Comparative phytochemical and bioactivity studies on botanically different bee pollen samples and their flower sources

Bee pollen is produced by honeybees using flower pollen grains. Therefore, flower pollen serves as a reliable indicator of the botanical origin of bee pollen. As the chemical composition of bee pollen is directly associated with its pharmacological efficacy and potential health benefits, identification of its origin has a critical importance. This study represents the first investigation of the phytochemical content and biological activity of bee pollen samples originated either from petalous (Hedera helix), or apetalous flowers (Castanea sativa, Salix, and Quercus spp.) collected from Türkiye and Slovenia, comparatively with their related floral sources as H. helix, C. sativa, S. alba, and Q. pubescens. High-performance thin-layer chromatography (HPTLC) identified the botanical origin of each bee pollen sample by revealing the similarity of their chemical fingerprints to those of the corresponding floral sources. Marker compounds detected in H. helix anthers and related bee pollen (quercetin-3-O-β-glucopyranosyl-(1→2)-β-galactopyranoside, afzelin, and platanoside) and C. sativa, S. alba, and Q. pubescens androecia and related bee pollen samples (N1,N5,N10-tricaffeoylspermidine) were isolated from bee pollen samples and their structures were elucidated by nuclear magnetic resonance (NMR) and mass spectrometry (MS). These marker compounds as well as chlorogenic acid and 3,5-dicaffeoylquinic acid (in H. helix anthers) and quercetin, myricitrin, hyperoside, quercitrin, isoquercitrin, and rutin (in C. sativa, S. alba, and/or Q. pubescens androecia samples) were quantified using newly developed and validated ultra/high-performance liquid chromatography (UPLC/HPLC) methods. Further, the antioxidant and xanthine oxidase (XO) enzyme inhibition activities of samples and marker compounds were evaluated by spectrophotometric and effect-directed chromatographic analyses.