Cyclopeptide alkaloids from stems of Paliurus ramossisimus.

Three 13-membered cyclopeptide alkaloids, paliurines G, H and I, together with six known alkaloids, nummularine H, daechuine-S3, paliurines A-C and F, were isolated from the stem of Paliurus ramossisimus by a combination of centrifugal partition chromatography and preparative TLC. Their structures were characterized and established on the basis of spectral analysis. A preliminary study indicated that nummularine H could shorten the methohexital induced sleeping time.