A new rearranged abietane diterpene from Clerodendrum inerme with antioxidant and cytotoxic activities

Eight compounds were isolated from the leaves of Clerodendrum inerme, including one new rearranged abietane diterpene, crolerodendrum B (1). Their structures were determined by means of spectroscopic methods including one-dimensional and two-dimensional nuclear magnetic resonance (1-D and 2-DNMR), high-resolution electrospray ionisation mass spectrometry (HR-ESI-MS) and circular dichroism (CD). The DPPH radical scavenging and cytotoxic activities of isolated compounds against MCF7 (breast), HCT116 (colon) and B16F10 (melanoma) cancer cell lines were evaluated. Compounds 1, 3 and 4 exhibited strong DPPH radical-scavenging effects (ED50 values of 17.6 +/- 2.1, 10.1 +/- 0.8 and 11.3 +/- 0.3M, respectively) and 4 showed strong cytotoxicity against the HCT116 cell line (IC50=3.46 +/- 0.01 mu M). [GRAPHICS] .