Antiplasmodial and antimicrobial activities of ent-abietane diterpenoids from the roots of Suregada zanzibariensis

Abstract

The root extract ofSuregada zanzibariensisBaill. afforded six previ-ously describedent-abietane diterpenoids, namely 7-oxo-ent-abieta-5(6),8(14),13(15)-trien-16,12-olide (1), mangiolide (2),8,14b:11,12a-diepoxy-13(15)-abietane-16,12-olide (3), 7b,11b,12b-trihydroxy-ent–abieta-8(14),13(15)-diene-16,12-olide (4), 8a,14-dihydro-7-oxo-jolkinolide E (5), jolkinolide A (6), together with 3b-sitosterol (7), scopoletin (8) and vanillin (9). Their structures werededuced through 1D and 2D NMR spectroscopic techniques, andHRESIMS, as well as by comparison of the NMR data with thosereported in the literature. The crude extract and compounds1–9were evaluated for their antiplasmodial, antifungal and antibacter-ial activities. Mangiolide (2) showed strongin vitroantiplasmodialactivity against chloroquine sensitive (D6) and resistant (W2)strains ofPlasmodium falciparumwith IC50values of 0.79 and0.87mg/mL, respectively, while3(IC501.24 and 1.17mg/mL) wasless active than2. Compound2also displayed antimicrobial activ-ity againstCryptococcusneoformans, methicillin-resistantStaphylococcusaureus(MRSA) and vancomycin-resistantEnterococcus faecium(VRE) with IC50values of 1.20, 3.90 and7.20mg/mL, respectively.