Article Text
Abstract
Objective To evaluate the in vitro antimicrobial effects of cyclodextrin-complexed and uncomplexed Manuka honey on bacteria commonly associated with blepharitis, and in vivo rabbit eye tolerability of a cyclodextrin-complexed methylglyoxal (MGO) Manuka Honey microemulsion (MHME).
Methods and analysis In vitro phase: Bacterial growth inhibition was assessed by area under the growth curve (AUC) for Staphylococcus aureus, and the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) for S. aureus, Staphylococcus epidermidis and Pseudomonas aeruginosa with cyclodextrin-complexed and uncomplexed Manuka honey were determined.
In vivo phase: Six rabbits were administered 20 µL of MHME (at 1:10 dilution) to the right eye (treated) and 20 µL of saline to the left eye (control) daily, for 5 days. Tear evaporation, production, osmolarity, lipid layer, conjunctival hyperaemia and fluorescein staining were assessed daily, before and 15 min after instillation.
Results In vitro phase: The relative AUC for cyclodextrin-complexed Manuka honey was lower than that of uncomplexed honey at both 250 and 550 mg/kg of MGO (both p <0.05). Cyclodextrin-complexed honey had lower MIC and MBC than uncomplexed honey for both S. aureus and S. epidermidis, but not P. aeruginosa.
In vivo phase: No significant changes were observed in the parameters assessed in either treated or control eyes (all p >0.05).
Conclusion Overall, antimicrobial potency of cyclodextrin-complexed Manuka honey was greater than uncomplexed honey. No significant immediate or cumulative adverse effects were observed with MHME application on rabbit eyes, supporting future conduct of clinical safety and tolerability trials in human subjects.
- Blepharitis
- Manuka honey
- cyclodextrin
- methylglyoxal
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Footnotes
Acknowledgements The authors are grateful to Angela Cunningham, BSc; Yen-Heng (Amy) Chen, BOptom; May Young, BOptom; Iana Pearce, BOptom; and William Perriam, BOptom, for their involvement in preliminary aspects of the work reported in this manuscript.
Contributors All authors took an active part in the design, conduct, data analysis, and publication drafting and approval.
Funding This research received unrestricted grant funding from the Faculty of Medical and Health Sciences at the University of Auckland and from Manuka Health, who themselves received grant support from the Ministry of Business, Innovation and Employment (MBIE PROP31150VCHMANUKAHEALTH).
Competing interests None declared.
Ethics approval University of Auckland Animal Ethics Committee UAAEC 001156.
Provenance and peer review Commissioned; externally peer reviewed.
Data sharing statement All data relating to the study are published in the manuscript and approaches to share this can be made to the corresponding author. Queries relating to the MGO Manuka Honey microemulsion can be made to Manuka Health New Zealand.