Antimicrobial, Antioxidant and Cytotoxic Properties of Four Types of Honey as Related to Their Phenolic and Flavonoid Contents

Author(s): Seif Eldin AM, Ahmed SK, Waleed SK, Khalid AK, Hamed AG, Mogbel AAE, Badria MS, Mohamed EA

This study explores the antibacterial and antifungal activity of four floral honey types (12 samples) (A. seyal, Zizuphus spina-christi, Cucurbita maxima and A. nilotica) as related to their phenolic content, antioxidant capacity, and assessing their cytotoxic effects. The cup-plate agar diffusion assay was employed to examine the antimicrobial potency against different pathogens including Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Aspergillus niger and Candida albicans. Scavenging activity, total phenolic, flavonoid contents, and cytotoxicity were determined by the DPPH radical scavenging, Folin–Ciocalteu, spectrophotometery, and Brine shrimp lethality, bioassays respectively. All assessed honeys significantly inhibited the growth of the tested pathogens. Both Acacias honey exhibited high antioxidants with IC50: 6.68 and 9.08 mg/ml respectively for A. seyal and A. nilotica. The total phenol content varied from 5.75 to 67.95 mg (GAE)/100 g while the overall flavonoid content varied from 0.15 to 0.5mg (QE)/100 g. All honey types expressed no cytotoxicity effects on cell lines. Thus the study, supports the existing antimicrobial activity of honey. However, the strong antimicrobial activity of Cucurbita and Ziziphus honeys, with their corresponded poor antioxidant furtherly provides evidence that the high levels of phenolic substances in honeys is not always the only cause of their antimicrobial potency.