Immunoregulatory effects of flavonoid-containing medicinal herbs in human peripheral blood mononuclear cells

Plant-derived medicinal products provide a prominent advantage due to their low toxicity to humans and combined effects of biologically active substances, mainly presented by polysaccharides, flavonoids and terpenoids. One of the mechanisms undedrlying effects from medicinal plants on the immunoregulationrelated events is mediated via controlled production of certain cytokines. Here we examined immunoregulatory activity of water extracts derived from medicinal plant raw materials (LRS) containing polyphenolic compounds – flavonoids (rutin, quercetin, called P-vitamins). The aim of the study was to assess profile and level of cytokines secreted by human peripheral blood mononuclear cedlls exposured to flavonoid-containing LRS water extracts. LRS (1:10) water extracts of the following species were used: black currant leaves (Ribes nigrum L.), field horsetail grass (Equisetum arvense L.), common yarrow grass (Achillea millefolium L.), licorice roots (Glycyrrhiza uralensis Fisch.), sand immortelle flowers (Helichrysum arenarium (L.) Moench), wild strawberry leaves (Fragaria vesca L.), fruit common bird cherry (Padus avium Mill.), tansy flowers (Tanacetum vulgare L.) and oat grass (Avena sativa L.) (all purchased at the pharmacy). Production of pro – (TNFα, IL-8, IL-1β) and anti-inflammatory (IL-10) cytokines was measured by using ELISA kits (“Cytokine”, Russia) in mononuclear cell culture supernatant treated with / without LRS (experiment and control group, respectively). Amount of flavonoids contained in flowers and leaves was quantified aftedr complexation reaction with aluminum chloride on UV-3600 spectrophotometer (Shimadzu, Japan). It was found that LRS water extracts predominantly inhibited production both of pro- (TNFα, IL-8, IL-1β) and anti-inflammatory (IL-10) cytokines so that magnitude of such suppressive effect ranged from 51.5±3.4 to 99.5±4.1% compared to untreated control samples (p < 0.05). Total flavonoid level in the LRS samples diirectly correlated with intensity of related immunoregulatory activity on cytokine secretion particularly TNFα (r = 0.65), IL-8 (r = 0.4), IL-1β (r = 0.48) and IL-10 (r = 0.68). The data of our study allow to conclude that extracts from the examined medicinal plant raw materials can be considered as promising components while developing new drugs with exhibiting immunoregulatory and antiflogogenic effects.