Another possible target for treatment is the inhibition of the synthesis of the required saccharides that are incorporated in the host cell glycoproteins. Several quinine derivatives showed that these saccharide moieties known as sialic acids could be inhibited by drugs such as hydroxychloroquine. The quinines, therefore, decrease the number of glycan targets that could be engaged by coronaviral spike proteins to facilitate cell entry [30,31,32]. However, quinine derivatives pose significant cardiotoxicity that precludes their application as a treatment for Covid-19 [33].