The antimicrobial activity of Sudanese honeys alone and in combination with plant extracts and ethylenediamineteraacetic acid (edta)

Honey and plant extracts have a long hitory of medicinal use in Sudan that continues to the present day. The antimicrobial properties of Manuka honey and its use as a topical wound treatment is now widely recognised but of limited availability in developing countries. This study examines the physico-chemical properties and antimicrobial activity of Sudanese honeys and synergistic interactions between selected honeys and plant extracts. A sample of 60 floral honeys from Sudan were collected direct from honey producers and 15 plant extracts were obtained from Sudan National Centre for Research. These were characterised and the antimicrobial activity against Escherchia coli (NCTC 10418) and Staphylococcus aureus (NCTC 6571) determined using bioassay and minimum inhibitory concentration methods. Selected honeys, Ethylenediaminetetractic acid (EDTA) and plant extracts were then studied for synergistic interactions. Although the honeys had similar physico-chemical characteristics as honeys from other published studies, none exhibited the non-peroxidal activity associated with Manuka honey. A number exhibited strong peroxidal activity. The type of hive used, the site of collection and producer (beekeeper) had a statistically significant impact on the antimicrobial activity. Acacia nioltica and Tamarindus indica plant extracts showed marked antimicrobial activity before and after autoclaving and were chosen for synergistic interaction with a selected honey. Synergy was screened using an agar diffusion bioassay using Canvas software to measure the change in area of zone of growth inhibition to determine bacteriostatic synergy. This was then confirmed using the time-kill curve method. Synergistic interaction was noted between honey and EDTA against Staphylococcus aureus and Acacia and EDTA against Escherichia coli. The results are discussed in relation to the medical use of honey and plant extracts in Sudan and concludes that there is a need to further explore the potential for local production of bioactive honeys for use in conjunction with plant extracts. The Sudanese government should conduct further translational research in this area.