Cholinesterase, α-glucosidase, tyrosinase and urease inhibitory activities of compounds from fruits of Rinorea oblongifolia C.H. Wright (Violaceae).

From Rinorea oblongifolia fruits, 3-Nor-4ß-friedelan-24-ol (1) and 3-decyl-6,7,8-trimethoxy-2H,5H-furo[4,3,2-de]isochromene-2,5-dione (4), new derivatives alongside, 28-hydroxyfriedelan-3-one (2), friedelin (3), 3,3',4,4',5'-pentamethylcoruleoellagic acid (5), hexamethylcoruleoellagic acid (6), 3',4,4',5,5'-pentamethylcoruleoellagic acid (7), and fatty compounds 8-11 were isolated and characterized using HRESIMS, EIMS, 1D and 2D NMR. In vitro enzyme inhibition of compounds 1, 2, 4, 5, 6 and 7 were evaluated on acetylcholinesterase (AChE), butyrylcholinesterase (BChE), α-glucosidase, urease and tyrosinase. Against AChE and BChE, the phenolic compounds 4, 5, 6, and 7 had good activity probably due to the phenolic nature and methoxy substituents. Compounds 4, 5, 6 and 7 exhibited good α-glucosidase inhibition especially compound 4 whose IC50 = 42.45 ± 0.46 µg/mL was close that of acarbose (IC50 = 20.52 ± 0.84 µg/mL) standard drug. Urease and tyrosinase were appreciably inhibited by the compounds. Overall results of enzyme inhibitory assays indicate Rinorea oblongifolia, fruits and its constituents as potential remedy for enzymatic disorders.

Chemical constituents from fruits of Cnestis ferruginea Vahl ex. DC (Connaraceae) and evaluation of their anticholinesterase and antiradical activities.

The phytochemical investigation of the DCM/MeOH (1:1) extract of the fruits of Cnestis ferruginea led to the isolation and characterization of one new quinic acid derivative, ferruginoic acid (1), together with six known compounds 2-7. Compounds 3-7 were reported for the first time from this species. The structures of compounds 1-7 were elucidated on the basis of 1 D and 2 D NMR spectroscopic data, mass spectrometry and by comparison of spectroscopic data with those from the literature. The anticholinesterase (AChE and BChE) activity and DPPH free radical scavenging assay of compounds 1, 3, 4 and 7 were evaluated. Ferruginoic acid (1) exhibited moderate anticholinesterase activity with IC50 value of 36.18 ± 1.78 µg/mL against AChE. Compounds 3, 4 and 7 showed high activity against free radical (DPPH•) scavenging assay (DPPH) with IC50 values 40.09 ± 0.96 µg/mL, 61.70 ± 0.78 µg/mL and 41.87 ± 0.62 µg/mL respectively. These results indicate that C. ferruginea and its constituents could be employed in the management of Alzheimer's disease.

Antifungal potential of extracts, fractions and compounds from Uvaria comperei (Annonaceae) and Oxyanthus unilocularis (Rubiaceae).

Phytochemical study of Uvaria comperei afforded an alkaloid, 8,9-dimethoxy-5H-phenanthridin-6-one (1), isolated and characterised (assignment of 1H and 13C NMR) for the first time from a natural source along with two flavonoids, (2S)-5-hydroxy-7,8-dimethoxyflavanone (2) and (2S)-7-hydroxy-5-methoxy-6,8-dimethylflavone (3). Clethric acid (4), oleanoic acid (5), ß-sitosterol 3-O-ß-D-glucopyranoside (9), ß-sitosterol palmitate (6) and a mixture of stigmasterol (7) and ß-sitosterol (8) were isolated from Oxyanthus unilocularis. The structures of these compounds were elucidated using modern spectroscopic techniques including1D and 2D Nuclear Magnetic Resonance (NMR) Spectroscopy (1H, 13C, 1H-1H COSY, HSQC, HMBC) and Mass Spectrometry. Some fractions and compounds from Uvaria comperei exhibited good antifungal activity against clinical isolates and standard strains of yeast species of Candida and Cryptococcus genera while extracts from Oxyanthus unilocularis displayed weak antifungal activity. The results obtained show that Uvaria comperei could be a potential source of antifungal drugs.