Rapid identification and preparative isolation of antioxidant components in licorice

Components identification and isomers differentiation in pigeon pea (Cajanus cajan L.) leaves by LC-MS

A valid and reliable method based on ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry using electrospray ionization was established to identify chemical constituents in the ethanol extract of pigeon pea leaves. A total of 58 compounds were detected both in positive and negative modes. Among them, 42 compounds, including 16 flavones, 1 flavonol, 5 flavanones, 9 isoflavones, 1 coumarin, 1 lactone, 6 stilbenes, 2 chalcones, and 1 other compound, were unambiguously identified or tentatively assigned in view of the retention time, the molecular formula, as well as the fragmentation patterns. Moreover, eight sets of isomers were differentiated by the ion trap mass spectrometry based on the fragment ion differences or the abundance differences of the same fragment ions. The energy-resolved mass spectrometry in light of the relative abundance of characteristic fragment ions was adopted in the study.

Purification of flavonoids from licorice using an off-line preparative two-dimensional normal-phase liquid chromatography/reversed-phase liquid chromatography method

An orthogonal (71.9%) off-line preparative two-dimensional normal-phase liquid chromatography/reversed-phase liquid chromatography method coupled with effective sample pretreatment was developed for separation and purification of flavonoids from licorice. Most of the nonflavonoids were firstly removed using a self-made Click TE-Cys (60 μm) solid-phase extraction. In the first dimension, an industrial grade preparative chromatography was employed to purify the crude flavonoids. Click TE-Cys (10 μm) was selected as the stationary phase that provided an excellent separation with high reproducibility. Ethyl acetate/ethanol was selected as the mobile phase owing to their excellent solubility for flavonoids. Flavonoids co-eluted in the first dimension were selected for further purification using reversed-phase liquid chromatography. Multiple compounds could be isolated from one normal-phase fraction and some compounds with bad resolution in one-dimensional liquid chromatography could be prepared in this two-dimensional system owing to the orthogonal separation. Moreover, this two-dimensional liquid chromatography method was beneficial for the preparation of relatively trace flavonoid compounds, which were enriched in the first dimension and further purified in the second dimension. Totally, 24 flavonoid compounds with high purity were obtained. The results demonstrated that the off-line two-dimensional liquid chromatography method was effective for the preparative separation and purification of flavonoids from licorice.

Pharmacological Effects of Glycyrrhiza spp. and Its Bioactive Constituents: Update and Review

The roots and rhizomes of various species of the perennial herb licorice (Glycyrrhiza) are used in traditional medicine for the treatment of several diseases. In experimental and clinical studies, licorice has been shown to have several pharmacological properties including antiinflammatory, antiviral, antimicrobial, antioxidative, antidiabetic, antiasthma, and anticancer activities as well as immunomodulatory, gastroprotective, hepatoprotective, neuroprotective, and cardioprotective effects. In recent years, several of the biochemical, molecular, and cellular mechanisms of licorice and its active components have also been demonstrated in experimental studies. In this review, we summarized the new phytochemical, pharmacological, and toxicological data from recent experimental and clinical studies of licorice and its bioactive constituents after our previous published review.

Countercurrent Separation of Natural Products: An Update

This work assesses the current instrumentation, method development, and applications in countercurrent chromatography (CCC) and centrifugal partition chromatography (CPC), collectively referred to as countercurrent separation (CCS). The article provides a critical review of the CCS literature from 2007 since our last review (J. Nat. Prod. 2008, 71, 1489-1508), with a special emphasis on the applications of CCS in natural products research. The current state of CCS is reviewed in regard to three continuing topics (instrumentation, solvent system development, theory) and three new topics (optimization of parameters, workflow, bioactivity applications). The goals of this review are to deliver the necessary background with references for an up-to-date perspective of CCS, to point out its potential for the natural product scientist, and thereby to induce new applications in natural product chemistry, metabolome, and drug discovery research involving organisms from terrestrial and marine sources.

