Cytotoxic clerodane diterpenoids from the roots of Mast

A study of diterpenoids as active ingredients against cancer from the active roots extract of Casearia barteri Mast. (IC 50 = 1.57 μg mL −1 ) led to the isolation of six new clerodane diterpenoids, named as barterins A-F ( 1-6 ) alongside seven known compounds, caseamembrin A, caseamembrin E, casearlucin A, graveospene G, N-trans -feruloyltyramine, N-cis -feruloytyramine and sitosterol-3- O -β- D -(6- O -palmitoyl)-glucopyranoside. Their structures were elucidated based on NMR spectroscopic data and mass spectrometry. The absolute configurations of 1-6 were established by the time-dependent density functional theory (TDDFT), electronic circular dichroism (ECD) calculations and experimental data analysis. The cytotoxic effects of compounds 1-6 were evaluated against a human cervix carcinoma cell line KB -3-1. Barterins A-D ( 1-4 ) showed cytotoxic effects against the KB -3-1 cell line with IC 50 values ranging from 1.34-4.73 μM. A study of diterpenoids as active ingredients against cancer from the active roots extract of Casearia barteri Mast.