Graphical Discrimination of New Zealand Honey from International Honey Using Elemental Analysis.

This study investigated the potential of utilising the elemental fingerprinting of honey to differentiate New Zealand (NZ) honey from that of international origin. Twenty elements were analysed by ICP-MS in 352 honeys from 34 various countries. Of these, 323 honeys (245 New Zealand honeys, 78 international) and two subsets of data (NZ and European origin, n = 306, and, NZ and Denmark/Germany, n = 280) were visualised using principal component analysis (PCA). For the NZ/Europe subset, 42.2% of data was explained in the first two principal components. Statistical classification rules were also derived using linear discriminant analysis (LDA) and decision tree analysis. Various combinations of elements were explored for classification, considering the effect of soil-derived elements and those from anthropogenic sources. A high degree of accuracy (at least 90%) for the characterisation of New Zealand honey was observed for all statistical models, showing the robustness of these analyses. When using decision tree analysis to distinguish New Zealand samples from international samples, a tree with five terminal nodes (using Cs, Ba and Rb) was created with 92.4% accuracy. This work has demonstrated that elemental fingerprints of honey are a promising tool for categorising New Zealand honey from other geographical locations.

Plasma concentration of prophylactic cefazolin best correlates with lean body mass measured by bioimpedance analysis in lumbar spine surgery: Results of a pilot study.

The aim of this study was to determine the association between measures of body composition and the concentration of plasma and paraspinal muscle cefazolin. Secondly, we aimed to confirm the efficacy of our hospital dosing regimen in achieving the minimum inhibitory concentration (MIC) at the surgical site. Patients undergoing posterior-based lumbar spine surgery had body composition analysed using bioimpedance analysis. All received 2 g of cefazolin at anaesthetic induction in line with hospital guidelines. Cefazolin concentration was measured in plasma (30-minites) and muscle (30- and 60-minuites) using high-performance liquid chromatography. 20 patients were recruited (mean age 61.5 years; 12 female). Mean plasma cefazolin concentrations were 34.1 +/- 10.2 mg/L; mean muscle concentrations 44.4 +/- 18.6 mg/kg and 43.8 +/- 20.4 mg/kg at 30- and 60-minutes respectively. Univariate analysis showed significant correlation between plasma cefazolin concentration and lean mass weight, absolute body weight, height, dry lean mass, total water, total body water, extracellular and intracellular water volume. Linear regression analysis showed lean mass weight the best predictor of plasma cefazolin concentration. Muscle cefazolin concentration was dependent on the plasma concentration. Using a MIC of 2 mg/L and 2 mg/kg for Staphylococcus aureus, MIC was achieved in all samples. In summary, plasma cefazolin concentration was best predicted by lean body mass. Further work should consider the influence of body composition on antibiotic delivery in extremes of body mass index. Local hospital guidelines are effective at achieving MIC against S. aureus.

Accelerated loss of diastase in manuka honey: Investigation of manuka specific compounds.

Diastase is used internationally as a quality monitor for excessive heat treatment and prolonged storage of honey; honey must contain an activity of at least 8 diastase numbers (DN) for it to be considered export quality. Freshly harvested manuka honey can have diastase activity close to the export threshold of 8 DN without excess heating, increasing susceptibility for export failure. This research investigated the effect of compounds unique to or high in concentration in manuka honey on diastase activity. Investigation of the effect of methylglyoxal, dihydroxyacetone, 2-methoxybenzoic acid, 3-phenyllatic acid, 4-hydroxyphenyllactic acid and 2'-methoxyacetophenone on diastase activity was carried out. Manuka honey was stored at 20 and 27 °C and clover honey spiked with compounds of interest were stored at 20, 27 and 34 °C and monitored overtime. Methylglyoxal and 3-phenyllactic acid were found to accelerate the loss of diastase above the loss normally observed with time and elevated temperature.

The conserved and high K-to-Na ratio in sunflower pollen: Possible implications for bee health and plant-bee interactions.