MLK3 is a novel target of dehydroglyasperin D for the reduction in UVB-induced COX-2 expression in vitro and in vivo

Dehydroglyasperin D (DHGA-D), a compound present in licorice, has been found to exhibit anti-obesity, antioxidant and anti-aldose reductase effects. However, the direct molecular mechanism and molecular targets of DHGA-D during skin inflammation remain unknown. In the present study, we investigated the effect of DHGA-D on inflammation and its mechanism of action on UVB-induced skin inflammation in HaCaT human keratinocytes and SKH-1 hairless mice. DHGA-D treatment strongly suppressed UVB-induced COX-2 expression, PGE2 generation and AP-1 transactivity in HaCaT cells without affecting cell viability. DHGA-D also inhibited phosphorylation of the mitogen-activated protein kinase kinase (MKK) 3/6/p38, MAPK/Elk-1, MKK4/c-Jun N-terminal kinase (JNK) 1/2/c-Jun/mitogen, and stress-activated protein kinase (MSK), whereas phosphorylation of the mixed-lineage kinase (MLK) 3 remained unaffected. Kinase and co-precipitation assays with DHGA-D Sepharose 4B beads showed that DHGA-D significantly suppressed MLK3 activity through direct binding to MLK3. Knockdown of MLK3 suppressed COX-2 expression as well as phosphorylation of MKK4/p38 and MKK3/6/JNK1/2 in HaCaT cells. Furthermore, Western blot assay and immunohistochemistry results showed that DHGA-D pre-treatment significantly inhibits UVB-induced COX-2 expression in vivo. Taken together, these results indicate that DHGA-D may be a promising anti-inflammatory agent that mediates suppression of both COX-2 expression and the MLK3 signalling pathway through direct binding and inhibition of MLK3.

Structures of new phenolics isolated from licorice, and the effectiveness of licorice phenolics on vancomycin-resistant Enterococci

Licorice, which is the underground part of Glycyrrhiza species, has been used widely in Asian and Western countries as a traditional medicine and as a food additive. Our continuous investigation on the constituents of roots and stolons of Glycyrrhiza uralensis led to the isolation of two new phenolics, in addition to 14 known compounds. Structural studies including spectroscopic and simple chemical derivatizations revealed that both of the new compounds had 2-aryl-3-methylbenzofuran structures. An examination of the effectiveness of licorice phenolics obtained in this study on vancomycin-resistant strains Enterococcus faecium FN-1 and Enterococcus faecalis NCTC12201 revealed that licoricidin showed the most potent antibacterial effects against both of E. faecalis and E. faecium with a minimum inhibitory concentration (MIC) of 1.9 × 10-5 M. 8-(γ,γ-Dimethylallyl)-wighteone, isoangustone A, 3'-(γ,γ-dimethylallyl)-kievitone, glyasperin C, and one of the new 3-methyl-2-phenylbenzofuran named neoglycybenzofuran also showed potent anti-vancomycin-resistant Enterococci effects (MIC 1.9 × 10-5-4.5 × 10-5 M for E. faecium and E. faecalis). The HPLC condition for simultaneous detection of the phenolics in the extract was investigated to assess the quality control of the natural antibacterial resource, and quantitative estimation of several major phenolics in the extract with the established HPLC condition was also performed. The results showed individual contents of 0.08%-0.57% w/w of EtOAc extract for the major phenolics in the materials examined.

Structures of two new flavonoids and effects of licorice phenolics on vancomycin-resistant Enterococcus species

Since our previous study revealed that several licorice phenolics have antibacterial effects on methicillin-resistant Staphylococcus aureus (MRSA), and suppressive effects on the oxacillin resistance of MRSA, we further investigated effectiveness of licorice constituents on vancomycin-resistant Enterococcus (VRE) bacteria, and purified 32 phenolic compounds. Two flavonoids among them were characterized structurally, and identified their structures as demethylglycyrol (31) and 5,7-di-O-methylluteone (32), respectively. Examination of antibacterial effects of licorice phenolics showed that 3-arylcoumarins such as licoarylcoumarin (9) and glycycoumarin (26), and 2-arylcoumarones such as gancaonin I (17), have moderate to potent antibacterial effects on the VRE strains used in this study.

