[A novel dammarane-type saponin from Gynostemma pentaphyllum and its neuroprotective effect].

One new and two known dammarane-type saponins were isolated from the leaves of Gynostemma pentaphyllum using various chromatographic methods. Their structures were identified by HR-ESI-MS,~( 1)H-NMR, ~(13)C-NMR, 2 D-NMR spectra as 2α,3ß,12ß,20,24(S)-tetrahdroxydammar-25-en-3-O-[ß-D-glucopyranosyl(1→2)-ß-D-glucopyranosyl]-20-O-ß-D-xylopyranosyl(1→6)-ß-D-glucopyranoside(1, a new compound, namely gypenoside J5) and 2α,3ß,12ß,20,24(R)-tetrahdroxydammar-25-en-3-O-[ß-D-glucopyranosyl(1→2)-ß-D-glucopyranosyl]-20-O-ß-D-xylopyranosyl(1→6)-ß-D-glucopyranoside(2) and 2α,3ß,12ß,20-tetrahydroxy-25-hydroperoxy-dammar-23-en-3-O-[ß-D-glucopyranosyl(1→2)][ß-D-glucopyranosyl]-20-O-[ß-D-xylopyranosyl(1→6)]-ß-D-glucopy-ranoside(3), respectively. Compounds 1 and 2 were a pair of C-24 epimers. All compounds showed weak cytotoxicity agxinst H1299, HepG2, PC-3, SH-SY5 Y cancer cell lines. However, they exerted protective effect against SH-SY5 Y cellular damage induced by H_2O_2 dose-dependently, of which compound 1 displayed the strongest antioxidant effect. The present study suggested that G. pentaphyllum has antioxidative potential and the saponins from G. pentaphyllum are considered as the active compounds with neuroprotecitve effect.

Dammarane-type saponins from Gynostemma pentaphyllum and their cytotoxicities.

Heat-processed Gynostemma pentaphyllum has shown strong activity against human lung carcinoma A549 cells. In this study, two dammarane-type saponins together with two known compounds were isolated from the ethanol extract of the heat-processed leaves of G. pentaphyllum. They were identified as 2α,3ß,12ß-trihydroxydammar-20(22),24-diene-3-O-ß-D-glucopyranoside (1, namely damulin E), 2α,3ß,12ß-trihydroxydammar-20,24-diene-3-O-ß-D-glucopyranoside (2, namely damulin F), damulin A (3) and damulin B (4), respectively, using NMR and mass spectra. Damulin E and damulin F showed moderate activity against A549, H1299, T24, SH-SY5Y and K562 cell lines in vitro using CCK-8 assay.

Protective effects of four new saponins from Gynostemma pentaphyllum against hydrogen peroxide-induced neurotoxicity in SH-SY5Y cells.

Gynostemma pentaphyllum has been used as a medicine-food homologious health product in China for a long time. This research aimed to isolate and identify its active compounds with protective effects against hydrogen peroxide induced SH-SY5Y cell death. Four new dammarane-type saponins were isolated from G. pentaphyllum using various chromatographic methods. They were identified as gypenoside S1 (1), gypenoside S3 (2), gypenoside S2 (3) and gypenoside S4 (4), respectively by HRESIMS and NMR spectra. Their cytotoxic activity was evaluated against three human cancer cell lines, A549 (lung), HepG2 (liver), SH-SY5Y (nerve), by MTT method. They showed low cytotoxicities with the IC50 values of more than 100 µM on three cancer cell lines. However, they appeared protective effects against hydrogen peroxide induced SH-SY5Y cell death in a dose-dependent manner. They recovered cell viability more than 69% at the concentration of 20 µM from 66%, while as vitamin C to 67%. Compound 3 and 4 recovered more than 79% at 100 µM. The present study suggests that G. pentaphyllum has antioxidative potential and the saponins from G. pentaphyllum are considered as the active compounds with safe and neuroprotecitve effect.

Novel dammarane-type saponins from Gynostemma pentaphyllum and their neuroprotective effect.

Three novel dammarane-type saponins, 2α,3ß,12ß,20(S),24(S)-pentahydroxydammar-25-ene-3-O-ß-D-glucopyranosyl-(1→2)-ß-D-glucopyranosyl-20-O-ß-D-glucopyranoside (1, namely gypenoside J1), 2α,3ß,12ß,20(S),25-pentahydroxydammar-23-ene-3-O-ß-D-glucopyranosyl-(1→2)-ß-D-glucopyranosyl-20-O-ß-D-glucopyranoside (2, namely gypenoside J2) and 2α,3ß,12ß,20(S)-tetrahydroxydammar-25-en-24-one-3-O-ß-D-glucopyranosyl-(1→2)-ß-D-glucopyranosyl-20-O-ß-D-xylopyranosyl-(1→6)-ß-D-glucopyranoside (3, namely gypenoside J3) along with one known gypenoside (gypenoside LVII) were isolated from the aerial parts of G. pentaphyllum using various chromatographic methods. Their structures were elucidated on the basis of IR, 1D- (1H and 13C), 2D-NMR spectroscopy (HSQC, HMBC and COSY), and mass spectrometry (ESI-MS/MS). Their activity was tested using CCK-8 assay. These four compounds showed little anti-cancer activity with IC50 values more than 100 µM against four types of human cancer lines. The effects of them against H2O2-induced oxidative stress in human neuroblastoma SH-SY5Y cells were evaluated and they all showed potential neuroprotective effects with 3.64-18.16% higher cell viability than the H2O2-induced model group.

