Antiplasmodial and antimicrobial activities of ent-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), 8,14ß:11,12α-diepoxy-13(15)-abietane-16,12-olide (3), 7ß,11ß,12ß-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 3ß-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 IC50 values of 0.79 and 0.87 µg/mL, respectively, while 3 (IC50 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 IC50 values of 1.20, 3.90 and 7.20 µg/mL, respectively.

Cytotoxic alkaloids from the root of Zanthoxylum paracanthum (mildbr) Kokwaro.

Chemical investigation of the root of Zanthoxylum paracanthum afforded 1 new alkamide derivative, (2E,4E)-6-oxo-N-isobutyldeca-2,4-dienamide (1) together with 10 known congeners including one phenolic amide (2), four benzophenanthridines (3 - 6), three indolonaphthyridines (7 - 9) and two lignans (10 and 11). Their structures were elucidated by a combination of spectroscopic and spectrometric data. Using resazurin reduction assay, the crude extract (10 µg/mL) and isolates (10 µM) were screened for their cytotoxic activities against the drug-sensitive (CCRF-CEM) leukemia cell line and its multidrug-resistant counterpart (CEM/ADR5000). Compounds 3, 4 and 6 showed cytotoxicity against CCRF-CEM with IC50 values of 2.00 ± 0.33, 2.31 ± 0.20 and 0.11 ± 0.04 µM, respectively. Only compound 6 exhibited strong cytotoxic activity against CEM/ADR5000 with an IC50 value of 2.34 ± 0.34 µM in comparison with the standard drug doxorubicin which showed IC50 values of 0.01 ± 0.14 (CCRF-CEM) and 26.78 ± 3.30 µM (CEM/ADR5000).