Sodium (Na) concentrations are low in plant tissues, and its metabolic function in plants is minor; however, Na is a key nutrient for plant consumers. Previous studies have thus far focused on Na concentration. Nevertheless, a balanced potassium (K) to Na ratio (K:Na) is more important than Na concentration alone since food with high K:Na has detrimental effects on consumers irrespective of Na concentration. Therefore, plants may actively regulate K:Na in their tissues and products, shaping plant-insect interactions. Studies considering nutritional aspects of plant-insect interactions have focused on nonreproductive tissues and nectar. In this study, we consider pollen as serving a primary reproductive function for plants as well as a food of pollinivores. Plants might regulate K:Na in pollen to affect their interactions with pollinivorous pollinators. To investigate whether such a mechanism exists, we manipulated Na concentrations in soil and measured the proportion of K, Na, and 13 other nutrient elements in the pollen of two sunflower (Helianthus annuus) cultivars. This approach allowed us to account for the overall nutritional quality of pollen by investigating the proportions of many elements that could correlate with the concentrations of K and Na. Of the elements studied, only the concentrations of Na and K were highly correlated. Pollen K:Na was high in both cultivars irrespective of Na fertilization, and it remained high regardless of pollen Na concentration. Interestingly, pollen K:Na did not decrease as pollen increased the Na concentration. We hypothesize that high K:Na in pollen might benefit plant fertilization and embryonic development; therefore, a tradeoff might occur between producing low K:Na pollen as a reward for pollinators and high K:Na pollen to optimize the plant fertilization process. This is the first study to provide data on pollen K:Na regulation by plants. Our findings broaden the understanding of plant-bee interactions and provide a foundation for a better understanding of the role of the soil-plant-pollen-pollinator pathway in nutrient cycling in ecosystems. Specifically, unexplored costs and tradeoffs related to balancing the K:Na by plants and pollinivores might play a role in past and current shaping of pollination ecology.

Low copper levels measured in the aortic wall of New Zealand patients with non-syndromic ascending thoracic aortic aneurysm.

OBJECTIVES: Studies in animals have shown causal relationships between copper (Cu) deficiency and the development of thoracic aortic aneurysms (TAAs) [1, 2]. Cu deficiency is widespread in New Zealand (NZ) soils; the high soil pH from the use of lime fertilizers reduces the bioavailability of Cu for grazing animals and growing plants; this, in turn, reduces Cu availability in the NZ human food chain. Our study is a pilot study to explore associations between Cu and TAA. We measured Cu levels in aneurysmal aortic tissues in patients undergoing Bentall procedures and non-aneurysmal aortic tissue from coronary artery bypass graft patients. METHODS: Aortic samples were collected from 2 groups of patients during elective open-heart surgery over 4 months between November 2017 and February 2018. The groups were a TAA group, patients with non-syndromic aortic aneurysm and without the bicuspid aortic valve or known infectious or inflammatory condition (ANEURYSM; n = 13), and a control coronary artery bypass graft group (CONTROL; n = 44). Standardized digested dry tissue weighed samples were analysed from both groups. Tissue extraction of trace elements was carried out using HCl-H2O2 digestion and a highly sensitive analytical technique, inductively coupled plasma mass spectrometry-used to measure elemental concentrations. RESULTS: Cu concentration (mean ± SD) was significantly lower in ANEURYSM (3.34 ± 0.16 µg/g) when compared to the CONTROL group tissues (4.33 ± 0.20 µg/g) (dry weight; mean ± SD; Student's t-test, P < 0.05). Over 46% of the Aneurysm patients were Maori and live in a geographically Cu-deficient NZ territory. CONCLUSIONS: Cu deficiency may play a role in the development or progression of non-syndromic ascending aortic aneurysms in NZ. Maori patients are more at risk as they commonly live in rural NZ, dependent on locally grown nutritional sources. Further studies are required to confirm this exciting finding and to establish cause and effect relationship.

Investigation of inorganic elemental content of honey from regions of North Island, New Zealand.

