(+)/(−)-Corydecumbenpines A and B, two pairs of dimeric phthalide-benzophenanthridine alkaloids with cytotoxicity from Corydalis decumbens

Abstract

Four pairs of previously undescribed enantiomers, including two pairs of dimeric phthalide-benzophenanthridine alkaloid and two pairs phthalides derivatives, corydecumbenpines A–D, were isolated from the rhizomes of Corydalis decumbens. Their planar structures were elucidated by extensive spectroscopic analysis including UV, IR, HRESIMS, 1D and 2D NMR. Optically pure compounds were obtained by chiral chromatography and their absolute configurations were determined by single-crystal X-ray crystallography and comparison of experimental and calculated ECD spectra. Corydecumbenpines A and B were previously undescribed phthalideisoquinolines which were benzophenanthridine linked to phthalide and corydecumbenpines C and D were previously undescribed phthalide hemiacetal derivatives. (+)-Corydecumbenpine A showed cytotoxic activity on A549, GIST-882, and PANC-1 cell lines with IC₅₀ values of 10.1 μM, 8.2 μM, and 7.1 μM respectively.