Two new pregnane alkaloids, (20S)-20α-cinnamoylamino-3β-dimethylamino-5-en-pregnane (1) and (20S)-20α-cinnamoylamino-3β-dimethylamino-pregnane (2), and four known alkaloids (+)-(20S)-20-(dimethylamino)-3-(3'R-isopropyl)-lactam-5α-pregn-2-en-4-one (3), axillaridine A (4), pachysamine M (5) and 20α-dimethylamino-16β-hydroxy-3β-senecioylamino-pregn-5-ene (6) were obtained from the whole herb of Pachysandra terminalis Sieb. et Zucc. Their structures were determined by various spectral techniques and computed electronic circular dichroism (ECD) data. Compounds 1-4 were tested for cytotoxicity against three human tumor cell lines and a human umbilical vein endothelial cell (HUVEC) line. Compound 4 exhibited moderate cytotoxicity against MCF-7, U251 and A549 cells with IC50 values of 15.01 ± 0.47 μM, 20.13 ± 1.34 μM and 20.04 ± 1.16 μM, respectively; compounds 1-3 showed weak cytotoxic activity against three tumor cells.
Keywords: Pachysandra terminalis Sieb. et Zucc.; alkaloids; cytotoxic activity; structure identification.