[Effects of flavonoids from Gynostemma pentaphyllum on A549 cells damaged by hydrogen peroxide].

This study focuses on the therapeutical effect of flavonoids from Gynostemma pentaphyllum on human lung carcinoma A549 cells induced by H2O2 oxidative stress and its possible mechanisms. The oxidative damage model was established using different concentrations H2O2 to induce A549 cell for different hours, and then treated with the flavonoids for 10 hours. The effects of flavonoids from G. pentaphyllum on cell viability of A549 cell damaged by H2O2 were detected by MTT assay. The contents of ROS were detected by DCFH-DA fluorescent probe method via flow cytometer. The contents of MDA, SOD and GSH were detected by TBA，NBT and DTNB-linked colorimetry assay, respectively. Expressions levels of Nrf2, NQO1 and HO-1 in A549 cells were evaluated by Western blot. The results showed that the cell activity was decreasing with the rise of H2O2 concentration within the range of 200-700 µmol·L⁻¹. The cell viability was 60.4% after treated with 500 µmol·L⁻¹H2O2 for 10 h, so it was chosen to be as an oxidant stress model. Compared with normal group，the contents of SOD, GSH and HO-1 expressions were lower after damaged with H2O2. On the contrary, the contents of ROS and MDA expressions were increased. Compared with model group, the contents of SOD, GSH and the expressions of Nrf2, NQO1 and HO-1 were increased after treated with flavonoids from G. pentaphyllum. The above results demonstrate that flavonoids from G. pentaphyllum may attenuate the effect of H2O2-induced oxidative stress on A549 cell by resisting oxidation. The finding may provide a biological evidence for the application of the G. pentaphyllum to fight the oxidative stress related diseases.

The inhibitory effect of gypenoside stereoisomers, gypenoside L and gypenoside LI, isolated from Gynostemma pentaphyllum on the growth of human lung cancer A549 cells.

ETHNOPHARMACOLOGICAL RELEVANCE: Gypenosides are major constituents in Gynostemma pentaphyllum (Thunb.) Makino. Previous studies have shown that gypenosides isolated from G. pentaphyllum possess inhibitory effect on the growth of cancer cells, especially A549 cells, with structure-activity relationship (SAR). However, the underlying mechanism of gypenoside-induced A549 cell death remains to be clarified. AIM OF THE STUDY: To further investigate SAR and the underlying mechanism of gypenosides in A549 cells. MATERIALS AND METHODS: Gypenosides were isolated from G. pentaphyllum using chromatography methods and identified using MS and NMR data. The cytotoxicity was determined with CCK-8 assay. The effects of gypenosides on apoptosis, cell cycle and migration were investigated through cell morphology observation, flow cytometry analysis and key proteins detection. RESULTS: Three gypenosides, 2α,3ß,12ß,20(S)-tetrahydroxydammar-24-ene-3-O-ß-D-glucopyranoside-20-O-ß-D-glucopyranoside, gypenoside L and gypenoside LI were isolated from G. pentaphyllum. Gypenoside stereoisomers, gypenoside L (S configuration at C20) and gypenoside LI (R configuration at C20) showed stronger activity against A549 cells. Furthermore, both induced A549 cell apoptosis through intrinsic and extrinsic pathways evidenced by reducing mitochondrial membrane potential (MMP), generating reactive oxygen species (ROS), releasing more cytochrome c and down-regulating procaspase 8. However, gypenoside L blocked A549 cells in G0/G1, while gypenoside LI induced G2/M arrest, which was further verified by different expression of CDK1, CDK2 and CDK4. In addition, both inhibited A549 cell migration, which was evidenced by down-regulation of MMP-2/9 as well as scratch wound assay and transwell assay. CONCLUSION: C20 of gypenoside played an important role in A549 cell cytotoxicity and gypenoside stereoisomers could be used as potential multi-target chemopreventive agents for cancer.

SNARE-Encoding Genes VdSec22 and VdSso1 Mediate Protein Secretion Required for Full Virulence in Verticillium dahliae.

Proteins that mediate cellular and subcellular membrane fusion are key factors in vesicular trafficking in all eukaryotic cells, including the secretion and transport of plant pathogen virulence factors. In this study, we identified vesicle-fusion components that included 22 soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs), four Sec1/Munc18 (SM) family proteins, and 10 Rab GTPases encoded in the genome of the vascular wilt pathogen Verticillium dahliae Vd991. Targeted deletion of two SNARE-encoding genes in V. dahliae, VdSec22 and VdSso1, significantly reduced virulence of both mutants on cotton, relative to the wild-type Vd991 strain. Comparative analyses of the secreted protein content (exoproteome) revealed that many enzymes involved in carbohydrate hydrolysis were regulated by VdSec22 or VdSso1. Consistent with a role of these enzymes in plant cell-wall degradation, pectin, cellulose, and xylan utilization were reduced in the VdSec22 or VdSso1 mutant strains along with a loss of exoproteome cytotoxic activity on cotton leaves. Comparisons with a pathogenicity-related exoproteome revealed that several known virulence factors were not regulated by VdSec22 or VdSso1, but some of the proteins regulated by VdSec22 or VdSso1 displayed different characteristics, including the lack of a typical signal peptide, suggesting that V. dahliae employs more than one secretory route to transport proteins to extracellular sites during infection.