Polyphenolic profile and antioxidant properties of bee-collected pollen from sunflower (Helianthus annuus L.) plant

The aim of this work was to determine phenolic profile and antioxidant properties of methanolic (MEP) and ethanolic (EEP) extracts of monofloral bee-collected sunflower pollen from Serbia. In total, 37 different polyphenols (19 flavonol glycosides and 18 other polyphenols) were identified by UHPLC/MS-MS Orbitrap analysis. The different phenolic profile of MEP and EEP was observed with flavonols as most abundant, 94.1% (MEP) and 93.4% (EEP), out of which flavonoid glycosides represented 73.2% (MEP) and 66.1% (EEP). The higher amount of total phenolics was recorded in EEP (200.58 mg/kg DW) than in MEP (244.44 mg/kg DW). The quercetin 3-O-galactoside was the major compound in both extracts, 112.86 mg/kg in MEP and 128.64 mg/kg in EEP. The presence of coumaroylated and acetylated flavonoid glycosides were registered, among which the quercetin 3-O-(6 ''-acetyl)hexoside was recored in the significant amount in MEP (111.10 mg Q3G/kg DW), whereas in EEP the content of coumaroylated kaempferol glycosides (137.95 mg Q3G/kg DW) was significantly higher. The ferric reducing power and ABTS radical scavenging activity assays revealed that pollen extracts possessed significant antioxidant activity. The monofloral bee-collected pollen of Helianthus annuus L. can be used as good food supplement with high flavonoids content and antioxidant activity