[Studies on chemical constituents from roots of Caragana sinica].

OBJECTIVE: To study the chemical constituents in roots of Caragana sinica. METHOD: The constituents were isolated by silica gel column chromatography, and their structures were identified by spectroscopic methods. RESULT: Seven compounds were identified as (+) - stenophyllol B (1), 4-hydroxybenzoic acid (2), odoratin (3), resveratrol (4), cararosinol A (5), leachinol C (6), carasinaurone (7) respectively. CONCLUSION: Compound 1 was a new compound which was the enantiomer of stenophyllol B. Compounds 2-6 were obtained from the plant for the first time.

[Anti-HIV chemical constituents of aerial parts of Caragana rosea].

This study was intended to look for anti-HIV chemical constituents of aerial parts of Caragana rosea Turcz. Column chromatographic technique was used for the isolation and purification of constituents of Caragana rosea under the guide of anti-HIV assay. The structures were established on the basis of physical and chemical properties and spectroscopic data. Five compounds were obtained from the EtOAc fraction of aerial parts of Caragana rosea and identified as myricetin (1), mearnsetin (2), p-hydroxy cinnamic acid (3), cararosinol A (4) and cararosinol B (5). At the same time, one possible transformation route between cararosinol B and kobophenol A, another resveratrol tetramer isolated from this plant previously, was proposed. Compounds 4, 5 are new resveratrol tetramers, compounds 1 -3 were isolated from this plant for the first time. All compounds showed no activities in an in vitro assay against HIV-1.

[Studies on the chemical constituents from Caragana intermedia].

OBJECTIVE: To study the chemical constituents from Caragana intermedia. METHODS: The compounds were separated by chromatography methods. Their structures were identified by spectral analysis. RESULTS: Eight compounds were isolated and identified as 7,5'-dihydroxy-3 '-methoxyisoflavone-7-O-beta-D-glucoside (1), isorhamnetin 7-O-alpha-L-rhamnoside (2), 3, 4-dihydroxybenzoic acid (3), N-trans-caffeoyltyramine (4), D-3-O-methyl-inositol (5),7alpha-hydroxy-beta-sitosterol (6),7beta-hydroxy-beta-sitosterol (7) and stearic acid (8). CONCLUSION: All these compounds were obtained from this plant for the first time.

Hypericum sampsonii induces apoptosis and nuclear export of retinoid X receptor-alpha.

Natural products derived from plants provide a rich source for development of new anticancer drugs. Recent studies suggest that modulation of subcellular localization of retinoid X receptor-alpha (RXRalpha) represents a potential approach for inducing cancer cell apoptosis. In this study, we screened a herbal library for inducing translocation of RXRalpha from the nucleus to the cytoplasm. Our results revealed that the extract of Hypericum sampsonii, a member of the genus Hypericum, had remarkable effect on RXRalpha subcellular localization in various cancer cells. Treatment of NIH-H460 human lung cancer cells with H. sampsonii extract resulted in relocalization of RXRalpha from the nucleus to the cytoplasm. Cytoplasmic RXRalpha induced by H. sampsonii was associated with mitochondria, accompanied with cytochrome c release and apoptosis. H. sampsonii extract effectively inhibited the growth of various cancer cell lines, including NIH-H460 lung cancer, MGC-803 stomach cancer and SMMC7721 liver cancer cells. The growth inhibitory effect of H. sampsonii extract depended on levels of RXRalpha, as it failed to inhibit the growth of CV-1 cells lacking detectable RXRalpha, whereas transfection of RXRalpha into CV-1 cells restored its apoptotic response to H. sampsonii. Furthermore, the apoptotic effect of H. sampsonii was significantly enhanced when RXRalpha was overexpressed in NIH-H460 cells. Together, our results demonstrate that H. sampsonii contains ingredient(s) that induce apoptosis of cancer cells by modulating subcellular localization of RXRalpha.

Metabolites and the pharmacokinetics of kobophenol A from Caragana sinica in rats.

This research aims to study the metabolism and pharmacokinetics of phytoestrogen kobophenol A (1), the main active compound of Caragana sinica (Buc'hoz) Rehd. (Fabaceae), in rats. Metabolites of 1 in rats' feces were isolated and purified by multi-chromatograph techniques; three new metabolites of 1, named koboquinone A (M1), koboquinone B (M2) and koboquinone C (M3), were isolated, purified from rats' feces after they being orally administered with 1. Structure identification of the metabolites was fulfilled by spectroscopic analysis. M1 and M2 are structurally different to those natural occurring stilbene tetramers, which also have para-quinone structure. M1 also showed the activity of stimulating the proliferation of cultured osteoblasts. The pharmacokinetics of 1 in rats could be described by a two-compartmental model (P<0.05). The half-life was 0.68 h for i.v. administration and 5.78 h for oral administration. The oral bioavailability of 1 was calculated to be 2.0%; rats tissue distribution experiments show that 1 was prominently concentrated in livers. Both of the low oral bioavailability and the rapid reduction of 1 in blood indicated a suitable formulation is needed while it is developed as a new drug.

