18alpha-Glycyrrhetinic acid

Liver-targeted liposomes for codelivery of curcumin and combretastatin A4 phosphate: preparation, characterization, and antitumor effects.[Pubmed:30880980]

Int J Nanomedicine. 2019 Mar 8;14:1789-1804.

Background: Recent efforts have been focused on combining two or more therapeutic approaches with different mechanisms to enhance antitumor therapy. Moreover, nanosize drug-delivery systems for codelivering two drugs with proapoptotic and antiangiogenic activities have exhibited great potential in efficient treatment of cancers. Methods: Glycyrrhetinic acid (GA)-modified liposomes (GA LPs) for liver-targeted codelivery of curcumin (Cur) and combretastatin A4 phosphate (CA4P) were prepared and characterized. In vitro cellular uptake, cytotoxicity, cell migration, in vivo biodistribution, antitumor activity, and histopathological studies were performed. Results: Compared with unmodified LPs (Cur-CA4P LPs), Cur-CA4P/GA LPs were taken up effectively by human hepatocellular carcinoma cells (BEL-7402) and showed higher cytotoxicity than free drugs. In vivo real-time near-infrared fluorescence-imaging results indicated that GA-targeted LPs increased accumulation in the tumor region. Moreover, Cur-CA4P/GA LPs showed stronger inhibition of tumor proliferation than Cur, Cur + CA4P, and Cur-CA4P LPs in vivo antitumor studies, which was also verified by H&E staining. Conclusion: GA-modified LPs can serve as a promising nanocarrier for liver-targeted co-delivery of antitumor drugs against hepatocellular carcinoma.

Glycyrrhetinic Acid Improves Insulin-Response Pathway by Regulating the Balance between the Ras/MAPK and PI3K/Akt Pathways.[Pubmed:30871060]

Nutrients. 2019 Mar 12;11(3). pii: nu11030604.

Glycyrrhetinic acid (GA), a bioactive component in the human diet, has been reported to improve hyperglycemia, dyslipidemia, insulin resistance and obesity in rats with metabolic syndrome. However, GA-specific target proteins and the mechanisms involved in the downstream signaling and cross-talk to improve insulin sensitivity have not been fully elucidated. In this study, the potential targets of GA were identified by chemical proteomics strategies using serial GA probes for target fishing and cell molecular imaging. Intracellular enzyme activity evaluation and insulin resistance models were used for validating the function of the target proteins on the downstream insulin signaling pathways. Collectively, our data demonstrate that GA improved the insulin-responsive pathway and glucose consumption levels via multiple diabetogenic factors that activated the insulin signaling pathway in HepG2 cells. GA improved Glucose transporter 4(GLUT4) expression by targeting the Ras protein to regulate the mitogen-activated protein kinase (MAPK) pathway. GA exhibited a strong inhibitory effect on IRS1ser307 phosphorylation in cells treated with the Protein kinase C (PKC) activator Phorbol 12-myristate 13-acetate (PMA.) Consistently, IRS1ser307 phosphorylation was also inhibited by GA in Free fatty acid (FFA)-treated HepG2 cells. GA also inhibited the PMA-induced phosphorylation of IkappaB kinase alpha/beta (IKKalpha/beta), c-Jun N-terminal kinase (JNK) and p38 proteins (P38), suggesting that IKKalpha/beta, JNK and P38 activation is dependent on PKC activity.

Synthesis and structure-activity relationship studies of water-soluble beta-cyclodextrin-glycyrrhetinic acid conjugates as potential anti-influenza virus agents.[Pubmed:30731401]

Eur J Med Chem. 2019 Mar 15;166:328-338.

