CYTOTOXIC CYCLOLIGNANS FROM KOELREUTERIA-HENRYI

Chemical investigation of the cytotoxic fraction of Koelreuteria henry i resulted in the isolation of three cyclolignans. A new cyclolignan, named koelreuterin-1 was elucidated as l-6(8H)-one,5-(7-methoxy-1,3-be nzodioxol-5-yl)[1]. Two known cyclolignans were characterized as austr obailignan-1 [2] and austrobailignan-2 [3]. The structure elucidation of 1 was based on extensive H-1- and C-13-nmr spectral analyses. Furth er chemical conversion of 2 to 3 and oxidative transformation of 2 to 1 unambiguously confirmed the structure of 1. The cytotoxicity and tub ulin polymerization inhibitory activity of 1-3 are discussed.