Flavonoidal glycosides and in vitro antioxidant activity of Bignonia binata Thunb. leaves Family Bignoniaceae and in silico evidence of their potential anti-COVID-19 activity.

One O- and three C-flavonoidal glycosides were isolated from the EtOAc and aqueous fractions of the total ethanolic extract of Bignonia binata Thunb. leaves (TEEBB). The structure elucidation of the compounds was based on both 1D and 2D NMR spectroscopic experimental analyses and ESI-MS, as well as by comparison with the literature, they were identified as chrysoeriol 7-O-β-D-glucopyranoside (1), apigenin-6,8-di-C-β-D-glucopyranoside (2), luteolin 6,8-di-C-β-D-glucopyranoside (3) and apigenin 6-C-α-L-arabinopyranosyl-8-C-β-D-glucopyranoside (4). Whereas, compounds 1 and 3 were isolated for the first time from family Bignoniaceae and compound 4 for the first time from Bignonia genus. Additionally, the antioxidant potency evaluation of the TEEBB and different fractions revealed the high potency of the 50% MeOH sub-fraction of the aqueous fraction (50%MAqF) as DPPH radical scavenger, followed by the EtOAc fraction. Likewise, the highest antioxidant capacity was obtained by the EtOAc fraction and 50%MAqF in phosphomolybdate assay. Molecular docking simulation of the isolated flavonoidal glycosides to SARS-CoV-2 Mpro revealed their high binding affinity and their therapeutic potential against COVID-19.