A new ent-clerodane diterpenoid from Crassocephalum bauchiense Huch. (Asteraceae)

Abstract

A phytochemical investigation of the whole plant of Crassocephalum bauchiense Huch. resulted in the isolation of a new clerodane diterpenoid, ent-2β,18,19-trihydroxycleroda-3,13-dien-16,15-olide (1), together with two known flavonoids 3',5-dihydroxy-4',5',6,7,8-pentamethoxyflavone (2) and 4',5-dihydroxy-3',5',6,7,8-pentamethoxyflavone (3). The compounds were tested against the chloroquine-sensitive 3D7 strain of Plasmodium falciparum. Compound 2 showed weak activity (IC50 = 10.1 g/mL) whilst compounds 1 and 3 were inactive. The structures of the compounds were elucidated by using detailed spectral analyses, especially (1)H and (13)C NMR, (1)H-(1)H COSY, NOESY, HMBC and HR-ESI-MS.

Clerodane diterpenes: sources, structures, and biological activities

“…Type III subtype IIa with C3/C4 double bond58,70,72,155,163,164,175,183,189,213,[215][216][217][218][219][220][221][222][223][224][225][226][227][228] (Table 16compounds 530-575 found in ESI †).A wide range of substituents are found on the decalin and butenolide moieties in type III subtype IIa compounds. With CO 2 H at the decalin C-4 position and OMe or H, respectively, at the butenolide C-4 position, limbatolides B (533) and C (534) from Otostegia limbata inhibited acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes in a concentration-dependent manner with IC 50 values of 47.2, 103.7 and 17.5, 14.2 mM, respectively.…”