title: Leptosperin is a distinct and detectable fluorophore in Leptospermum honeys.
abstract: New Zealand manuka (Leptospermum scoparium) honey exhibits two unique fluorescence signatures that distinguish it from other honey types. One of these is the MM1 fluorescence marker (270-365nm excitation-emission) which we show is due to a Leptospermum nectar-derived compound, leptosperin. Synthetic or honey-purified leptosperin not only displayed an identical fluorescence spectrum, but supplementation of leptosperin into clover or artificial honeys generated the MM1 fluorescence signature. There was a quenching effect of the honey matrix on leptosperin fluorescence but otherwise leptosperin was chemically stable over prolonged storage at 37°C. Leptosperin was also present in the woody-fruited Australian Leptospermum species at elevated concentrations but virtually absent in Leptospermum subtenue suggesting its elevated expression developed following the mid-Miocene separation of the genus. These findings suggest that fluorescence spectroscopy could offer a rapid and high-throughput screening method for identification of Leptospermum honeys using the MM1 fluorescence marker.
authors: School of Biological Sciences and Institute for Innovation in Biotechnology, University of Auckland, PB92019 Auckland, New Zealand.
authors: Jessie
authors: J
authors: Bong
authors: School of Biological Sciences and Institute for Innovation in Biotechnology, University of Auckland, PB92019 Auckland, New Zealand; Comvita NZ Limited, Wilson South Road, Paengaroa, PB1, Te Puke, New Zealand.
authors: Gordana
authors: G
authors: Prijic
authors: Analytica Laboratories Limited, Ruakura Research Centre, 10 Bisley Road, PB3123 Hamilton, New Zealand.
authors: Terry J
authors: TJ
authors: Braggins
authors: School of Biological Sciences and Institute for Innovation in Biotechnology, University of Auckland, PB92019 Auckland, New Zealand; Comvita NZ Limited, Wilson South Road, Paengaroa, PB1, Te Puke, New Zealand.
authors: Ralf C
authors: RC
authors: Schlothauer
authors: School of Biological Sciences and Institute for Innovation in Biotechnology, University of Auckland, PB92019 Auckland, New Zealand; Comvita NZ Limited, Wilson South Road, Paengaroa, PB1, Te Puke, New Zealand.
authors: Jonathan M
authors: JM
authors: Stephens
authors: School of Biological Sciences and Institute for Innovation in Biotechnology, University of Auckland, PB92019 Auckland, New Zealand; Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, PB92019, Auckland, New Zealand. Electronic address: k.loomes@auckland.ac.nz.
authors: Kerry M
authors: KM
authors: Loomes
mesh_terms: D001315:Australia; D005453:Fluorescence; D005456:Fluorescent Dyes; D057166:High-Throughput Screening Assays; D006722:Honey / Q000032:analysis*; D031649:Leptospermum / Q000737:chemistry*; D057048:Plant Nectar / Q000737:chemistry*; D013050:Spectrometry, Fluorescence
chemical_list: D005456:Fluorescent Dyes; D057048:Plant Nectar
keywords: Fluorescence; Leptosperin; Leptospermum; Manuka (Leptospermum scoparium); Methyl syringate