Caffeic acid derivatives and polymethoxylated flavonoids from cat's whiskers (Orthosiphon stamineus) form stable complexes with SARS-CoV molecular targets: an in silico analysis

Cat's whiskers or the 'misai kucing' is an herbal plant native to the Southeast Asian region. The polyphenol enriched leaf extract contains numerous medicinal properties of major pharmaceutical interest. In this study, selected cat's whiskers polyphenols were screened computationally to predict the minimum binding affinities with severe acute respiratory syndrome coronavirus (SARS-CoV) molecular targets. Molecular docking analysis showed that the caffeic acid derivatives and polymethoxylated flavonoids from cat's whiskers bound stably to the binding pocket regions of SARS-CoV molecular targets at - 4.2 to - 7.1 kcal/mol. Furthermore, these cat's whiskers polyphenol-bound SARS-CoV complexes were held fairly strongly by hydrophobic interactions, hydrogen bonds, and electrostatic interactions at various extents.