Cardiac glycosides from Streblus asper with potential antiviral activity

Ten undescribed cardiac glycosides, strasperosides A−J, together with twelve known analogues, were isolated from Streblus asper Lour. Their structures were elucidated on the basis of spectroscopic analysis, electronic circular dichroism data, and chemical methods. These cardiac glycosides showed diversity in steroid skeleton and sugar moiety. Strasperosides A and B are a pair of unusual stereoisomers featuring different orientation of the lactone motif. Ten cardiac glycosides demonstrated potent antiviral effects on HSV-1 in vitro with the IC50 values from 0.19 ± 0.08 to 1.03 ± 0.25 μM and the therapeutic indices from 66.61 ± 5.08 to 326.75 ± 11.75. Ten undescribed cardiac glycosides, together with twelve known analogues were isolated from Streblus asper Lour. Their structures were elucidated on the basis of spectroscopic analysis, electronic circular dichroism data, and chemical methods. Ten cardiac glycosides demonstrated potent antiviral effects on HSV-1 in vitro. [Display omitted] •Twenty-two cardiac glycosides were isolated from Streblus asper.•Ten undescribed cardiac glycosides were isolated from Streblus asper.•Some of the isolates showed potent antiviral effects on HSV-1 in vitro.