Diterpenes and phenylpropanoids from Clerodendrum splendens.

Four new clerodane diterpenes (1-4) and one new phenylpropanoid (5) have been isolated from Clerodendrum splendens aerial parts, together with nine known compounds. Their structures were determined by spectroscopic and spectrometric analysis and chemical methods. The absolute configuration of the 15,16-diol moiety in 4 was determined by Snatzke's method. Antiproliferative activity of diterpenes in HeLa cells was also evaluated. The IC50 values were 98 ± 11 µM for 3 and 101 ± 8 µM for 1, respectively.