Cytotoxic and Antiviral Triterpenoids from the Mangrove Plant Sonneratia paracaseolaris

A chemical investigation was conducted on the aerial parts of the mangrove plant Sonneratia paracaseolaris, yielding five new triterpenoid paracaseolins A–E (1–4, and 11) together with twelve known analogues (5–10, 12–17). Their structures were established by extensive spectroscopic methods and comparisons their spectroscopic data with those of the known related compounds. The cytotoxicities against P388, HeLa, A549, and K562 tumor cell lines and anti-H1N1 (Influenza A virus) activities for the isolates were evaluated. Compound 4 showed potent cytotoxicity against the A549 cell line with an IC(50) value of 1.89 µM, and compound 1 exhibited significant anti-H1N1 virus activity with an IC(50) value of 28.4 µg/mL. A preliminary structure activity relationship was discussed.