Bioassay directed antiplasmodial constituents from Clerodendrum infortunatum L. (Lamiaceae), an ethnomedicinal plant of Assam.

Eight compounds have been identified from the bioactive fractions of Clerodendrum infortunatum L. leaf and root. NMR experiments and HRMS data were used to confirm the structures of the isolated compounds, and data compared to the existing literature. Among eight compounds, 3β-hydroxy-30-nor-urs-21-en-20-one (3) and 22-dehydroclerosterol-3-O-β-D-glucopyranoside (8) have considerable antiplasmodial activities against 3D7 strain of Plasmodium falciparum with IC 50 value 13.82 and 11.42 μM respectively compared to the positive control value 0.892 μM. The remarkable antiplasmodial property of these two compounds lends credence to the use of C.infortunatum L. against malaria and thus provides a new template for the design of an antiplasmodial molecule. This is the first report of compounds such as (24S)-ethylcholesta-5, 22, 25-triene-3β-ol (2), 3β-hydroxy-30-nor-urs-21-en-20-one (3), Clerosterol (4) and 22-dehydroclerosterol-3-O-β-D-glucopyranoside (8) exhibiting antiplasmodial properties.