Indigenous New Zealand honeys exhibit multiple anti-inflammatory activities

Recent evidence suggests a potential role for honeys in mediating clinical inflammation and tissue damage. Here, we investigated the anti-inflammatory activity of a selection of previously untested indigenous New Zealand (NZ) honeys. We found that several, but not all, New Zealand rewarewa, manuka and kanuka honey samples exhibited potent, dose-dependent reduction of human neutrophil superoxide production in vitro. This inhibitory activity did not correlate with levels of known phenolic-based free radical scavengers. Furthermore, the active honeys did not scavenge superoxide generated in a cell-free xanthine/xanthine oxidase assay. In C57BL/6 J mice, topical application of manuka and rewarewa honey samples with the highest in vitro activity suppressed arachidonic acid-induced ear oedema, and rewarewa honey suppressed both oedema and leukocyte (monocyte and neutrophil) infiltration. Together, these findings demonstrate that some indigenous NZ honeys exhibit clinically relevant anti-inflammatory activity. Further investigation is warranted to identify the active component(s) and mechanisms responsible for these activities and to determine potential applications for anti-inflammatory honeys in the topical treatment of clinical inflammation.