This study is the first large-scale survey of the presence of dihydroxyacetone (DHA) in the nectar of the Australian Leptospermum tree species. The work undertaken supports the growing global demand for bioactive Leptospermum honey. Leptospermum honey derived from L. scoparium in New Zealand, also referred to as Ma̅nuka honey, has a reputation for wound-healing and antimicrobial properties, which is based on its methylglyoxal (MGO) content. High-DHA nectar correlates to high-MGO honey, but not all Leptospermum species produce DHA in their nectar. This study investigates 55 of the 84 Leptospermum species native to Australia for their DHA-producing capability, with the DHA to total sugar (DHA:Tsugar) ratio of nectar samples determined by HPLC-PDA. DHA:Tsugar ranged from nondetectable in L. laevigatum, L. coriaceum, and L. trinervium to >16 000 mg/kg in L. speciosum and L. whitei. High-DHA Leptospermum species were identified for beekeepers to target for honey production and plantation development.
Keywords: Australia; Leptospermum; dihydroxyacetone; high-performance liquid chromatography; honey; nectar.