Antimalarial diterpenoids from Vitex rotundifolia: Isolation, structure elucidation, and in vitro antiplasmodial activity.

Vitex rotundifolia is an important medicinal plant frequently employed in traditional medicines for the treatment of various ailments. Although this plant species has been under exploration for its constituents by various research groups including our own group, no reports were found regarding the antimalarial potential of this plant or of its purified phytochemicals. Phytochemical investigation of this plant yielded three new (1-3) and five known (4-8) diterpenoids. These compounds were purified by modern chromatographic techniques and their structures were determined by advanced spectroscopic techniques such as nuclear magnetic resonance (NMR) and high-resolution mass spectrometry (HRMS). The in vitro antiplasmodial activities were encouraging, as compounds 2, 6, and 8 were found to have significant IC50 values of 1.2, 1.3 and 11.0 µM, respectively against Plasmodium falciparum.

Isolation and characterization of antiplasmodial constituents from the marine sponge Coscinoderma sp.

Six known compounds, namely two halisulfates 1 and 2 and four epidioxy sterols 3-6, were isolated from the marine sponge Coscinoderma sp. The structures of these compounds were confirmed by nuclear magnetic resonance (1H and 13C NMR) spectroscopy, and their antiplasmodial activities were determined against the chloroquine-resistant Dd2 strain of Plasmodium falciparum. The epidioxy steroids 3-6 all showed moderate to weak antiplasmodial activity, with IC50 values of 2.7 µM for (24S)-5α,8α-epidioxy-24-methylcholesta-6-en-3ß-ol (3), 11.6 µM for 5α,8α-epidioxycholesta-6,24(28)-dien-3ß-o1 (4), 2.33 µM for 5α,8α-epidioxy-24-methylcholesta-6,9(11)-24(28)-trien-3ß-ol (5), and between 12 and 24 µM for 5α,8α-epidioxycholesta-6-en-3ß-ol (6). In contrast, halisulfate 2 (1) was inactive, and halisulfate 1 (2) had an of IC50 value of about 24 µM.

Bioactive Neolignans and Other Compounds from Magnolia grandiflora L.: Isolation and Antiplasmodial Activity.

Bioassay-guided fractionation of a methanol extract of Magnolia grandiflora against Plasmodium falciparum yielded two new (1 and 2) and six known (3 - 8) bioactive compounds. The structures of the new compounds were assigned by mass spectrometric and 1D- and 2D-NMR data. Known compounds were identified by comparison of 1 H-NMR and MS data with literature data. The two known neolignans 3 and 4 showed moderate antiplasmodial activity with the IC50 values of 2.8 ± 0.1 and 3.4 ± 0.1 µm, respectively. Weak antiplasmodial activity was recorded for compounds 1, 2, 5, 6, 7, and 8, with the IC50 values of 38 ± 2, 23 ± 2, 16.5 ± 0.2, 86 ± 1, 44 ± 4, and 114 ± 9 µm, respectively.