Glycyrrhetinic acid (GA) is a major constituent of the herb Glycyrrhiza glabra, and many of its derivatives demonstrate a broad spectrum of antiviral activities. In the current study, 18 water-soluble beta-cyclodextrin (CD)-GA conjugates, in which GA was covalently coupled to the primary face of beta-CD using 1,2,3-triazole moiety along with varying lengths of linker, were synthesized via copper-catalyzed azide-alkyl cycloaddition reaction. Benefited from the attached beta-CD moiety, all these conjugates showed lower hydrophobicity (AlogP) compared with their parent compound GA. With the exception of per-O-methylated beta-CD-GA conjugate (35), all other conjugates showed no significant cytotoxicity to MDCK cells, and these conjugates were then screened against A/WSN/33 (H1N1) virus using the cytopathic effect assay. The preliminary results indicated that six conjugates showed promising antiviral activity, and the C-3 and C-30 of GA could tolerate some modifications. Our findings suggested that GA could be used as a lead compound for the development of potential anti-influenza virus agents.

Protective Effects of 18beta-Glycyrrhetinic Acid on Monocrotaline-Induced Pulmonary Arterial Hypertension in Rats.[Pubmed:30723409]

Front Pharmacol. 2019 Jan 22;10:13.

Pulmonary arterial hypertension (PAH) is a destructive and rare disorder characterized by a progressive increase in pulmonary artery pressure and vasoconstriction, ultimately leading to right ventricular failure and death. 18beta-Glycyrrhetinic acid (18beta-GA) is an active ingredient in the commonly used Chinese herbal medicine radix glycyrrhizae, and it possesses antioxidant, anti-inflammatory, anti-tumor, and other pharmacological properties. This study aimed to determine whether 18beta-GA has protective effects against monocrotaline (MCT)-induced PAH and whether it is associated with oxidative stress. The PAH of rats was induced by MCT (60 mg/kg) and oral administration of 18beta-GA (100, 50, or 25 mg/kg/day), sildenafil (30 mg/kg), or saline for 21 consecutive days. The development of PAH was evaluated by hemodynamic parameters and right ventricular hypertrophy index. Hematoxylin and eosin staining, Masson trichrome staining, and electron microscopy were used to determine the degree of vascular remodeling and proliferation in lung tissue. Moreover, the antioxidant capacity and malondialdehyde levels in the lungs were measured according to the instructions provided by the test kits, and the expression levels of nicotinamide adenine dinucleotide phosphate oxidase-2 (Nox2) and Nox4 were detected through Western blot analysis. Results of our study indicated that 18beta-GA treatment significantly improved the hemodynamic and pathomorphological data of the rats, reduced the changes in oxidative stress biomarkers, and inhibited Nox2 and Nox4 expression. Our research indicated that 18beta-GA has a protective effect against MCT-induced PAH by inhibiting oxidative stress in rats.

Liver-Targeted Combination Therapy Basing on Glycyrrhizic Acid-Modified DSPE-PEG-PEI Nanoparticles for Co-delivery of Doxorubicin and Bcl-2 siRNA.[Pubmed:30723405]

Front Pharmacol. 2019 Jan 22;10:4.

Combination therapy based on nano-sized drug delivery system has been developed as a promising strategy by combining two or more anti-tumor mechanisms. Here, we prepared liver-targeted nanoparticles (GH-DPP) composed of 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-polyethylene glycol-polyetherimide (DSPE-PEG-PEI) with Glycyrrhetinic acid-modified hyaluronic acid (GA-HA) for co-delivery of doxorubicin (DOX) and Bcl-2 siRNA. Particles size, zeta potential and morphology were determined for the drug-loaded GH-DPP nanoparticles (siRNA/DOX/GH-DPP). Cellular uptake and in vitro cytotoxicity were analyzed against HepG2 cells. In vivo bio-distribution and anti-tumor therapeutic effects of siRNA/DOX/GH-DPP were evaluated in H22-bearing mice. The results showed that siRNA/DOX/GH-DPP nanoparticles were nearly spherical and showed dose-dependent cytotoxicity against HepG2 cells. Compared to Glycyrrhetinic acid-free co-delivery system (siRNA/DOX/DPP) and GH-DPP nanoparticles for delivery of DOX or Bcl-2 siRNA alone, siRNA/DOX/GH-DPP nanoparticles could induce more cellular apoptosis, and showed higher anti-tumor effect. Herein GH-DPP nanoparticles could simultaneously deliver both chemotherapy drugs and siRNA into the tumor region, exhibiting great potential in anti-tumor therapy.