Flavonoid compounds of buah merah (Pandanus conoideus Lamk) as a potent SARS-CoV-2 main protease inhibitor: in silico approach

BACKGROUND: COVID19 is a global pandemic that threatens all nations. As there is no effective antiviral drug for COVID19, we examined the potency of natural ingredients against the SARS-CoV-2 main protease (PDB ID 6YNQ). Buah merah is a typical fruit from Papua, Indonesia, which is known to contain high levels of carotenoids and flavonoids. The contents have been proven to be effective as antiparasitic and anti-HIV. An in silico approach to 16 metabolites of buah merah (Pandanus conoideus Lamk) was carried out using AutoDock Vina. Furthermore, the study of the dynamics of ligand–protein interactions was carried out using CABS Flex 2.0 server to determine the test ligand and receptor complexes' stability. ADMET prediction was also carried out to study the pharmacokinetic profile of potential antiviral candidates. RESULT: The docking results showed that 3 of the 16 buah merah metabolites were potent inhibitors against the SARS-CoV-2 main protease. The flavonoid compounds are quercetin 3′-glucoside, quercetin 3-O-glucose, and taxifolin 3-O-α-arabinopyranose with a binding affinity of − 9.7, − 9.3, and − 8.8, respectively, with stable ligand–protein complex. ADMET study shows that the three compounds are easily dissolved, easily absorbed orally and topically, have a high unbound fraction, low toxicity, and non-irritant. CONCLUSION: We conclude that quercetin 3′-glucoside, quercetin 3-O-glucose, and taxifolin 3-O-α-arabinopyranose can be used and improved as potential anti-SARS-CoV-2 agents in further study.