RESUMO
A new 3,8''-flavanone-flavonol dimer gnidiflavanone-flavonol (1) and 10 known compounds (2-11), including four rare primula-type flavones 2-5, were isolated from the roots of Gnidia apiculata. Compounds 2-5 and 7 were reported for the first time from the plant family Thymelaeceae. Structures of the isolated compounds were established by spectroscopic data, including 1D and 2D NMR (COSY, HMBC, HSQC and ROESY) and mass spectrometry, as well as by the comparison with literature data. The crude roots extract and isolated compounds were evaluated for antimicrobial and antiplasmodial activities. Among isolated compounds, 6-hydroxyflavone (4) and 6-O-acetylflavone (4a) showed antiplasmodial activity against chloroquine-sensitive (D6) and chloroquine-resistant (W2) strains of Plasmodium falciparum.
RESUMO
Phytochemical investigation of the methanolic extract of Monodora minor Engl. & Diels (Annonaceae) stem bark yielded a new indole (E)-4-(1H-indol-5-yl)-but-3-en-2-one (1), a known indole 5-formyl-1H-indole (2) and an ubiquitous steroid sitosterol (3). The investigations of the methanolic extract of Uvaria tanzaniae Verdc. (Annonaceae) root bark yielded two previously reported C-benzylated dihydrochalcones namely uvaretin (4) and diuvaretin (5). Structures of the isolated compounds were elucidated based on NMR spectroscopy and high resolution electron ionization mass spectrometry (HR-EI-MS) data. All compounds were tested against Trypanosoma brucei brucei and Plasmodium falciparum. At a single concentration (20 µM) in the antitrypanosomal and antiplasmodial assays, compound 4 exhibited remarkable activities against T. brucei brucei and P. falciparum with percentage inhibition of 97.3% and 83.0% respectively, whereas compounds 1, 2, 3 and 5 were inactive. In a dose response antiplasmodial assay compound 4 exhibited moderate activity against P. falciparum with an IC50 value of 7.20 µM.
