African Journal of
Biochemistry Research

  • Abbreviation: Afr. J. Biochem. Res.
  • Language: English
  • ISSN: 1996-0778
  • DOI: 10.5897/AJBR
  • Start Year: 2007
  • Published Articles: 425

Full Length Research Paper

A Biflavonoid and a Carotenoid from Rhus leptodictya: Isolation, Characterization and Antibacterial Properties

Songca SP1*, Sebothoma C2, Samuel BB3 and Eloff JN3
1Faculty of Science, Engineering and Technology, P.O. Box 19712, Tecoma, 5247, East London, South Africa. 2Department of Chemistry and Biochemistry, Faculty of Science, University of Limpopo, Private Bag X 235, Medunsa, 0204, South Africa. 3Department of Paraclinical Science, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, 0110, Pretoria, South Africa.
Email: [email protected]

  •  Accepted: 21 November 2012
  •  Published: 30 November 2012


Acetone extracts of the leaves of Rhus Leptodictyawere studied for antibacterial activity usingbioautography and micro titre plate assay techniques against four nosocomial bacterial pathogens - Escherichia coliPseudomonas aeruginosaStaphylococcus aureus, andEnterococcus faecalis. A bioassay guided fractionation showed that the activity was concentrated in the carbon tetrachloride fraction. A bioautography fingerprint showed that three major compounds were responsible for the antibacterial activity. Two of these compounds were isolated by a combination of solvent - solvent fractionation and chromatographic techniques. They were characterised by 1HNMR, 13CNMR and 2D-NMR as 2,3-dihydro-amentoflavone, a biflavonoid andlutein, a carotenoid. This is the first report on the isolation of bioactive compounds from Rhus leptodictya.The four test organisms were sensitive to the two bioactive compounds. We found that Gram-positive organisms were more sensitive to 2,3-dihydro-amentoflavone with MIC values of 0.03 and 0.02 mg/ml to E. faecalis and S. aureus, respectively; while Gram-negative organisms were more sensitive to Lutein with MIC values of 0.06 and 0.09 to P. aeruginosa and E. coli, respectively. The cytotoxicity was determined using a methyl thiazole tetrazolium (MTT) based colorimetric assay against Vero monkey kidney cells. The MTT assay indicated that the LC50 of 2,3-dihydroxy-amentoflavone to Vero cells was 9.4 µg/ml while the LC50 of lutein was 9.8 µg/ml. Therefore, while the two compounds were very active against test organisms of nosocomial origin, they were also quite toxic.


Key words: Rhus leptodictya, bioautography, 2,3-dihydro-amentoflavone, lutein, anacardiaceae.