Evaluating the SARS-CoV-2 spike glycoprotein as a molecular target for therapeutic development

The SARS-CoV-2 virus gains entry into host cells by binding its spike glycoprotein (S-glycoprotein) to the angiotensin 2 receptor. This viral protein contains several conserved regions, such as the receptor binding domain region, making it an ideal target for treating COVID-19. Notably, the majority of existing vaccines elicit antigenic reaction by targeting this protein epitope. This study evaluated the binding affinities of 44 different drugs against the SARS-CoV-2 S-glycoprotein, considering their toxicity profiles and previous clinical studies at different testing stages. Our results revealed that maraviroc and estradiol benzoate exhibited high affinities (−7.7 and −7.6 kcal mol−1, respectively), while other ligands, such as indinavir and ritonavir, showed affinity at lower levels. Among the drugs with high affinity, toxicity levels ranged from harmful if swallowed (300 mg/kg < LD50 < 2000 mg/kg) to non-toxic (LD50 > 5000 mg/kg), with only three having undergone clinical testing, yielding promising or controversial results. Furthermore, emtricitabine and docosanol, previously explored as COVID-19 treatments, exhibited the lowest affinities (−4.7 and −3.9 kcal mol−1, respectively), with associated harmful effects if swallowed. These results provide essential information about drug interaction against the SARS-CoV-2 S-glycoprotein and potential treatment pathways for COVID-19.