Bioassay-Guided Isolation and Identification of Cytotoxic Compounds from Fruits.

The fruit extract of yielded a total of 19 compounds, including two novel spiro-biflavonoid enantiomers ( and ) and a chalcone derivative (). Their structures were determined through spectroscopic analysis. The enantiomers of the racemic mixture of compound were successfully resolved into (+)- and (-)- using chiral-phase HPLC. Single-crystal X-ray diffraction analysis was also used to confirm the structure of . The enantiomeric configurations of and were determined through a comparison of the calculated and experimental electronic circular dichroism spectra. Compounds (melanervin), (methyl betulinate), (3--acetylbetulinic acid), and (pyracrenic acid) were found to be highly cytotoxic, with compound showing superior growth inhibition of nonsmall cell lung cancer cells (A549 cells) (IC 2.8 ± 0.1 μM) compared to cisplatin (IC 3.3 ± 0.0 μM), a positive control chemotherapeutic drug. Both compound and cisplatin were significantly more cytotoxic toward A549 lung cancer cells compared to nontumorigenic Vero E6 cells.