Phenotypic and functional maturation of murine dendritic cells induced by 18 alpha- and beta-glycyrrhetinic acid

Abstract

Various studies have described glycyrrhizin (GL), an active triterpenoic saponin extract of licorice roots, as an anti-inflammatory, antiviral, antimicrobial, anti-tumor and immunomodulating agent. The activity of GL has been mainly attributed to its metabolites, 18-alpha (GA) and 18-beta-glycyrrhetinic acid (GB), which their mechanism of action on the immune system cells is not clearly known. In this study, we have investigated the effects of GA and GB on the immune system by targeting dendritic cells and analyzing phenotypic and functional maturity of murine dendritic cells (DCs) after treatment with these components. Stimulation of DCs with GA and GB resulted in up-regulation of CD40, CD86 and MHC-II molecules indicating their effects on the maturation of DCs. These components induced the allogenic immunostimulatory capacity of DCs by stimulating the proliferation of T cells and production of the T helper (h)1-promoting cytokine, IL-12. They also increased the production of IFN-γ by T cells in mixed-lymphocyte reaction. In conclusion, these results indicate that GA and GB may insert their immunomodulatory effects by enhancing DC maturation and modulating Th1/Th2 response through an increase in Th1 responses, implying their beneficial in host defense against infectious diseases.

The antiviral and antimicrobial activities of licorice, a widely-used Chinese herb

“…In addition, many studies have reported that the six active compounds listed in this paper, GL, GA, LCA, LCE, GLD and LTG, possess other activities. For example, GL and GA also have antitumor 39 , 40 , anti-inflammatory 41 , 42 , and immunoregulatory activities 12 , 43 , 44 . LCA, LCE, LTG and GLD also have inhibitory effects on diabetes 45 , 46 , 47 , 48 .…”

“…The roots and rhizomes are the main medicinal parts of licorice. Numerous studies have revealed many pharmacological activities of licorice, such as antiviral 4 , 5 , anti-inflammatory 6 , 7 , antitumor 8 , 9 , antimicrobial 10 , 11 and many other activities 12 , 13 . Among the pharmacological activities of licorice mentioned above, the antiviral and antimicrobial activities have been most commonly reported.…”

Plant Components for Immune Modulation Targeting Dendritic Cells: Implication for Therapy

“…Recently they have indicated that the extract of licorice roots containing 18-α and 18-β-glycyrrhetinic acid can increase DC maturation and modulate Th1/Th2 response through Th1 response enhancement, so licorice roots influence the host defense against infectious diseases. That's why it has shown anti-inflammatory, antiviral, antimicrobial, antitumor and immunomodulating activity in folk medicine [92].…”

Phytochemical composition, health effects, and crop management of liquorice (Glycyrrhiza glabraL.): Α medicinal plant

“…(93) Furthermore, liquorice extracts and their individual bioactive compounds provide several other health benefits for kidney, cardiovascular, immunological, respiratory, endocrine and central nervous systems which need to be underlined, since so far many physiological effects of liquorice on human body systems have been confirmed. (66,85,(100)(101)(102)(103)(104)(105)(106)(107)(108)(109)(110)(111)(112)(113)(114) The health benefits of liquorice and its constituents have been suggested to be attributed to various physiological mechanisms, including modulation of vascular injury and atherogenesis, (111) inhibition of tyrosinase activity, (103) improvement of the brain energy supply, (110) increased glucose tolerance, (112) activation of the immune system, (101) protection against the oxidative stress of the liver, (95) memory enhancing effects (105) and improvement of the renal function. (114) Other physiological effects of liquorice on human body systems are presented in Table 2.…”