Abstract
Many experimental studies have demonstrated the favorable biological activities of plants belonging to the genus Rubus, but little is known of the role of Rubus leaf extracts in the modulation of the surface membrane expression and activity of endothelial apyrase. The aim of this study was to assess the influence of 1–15 μg/ml Rubus extracts on CD39 expression and enzymatic activity, and on the activation (ICAM-1 expression) and viability of human umbilical vein endothelial cells (HUVEC). The polyphenolic contents and antioxidative capacities of extracts from dewberry (R. caesius L.) and raspberry (R. idaeus L.) leaves were also investigated. The techniques applied were flow cytometry (endothelial surface membrane expression of ICAM-1 and CD39), malachite green assay (CD39 activity), HPLC-DAD (quantitative analysis of polyphenolic extract), ABTS, DPPH and FRAP spectrometric assays (antioxidant capacity), and the MTT test (cell viability). Significantly increased CD39 expressions and significantly decreased ATPDase activities were found in the cells treated with 15 μg/ml of either extract compared to the results for the controls. Neither of the extracts affected cell proliferation, but both significantly augmented endothelial cell ICAM-1 expression. The overall antioxidant capacities of the examined extracts remained relatively high and corresponded well to the determined total polyphenol contents. Overall, the results indicate that under in vitro conditions dewberry and raspberry leaf extracts have unfavorable impact on endothelial cells.
Highlights
The proper functioning of platelets, leukocytes, and endothelial cells (EC) is crucial for maintaining hemostasis [1]
Polyphenolic content and the antioxidant activity of extracts obtained from dewberry and raspberry leaves The phenolic compound profile of the dewberry and raspberry leaf extracts is presented in Tables 1 and 2
Some studies suggest that the cardioprotective influence of polyphenols is related to their ability to prevent the oxidation of low-density lipoprotein and influence platelet dysfunction and smooth muscle cell migration and proliferation, while others report that it may be based on their ability to modulate endothelial function, i.e. to promote the anti-inflammatory response in endothelial cells [33,34,35]
Summary
The proper functioning of platelets, leukocytes, and endothelial cells (EC) is crucial for maintaining hemostasis [1]. Endothelial cells employ three biochemical systems to control platelet reactivity and regulate blood fluidity. Two of these produce the autacoids nitric oxide (NO) and prostacyclin upon interaction with agonists, while the third is based on CD39, an integral component of the endothelial cell surface. ATPDase regulates the concentrations of extracellular tri- and diphosphate nucleosides, which appear in the blood as a consequence of blood cell lysis, tissue damage, and the secretory response of blood platelets. The product of this phosphate removal reaction is AMP, which is subsequently hydrolyzed to adenosine via another antigen expressed on endothelial cells, CD73, which shows ecto-5’-nucleotidase activity. Very little is known about the role of polyphenols in the regulation of endothelial apyrase function [8, 10]
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