Bioactivity and potential health benefits of licorice

Licorice is an herbal plant named for its unique sweet flavor. It is widely used in the food and tobacco industries as a sweetener. Licorice is also used in traditional Chinese medicine (TCM) and complementary medicine. Because the use of licorice has long been a part of TCM, the details of its therapeutic applications have been thoroughly established. In modern science, licorice is of interest because of its broad range of applications. Extracts of and compounds isolated from licorice have been well studied and biologically characterized. In this review, we discuss the nutraceutical and functional activities of licorice as well as those of the extracts of and the isolated compounds from licorice, including agents with anti-inflammatory activity, cell-protective abilities, and chemopreventive effects. The side effects of licorice are also enumerated. A comparison of the activities of licorice described by modern science and TCM is also presented, revealing the correspondence of certain characteristics.

Rapid identification of aldose reductase inhibitory compounds from Perilla frutescens

The ethyl acetate (EtOAc) soluble fraction of methanol extracts of Perilla frutescens (P. frutescens) inhibits aldose reductase (AR), the key enzyme in the polyol pathway. Our investigation of inhibitory compounds from the EtOAc soluble fraction of P. frutescens was followed by identification of the inhibitory compounds by a combination of HPLC microfractionation and a 96-well enzyme assay. This allowed the biological activities to be efficiently matched with selected HPLC peaks. Structural analyses of the active compounds were performed by LC-MSⁿ. The main AR inhibiting compounds were tentatively identified as chlorogenic acid and rosmarinic acid by LC-MSⁿ. A two-step high speed counter current chromatography (HSCCC) isolation method was developed with a solvent system of n-hexane-ethyl acetate-methanol-water at 1.5 : 5 : 1 : 5, v/v and 3 : 7 : 5 : 5, v/v. The chemical structures of the isolated compounds were determined by ¹H- and ¹³C-nuclear magnetic resonance spectrometry (NMR). The main compounds inhibiting AR in the EtOAc fraction of methanol extracts of P. frutescens were identified as chlorogenic acid (2) (IC₅₀ = 3.16 μM), rosmarinic acid (4) (IC₅₀ = 2.77 μM), luteolin (5) (IC₅₀ = 6.34 μM), and methyl rosmarinic acid (6) (IC₅₀ = 4.03 μM).

Isoangustone A, a novel licorice compound, inhibits cell proliferation by targeting PI3K, MKK4, and MKK7 in human melanoma

Licorice root is known to possess various bioactivities, including anti-inflammatory and anticancer effects. Glycyrrhizin, a triterpene compound, is the most abundant constituent of dried licorice root. However, high intake or long-term consumption of glycyrrhizin causes several side effects, such as hypertension, hypertensive encephalopathy, and hypokalemia. Therefore, finding additional active compounds other than glycyrrhizin in licorice that exhibit anticancer effects is worthwhile. We found that isoangustone A (IAA), a novel flavonoid from licorice root, suppressed proliferation of human melanoma cells. IAA significantly blocked cell-cycle progression at the G1-phase and inhibited the expression of G1-phase regulatory proteins, including cyclins D1 and E in the SK-MEL-28 human melanoma cell line. IAA suppressed the phosphorylation of Akt, GSK-3β, and JNK1/2. IAA also bound to phosphoinositide 3-kinase (PI3K), MKK4, and MKK7, strongly inhibiting their kinase activities in an ATP-competitive manner. Moreover, in a xenograft mouse model, IAA significantly decreased tumor growth, volume, and weight of SK-MEL-28 xenografts. Collectively, these results suggest that PI3K, MKK4, and MKK7 are the primary molecular targets of IAA in the suppression of cell proliferation. This insight into the biologic actions of IAA provides a molecular basis for the potential development of a new chemotherapeutic agent.

