Four new dilignans from the roots of Wikstroemia indica.

Phytochemical investigation of the roots of Wikstroemia indica led to the isolation of four new dilignans (1-4). Their structures were established on the basis of the spectroscopic data including UV, IR, high resolution-electron ionization-mass spectrometry (HR-ESI-MS), 1D- and 2D-NMR (1H-1H correlation spectroscopy (COSY), heteronuclear single quantum coherence (HSQC), heteronuclear multiple bond correlation (HMBC) and rotating frame Overhauser enhancement spectroscopy (ROESY)). These dilignans were screened for their in vitro antiviral activities against respiratory syncytial virus (RSV) with cytopathic effect (CPE) reduction assay.