Xylanins A-P, sixteen new guaiane-type dimers from the branches and leaves of Xylopia vielana with anti-proliferative activity against PANC-1 cell line.

Sixteen previously undiscovered guaiane-type sesquiterpene dimers, xylanins A-P (1-16), along with six known analogues (17-22), were isolated from the branches and leaves of Xylopia vielana with chromatographic techniques. Their structures including absolute configurations were determined by high-resolution electrospray ionization mass spectrometry (HR-ESI-MS), nuclear magnetic resonance (NMR) data, electron circular dichroism (ECD) spectra, as well as X-ray crystallographic analysis. In cytotoxicity test, we found that five compounds (6, 7, 8, 9 and 12) had cytotoxic activities in vitro against the human pancreatic cancer (PANC-1) and human prostate cancer (PC-3) cell lines. Of these compounds, compound 8 showed a relatively greater cytotoxic effect against PANC-1 cell lines with half maximal inhibitory concentration (IC50) value of 1.06 μM. Flow cytometry analysis showed that the apoptosis rate of PANC-1 cells increased with increasing concentrations of compound 8, and also demonstrated that the cell cycle of PANC-1 cells was arrested at S phase by the treatment of compound 8. By the invasion test, compound 8 was found to restrain the invasion of PANC-1 cells. In autophagy assay, we observed increased microtubule-associated protein 1 light chain 3 (LC3) by immunofluorescence in the compound 8-treated group.