Licorice-derived dehydroglyasperin C increases MKP-1 expression and suppresses inflammation-mediated neurodegeneration

Recent studies have demonstrated that microglial hyperactivation-mediated neuroinflammation is involved in the pathogenesis of several neurodegenerative diseases. Thus, inhibiting microglial production of the neurotoxic mediator tumor necrosis factor-α (TNF-α) is considered a promising strategy to protect against neurodegeneration. Here, we investigated the inhibitory effect of licorice-derived dehydroglyasperin C (DGC) on lipopolysaccharide (LPS)-induced TNF-α production and inflammation-mediated neurodegeneration. We found that DGC pre-treatment attenuated TNF-α production in response to LPS stimulation of BV-2 microglia. DGC pre-treatment attenuated LPS-induced inhibitor of κB-α (IκB-α) and p65 phosphorylation and decreased the DNA binding activity of nuclear factor-κB (NF-κB). DGC pre-treatment also inhibited LPS-mediated phosphorylation of p38 mitogen-activated protein kinases (MAPKs) and extracellular signal-regulated kinase (ERK). Interestingly, DGC treatment of BV-2 microglia significantly increased MAPK phosphatase 1 (MKP-1) mRNA and protein expression, which is a phosphatase of p38 MAPK and ERK, suggesting that the DGC-mediated increase in MKP-1 expression might inhibit LPS-induced MAPKs and NF-κB activation and further TNF-α production. We also found that LPS-mediated microglial neurotoxicity can be attenuated by DGC. The addition of conditioned media (CM) from DGC- and LPS-treated microglia to neurons helped maintain healthy cell body and neurite morphology and increased the number of microtubule-associated protein 2-positive cells and the level of synaptophysin compared to treatment with CM from LPS-treated microglia. Taken together, these data suggest that DGC isolated from licorice may inhibit microglia hyperactivation by increasing MKP-1 expression and acting as a potent anti-neurodegenerative agent.

CDK2 and mTOR are direct molecular targets of isoangustone A in the suppression of human prostate cancer cell growth

Licorice extract which is used as a natural sweetener has been shown to possess inhibitory effects against prostate cancer, but the mechanisms responsible are poorly understood. Here, we report a compound, isoangustone A (IAA) in licorice that potently suppresses the growth of aggressive prostate cancer and sought to clarify its mechanism of action. We analyzed its inhibitory effects on the growth of PTEN-deleted human prostate cancer cells, in vitro and in vivo. Administration of IAA significantly attenuated the growth of prostate cancer cell cultures and xenograft tumors. These effects were found to be attributable to inhibition of the G1/S phase cell cycle transition and the accumulation of p27(kip1). The elevated p27(kip1) expression levels were concurrent with the decrease of its phosphorylation at threonine 187 through suppression of CDK2 kinase activity and the reduced phosphorylation of Akt at Serine 473 by diminishing the kinase activity of the mammalian target of rapamycin (mTOR). Further analysis using recombinant proteins and immunoprecipitated cell lysates determined that IAA exerts suppressive effects against CDK2 and mTOR kinase activity by direct binding with both proteins. These findings suggested that the licorice compound IAA is a potent molecular inhibitor of CDK2 and mTOR, with strong implications for the treatment of prostate cancer. Thus, licorice-derived extracts with high IAA content warrant further clinical investigation for nutritional sources for prostate cancer patients.

Analysis of the inhibitory activity of Abeliophyllum distichum leaf constituents against aldose reductase by using high-speed counter current chromatography

We isolated five phenolic glycosides (acteoside, eutigoside B, isoacteoside, rutin and cornoside) from Abeliophyllum distichum leaves by high-speed counter current chromatography (HSCCC) using a solvent system of ethyl acetate:n-butanol:water (8:0.7:5). We determined the purity of the 5 compounds by high-performance liquid chromatography, and confirmed their chemical structures by using nuclear magnetic resonance data. We examined the inhibitory effect of these compounds on rat lens aldose reductase. Among these compounds, acteoside (1) showed the most potent inhibitory effect, with an IC₅₀ value of 1.39 μM. The inhibitory effect of 1 was 5.0 times greater than that of quercetin (7.05 μM), which was used as a positive control. These results suggest that acteoside may be a promising agent for the prevention or treatment of diabetic complications. Moreover, HSCCC is a promising method for the isolation and purification of biologically active compounds from natural products.

