Abietane diterpenoids and other constituents from Clerodendrum trichotomum.

The genus Clerodendrum Linn., originally belonging to Verbenaceae, was assigned to Lamiaceae by APG (Angiosperm Phylogeny Group) Ⅱ. Seven abietane diterpenoids ( 1 –7) along with three anthraquinones ( 8 – 10 ) and one neolignan (11 ) were isolated and identified from the stems of Clerodendrum trichotomum Thunb.. Among them, compounds 4 , 6 and 8 – 11 were reported from the genus Clerodendrum Linn. for the first time. Compounds 1 , 3 and 7 were obtained from this species for the first time. Isolation of abietane diterpenoids from C. trichotomum could further comfirm that the genus Clerodendrum belongs to Lamiaceae rather than Verbenaceae. [ABSTRACT FROM AUTHOR]