Unusual diarylheptanoid-phenylpropanoid adducts and diarylheptanoid alkaloids from Pellacalyx saccardianus

Two pairs of enantiomeric diarylheptanoid-phenylpropanoid adducts bearing a cyclohexenone core, (±)-saccardianones A and B (1 and 2), an alkaloidal diarylheptanoid-phenylpropanoid adduct bearing a 4-piperidone core, (±)-saccardianine A (3), a pair of enantiomeric dimeric diarylheptanoid alkaloids bearing a tetrahydropyridine core, (±)-saccardianine B (4), and a suspected degradation product, saccardianine C (5), in addition to a known diarylheptanoid, platyphyllenone (6), were isolated from the leaves of Pellacalyx saccardianus. Their chemical structures were elucidated based on detailed analyses of the NMR and MS data. The structure of (±)-(1) was also confirmed by X-ray diffraction analysis. Compounds (±)-2 and 6 exhibited selective cytotoxicity towards the AsPC-1 and PANC-1 pancreatic cancer cell lines, respectively.