Genoprotective Effect of the Chinese Herbal Decoction Xiao Jian Zhong Tang

The Chinese herbal decoction formula Xiao Jian Zhong Tang (XJZT) is one of the classic formulas from the classic traditional Chinese medicine (TCM). Previous studies on XJZT found that it is effective for treating peptic ulcer, irritable bowel syndrome, functional gastroenteritis and similar psychosomatic disorders of the digestive organs. It has also been shown that all the herbs used in XJZT contain antioxidants. In this study, we investigated the in vitro DNA protection effect of the individual herb extracts and the whole formula. Water extract of the herbs and XJZT were used to pre-treat human lymphocytes. The lymphocytes were then exposed to hydrogen peroxide. The in vitro DNA protection effect of the herbs was investigated by comet assay. No DNA protective effect ( P <0.05) was found for individual herb extracts, but XJZT showed protection of human lymphocytic DNA upon oxidative stress ( P<0.05). The in vitro DNA protection effect of XJZT was conferred by the synergistic effect of the herbs, while the individual herbs had no such effect.

Dehydroglyasperin C, a component of liquorice, attenuates proliferation and migration induced by platelet-derived growth factor in human arterial smooth muscle cells

Liquorice is one of the botanicals used frequently as a traditional medicine in the West and in the East. Platelet-derived growth factor (PDGF)-BB is involved in the development of CVD by inducing abnormal proliferation and migration of vascular smooth muscle cells. In our preliminary study, dehydroglyasperin C (DGC), an active compound of liquorice, showed strong antioxidant activity. Since phytochemicals with antioxidant activities showed beneficial effects on chronic inflammatory diseases, the present study aimed to investigate the effects of DGC on PDGF-induced proliferation and migration of human aortic smooth muscle cells (HASMC). Treatment of HASMC with DGC for 24 h significantly decreased PDGF-induced cell number and DNA synthesis in a dose-dependent manner without any cytotoxicity, as demonstrated by the 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyltetrazolium bromide test and thymidine incorporation. Upon cell cycle analysis, DGC blocked the PDGF-induced progression through the G0/G1 to S phase of the cell cycle, and down-regulated the expression of cyclin-dependent kinase (CDK); 2, cyclin E, CDK4 and cyclin D1. Furthermore, DGC significantly attenuated PDGF-stimulated phosphorylation of PDGF receptor-b, phospholipase C-g1, AKT and extracellular-regulated kinase 1/2, and DGC inhibited cell migration and the dissociation of actin filaments by PDGF. In a rat vascular balloon injury model, DGC suppressed an excessive reduction in luminal diameters and neointimal formation compared with the control group. These results demonstrate the mechanistic basis for the prevention of CVD and the potential therapeutic properties of DGC.

Antioxidant activities of licorice-derived prenylflavonoids

Glycyrrhiza uralensis (or licorice) is a widely used Oriental herbal medicine from which the phenylflavonoids dehydroglyasperin C (DGC), dehydroglyasperin D (DGD), and isoangustone A (IsoA) are derived. The purpose of the present study was to evaluate the antioxidant properties of DGC, DGD, and IsoA. The three compounds showed strong ferric reducing activities and effectively scavenged DPPH, ABTS⁺, and singlet oxygen radicals. Among the three compounds tested, DGC showed the highest free radical scavenging capacity in human hepatoma HepG2 cells as assessed by oxidant-sensitive fluorescent dyes dichlorofluorescein diacetate and dihydroethidium bromide. In addition, all three compounds effectively suppressed lipid peroxidation in rat tissues as well as H₂O₂-induced ROS production in hepatoma cells. This study demonstrates that among the three phenylflavonoids isolated from licorice, DGC possesses the most potent antioxidant activity, suggesting it has protective effects against chronic diseases caused by reactive oxygen species as well as potential as an antioxidant food additive.

