Plant Phenolic Compounds as Immunomodulatory Agents

Abstract

Immunology is a source of continuous discoveries; Immunology was and still is a source of continuous discoveries. Immunomodulation encompasses all therapeutic interventions aimed at modifying the immune response. Immunostimulation is desirable to prevent infection in states of immunodeficiency and to fight infections and cancer. On the other hand, immunosuppressive agents inhibit the activity of the immune system, and they are used to prevent the rejection of transplanted organs and tissues and to treat autoimmune diseases or diseases that are most likely of autoimmune origin (e.g., rheumatoid arthritis, systemic lupus erythematosus, Crohn's disease, ulcerative colitis, etc.), or other nonautoimmune inflammatory diseases (e.g., allergic asthma). The discovery of immunomodulatory agents from medicinal plants devoid of toxic side effects, with enhanced bioavailability and that can be used for a long duration, is of great actuality. Research on natural immunomodulators provides a therapeutic solution that addresses a multitude of disorders. Plant phenolic compounds already proved beneficial effects in cardiovascular diseases, diabetes, and cancer, exerting mainly antioxidant and anti-inflammatory effects. The concepts of "immunomodulatory," "anti-inflammatory," and "antioxidant" are often strongly related, and a review of phenolic compound action on immune system should be analyzed in a context, revealing their mechanism of action on effector cells and also on the system as a whole.

Chemical characterization and immunostimulatory activity of phenolic acid bound arabinoxylans derived from foxtail and barnyard millets

“…Arabinoxylans are well reported immune stimulators and tend to increase the release of proinflammatory mediators Zhang, Li, Smith, & Musa, 2015). Activation of mononuclear cells and an increase of the phagocytic response are induced by several phytophenols like daidzein, procyanidin A1, C1, kaempferritin, geraniin, isocorilagin, Oenothein B, and Morin hydrate (Grigore, 2017). Further, phenolic acids are also reported to stimulate splenocyte proliferation, NK, and CTL cell cytotoxicity and lysosomal enzyme activity in murine peritoneal macrophages…”

“…nuclear cells and an increase of the phagocytic response are induced by several phytophenols like daidzein, procyanidin A1, C1, kaempferritin, geraniin, isocorilagin, Oenothein B, and Morin hydrate(Grigore, 2017). Further, phenolic acids are also reported to stimulate splenocyte proliferation, NK, and CTL cell cytotoxicity and lysosomal enzyme activity in murine peritoneal macrophages(Kilani-jaziri et al, 2017).…”

Extraction of Kaempferol and Its Glycosides Using Supercritical Fluids from Plant Sources: A Review

“…Flavonoids are polyphenolic compounds that are found in fruits, vegetables, leaves and flowers, and represent the most abundant secondary metabolites in nature. According to their structure, they can be classified into chalcones, flavonols, flavanonols, flavones, flavanols, flavanones, anthocyanins, aurones, isoflavones and phlobaphenes; flavonols (quercetin, kaempferol, myricetin and galangin, among others) being the most common in the plant kingdom ( 27 , 28 ). The ability of flavonoids to be effective antioxidants generally depends on three factors: the chelation potential of metal that depends strongly on the arrangement of hydroxyl and carbonyl groups around the molecule, the presence of hydrogen-donating substituents or electrons able to reduce free radicals, and the ability of flavonoid to remove the unpaired electron, leading to the formation of a stable phenoxyl radical ( 29 ).…”

Plant Phenolics as Pathogen-Carrier Immunogenicity Modulator Haptens

“…Although plant-based chemical compounds pose different biological activities [ 26 , 27 ], some plant phenolics exhibit anergic properties itself by means of not fully understood mechanisms [ 28 - 30 ]. However, the mechanisms of action to reduce the immunogenicity of the carrier bases in the structural modification thereof [ 31 ].…”