Bioactivities of extracts and pure compound from monofloral bee pollen of western honeybee apis mellifera

Abstract

Bee pollen is one of interesting bee products which contain many bioactive compounds. However, its constituents depend on habitats and species of food plants. That results in a variety of bioactivities. In Thailand, there are many types of bee pollen, but there are few reports on their biological activities. In this study, bee pollen of A. mellifera was focused. Six types of monofloral bee pollen were harvested and identified as floral pollen of tea (Camellia sinensis L.), sunflower (Helianthus annuus L.), giant sensitive plant (Mimosa diplotricha), lotus (Nelumbo nucifera), leuuang tipwan (Xyris complanata), and sap raeng sap ka (Ageratum conyzoides) flowers. The crude extracts were prepared sequentially with methanol, dichloromethane, and hexane. Total phenolic and flavonoid contents were determined. Then, antioxidant capacity and enzyme inhibitory properties were tested. For phenolic and flavonoid contents, it was found that dichloromethane is the most suitable partition solvent, especially partitioned extracts of H. annuus L. and M. diplotricha had the highest phenolic content. Meantimes, the extracts of M. diplotricha had the highest flavonoid content which coincided to the highest antioxidant properties in many assays (ABTS, DPPH, TEAC, and FRAP). For enzyme inhibitory activity, the extracts of M. diplotricha, X. complanata, C. sinensis L., and H. annuus L. were effective inhibitors for lipoxygenase, α-amylase, lipase, and tyrosinase, respectively. In contrast, none of the extracts showed acetylcholinesterase inhibitory activity. According to the interesting activity in terms of the half-maximal inhibitory concentration (IC50) of the H. annuus L. and M. diplotricha extracts, they were purified by chromatographic techniques. By chemical structure analysis, it was found that palmitic acid, linoleic, and linolenic acids belonging to the group of free fatty acids were the major active compounds presenting porcine pancreatic lipase inhibitory activities. Also, triferuloyl spermidines isolated from M. diplotricha bee pollen exhibited as antioxidants and anti-lipoxygenase agents. In addition, the inhibitory effect of safflospermidine A and B isolated from H. annuus L. bee pollen on melanogenesis in B16F10 melanoma cells was studied. Safflospermidine mixture significantly reduced intracellular and extracellular melanin levels in B16F10 cells with no cytotoxicity. This study demonstrated that the predominant biological activity was depended on types of bee pollen. Therefore, bee pollens have the potential to be used as nutraceutical food. Also, anti-melanogenesis agents were rich in H. annuus L. bee pollen extract which can be developed to be an additive in cosmetic products.