Determination of geographical origin of honey is important to consumers to confirm authenticity. This study investigated the elemental fingerprint of 181 honey samples collected from apiary sites in six regions of North Island, New Zealand to determine if differences were observed due to region of collection or land use surrounding the hive (e.g. agricultural, rural, urban). Using principal component analysis, soil related elements (Ca, K, Mg, Mn, Na) provided 75.2% discrimination of samples in the first two principal components. Overall, low concentrations of heavy metals were observed; lead was present in close proximity to highly trafficked roads (28.1% of samples; 9.50-76.5 µg kg-1) and cadmium was primarily present in honey collected from agricultural land in the Waikato (<51.6 µg kg-1). The use of an elemental fingerprint of New Zealand honey may be advantageous to determine the geographical origin compared to honey produced from other countries.

Optimised approach for small mass sample preparation and elemental analysis of bees and bee products by inductively coupled plasma mass spectrometry.

The elemental fingerprint of honey, pollen and bees are useful biomonitors of anthropogenic activities across the world. Elements in honey and pollen may also be analysed for their nutritional value and potential toxicity. There are currently limited studies that address the use of small sample masses while retaining good reproducibility and detection limits during elemental analysis. The aim of this study was to develop a simple analytical method to quantify 39 major, minor, trace and rare earth elements in small mass samples of bees, honey and pollen by inductively coupled plasma mass spectrometry. The final method was validated for 20-200 mg bee, 20-100 mg pollen or 50-200 mg of honey with 0.2 mL nitric acid followed by 0.1 mL hydrogen peroxide in a digestion block (80 °C, 2 h total); samples were made up to a final volume of approximately 6 mL. The method reduces the volume of chemicals used, limits sample manipulation and improves detection limits over traditional digestion methods. The sample preparation and analysis method were deemed to be satisfactory for the three matrices examined, with spike recoveries ranging from 96 (B) to 129% (As) for trace elements and 91 (Pr) to 112% (La) for rare earth elements, and acceptable detection limits (down to 5.07 µg kg-1 for Co using 30 mg sample mass, pollen). Precision was acceptable with the relative percent standard deviation of fully homogenised samples ranging from 0.53 (K, bee, 20 mg) to 24% (As, 30 mg, bee) across the three matrices and all masses analysed. This small mass digestion method enables the analysis of a single bee allowing a more distinctive elemental signature to be determined. Similarly, pollen from fewer flowers of the same species can be pooled together which is advantageous for analysis of flowers that produce little pollen.

Kinetics of conversion of dihydroxyacetone to methylglyoxal in New Zealand manuka honey: Part IV - Formation of HMF.

During a study of the conversion of dihydroxyacetone (DHA) to methylglyoxal (MGO) in maturing New Zealand manuka honey, the kinetics of formation of 5-(hydroxymethyl)furfural (HMF) was studied at temperatures from 4 to 37°C. Formation of HMF was first-order during an induction period and zero-order thereafter indicating that the mechanism includes the formation of certain critical intermediates and that these require time to build up; the duration of the induction period depended primarily upon temperature. The zero-order rate constant at 37°C was the same for manuka honey and clover honey doped with 2000 or 10,000mg/kg DHA and for artificial honey with 2000mg/kg of DHA and either alanine or proline and alanine added. Zero-order rate constants for artificial honey with added amino acids were less than for a control without amino acids. A simulation was created to predict the formation of HMF over time at 37°C in manuka honey.

Kinetics of conversion of dihydroxyacetone to methylglyoxal in New Zealand manuka honey: Part I--Honey systems.

The kinetics of conversion of dihydroxyacetone (DHA) to methylglyoxal (MGO) were investigated in manuka honeys and DHA-doped clover honeys stored between 4 and 37°C. Both the disappearance of DHA and appearance of MGO were confirmed as overall, first order reactions, albeit probably composites of multiple reactions. Increasing the storage temperature accelerated the rate of DHA loss and the initial rate of formation of MGO, but better conversion efficiency was observed at lower temperature. At 37°C, more MGO was lost at later times in manuka honey compared to DHA-doped-clover honey. Thirty-seven New Zealand manuka honeys and four clover honeys were analysed for various chemical and physical properties; comparison of rate constants and these parameters identified some positive correlations.

