New lignans from Phyllanthodendron dunnianum

A new lignan phyllanins A (1) and a lignan phyllanins B (2) for which the absolute configuration was determined for the first time, along with four known lignans (3-6) were isolated from the branch and leaf extracts of Phyllanthodendron dunnianum. Their planar structures were mainly determined by a combination of 1D and 2D NMR, HRESIMS spectral analyses, and the absolute configurations of the compounds 1 and 2 were established by DFT GIAO ¹³C NMR and electronic circular dichroism (ECD) calculations. In addition, all these six lignans were firstly tested for the antibacterial activities against MRSA, Staphylococcus aureus, Enterococcus faecalis, Pseudomonas aeruginosa and Escherichia coli. Among these compounds, 2 and 5 showed potential antibacterial activities against MRSA and S. aureus with MIC values of 4 and 8 µg/mL, respectively.