Antiplasmodial and antimicrobial activities of e nt -abietane diterpenoids from the roots of Suregada zanzibariensis .

The root extract of Suregada zanzibariensis Baill. afforded six previously described ent -abietane diterpenoids, namely 7-oxo- ent -abieta-5(6),8(14),13(15)-trien-16,12-olide ( 1 ), mangiolide ( 2 ), 8,14 β :11,12 α -diepoxy-13(15)-abietane-16,12-olide ( 3 ), 7 β ,11 β ,12 β -trihydroxy- ent -abieta-8(14),13(15)-diene-16,12-olide ( 4 ), 8α,14-dihydro-7-oxo-jolkinolide E ( 5 ), jolkinolide A ( 6 ), together with 3 β -sitosterol ( 7 ), scopoletin ( 8 ) and vanillin ( 9 ). Their structures were deduced through 1D and 2D NMR spectroscopic techniques, and HRESIMS, as well as by comparison of the NMR data with those reported in the literature. The crude extract and compounds 1 - 9 were evaluated for their antiplasmodial, antifungal and antibacterial activities. Mangiolide ( 2 ) showed strong in vitro antiplasmodial activity against chloroquine sensitive (D6) and resistant (W2) strains of Plasmodium falciparum with IC 50 values of 0.79 and 0.87 µg/mL, respectively, while 3 (IC 50 1.24 and 1.17 µg/mL) was less active than 2 . Compound 2 also displayed antimicrobial activity against Cryptococcus neoformans , methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecium (VRE) with IC 50 values of 1.20, 3.90 and 7.20 µg/mL, respectively.