Anti-HIV bioactive stilbene dimers of Caragana rosea.

Bioassay-guided fractionation of the ethanol extract of the aerial parts of Caragana rosea Turcz. led to the isolation of two new (cararosinol C and cararosinol D) and four known [scirpusin A (1), cis-scirpusin A (2), maackin (3), scirpusin B (4)] stilbene dimers. This is the first identification of these compounds from this plant and the first time that compound 2 has been isolated as a natural compound. Their structures were established mainly by spectral means. An in vitro assay against HIV-1 (IIIB), demonstrated compounds 1 and 4 to be active against HIV, with EC50 values of 10 microg/mL and 7 microg/mL respectively.

Two new oligostilbenes from Caragana sinica.

A new resveratrol dimer, carasiphenol A (1), and a new resveratrol trimer, carasiphenol B (2), have been isolated from the aerial parts of Caragana sinica. Their structures have been elucidated from spectroscopic evidence, especially HMBC and NOE experiments. The relative configuration of the known dimer pallidol (6) was confirmed by X-ray diffraction.

[Studies on flavonoid constituents of Caragana intermediia].

AIM: To study the chemical constituents of Caragana intermedia. METHODS: The compounds were separated by chromatography methods, their structures were identified by spectral analysis. RESULTS: Ten compounds were isolated and identified as 5,7,4'-trihydroxy-3,3'-dimethoxyflavone (1), 3,5,7,8,4'-pentahydroxy-3'-methoxyflavone(2), puercetin(3), limocitrin(4), 5,7,3',4'-tetrahydroxy-3-methoxyflavone(5), 7,3',5'-trihydroxyflavanone(6), 5,7,3',4'-tetrahydroxy-3,8-dimethoxyflavone(7), butein(8), liquiritigenin(9) and 5,7,4'-trihydroxy-3,8-dimethoxyflavone(10). CONCLUSION: Compound 6 is a new compound and the others were obtained from this plant for the first time.

Constituents from the stems of Goniothalamus griffithii.

A new cyclopeptide, grifficyclocin A (1), and a new aporphine alkaloid, griffinin (2) were isolated together with two known styryllactones from the stems of Goniothalamus griffithii. Their structures were identified spectroscopically and chemically. Among them, the griffinin (2) was isolated as the enol form in two tautomers, and the two known styryllactones, goniothalamin (3) and 8- O-acetylgoniotriol (4), showed selective in vitro antitumor activities.

[The binding sites of estrogen receptor for miyabenol C and kobophenol A].

To examine the binding sites of miyabenol C (Miy C) and kobophenol A ( Kob A) with estrogen receptor (ER), computer modeling was applied to determine 3D structure of Miy C and Kob A. Molecular docking of the components to ER was carried out to find the binding sites between them. PCR mutagenesis was used to change the structure of ER cDNA. After the mutated sites were confirmed by DNA sequencing, report gene assay was used to study the effects of Miy C and Kob A on the trans-activating ability of ER. Results indicated that the effect of Miy C on the trans-activating ability of mutant 1 of ER [M1ER (ER M(517)AG(521)D)] was decreased, and Kob A had no stimulating effects on the trans-activating ability of M1ER. Miy C and Kob A had no stimulating effects on the trans-activating ability of mutant 2 of ER [M2ER (ER E(353)GR(394)G)]. Therefore, the ER sites for Miy C and Kob A may be located at Glu(353), Arg(394), Met(517) and Gly(521).

Assessment of estrogenic activity of natural compounds using improved E-screen assay.

AIM: To improve E-screen assay and make it more accurate to screen estrogenic compounds. METHODS: Estrogen receptor antisense RNA expression plasmid (pCASER) was constructed and introduced into MCF-7 with lipofectAMINE(TM), and positive clones were screened out with G418. PCR amplification was employed to identify whether estrogen receptor (ER) cDNA fragment had been inserted into MCF-7 cell genomes. Western blot was applied to detect the expression of ER. Cell growth was determined by MTT assay. RESULTS: One ER antisense clone (MTASER) had been screened out. The effects of 17beta-estradiol, genistein, droloxifen, miyabenol C, and kobophenol A on MCF-7 were stronger than those effects on MTASER. Epidermal growth factor (EGF) had equivalent stimulatory effects on the proliferation of MCF-7 and MTASER. CONCLUSION: The improved E-screen assay could screen estrogenic compounds more accurately than original E-screen assay did.