Radical scavenging and xanthine oxidase inhibitory activity of phenolic compounds from Bridelia ferruginea stem bark

Bridelia ferruginea Benth. (Euphorbiaceae) is a subtropical medicinal plant widely used in traditional African medicine against various diseases, including rheumatic pains. Seven of its constituents (3-O-methylquercetin (1), 3,7,3′,4′-tetra-O-methylquercetin (rutisin, 2), myricetin (3), 3′,4′,5′-tri-O-methylmyricetin (ferrugin, 4), 3,3′,4′,5′-tetra-O-methylmyricetin (5), quercetin 3-O-glucoside (6), and a biflavanol gallocatechin-[4′-O-7]-epigallocatechin (7)) have been evaluated in-vitro in the xanthine-xanthine oxidase enzymatic system for inhibition of xanthine oxidase and radical scavenging activity. Results indicated that compounds 1, 3, 4 and 6 exhibited, at different levels, xanthine oxidase inhibiting and superoxide scavenging activity at micromolar concentrations, whereas compound 7 showed scavenging activity only. Compounds 2 and 5 were inactive in both cases. Study of the structure-activity relationship demonstrated that for flavonoids the xanthine oxidase inhibitory activity was reduced by methylation of the hydroxyl functionality at C-3 and in rings A and B. These results may partly explain and support the use of B. ferruginea stem bark for the treatment of rheumatic pains in traditional medicine.

Complement-Inhibiting Constituents of Bridelia ferruginea Stem Bark

A bioassay-guided fractionation of an 80% acetone extract from BRIDELIA FERRUGINEA stem bark showing a dose-dependent inhibitory effect towards both the classical and the alternative pathways of the complement system resulted in the isolation of a biflavanol (gallocatechin-(4'- O-7)-epigallocatechin) ( 1), 3,5-dicaffeoylquinic acid ( 2), 1,3,4,5-tetracaffeoylquinic acid ( 3), and a series of 3-methoxyflavone derivatives, including quercetin 3-methyl ether ( 4), quercetin 3,7,3',4'-tetramethyl ether ( 5), myricetin 3',4',5'-trimethyl ether ( 6; new compound) named ferrugin, myricetin 3,3',4',5'-tetramethyl ether ( 7), myricetin ( 8), and quercetin 3- O-glucoside ( 9) as the active constituents. Especially the biflavanol 1 and the caffeoyl esters of quinic acid 2 and 3 showed a strong inhibitory effect (IC (50) < 10 microM) on the classical pathway, compared to rosmarinic acid. Also on the alternative pathway, the biflavanol 1, the quinic acid derivatives 2 and 3, and some of the 3-methoxyflavones 5, 7 and 8 were more active than rosmarinic acid. The quinic acid derivatives were shown to be inhibitors of the C1 component and the terminal route of the complement system.

Complement-modulating properties of a kaempferol 7-O-rhamnosylsophoroside from the leaves of Morinda morindoides

A kaempferol 7-O-rhamnosylsophoroside isolated from the leaves of Morinda morindoides showed dose-dependent complement-modulating properties towards both the classical (inhibiting effect) and alternative (activating effect) pathways of the complement system. Its structure was elucidated by chemical and spectroscopic methods as kaempferol 7-O-[alpha-L-rhamnopyranosyl-(1-->6)]-[beta-D-glucopyranosyl-(1-->2)]-be ta-D-glucopyranoside, a new natural product which was named morindaoside.

Structure and chemotherapeutical activity of a polyisoprenylated benzophenone from the stem bark of Garcinia huillensis

The stem bark of Garcinia huillensis grown in Zaïre and used in central-African traditional medicine has been subjected to a bioassay-guided fractionation. The chemotherapeutically active petroleum ether extract afforded fatty acids, aliphatic alcohols, triterpenes and a polyisoprenylated benzophenone, which was identified as garcinol, also named camboginol. This compound has been shown to exhibit chemotherapeutical activity gram-positive and gram-negative cocci, mycobacteria and fungi. On the other hand garcinol has been found to be inactive against gram-negative enteric bacilli, yeasts and viruses.