Two New Stilbenes from the Leaves and Stems of Bletilla striata and Their Anti-SARS-CoV-2 Activity

With the aim of screening more bioactivity metabolites, in this study, two new stilbenes, 5-methoxy-6-(4- methoxystyryl)benzofuran (1) and 6-(4-methoxystyryl)benzofuran-5-ol (2) were isolated from the leaves and stems of Bletilla striata. Their structures were established by their 1D, 2D NMR, and MS spectral data. Interestingly, the anti-SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) activity revealed that compound 1 exhibited potential anti-SARS-CoV-2 activity with IC50 of 15.2 μM for the delta strain and 22.8 μM for the omicron BA.1 strain; compound 2 also showed potential anti-SARS-CoV-2 activity with IC50 of 10.2 μM for the delta strain and 16.8 μM for the omicron BA.1 strain. These values are lower than that of a positive control (with IC50 of 1.2 μM for the delta strain and 3.4 μM for the omicron BA.1 strain).