemical and spectroscopic analysis, the structures have been elucidated as 2-beta-D-glucosyl-3-methylpropanol (VIII), syringin (IX), eleatheroside E (X) and syringenin-4'-O-D-apiosylglucoside (XI). VIII is a new glucoside of aliphatic diol and named 3-beta-D-glucopyranosyloxy-butanol-2. Three other compounds (IX-XI) were found for the first time in this plant.

[Studies on the chemical constituents of Flemingia philippinensis].

Two new prenylated flavonoids, flemiphilippinin C (I) and flemiphilippinin D (II) have been isolated from the root of Flemingia philippinensis (Merr. et Rolfe) Li along with four known compounds. The structure of I and II were elucidated as 7-(.4'-hydroxy-3'-methoxyphenyl)-5-hydroxy-2, 2-dimethyl-10-prenyl-2H,6H-benzo-[1,2-b:5,4-b']dipyran-6-one and 5,7,2',4'-tetrahydroxy-6,8-diprenylisoflavanone, respectively, on the basis of chemical and spectroscopic data. The four known compounds were identified as 5,7,3',4'-tetrahydroxy-6,8-diprenylsilflavone (III), flemichin D (IV), beta-sitosterol (VI) and lupeol (VII), and a mixture of n C22-C30 aliphatic acid (V). Compounds III and IV showed significant cytotoxic activities against P388 cell cultures.

[Studies on the chemical components of Viscum coloratum VII. isolation and structure of viscumneoside VII].

From the ethanol extract of Viscum coloratum (Kom.) Nakai, a new flavonoid has been isolated. Based on chemical and spectroscopic analysis, the structure of VII has been elucidated as rhamnazin-3-0-beta-D-apisoyl-(1----2)-[6"-O-(3-hydroxy-3- methylglutarate)]- glucoside and named Viscumneoside VII.

[Studies on the chemical components of Viscum coloratum. VI. Chirality of the acyl group of viscumneoside IV].

In order to determine the absolute configuration of the chiral center of viscumneoside IV, which was isolated from Viscum coloratum (Kom) Nakai, (R, S)-mevalonolactone was synthesized as shown in scheme 1. Then treatment with (S) (-)-1-phenylethylamine in THF gave two diasteromeric amides, which were transformed into the monoacetates and separated by HPLC. The first eluted peak (tR10.07 min.) had the (R)-configuration and the second one the (S)-configuration (tR11.20 min). Viscumneoside IV was treated with borane and hydrolyzed to give mevalonolactone which was treated with (S)-(-)-1-phenylethylamine in THF as mentioned above. The monoacetates of the resulting amides were subjected to HPLC. By comparison with the reference peaks, the absolute configuration at the acyl moiety of viscumneoside IV was shown to have the (R)-configuration.

[Determination of saikosaponins in radix Bupleuri using HPLC].

A high performance liquid chromatographic method for the determination of saikosaponin a, c and d in Radix Bupleuri was developed. YMC-pack A-314 ODS column (6 x 300mm) with an eluent consisting of acetone-water (58:42) at a flow rate of 1.2 ml/min was used. The saikosaponins were monitored by a differential refractometer without being converted into the corresponding diene derivatives in advance. Megestrol was used as the internal standard. The recovery rate of saikosaponins was higher than 95% and the coefficient of variation (CV) was 3.08%. The contents of saikosaponins a, c and d of 13 species of Radix Bupleuri collected in different districts of China were evaluated by this method.