Abstract
Bee-pollen is an apiary product of great interest owing to its high nutritional and therapeutic properties. This study aimed to assess the cellular antioxidant activity and the antihemolytic effects of Castanea, Rubus, and Cistus bee-pollens on oxidized human erythrocytes. In addition, the antimicrobial potential of each sample was tested on three Gram-negative and two Gram-positive bacteria. Finally, the effect of Castanea bee-pollen, showing better phytochemical content, was analyzed on human microvascular endothelial cells (HMEC-1) exposed to thapsigargin, used to induce endoplasmic reticulum stress (ER-stress). Our results showed good biological activities of all bee-pollen samples, which, under oxidative conditions, significantly improved the erythrocytes’ antioxidant activity and limited cell lyses. Moreover, all samples exerted antimicrobial activity with different selectivity among the tested microorganisms, with minimal inhibitory concentration values ranging from 5 to 10 mg/mL. Finally, thapsigargin treatment increased intracellular ROS (reactive oxygen species) production and up-regulated the expression of factors involved in the ER-stress and inflammatory pathways. Conversely, Castanea bee-pollen was effective in reducing gene overexpression, as well as the oxidation process arising from thapsigargin treatment, with a maximum protective effect at 10 µg/mL. In conclusion, bee-pollens, mainly Castanea species, represent good natural antibacterial and potential nutraceutical products useful in the prevention of free radical and ER-stress associated diseases.
Highlights
Apicultural products have been used for centuries in alternative medicine, in diets, or as dietary supplementation for their health and positive implications
In a previous study, we investigated the botanical origin, chemical and antioxidant compounds profile, and the free-radical scavenging activity of polyfloral Tuscan bee-pollen composed by three botanical species, Castanea sp., Rubus sp., and Cistus sp
Both the Cellular Antioxidant Activity (CAA)-RBC and hemolysis tests are based on the use of AAPH, an oxidizing agent whose thermal decomposition in peroxyl radicals causes damage to the erythrocytes’ membrane through lipid and protein peroxidation and, at high doses, erythrocytes’ lysis
Summary
Apicultural products have been used for centuries in alternative medicine, in diets, or as dietary supplementation for their health and positive implications. Bee-pollen is an apiary product that is receiving great attention as a functional food for its high nutritional value and therapeutic properties, including antioxidant, anti-inflammatory, antimicrobial, antifungal, antimutagenic, and antitumor effects; besides, bee-pollen is an important source of energy, bioactive compounds, and proteins for human nutrition [1,2,3,4,5]. To the best of our knowledge, no data on bee-pollen’s effects on endoplasmic reticulum stress are available in the literature. We analyzed the effects of Castanea bee-pollen, having the highest phytochemicals content, on the functional properties of human microvascular endothelial cells (HMEC-1) exposed to thapsigargin, a plant-derived sesquiterpene lactone used to induce endoplasmic reticulum (ER) stress
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