Abstract
Two new [(+)-cyrillins A (1) and B (2)] and four known barrigenol-like triterpenoids (3-6), along with betulinic acid and (+)-3β-O-trans-feruloylbetulinic acid, were isolated from a sample-restricted CH2Cl2-soluble extract of the bark of Cyrilla racemiflora, collected in Dominica. The structures of the new compounds were elucidated by interpretation of their spectroscopic data, and the absolute configuration of the cyclic 1,2-diol unit of (+)-cyrillin A (1) was ascertained by analysis of the electronic circular dichroism (ECD) spectrum induced with [Mo2(OAc)4]. In the case of (+)-cyrillin B (2), which was found to contain a diangeloylated glucose residue, the structure proposed was supported by analysis of its MS(2) and MS(3) spectra. All compounds isolated were evaluated for their cytotoxicity against HT-29 human colon cancer cells, and the known compound, (+)-barringtogenol B (3), was found to be the most potent, exhibiting an IC50 value of 1.7 μM. This compound also showed inhibitory activity toward the CCD-112CoN human normal colon cell line, with an IC50 value of 5.9 μM, indicating a lack of cytotoxic selectivity.