In vitro antimicrobial activity of the leaf extract of Harungana madagascariensis Lam. ex Poir. (Hypericaceae) against strains causing otitis externa in dogs and cats

Abstract

Otitis externa in dogs and cats is always caused by a combination of yeasts and bacteria, among which the most important are Malassezia pachydermatis, Staphylococcus intermedius and Pseudomonas species. These organisms often develop resistance to classical antimicrobial agents. Therefore, the aim of this study was to investigate the antimicrobial activities of an ethyl acetate leaf extract of Harungana madagascariensis against the organisms cited, to carry out the phytochemical investigation of this extract and to determine its bioactive chemical class using dilution techniques, the bioautography method and the standard phytochemical method described by Harborne (1973). Phytochemical analysis revealed the presence of saponins, tannins, flavonoids, alkaloids and anthracenic derivatives. The bioassay showed that the antimicrobial properties may be attributed to astilbin, a flavanone derivative identified on the basis of its spectroscopic data. The results suggest that the extract could be used in an antimicrobial preparation effective against the whole range of organisms incriminated in otitis externa in dogs and cats, with a minimal inhibitory concentration (MIC) of 250 µg/ml.

Nutrient Composition and In Vitro Antioxidant Properties of Harungana madagascariensis Stembark Extracts

“…10 Documented scientific studies indicate isolation of compounds like anthrones, anthraquinones, xanthones, flavonoids, and essential oils from this plant. [11][12][13] Also, various parts of the plant have been reported to possess antiprotozoan activity, 14 antifungal and antimicrobial activity, [15][16][17] antioxidant and modulatory effect on cyclophosphamide-induced neurotoxicity, 18 as well as acting as antioxidant markers in alloxan-induced diabetic and carrageenan-induced inflammatory disorders in rats. To our knowledge, the levels of minerals, vitamins, antinutrients, acute toxicity, and in vitro antioxidant activity of the stembark of H. madagascariensis have not been reported despite its widespread use.…”

Astilbin inhibits the adhesion of T lymphocytes via decreasing TNF-α and its associated MMP-9 activity and CD44 expression

“…This flavanoid has been reported to show antioxidative [10], insecticidal [11], antibacterial [12], antimicrobial [13] antinociceptive and antiedematogenic [14] activities formerly. Our study has demonstrated its immunosuppressive activities including improvement of immunologic liver injury [15], collagen-induced arthritis [16] and contact hypersensitivity Figure 1 Effect of astilbin on the adhesion of Jurkat cells to fibronectin, type IV collagen, hyaluronate or ECV-304 cells.…”

Topical ear treatment – options, indications and limitations of current therapy

“…Results from the study suggest that the extract could be used as an antimicrobial preparation for OE (Moulari et al . ). A recent open pilot study considered the efficacy of medical grade honey (MGH) in the management of canine OE.…”