Biological activity of five antibacterial flavonoids from Combretum erythrophyllum (Combretaceae)

• Published in: Journal of ethnopharmacology 2004-08, Vol.93 (2), p.207-212
• Main Authors: Martini, N.D, Katerere, D.R.P, Eloff, J.N
• Format: Article
• Language: English
• Subjects: Anti-Bacterial Agents - administration & dosage; Anti-Bacterial Agents - pharmacology; Anti-Bacterial Agents - therapeutic use; Anti-inflammatory; anti-inflammatory activity; antibacterial properties; Antimicrobial; Antioxidant; antioxidant activity; Aspergillus niger - drug effects; Biological and medical sciences; Combretum; Combretum erythrophyllum; cytotoxicity; Flavonoids; Flavonoids - administration & dosage; Flavonoids - pharmacology; Flavonoids - therapeutic use; General pharmacology; Gram-Negative Bacteria - drug effects; Gram-Positive Bacteria - drug effects; Humans; Medical sciences; medicinal plants; Microbial Sensitivity Tests; Pharmacognosy. Homeopathy. Health food; Pharmacology. Drug treatments; Phytotherapy; Plant Extracts - administration & dosage; Plant Extracts - pharmacology; Plant Extracts - therapeutic use; Plant Leaves; Toxicity; traditional medicine
• ISSN: 0378-8741; 1872-7573
• DOI: 10.1016/j.jep.2004.02.030

Preliminary studies with Combretum erythrophyllum showed antimicrobial activity against Gram-positive and Gram-negative bacteria. Seven antibacterial flavonoids were subsequently isolated by bioassay-guided fractionation, i.e. apigenin; genkwanin; 5-hydroxy-7,4′-dimethoxyflavone, rhamnocitrin; kaempferol; quercetin-5,3′-dimethylether; rhamnazin. All compounds had good activity against Vibrio cholerae and Enterococcus faecalis, with MIC values in the range of 25–50 μg/ml. Rhamnocitrin and quercetin-5,3′-dimethylether also inhibited Micrococcus luteus and Shigella sonei at 25 μg/ml. With the exception of 5-hydroxy-7,4′-dimethoxy-flavone the flavonoids were not toxic towards human lymphocytes. This compound is potentially toxic to human cells and exhibited the poorest antioxidant activity whereas rhamnocitrin and rhamnazin exhibited strong antioxidant activity. Genkwanin; rhamnocitrin; quercetin-5,3′-dimethylether; rhamnazin had a higher anti-inflammatory activity than the positive control mefenamic acid. Although these flavonoids are known, this is the first report of biological activity with several of these compounds.