Planta Med 2007; 73 - SL_014
DOI: 10.1055/s-2007-986732

The possible interaction between an edible insect and five antibacterial kaempferol methyl ethers isolated from Dodonaea viscosa Jacq. var. angustifolia (Sapindaceae) leaf extracts

JN Eloff 1, LS Teffo 1, RB Toms 2, AM Aderogba 1
  • 1Phytomedicine Programme, University of Pretoria; Private Bag X04, Onderstepoort 0110 South Africa
  • 2Transvaal Museum, Northern Flagship Institution, P.O. Box 413, Pretoria, 0001 South Africa

Dodonaea viscosa Jacq. var. angustifolia (Sapindaceae) a medicinal plant used in folk medicine to treat diseases and inflammatory conditions was investigated for its antioxidant and antibacterial properties because it is the sole host plant for the edible stinkbug, Encosternum delegorguei Spinola, a traditional delicacy for the Vhavenda tribe of Limpopo Province of South Africa. As insects are known to sequester compounds from their host plants [1], we were interested to investigate the medicinal properties of D. viscosa and determine if the same compounds occur in the insect. D. viscosa methanol leaf extracts has antibacterial activity against several bacteria and viruses [2]. Bioassay guided fractionation of dichloromethane and acetone fractions from serial extraction of Dodonaea viscosa Jacq. var. angustifolia leaf powder yielded 3, 5, 7-trihydroxy-4′-methoxyflavone (kaempferide) (1); 5, 7, 4'-trihydroxy-3, 6-dimethoxyflavone (2); 5, 7-dihydroxy-3, 6, 4'-trimethoxyflavone (santin) (3); and 5-hydroxy -3, 7, 4'-trimethoxyflavone (4) and kaempferol (5). MIC of isolated compounds against Staphylococcus aureus, Enterococcus faecalis, Escherichia coli and Pseudomonas aeruginosa varied from 16µg/ml to more than 250µg/ml. Good structure activity relationships could be established. There were no ninhydrin positive compounds present in insect extracts (i.e. peptides frequently responsible for antibacterial activities in many insects probably absent). From bioautography of insect extracts zones of inhibition coinciding with the Rf of some isolated compounds were found indicating that some of the compounds present in D. viscosa could be present in the insect.

Acknowledgements: The NRF provided funding.

References: [1] Harborne, J.B., 1982. The Flavonoids: Advances in Research. In: T.J. Mabry (Ed.), Chapman and Hall Ltd. Cambridge, UK. [2] Getie, M., et al. (2003) Fitoterapia 74: 139–143