African Journal of
Pharmacy and Pharmacology

  • Abbreviation: Afr. J. Pharm. Pharmacol.
  • Language: English
  • ISSN: 1996-0816
  • DOI: 10.5897/AJPP
  • Start Year: 2007
  • Published Articles: 2248

Full Length Research Paper

Susceptibility of fish-associated Flavobacterium spp. isolates to cinnamaldehyde, vanillin and Kigelia africana fruit extracts

Hafizah Y. Chenia* and Sarisha Singh    
Microbiology (Westville Campus), School of Life Sciences, University of KwaZulu-Natal, Private Bag X54001, KwaZulu-Natal, 4001, South Africa.    
Email: [email protected]

  •  Accepted: 28 June 2013
  •  Published: 08 August 2013


Phytochemicals are being explored as therapeutic alternatives in aquaculture since they have de-stressing, growth-promoting, appetite-increasing, immune-stimulating, and antimicrobial properties.  The susceptibility of 28 Flavobacterium johnsoniae-like isolates and nine selectedFlavobacterium spp. isolates to three phytochemicals, viz.: cinnamaldehyde (10 - 250 µg/ml), vanillin (5 - 500 µg/ml) and four crude Kigelia africana extracts (4 – 10 mg/ml ethyl acetate, dichloromethane, methanol and hexane), were assessed using disk diffusion assays and compared to standard antimicrobial agents, ampicillin and tetracycline using activity indices.  Cinnamaldehyde (250 µg/ml) was more effective than 250 µg/ml vanillin, which was ineffective even at higher concentrations.  K. africana extract (4 mg/ml) antibacterial efficacy decreased in the following order: Ethyl acetate, methanol, dichloromethane and hexane.  The 10 mg/ml methanolic K. africana extract was most effective, with 100% of isolates displaying susceptibility, irrespective of the isolation source.  Methanolic extract (10 mg/ml) activity indices ≥ 1 were obtained for 67.9 and 71.4% of isolates, respectively, relative to AMP10 and TE30.  Cinnamaldehyde and the K. africana methanol extract are promising candidates to be tested for their efficacy in the treatment of Flavobacterium-associated fish infections.  These phytochemicals might be environmentally-friendly, cost-effective alternatives to antimicrobial agent use in aquaculture, with a lesser potential of resistance development.


Key words: Aquaculture, Flavobacterium, phytotherapy.