Identification of Potential TMPRSS2 Inhibitors for COVID-19 Treatment in Chinese Medicine by Computational Approaches and Surface Plasmon Resonance Technology.

BACKGROUND: Coronavirus disease-19 (COVID-19) pneumonia continues to spread in the entire globe with limited medication available. In this study, the active compounds in Chinese medicine (CM) recipes targeting the transmembrane serine protease 2 (TMPRSS2) protein for the treatment of COVID-19 were explored. METHODS: The conformational structure of TMPRSS2 protein (TMPS2) was built through homology modeling. A training set covering TMPS2 inhibitors and decoy molecules was docked to TMPS2, and their docking poses were re-scored with scoring schemes. A receiver operating characteristic (ROC) curve was applied to select the best scoring function. Virtual screening of the candidate compounds (CCDs) in the six highly effective CM recipes against TMPS2 was conducted based on the validated docking protocol. The potential CCDs after docking were subject to molecular dynamics (MD) simulations and surface plasmon resonance (SPR) experiment. RESULTS: A training set of 65 molecules were docked with modeled TMPS2 and LigScore2 with the highest area under the curve, AUC, value (0.886) after ROC analysis selected to best differentiate inhibitors from decoys. A total of 421 CCDs in the six recipes were successfully docked into TMPS2, and the top 16 CCDs with LigScore2 higher than the cutoff (4.995) were screened out. MD simulations revealed a stable binding between these CCDs and TMPS2 due to the negative binding free energy. Lastly, SPR experiments validated the direct combination of narirutin, saikosaponin B1, and rutin with TMPS2. CONCLUSIONS: Specific active compounds including narirutin, saikosaponin B1, and rutin in CM recipes potentially target and inhibit TMPS2, probably exerting a therapeutic effect on COVID-19.

Monomer gypenoside LI from Gynostemma pentaphyllum inhibits cell proliferation and upregulates expression of miR-128-3p in melanoma cells.

Gypenosides have anticancer activity against many cancers. Gypenoside LI is a gypenoside monomer from Gynostemma pentaphyllum, its pharmacological functions in melanoma have not been reported. In this study, we found that gypenoside LI had a potent cytotoxic effect on melanoma cells. Gypenoside LI can induce intrinsic apoptosis along with S phase arrest. Furthermore, gypenoside LI inhibited the colony formation ability of melanoma through inhibition of the Wnt/ß-catenin signaling pathway. Interestingly, we also found that gypenoside LI can induce the upregulation of the tumor suppressor miR-128-3p during melanoma apoptosis. In contrast, gypenoside LI induced apoptosis, cell cycle arrest, and inhibition of the Wnt/ß-catenin signaling pathway, which were abolished by overexpression of the miR-128-3p inhibitor in A375 cells. Taken together, these results showed that gypenoside LI could inhibit human melanoma cells through inducing apoptosis, arresting cell cycle at the S phase and suppressing the Wnt/ß-catenin signaling pathway in a miR-128-3p dependent manner.

Inhibitory Effect of Damulin B from Gynostemma pentaphyllum on Human Lung Cancer Cells.

Damulin B, a dammarane-type saponin from steamed Gynostemma pentaphyllum, exhibits the strongest activity against human lung carcinoma A549 cells among the isolated active saponins. In this study, the structure-activity relationship of a series of saponin compounds was discussed. The inhibitory effect of damulin B on human lung cancer A549 and H1299 cells was investigated from apoptosis, cell cycle, and migration aspects. In vitro, human lung cancer cells were more susceptible to damulin B treatment than human normal fibroblasts. Damulin B exhibited a strong cytotoxic effect, as evidenced by the increase of apoptosis rate, reduction of mitochondrial membrane potential (MMP), generation of reactive oxygen species, and G0/G1 phase arrest. Furthermore, damulin B activated the following: both intrinsic and extrinsic apoptosis pathways along with early G1 phase arrest via the upregulation of the Bax, Bid, tBid, cleaved caspase-8, and p53 expression levels; downregulation of the procaspase-8/-9, CDK4, CDK6, and cyclin D1 expression levels; and more release of cytochrome c in the cytoplasm. In addition, antimigratory activities and suppressive effects on metastasis-related factors, such as MMP-2 and MMP-9, accompanied by the upregulation of IL-24 were revealed. Altogether, the results proved that damulin B could inhibit human lung cancer cells by inducing apoptosis, blocking the cell cycle at early G0/G1 phase and suppressing the migration. Hence, damulin B has potential therapeutic efficacy against lung cancer.

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.