The effects of biologically active substances in medicinal plants on the metabolic activity of neutrophils

Neutrophils are the typical effector cells of the innate immune response because they are the first leukocytes to be recruited to an inflammatory site where they engulf invading microorganisms and destroy them by multiple oxidative and non-oxidative mechanisms. The destructive potential of neutrophils requires the tight control of their recruitment into tissue compartments and the production of inflammatory mediators such as reactive oxygen species. These oxidants can be highly toxic not only for infectious agents but also for neighbouring host tissues resulting in various autoimmune and inflammatory diseases. Thus, a significant attention in medicine is paid to approaches designed to modulate the metabolic activity of neutrophils. Synthetic steroid and non-steroid compounds with adverse side effects are commonly used for this purpose. The effects of natural substances which can modulate the metabolic activity of neutrophils and which simultaneously would not exert any significant unfavourable side effects have recently been investigated. Suitable candidates for this purpose might be compounds contained in herbs. These include especially polysaccharides and polyphenols, but also terpenes. The aim of the present paper is to summarize contemporary knowledge on the effects of compounds from herbs on the metabolic activity of mammalian neutrophils.