Molecular Docking Approach of Natural Compound from Herbal Medicine in Java against Severe Acute Respiratory Syndrome Coronavirus-2 Receptor

Indonesia's diversity of natural resources presents an intriguing opportunity for the exploration of potential herbal medicines. Numerous compounds, both purified and crude, have been reported to exhibit antiviral activity. The ACE-2 receptor may be a therapeutic target for SARS-CoV-2 infection. We used a search engine to search for herbal medicines with ACE-2 inhibitory activity to predict the potential inhibition of natural compounds (i.e., theaflavin, deoxypodophyllotoxin, gallocatechin, allicin, quercetin, annonamine, Curcumin, 6-gingerol, and cucurbitacin B) to SARS-CoV2 – ACE-2 complex. We performed molecular docking analysis using the ACE-2 protein target from Protein Data Bank. Protein stabilization was carried out to adjust to the body's physiology, carried out using Pymol by removing water atoms and adding hydrogen atoms. Ligands of active compounds from natural resources were selected and downloaded from the PubChem database, then optimized by Pymol software. The complexes of the tested ligand compounds and ACE-2 receptors, which have a bond strength smaller than the control were selected for analysis. Theaflavin, Deoxypodophyllotoxin, Gallocatechin, Curcumin, and Cucurbitacin B had a strong bond affinity than the control ligands. Based on our data, deoxypodophylotoxin and Curcumin had the same interaction amino acid residus compare to the control ligand. This study concludes that deoxypodophyllotoxin and Curcumin have the greatest potential to inhibit the formation of the SARS-Cov2-ACE-2 complex; additionally, these compounds exhibit favorable pharmacological and pharmacodynamic properties. It is suggested that additional research be conducted to determine the biological effects of deoxypodopyllotoxin and Curcumin on ACE-2 receptors.

Improvement of Cucurbitacin B Content in Cucumis melo Pedicel Extracts by Biotransformation Using Recombinant β-Glucosidase

For the efficient biotransformation of cucurbitacin B 2-o-β-d-glucoside (CuBg) to cucurbitacin B (CuB) in Cucumis melo pedicel extracts, the β-glucosidase gene bglS—consisting of 1344 bp (447 amino acids) from Streptomyces sp. RW-2—was cloned and expressed in Escherichia coli BL21(DE3). The activity of recombinant β-glucosidase with p-nitrophenyl-β-d-glucoside (pNPG) as a substrate was 3.48 U/mL in a culture. Using the recombinant β-glucosidase for the biotransformation of C. melo pedicel extracts, CuBg was converted into CuB with a conversion rate of 87.6% when the concentration of CuBg was 0.973 g/L in a reaction mixtures. The concentration of CuB in C. melo pedicel extracts was improved from 13.6 to 20.2 g/L after biotransformation. The present study provides high-efficiency technology for the production of CuB from its glycoside by biotransformation.

Cucurbitacin B Inhibits Cell Proliferation by Regulating X-Inactive Specific Transcript Expression in Tongue Cancer

Cucurbitacin B (CuB), a natural product, has anti-tumor effects on various cancers. In order to investigate the expression of long non-coding RNAs (lncRNA), we carried out RNA sequencing (RNA-seq) and quantitative PCR (qPCR). The data indicated that CAL27 and SCC9 tongue squamous cell carcinoma (TSCC) cells had reduced expression of X-inactive specific transcript (XIST) after CuB treatment. Moreover, our results showed increased expression of XIST in human tongue cancer. In this study, CuB treatment inhibited proliferation, migration and invasion of SCC9 cells, and induced cellular apoptosis. Interestingly, knockdown of XIST led to inhibition of cell proliferation and induced apoptosis in vitro. In addition, reduced expression of XIST suppressed cell migration and invasion. MicroRNA 29b (miR-29b) was identified as a direct target of XIST. Previous reports indicated that miR-29b regulates p53 protein. Our results suggest that increased expression of miR-29b induces cell apoptosis through p53 protein. The clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (CRISPR/Cas9) system validated the role of XIST knockout in tumor development in vivo. Together, these results suggest that CuB exerts significant anti-cancer activity by regulating expression of XIST via miR-29b.