Search

Background: The liver is the central organ for cholesterol homoeostasis, and its dysfunction might cause liver pathological alterations including hepatocellular carcinomas (HCCs). 3β-hydroxysteroid-Δ24 reductase (DHCR24), a crucial enzyme of cholesterol biosynthetic pathway, is involved in lipid rafts formation. Genkwadaphnin (GD) is a daphnane diterpene isolated from the flower buds of Daphne genkwa Siebold et Zuccarini (Thymelaeaceae)., Methods: We evaluated in vitro and in vivo effect of GD using HCC cells and BALB/c nude mice. Microarray assays were used to identify the differential genes by GD. DHCR24 expression and activity, cholesterol level, lipid rafts structure and the role of DHCR24 in human HCC specimens were tested by various molecular biology techniques., Results: High expression of DHCR24 in human HCC specimens was correlated with poor clinical outcome. Interfering DHCR24 altered growth and migration of HCC cells. GD inhibited growth and metastasis of HCC cells both in vivo and in vitro. GD suppressed DHCR24 expression and activity, as well as DHCR24-mediated cholesterol biosynthesis and lipid rafts formation, then further inhibited HCC cell invasion and migration., Conclusions: Our data suggest that DHCR24-mediated cholesterol metabolism might be an effective therapeutic strategy in HCC, and natural product GD might be a promising agent for HCC therapy.

Furanoid 8-epidiosbulbin E acetate (EEA) is a major constituent of herbal medicine Dioscorea bulbifera L. (DB), a traditional Chinese medicine herb. Our preliminary studies demonstrated that administration of EEA caused acute hepatotoxicity in mice, and the observed toxicity required cytochromes P450-mediated metabolism. Metabolic activation studies of EEA were performed in vitro and in vivo. Microsomal incubations of EEA supplemented with N-acetyl lysine (NAL) and glutathione (GSH) generated six metabolites (M1-M6). M1-M4 were characterized as pyrrole derivatives, and M5 and M6 were pyrrolinones. M2-M6 were detected in bile and/or urine of rats given EEA. Dimethyldioxirane-mediated oxidation of EEA in the presence of NAL and GSH produced M1-M6, all of which were generated in microsomal incubations. The structures of M3 and M6 were confirmed by (1)H and (13)C NMR. These findings provide evidence for the metabolic activation of EEA to the corresponding cis-enedial intermediate both in vitro and in vivo. Ketoconazole inhibited the microsomal production of the cis-enedial, and P450 3A4 was found to be the primary enzyme involved in the bioactivation of EEA.

Yuanhuacine (YHL-14), the major component of daphnane diterpene ester isolated from the flower buds of Daphne genkwa, has been reported to have activity against cell proliferation in various cancer cell lines. Nevertheless, the potential mechanism has not been explored yet. Here we demonstrate that YHL-14 inhibits bladder and colon cancer cell growth through up-regulation of p21 expression in an Sp1-dependent manner. We found that YHL-14 treatment resulted in up-regulation of p21 expression and a significant G2/M phase arrest in T24T and HCT116 cells without affecting p53 protein expression and activation. Further studies indicate that p21 induction by YHL-14 occurs at the transcriptional level via up-regulation of Sp1 protein expression. Moreover, our results show that p38 is essential for YHL-14-mediated Sp1 protein stabilization, G2/M growth arrest induction, and anchorage-independent growth inhibition of cancer cells. Taken together, our studies demonstrate a novel mechanism of YHL-14 against cancer cell growth in bladder and colon cancer cell lines, which provides valuable information for the design and synthesis of other new conformation-constrained derivatives on the basis of the structure of YHL-14 for cancer therapy.

Four new daphnane-type diterpenes, genkwadanes A-D (1-4), together with 19 known ones, were isolated from ethanol extract of the flower buds of Daphne genkwa. Their structures were determined on the basis of extensive spectroscopic data. Among them, daphnane-type diterpene with a 1,10-double bond (1) was isolated from this plant for the first time. The cytotoxicity of all compounds 1-23 against the 10 selected human cancer cell lines was assayed. A number of compounds exhibited significant activities against the 10 cancer cell lines (IC50<9.56 μM). and most interestingly, all the compounds revealed preferred cytotoxicities on the HT-1080 cell line and displayed much stronger inhibitory activities (IC50<29.94 μM) compared with positive control 5-fluorouracil (IC50=35.62 μM), particularly, compounds 9-11, 13, 16 and 19 exhibited the strongest cytotoxicity activities against the HT-1080 cell line (IC50<0.1 μM)., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Main observation and conclusion: Nine undescribed dihydro‐β‐agarofuran sesquiterpenoid derivatives (1—9), along with a known analogue (10), were obtained from the leaves of Tripterygium wilfordii. Their gross structures were determined via extensive spectroscopic data, and the absolute configurations were elucidated by means of single‐crystal X‐ray diffraction analysis and electron circular dichroism (ECD) techniques, which include ECD exciton chirality, octant rule of saturated cyclohexanone and comparison between the experimental and calculated ECD spectra. All the isolated compounds were tested for their neuroprotective activities against H2O2‐induced cell injury in human neuroblastoma SH‐SY5Y cells. Compounds 5 and 6 improved cell viability by 16.15% and 15.12% compared with the H2O2 treated group at 25 μmol·L–1, respectively. [ABSTRACT FROM AUTHOR]

Summary of main observation and conclusion: Genkwadane F—I (1—4), four new diterpenes, along with four known ones (5—8), were isolated from the flower buds of D. genkwa. The structures including absolute configurations of 1—4 were determined based on the analysis of NMR and ECD calculations. All compounds were evaluated for their cytotoxicities against MCF‐7 and Hep3B cell lines, among which compounds 3 and 4 showed significant activities. Compound 4 exhibited the most potent activity with IC50 values of 1.33 μM against MCF‐7, and the IC50 values of compound 3 against MCF‐7 and Hep3B were 5.54 μM and 8.73 μM, respectively. Further studies by Hoechst 33258 staining and Annexin V/PI analysis demonstrated that compounds 3 and 4 could induce apoptosis to exhibit anti‐tumor activities. [ABSTRACT FROM AUTHOR]

Four new daphnane-type diterpenes, genkwadanes A-D (I)-(IV), resp., are isolated along with 19 known compounds from the flower buds of Daphne genkwa. [ABSTRACT FROM AUTHOR]