Synthesis, anti-microbial and anti-inflammatory activities of 18β-glycyrrhetinic acid derivatives

Thirteen 18β-glycyrrhetinic acid (GA) derivatives were obtained by reduction at C-11 position, oxidation at C-3 position and condensation at C-2 position of GA. Anti-microbial activity evaluation indicated that compounds 04, 05, 10, 13 and 14 showed more potent inhibitory activity against Staphylococcus aureus subsp. aureus, Staphylococcus epidermidis, Staphylococcus aureus than GA, especially compound 10, the inhibitory activity against Staphylococcus epidermidis was equaled with Ampicillin. Moreover, in vivo experiments exhibited that compound 10 also has anti-inflammatory effect, which could decrease about 59.69% TPA-induced ear edema of mice with the gavage treatment of 40.0 mg/mL. Immunohistochemistry results revealed that the effect of inhibition was related to inhibition of TPA-induced upregulation of the pro-inflammatory cytokines TNF-α and IL-1β. Furthermore, compound 10 also significantly decreased the expression level of p65 in NF-κB signaling pathway. In general, compound 10, both with antibacterial and anti-inflammatory activities, was expected to become a promising bio-functional agent.