Comparison of extraction of bee pollen volatiles using different SPME fibers and GC-MS analysis

Biochemijos katedraVytauto Didžiojo universiteta

Analysis of different geographic origin beecollected pollen using spectrophotometric and chromatographic techniques

The main aim of this study was to investigate and to identify biologically active compounds in bee-collected pollen from different geographic origin by means of spectrophotometric and chromatographic techniques. Bee pollen extractions were prepared by adding 20 ml of 80% methanol to 2 gram of raw material and 24 hour shaking in orbital shaker. The methanol extracts were filtered. Spectrophotometric methods were used to determine the total amount of phenolic compounds, flavonoids and antioxidant activity. The phenolic compounds content was determined using Folin–Ciocalteu method. It varied between 24.11 and 43.89 mg RE/g. The highest content of phenolic compounds was found in monofloral CHN_1 pollen 43.89 mg RE/g. The lowest content was found in polyfloral CHN_2 pollen - 24.11 mg RE/1 g. Similar tendency was observed for spectrophotometrically determined flavonoids content and total 2,2 – diphenyl – picrylhydrazyl (DPPH•) radical scavenging activity. Flavonoids content varied from 6.62 to 12.30 mg RE/g, free radical scavenging activity was in the range from 7.89 to 35.59 mg RE/g. Total amount of phenolic compounds showed strong correlation with antioxidant activity (correlation coefficient was 0.8507). For qualitative and quantitative analysis of bee pollen flavonoids a high performance liquid chromatography with electrochemical detection (HPLC-ED) was used. Four flavonoids were identified in all bee pollen samples: rutin, 2-hydroxycinnamic acid, naringenin and quercetinBiochemijos katedraVytauto Didžiojo universiteta

Chemometric analysis of bee pollen based on volatile and phenolic compound compositions and antioxidant properties

The aim of this study was to determine total amounts of phenolics and flavonoids, radical scavenging activities, and compositions of phenolic and volatile compounds in 14 samples of honeybee pollen collected in the Baltic region. Radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activities and total amounts of phenolics and flavonoids were evaluated using spectrophotometry. Volatiles from the headspace of the samples were analyzed using solid-phase microextraction (SPME) fiber coated with 100-μm polydimethylsiloxane layer, separated, and identified employing GC-mass spectrometry (MS). Forty-two volatiles were identified in the headspace. Nonanal (1.5–20.1 %), dodecane (1.2–-34.6 %), and tridecane (1.4–24.7 %) were found in all samples. Screening of phenolics and flavonoids was performed using high-performance liquid chromatography (HPLC) with electrochemical detection. 2-Hydroxycinnamic acid (43.4–179.9 μg/g), rutin (156.2–955.7 μg/g), and quercetin (24.0–529.8 μg/g) were detected in all tested samples. Total amounts of phenolic compounds and flavonoids varied between 24.1 and 45.5 mg/g, and 6.1 and 11.6 mg/g, respectively, expressed as rutin equivalents. The pollen extracts exhibited radical scavenging activity, which scattered widely in range of 7.1–39.2 mg/g, expressed as rutin equivalents. Radical scavenging activity correlated with the total content of phenolic compounds while correlation coefficient was 0.95. Chemometric evaluation was performed to classify the samples into clusters according to the observed dataBiochemijos katedraKauno technologijos universitetasVytauto Didžiojo universiteta