Total Phenols, Antioxidant Capacity and Antibacterial Activity of Manuka Honey Extract

摘要

Aims: To evaluate total phenols content (TPC), antioxidant capacity (TAC) and antibacterial activity of Manuka honey extract (MHE) and to compare such properties with those for unfractionated Manuka honey. Study Design: In vitro study. Place and Duration of Study: School of Biomedical Sciences, Ulster University, Coleraine, UK. Between September 2016 and September 2017. Methodology: MHE was prepared by solvent extraction using ethyl acetate. TPC was determined by Folin-Ciocalteu assay. The iron (III) reducing antioxidant capacity (IRAC) method was used to determine TAC. Antibacterial activity was evaluated using disc diffusion assay and 96-well microtiter plate methods with absorbance measured at 600 nm. Results: The TPC for MHE was 30-fold higher than the value for Manuka honey (33420 ± 1685 mg vs. 1018 ± 78 mg GAE/kg) while TAC values were ~100-times greater (83,198 ± 7064 vs. 793 ± 104 TEAC, respectively). Antibacterial activity assessed by disc diffusion for Manuka honey (18.5mm on S. aureus and 20 mm on E. coli ) was two times greater than for MHE (9mm for both S. aureus and E. coli ). The 96-well microtiter plate assay confirmed the greater antibacterial activity for Manuka honey compared to equal concentrations MHE. Conclusion: A polyphenol-rich Manuka honey extract with a high total antioxidant capacity, showed little or no antibacterial activity against E. coli and S. aureus in contrast with unfractionated Manuka honey.