Immunomodulatory Effects of Propolis and its Components on Basic Immune Cell Functions
Department of Dietetics and Food Assessment, Institute of Health Sciences, University of Natural Sciences and Humanities, Prusa 14, 08-110 Siedlce, Poland
Department of Dietetics and Food Assessment, Institute of Health Sciences, University of Natural Sciences and Humanities, Prusa 14, 08-110 Siedlce, Poland, E-mail: [email protected]
Propolis (bee glue) is a resinous hive product collected by honey bees from many plant sources in temperate and tropical climates. Its fairly complex chemical composition includes polyphenols, phenolic aldehydes, sequiterpenes, quinins, coumarins, amino acids, steroids and inorganic compounds. The contents of propolis depended especially on its location and plant sources. Consequently, the biological activity of propolis gathered from different phytogeographical areas can vary. Propolis is known to have a broad spectrum of biological properties, including antimicrobial, antioxidant, antiinflammatory, antiallergic, dermatoprotective, laxative, antidiabetic, antitumor and immunomodulatory activity. The immunomodulatory activity of propolis has been well-researched. This activity is attributed to flavonoids and some phenolic acids, mainly caffeic acid (cinnamic acid) phenethyl esters and artepillin C (3,5-diprenyl-4-hydroxycinnamic acid). Propolis and these components exhibited immunomodulatory effects on a wide spectrum of immune cells, including cells of lymphoid or monocytic lineages, mediated by the extracellular signal-regulated kinase 2 and mitogen-activated protein-kinase signalling pathway and by eukaryotic transcription factors: nuclear factor of activated T cells and nuclear factor κB. In vitro and in vivo assays have demonstrated that propolis activated monocytes/macrophages and neutrophils, increasing their microbicidal activity. It enhanced the lytic activity of natural killer cells against tumour cells. It also exhibited antiallergic effects, in part by inhibiting degranulation of mast cells or basophils. Propolis stimulated greater antibody production, suggesting that it could be used as an adjuvant in vaccines. Its inhibitory effects on lymphoproliferation might be linked to its antiinflammatory properties. However, this effect appeared to occur in the presence of high concentrations of propolis, while at low concentrations the effect is reversed, causing stimulation of lymphocyte proliferation.