LC-QqQ-MS/MS methodology for determination of purine and pyrimidine derivatives in unifloral honeys and application of chemometrics for their classification.

The new liquid chromatographic-triple quadrupole tandem mass spectrometry (LC-QqQ-MS/MS) method for determination of purine and pyrimidine derivatives in honey produced by Apis mellifera was developed. 13 compounds were determined in total of 130 unifloral honey samples of 13 varieties: uracil, thymine, thymidine, xanthine, guanine, adenine, uridine, pseudouridine, xanthosine, inosine, hypoxanthine, guanosine and cytidine. The levels of some of these compounds varied between the specific honey types. The most abundant were uridine (up to 44.66 mg/kg), xanthine (up to 20.48 mg/kg) and xanthosine (up to 19.22 mg/kg). The data were evaluated by principal component analysis (PCA) and k-nearest neighbors (k-NN) classification (selected 9 and 8 honey types, respectively) to examine differences between the honey varieties allowing their discrimination based on purine and pyrimidine derivatives amounts. The data allowed to distinguish between 8 honey types (balanced accuracy 82%) and for most of the varieties obtained classification rates ranged from 96 to 100%.

Honey as Source of Nitrogen Compounds: Aromatic Amino Acids, Free Nucleosides and Their Derivatives.

The content of selected major nitrogen compounds including nucleosides and their derivatives was evaluated in 75 samples of seven varieties of honey (heather, buckwheat, black locust, goldenrod, canola, fir, linden) by targeted ultra-high performance liquid chromatography-diode array detector - high-resolution quadrupole time-of-flight mass spectrometry (UHPLC-DAD-QqTOF-MS) and determined by UHPLC-DAD. The honey samples contained nucleosides, nucleobases and their derivatives (adenine: 8.9 to 18.4 mg/kg, xanthine: 1.2 to 3.3 mg/kg, uridine: 17.5 to 51.2 mg/kg, guanosine: 2.0 to 4.1 mg/kg; mean amounts), aromatic amino acids (tyrosine: 7.8 to 263.9 mg/kg, phenylalanine: 9.5 to 64.1 mg/kg; mean amounts). The amounts of compounds significantly differed between some honey types. For example, canola honey contained a much lower amount of uridine (17.5 ± 3.9 mg/kg) than black locust where it was most abundant (51.2 ± 7.8 mg/kg). The presence of free nucleosides and nucleobases in different honey varieties is reported first time and supports previous findings on medicinal activities of honey reported in the literature as well as traditional therapy and may contribute for their explanation. This applies, e.g., to the topical application of honey in herpes infections, as well as its beneficial activity on cognitive functions as nootropic and neuroprotective, in neuralgia and is also important for the understanding of nutritional values of honey.

Determination of Quality Criteria that Allow Differentiation Between Honey Adulterated with Sugar and Pure Honey.

This study used various parameters of honey to develop a potentially more robust approach to the detection of adulterated honey. For this purpose, 25 multifloral, natural honey samples and 20 samples of adulterated honey produced by bees that had been fed supplementary sucrose syrup were analysed. The mean total phenolic content of the natural honeys was considerably higher than in the adulterated honeys at 157 ± 13 and 35.2 ± 7.3 mg GAE/100 g, respectively. Similarly, considerable variation was determined between natural and adulterated honeys in terms of total flavonoids (3.3 ± 0.3 and 2.1 ± 0.4 mg QE/100 g, respectively), antiradical activity (87.9 ± 12 and 163 ± 11 mg/mL, respectively) and proline content (202 ± 26 and 71.1 ± 21.6 mg/kg, respectively.) The potassium, phosphorus, calcium and magnesium contents of natural honeys were also higher than in adulterated honeys (P < 0.01). In conclusion, the determination of the proline level, phenolic content, antioxidant activity and mineral profile may collectively provide a more holistic method approach to the differentiation of natural and adulterated honey, and also for comparing their food values.

Caracterização físico-química de amostras de mel de abelha africanizada dos municípios de Santa Helena e Terra Roxa (PR) / Physicochemical parameters of honey from samples from africanized honeybees in Santa Helena and terra roxa counties (PR)

O presente estudo teve como objetivo a caracterização físico-química de amostras de mel de Apis mellifera coletadas nos municípios de Santa Helena e Terra Roxa, localizados na região oeste do Estado do Paraná, Brasil. Foram coletadas 40 amostras de mel, sendo 20 do município de Santa Helena e 20 de Terra Roxa (PR), coletadas diretamente com os apicultores, as quais foram submetidas a análises físico-químicas de umidade, acidez, pH, cinzas, condutividade elétrica e cor, a fim de verificar se as mesmas apresentavam-se em conformidade com a legislação nacional vigente (Instrução Normativa nº 11), além de conhecer o perfil físico-químico do mel das diferentes localidades, na safra 2008/2009. Os dados encontrados foram submetidos à análise de variância e teste F a 5% de significância. Os resultados apresentaram diferença significativa (P<0,05) apenas entre os valores de acidez, tendo o mel oriundo de Terra Roxa apresentado valor mais alto (33,45±7,7meq.kg-1) que o de Santa Helena (24,53±6,3meq.kg-1). Em sua maioria, as amostras analisadas encontraram-se dentro das especificações determinadas pela legislação para as características físico-químicas, com exceção do parâmetro de umidade, que, apesar de não ter apresentado diferença significativa entre os valores encontrados para os dois municípios, estavam acima do limite estabelecido pela legislação (20 por cento) em 8 amostras do município de Santa Helena e em 7 de Terra Roxa, totalizando 37,5 por cento) das amostras. Essa característica pode ter deixado o produto mais susceptível à fermentação e pode ter sido ocasionada pela colheita imatura do mel...

This study aimed to physicochemically characterize the honey samples of Apis mellifera collected in Santa Helena and Terra Roxa counties, located in the western region of Paraná State, Brazil. Forty honey samples were collected, 20 in Santa Helena and 20 in Terra Roxa (PR) counties, directly from beekeepers, and were subjected to physico-chemical analyzes of moisture, acidity, pH, ashes, electrical conductivity and color, to verify whether they were in accordance with the existing national legislation (Instruction No. 11), in addition to knowing the physicochemical profile of different sites during the 2008/2009 season. The data were submitted to analysis of variance and F test at 5 percent significance level. The results showed significant differences (P<0.05) between values of acidity, and the honey samples from Terra Roxa presented a higher value (33.45±7.7 meq.kg-1) than Santa Helena (24 = 53±6.3 meq.kg-1). Most of the analyzed samples were within the specifications prescribed in the legislation for the physico-chemical parameters except for moisture, which despite having presented a significant difference between values obtained from two counties, were above the limits established by the legislation (20 percent) in eight samples in Santa Helena and seven in Terra Roxa counties, totaling 37.5 percent. This characteristic may have made the product more susceptible to fermentation, and may have been caused by harvesting immature honey...