TIRUCALLANE-TYPE TRITERPENOIDS - NMR AND X-RAY-DIFFRACTION ANALYSES OF 24-EPI-PISCIDINOL-A AND PISCIDINOL-A

A new tirucallane-type triterpenoid named 24-epi-piscidinol A (1) has been isolated from Castela texana (T. & G.) Rose (Simaroubaceae) and d etermined to have the structure 23R,24R,25-trihydroxytirucall-7-en-3-o ne by X-ray crystallographic analysis. Crystals of 24-epi-piscidinol A are monoclinic, space group C2, a = 23.84 (3), b = 7.012 (7), c = 17. 35 (2) Angstrom, beta = 103.46 (2)degrees. Another triterpenoid piscid inol A (2), crystallizes in the orthorhombic space group P2(1)2(1)2(1) with a = 10.659 (2), b = 14.499 (3), c = 17.922 (4) Angstrom, beta = 90 degrees. Two coumarino-lignans, cleomiscosin A and C, were also obt ained in the course of this work. This is the first time of isolation of tirucallane-type triterpenoids and coumarino-lignans from the genus Castela.