RESUMO
18ß-glycyrrhetinic acid (GA) is a well-known natural compound of oleanane-type triterpene and is found possessing antimicrobial and anti-inflammatory properties. Nonetheless, its relatively low bioactivity restricts its potential in pharmaceutical applications. To maximize the potential use of this natural herbal compound as antimicrobial and anti-inflammatory agents, the rational modification of GA to enhance its pharmacological activity with low toxicity and to understand the mechanism of action is critically essential. We reported herein the design and synthesis of a series of new GA derivatives. The antimicrobial activities of these new compounds were evaluated by inhibition zone test and minimum inhibitory concentration (MIC) assay. In addition, the anti-inflammatory activity was evaluated by LPS induced BV2 cells inflammation model and 12-O-tetradecanoyl phorbol-13-acetate (TPA) induced ear inflammation mice model. It was found that the derivatives functionalized with a di-substituted phenyl group at the 2-position of GA generally displayed high antimicrobial activity against Gram-positive bacteria (MIC down to 2.5 µM) and potent anti-inflammatory effects (inhibition of NO production up to 55%, comparable to dexamethasone). The in vitro and in vivo results also showed that GA-O-02 and GA-O-06 exert their anti-inflammatory activities through downregulation of NO, pro-inflammatory cytokines and chemokines (IL-1ß, IL-6, IL-12, TNF-α, MCP-1 and MIP-1α) and upregulation of anti-inflammatory cytokines (IL-10). The anti-inflammatory mechanism may involve the inhibition of NF-κB, MAPKs and PI3K/Akt related inflammatory signaling pathways and activation of Nrf2/HO-1 signaling pathway. The results demonstrated that GA-O-02 and GA-O-06 possess great application potential as potent antimicrobial and anti-inflammatory agents.
Assuntos
Ácido Glicirretínico , Fosfatidilinositol 3-Quinases , Animais , Antibacterianos , Anti-Inflamatórios/farmacologia , Anti-Inflamatórios/uso terapêutico , Ácido Glicirretínico/análogos & derivados , Ácido Glicirretínico/farmacologia , CamundongosRESUMO
INTRODUCTION: Oleanolic acid has been considered a good start molecule for synthetic exploitation. Thus hundreds of oleanane triterpenoids have been synthesized and patented. Also many oleanane saponins have been patented for their biological activities and possible pharmaceutical use. Areas covered: Patents reporting the biological activities of oleanane derivatives and saponins with oleanane-type aglycones were examined. Among the synthesized oleanane derivatives, the most promising seem to be 2-cyano-3,12-dioxoolean-1,9(11)-dien-28-oic acid derivatives which interfere with many pathways involved in inflammation, oxidative stress and cell proliferation. Regarding oleanane-type saponins, several patents claiming their antiproliferative activity or their possible use as adjuvants in vaccines, were reported. Expert opinion: Despite the great number of synthesized oleanane triterpenoids, only CDDO-Me entered clinical development as a possible drug for the treatment of chronic kidney disease (CKD) but a phase 3 clinical trial was terminated due to heart-related adverse effects. Further phase 2 clinical trials of CDDO-Me are in progress for the treatment of CKD and PAH (pulmonary arterial hypertension) patients without heart-related risk factors. Additional investigations leading to compounds with an improved activity/toxicity profile along with well-designed preclinical and clinical trials are needed. Regarding oleanane-type saponins, the real perspective seems to be as adjuvants in vaccines.