Authors : P.A. Onocha, D.A. Okorie, H.C. Krebs and B. Meier
Abstract: Bioactivity directed fractionation afforded four cytotoxic constituents from the bioactive methanolic leaf extract (LD50 30 μg mLG1) of Newbouldia laevis (Bignoniaceae) collected from Ibadan, Nigeria. Four pentacyclic triterpenoids namely 2α, 3β, 19α-trihydroxy-12-ursen-28-oic acid, 3β, 19α-dihydroxy-12-ursen-28-oic acid, 3β-hydroxy-12-ursen-28-oic acid, 3β-hydroxy 12-oleanen-28-oic acid were found to be the cytotoxic principles. These compounds demonstrated significant cytotoxicity in vitro against ST-57 brain tumor transformed fibroblasts with LD50 ranging from 0.4 μg mLG1 (compound 1) to 4 μg mLG1 (compound 4). These ursene and oleanene type triterpenoids are encountered for the first time in this plant. The structures of these compounds were established by spectral data.
P.A. Onocha, D.A. Okorie, H.C. Krebs and B. Meier, 2011. In vitro Cytotoxic Pentacyclic Triterpenoids of Newbouldia laevis. Research Journal of Medical Sciences, 5: 330-335.