QUANTIFICAÇÃO POR qRMN E ANÁLISE IN SILICO DE QUASSINOIDES ISOLADOS DE Picrolemma sprucei COMO POTENCIAIS INIBIDORES DE PROTEASE SARS-CoV-2

Abstract

As soon as the World Health Organization (WHO) declared Coronavirus disease 2019 (COVID-19) as a pandemic infection, major severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), non-structural proteins (Nsp) were analyzed as promising targets in virtual screening approaches using in silico techniques, such as molecular docking. Among these proteins is 3-chymotrypsin-like cysteine protease (3CLpro), also called the major protease, and RNA-dependent RNA polymerase (RdRp), which have been identified as targets because of their importance in viral replication steps. There is great interest in the search for new substances that may be candidates for new drugs in the treatment of COVID-19, and medicinal plants continue to be a very rich source in the search for new drugs. The specie Picrolemma sprucei, popularly known in the Amazon as caferana, is widely used in the region as an antimalarial. Previous investigations of P. sprucei roots and leaves resulted in the isolation of the main quassinoids of this species, neosergeolide and isobrucein B. In vitro studies of these substances have reported antitumor, antimalarial, anthelmintic, insecticidal activities. In this context, the present work aimed to quantify the quassinoids of P. sprucei, a medicinal plant that is native to the Amazon region, using qNMR and investigate the inhibitory potential of isobrucein B and neosergeolide on the 3CLpro and RdRp targets of SARS-CoV-2 through in silico approaches. The quantification was performed in a fraction (F2-F3) enriched with the quassinoids isobrucein B and neosergeolide using the PULCON method. In silico assays were performed using molecular docking to assess interactions and binding affinity between neosergeolide and isobrucein B ligands with SARS-CoV-2 3CLpro and RdRp targets, and online servers were used to estimate pharmacokinetic and toxicity. It was possible to determine the quantity of the two quassinoids isobrucein B and neosergeolide in the F2-F3 fraction (769.6 mg), which were present in significant amounts in the PsMeOH extract (5.46%). The results of the docking analysis, based on the crystallized structures of RdRp and 3CLpro, indicated that isobrucein B and neosergeolide are potential inhibitors of the two proteins evaluated, as well as showing the importance of hydrogen bonding and pi (π) interactions for the active sites foreseen for each target. The results suggest that P. sprucei quassinoids may interact with 3CLpro and RdRp targets. In vitro and in vivo experiments are needed to confirm the results of molecular docking and investigate the risks of using P. sprucei as a medicinal plant against COVID-19.