The chemical constituents of Piper kadsura and their cytotoxic and anti-neuroinflammtaory activities.

The n-hexane and CHCl₃ soluble fractions of the MeOH extract of the aerial parts of Piper kadsura were found to potently inhibit nitric oxide (NO) production in LPS-activated BV-2 cells, a microglial cell line. From the active fractions, a new stereoisomer of guaiane sesquiterpene, 1α,5β-guai-4(15)-ene-6β,10β-diol, kadsuguain A (1) and a new cyclohexadienone, kadsuketanone A (2), together with twelve known compounds (3-14) were isolated. The structures of these compounds were elucidated by extensive NMR spectral studies. The absolute configuration of 2 was determined by circular dichroism (CD) spectra. Compounds 2, 6, and 11-14 significantly inhibited both nitric oxide (NO) and prostaglandin E₂ (PGE₂) production in the LPS-activated microglia cells. In addition, compounds 4, 6, and 11-14 exhibited cytotoxicity against the A549, SK-OV-3, SK-MEL-2, and HCT15 human tumour cells.