Isoterchebulin and 4,6-O-isoterchebuloyl-D-glucose, novel hydrolyzable tannins from Terminalia macroptera

Two new hydrolyzable tannins, isoterchebulin (1) and 4,6-O-isoterchebuloyl- D-glucose (2), together with six known tannins, 3-8, were isolated from the bark of Terminalia macroptera. Their structures were elucidated by extensi ve 1D and 2D NMR studies, MS, and chemical transformations. Biological acti vities of all compounds were evaluated against the snail Biomphalaria glabr ata, the bacteria Bacillus subtilis and Pseudomonas fluorescens, the nemato de Caenorhabditis elegans, and four cancer cell lines (Hep G2, MCF-7/S, MDA -M8-231, and 5637 cells). All compounds except 3 showed antimicrobial activ ities against B. subtilis (MIC 8-64 mug/mL), whereas only 1 was active agai nst C. elegans (100 mug/mL) and B. glabrata (LC100 = 60 mug/mL). 3 and 8 we re toxic against 5637 cells with LC50 = 84.66 and 41.40 CIM, respectively.