Can Antimalarial Phytochemicals be a Possible Cure for COVID-19? Molecular Docking Studies of Some Phytochemicals to SARS-CoV-2 3C-like Protease

Objective: To evaluate the efficacy of reported anti-malarial phytochemicals as lead compounds for possible drug development against COVID-19. Methods: An in silico approach was used in this study to determine through molecular docking the binding affinities and site of binding of these phytochemicals to the 3C-like protease of COVID-19 which is considered as the main protease of the virus. Results: A number of anti-malarial phytochemicals like apigenin-7-O-glucoside, decurvisine, luteolin-7-O-glucoside, sargabolide J, and shizukaols A, B, F, and G showed predicted high binding energies with G values of -8.0 kcal/mol or higher. Shizukaols F and B demonstrated the best binding energies of -9.5 and -9.8, respectively. The acridone alkaloid 5-hydroxynoracronycine also gave a predicted high binding energy of -7.9 kcal/mol. Conclusion: This is for the first time that decursivine and several shizukaols were reported as potential anti-viral agents. These compounds merit further studies to determine whether they can be effective drug candidates against COVID-19.

A prenylated acridone alkaloid and ferulate xanthone from barks of Citrus medica (Rutaceae)

A new prenylated acridone alkaloid, medicacridone (1), and a new ferulate xanthone, medicaxanthone (5), together with 11 known compounds were isolated from the methanol extract of the bark of the Cameroonian medicinal plant Citrus medica. The structures of all compounds were determined by comprehensive analyses of their 1D and 2D NMR, mass spectral (EI and ESI) data, chemical reactions, and comparison with previously known analogues. The agar diffusion test delivered low to missing antimicrobial activities, corresponding with MICs > 1 mg mL–1, while compounds 1–6 and atalantoflavone (9) displayed weak cytotoxic activity against the human Caucasian prostate adenocarcinoma cell line PC-3, with IC50 values ranging from 60.5 to 80.0 μm versus doxorubicine with IC50=0.9 μm.

Acridone Alkaloids and Coumarins from the Stem Bark of Citropsis articulata (Rutaceae)

A new acridone alkaloid, citropsine A (1), and thirteen known compounds (2 - 14) were isolated from the MeOH extract of the stem bark of Citropsis articulata. Structures of all compounds were determined by detailed analyses of their 1D and 2D NMR spectra, mass spectrometric data and by comparison with previously known analogs.