Kasim Roba, Zufan Bedewi
Background: Ethiopia is one of the plant species-rich countries in the world and the centre of origin of many medicinal plants. Studying antimicrobial activities is vital to investigate plants resources for medicinal values and the study was conducted to identify and evaluate Croton macrostachyus honey’s antimicrobial sources from its nectar and pollen against mentioned bacteria.
Methods: Completely Randomised Design was used for the laboratory. After adjusting turbidity, consistent growth of bacterial culture was made using sterilized cotton. The extract of C. macrostachyus’ pollen 3.6 gm. was added to 12 ml of distilled water to prepare stock solutions as ppm stock solution and antimicrobial activities of pollen, nectar, and honey were tested against mentioned bacteria above. Data were inserted into Microsoft excel 2010 and imported to R software version 3.44. Multilevel analysis was used to see the interaction between bacteria species and each concentration of honey, nectar, and pollen of Croton and Anova was used to see the significance of these concentrations on bacteria species. A p-value of <0.05 was considered statistically significant.
Results: Results indicated that bacteria were more inhibited at 72 hours than 48 and 24 hours and the result identified honey’s antimicrobial source was due to pollen composition found in honey that only pollen had antimicrobial activities while nectar had no antimicrobial activities against both Gram-negative and Gram-positive bacteria mentioned above. Time has significant effects on tested bacteria (p=0.000) and treatments have significant effects on tested organisms (p=0.000). Honey inhibited the growth of more Gram-negative bacteria: Escherichia coli and Shigella boydii. Bacillus was mostly inhibited by crotons’ pollen than others.
Conclusion: Water extract of Crotons ‘pollen had antibacterial activities against all tested bacterial strains, but inhibited more Gram-positive bacteria; while Crotons’honey inhibited more Gram-negative bacteria than Gram-positive bacteria. Negative controls (sterilized water) and nectar did not show an inhibitory effect on tested bacteria, while positive control (Chloramphenicol) had antimicrobial activities. Further isolation and characterization of bioactive compounds from Croton macrostachyus pollen are useful to develop a novel botanical formulation for further applications.