Classification and Characterization of Manuka Honeys Based on Phenolic Compounds and Methylglyoxal

Abstract

Manuka honey from New Zealand is often considered to be a medicinal product of special value due to its high level of antimicrobial activity. Therefore, the distinct authentication of its botanical origin is of great importance. Aside from the common pollen analysis, it is in this respect particularly the analysis of the phenolic acids, flavonoids, and norisoprenoids that is described as useful. In the present study, numerous manuka honeys were analyzed by UPLC-PDA-MS/MS after solid-phase extraction and compared to other kinds of honey to define marker substances characteristic for manuka honeys. The PDA profiles obtained differed markedly from each other so that the individual honey samples could be assigned to three groups. For the honeys of group 1 the comparably high concentrations of 4-hydroxybenzoic acid, dehydrovomifoliol, and benzoic acid proved to be typical, whereas the profiles of group 2 showed high kojic acid and 2-methoxybenzoic acid intensities. The manuka honeys of group 3, on the other hand, yielded high amounts of syringic acid, 4-methoxyphenyllactic acid, and methyl syringate. Furthermore, the comprehensive comparison of manuka honeys to other unifloral honeys revealed that especially kojic acid, 5-methyl-3-furancarboxylic acid, leptosin, unedone, 2-methoxybenzoic acid, 4-methoxyphenyllactic acid, 3-hydroxy-1-(2-methoxyphenyl)penta-1,4-dione, and methyl syringate were useful for distinguishing manuka honeys from the other kinds of investigated honeys. Moreover, kojic acid, unedone, 5-methyl-3-furancarboxylic acid, 3-hydroxy-1-(2-methoxyphenyl)penta-1,4-dione, and lumichrome were identified in manuka honey for the first time.

Chemical profiles of honeys originating from different floral sources and geographic locations examined by a combination of three extraction and analysis techniques

“…It has previously been determined that high contents of syringic acid was typical of Manuka honeys originating from the East Coast of New Zealand [24]. The findings in this study are consistent with this prior observation, as syringic acid is not detected in Tasmanian Manuka honey.…”

“…It has previously been determined via solid phase extraction, liquid chromatography and mass spectrometry that high contents of syringic acid was typical of Manuka honeys originating from the East Coast of New Zealand [24]. This current study is consistent with this prior observation, as syringic acid is not detected in Tasmanian Manuka honey which had undergone repeated ethanol extractions and tentative identification via RP-HPLC-DAD analysis (see Table 5).…”

“…This variability has since been assigned to a specific geographic origin of New Zealand Manuka honey. Via solid phase extraction, liquid chromatography and mass spectrometry it was determined that high contents of syringic acid was typical of Manuka honeys originating from the East Coast of New Zealand [24].…”

Antioxidant Capacity and Chemical Profiles of Satureja montana L. Honey: Hotrienol and Syringyl Derivatives as Biomarkers

“…honey (content > 122.6 mg/kg) [18]and manuka(Leptospermum spp.) honey (45 mg/kg) [19]. It is interesting to note that this phenolic esterw as also detected in the honeys obtained from plants of different botanical families, viz., black locust, rape,s weet chestnut, clover, lime, dandelion, sunflower, and thyme [ 5].I na ddition, methyl syringate was found to contribute to the honey antibacterial activity,s ince the honey peroxide-generating system did not account for all of the observed antimicrobial activity [20].…”

Fluorescence: A Novel Method for Determining Manuka Honey Floral Purity

“…Many of these have received atention [7][8][9][10][11], and clearly, this honey carries a number of distinct compounds that may be diagnostic for classiication. For example, 2-methoxyacetophenone (Figure 1) [7,11] and 2-methoxybenzoic acid [10,11] have been proposed as loral markers for manuka honey.…”