Two new tanshinone derivatives from the rhizomes of Salvia miltiorrhiza and their antiviral activities

Two new naturally occurring products named salviamine G (1) and 4-methyl-9-(ethoxycarbonyl)-8-naphthoic acid (2) were isolated from the rhizomes of Salvia miltiorrhiza. Their structures were elucidated using spectroscopic data (UV, IR, HRESIMS, 1D and 2D NMR). Compounds 1 and 2 were screened for their inhibitory activity against HSV-1 and influenza A (H3N2) using acyclovir (ACV, IC₅₀ = 0.67 μM) and oseltamivir (IC₅₀ = 2.01 μM) as a positive control. Compound 1 exhibited moderate inhibitory activity against HSV-1 and influenza A (H3N2) with IC₅₀ values of 11.11 and 8.62 μM, respectively.