Kinetics of the conversion of dihydroxyacetone to methylglyoxal in New Zealand manuka honey: Part II--Model systems.

The irreversible dehydration reaction of dihydroxyacetone (DHA) to methylglyoxal (MGO) in a honey model system has been examined to investigate the influence of added perturbant species on the reaction rate. The secondary amino acid proline, primary amino acids (alanine, lysine and serine), and iron, or combinations of these perturbants, were added to artificial honey with either DHA or MGO and stored at 20, 27 and 37°C. These systems were monitored over time. A 1:1 conversion of DHA to MGO was not observed in any system studied, including the control system with no added perturbants. Addition of proline to the matrix increased consumption of DHA but did not produce any more MGO than the control sample. Lysine and serine behaved similarly. Alanine enhanced the conversion of DHA to MGO and had the best efficiency of conversion of DHA to MGO for the amino acids studied. An iron II salt enhanced the conversion of DHA to MGO, even in the presence of proline.

Kinetics of conversion of dihydroxyacetone to methylglyoxal in New Zealand manuka honey: Part III--A model to simulate the conversion.

A kinetic model for the conversion of dihydroxyacetone (DHA) to methylglyoxal (MGO) in honey is proposed; a building block approach was used to create the model. Artificial honeys doped with DHA and individual perturbants were fitted first, then multiple perturbants (alanine, proline and iron, and combinations of these) were fitted before comparing the simulation to real honey samples (doped clover and manuka honey). The main responses in the prediction model were DHA, MGO, proline, primary amino acids, acidity, 3-phenyllactic acid and 4-methoxyphenyllactic acid. Three temperatures (20, 27 and 37°C) were studied and the conversion of DHA to MGO was monitored over at least 1year. Differences in the conversion between clover doped with DHA and manuka honey were observed. The simulation fitted well for the honeys tested.

Isolation of maltol glucoside from the floral nectar of New Zealand manuka (Leptospermum scoparium).

Maltol glucoside (3-(ß-D-glucopyranosyloxy)-2-methyl-4H-pyran-4-one), 1, was isolated from a preparation of the floral nectar from the New Zealand manuka tree (Leptospermum scoparium). 1 eluted just after dihydroxyacetone in HPLC of underivatized nectar and showed a UV absorbance maximum of 258 nm. The structure of 1 was confirmed by NMR and high resolution mass spectrometry.

Effect of high pressure processing on the conversion of dihydroxyacetone to methylglyoxal in New Zealand manuka (Leptospermum scoparium) honey and models thereof.

The effect of high pressure processing (HPP) on the conversion of dihydroxyacetone (DHA) to methylglyoxal (MGO) was examined in New Zealand manuka honey and models thereof. The objective was to confirm that previously reported increases of MGO with HPP treatment originated from conversion of DHA. RP-HPLC was used to quantify DHA, MGO and hydroxymethylfurfural (HMF) after derivatisation with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA) or (in the case of MGO) separately with o-phenylenediamine (OPD). Fresh and stored manuka honey, clover honey with DHA added and artificial 26 honey with DHA added were subjected to nine different pressures and holding times and compared to untreated samples. There was no consistent trend of decrease in DHA or increase in MGO for any of the samples with any treatment. Samples showed random change generally within 5-10% of an untreated sample for MGO, DHA and HMF. HPP does not accelerate the conversion of DHA to MGO in honey.

Isolation by HPLC and characterisation of the bioactive fraction of New Zealand manuka (Leptospermum scoparium) honey.

Using HPLC a fraction of New Zealand manuka honey has been isolated, which gives rise to the non-peroxide antibacterial activity. This fraction proved to be methylglyoxal, a highly reactive precursor in the formation of advanced glycation endproducts (AGEs). Methylglyoxal concentrations in 49 manuka and 34 non-manuka honey samples were determined using a direct detection method and compared with values obtained using standard o-phenylenediamine derivatisation. Concentrations obtained using both the methods were similar and varied from 38 to 828 mg/kg.