Neuroprotective effects of dehydroglyasperin C through activation of heme oxygenase-1 in mouse hippocampal cells

Licorice, the root of the Glycyrrhiza species ( Glycyrrhiza uralensis Fisher), is known to have antioxidant, anti-inflammatory, antiviral, and antitumor properties. The objective of this study is to explore the neuroprotective effect of dehydroglyasperin C (DGC) against glutamate-induced oxidative stress in mouse hippocampal HT22 cells. DGC significantly reduced cytotoxicity and reactive oxygen species (ROS) generation induced by glutamate in HT22 cells, whereas DGC did not restore glutathione depletion caused by glutamate. In addition, it was further investigated whether DGC affected the expression of heme oxygenase (HO)-1, one of the major cellular antioxidant defense systems, and it was found that DGC dose-dependently increased HO-1 expression. DGC-mediated cytoprotection of HT22 neuronal cells from glutamate insult was abrogated by either HO-1 inhibitor (Tin protoporphyrin, SnPP) or AKT inhibitor (LY294002). In conclusion, the present results demonstrate for the first time that DGC protects neuronal cells against glutamate-induced oxidative injury through the induction of HO-1 expression, which is, in turn, activated maybe through Nrf2-Keap1 and PI3K/AKT signaling pathways.

Preparative isolation and purification of seven isoflavones from Belamcanda chinensis

INTRODUCTION

Isoflavonoids from Belamcanda chinensis are known to have a number of physiological benefits including anti-inflammatory, anti-angiogenic and anti-mutagenic properties. However, there have been no reports on the effective isolation and purification of isoflavonoids from B. chinensis.

OBJECTIVE

To develop an efficient method for the preparative isolation and purification of isoflavones from B. chinensis by high-speed counter-current chromatography (HSCCC).

METHODOLOGY

A two-step HSCCC isolation method was developed using solvent system of n-hexane-ethyl acetate-2-propanol-methanol-water (5:6:2:3.5:6, v/v) and of ethyl acetate-methanol-water (10:2:9, v/v). FLASH purification system (45% methanol, isocratic) was also used for further purification. The purities and chemical structures of the isolated compounds were determined by high-performance liquid chromatography-photodiode array detection (HPLC-PDA), electrospray ionisation-mass spectrometry (ESI-MS), ¹H- and ¹³C-nuclear magnetic resonance spectrometry (NMR) and nuclear overhauser enhancement (NOE).

RESULTS

HSCCC was successfully used for the preparative separation and purification of seven isoflavones, including tectoridin (145.4 mg, 97.5%), iridin (77.9 mg, 94.0%), irilin D (42.0 mg, 92.0%), tectorigenin (294.1 mg, 98.6%), iristectorigenin A (86.8 mg, 93.4%), irigenin (141.8 mg, 95.8%) and irisflorentin (73.4 mg, 94.7%) from the rhizomes of B. chinensis.

CONCLUSION

Two isoflavone glycosides and five isoflavone derivatives were successfully isolated and purified from the crude methanol extract of dried rhizomes of the B. chinensis by HSCCC.

Liquorice and glycyrrhetinic acid increase DHEA and deoxycorticosterone levels in vivo and in vitro by inhibiting adrenal SULT2A1 activity

The mineralocorticoid effects of liquorice are mediated by the inhibitory effects of one of its active components glycyrrhetinic acid on 11β-hydroxysteroid dehydrogenase type 2. However, liquorice is reputed to have many medicinal properties and also contains a number of other potentially biologically active compounds. Here we have investigated the wider effects of oral liquorice on steroidogenesis focussing particularly on possible inhibitory effects of glycyrrhetinic acid on adrenal sulfotransferase activity. Salivary steroids were profiled by ELISA in groups of normal male and female volunteers after consuming either liquorice-containing or non-liquorice-containing confectionary for one week. Cortisol and cortisone levels reflected expected inhibition of 11β-hydroxysteroid dehydrogenase type 2 by glycyrrhetinic acid. Salivary aldosterone was decreased but deoxycorticosterone, dehydroepiandrosterone and testosterone were increased. To assess whether glycyrrhetinic acid directly affected steroidogenesis, free and conjugated steroids were measured in incubates of adrenocortical H295 cells, firstly, in the presence or absence of forskolin and secondly, with radiolabeled deoxycorticosterone or dehydroepiandrosterone. Glycyrrhetinic acid inhibited cortisone and enhanced cortisol synthesis consistent with 11β-hydroxysteroid dehydrogenase type 2 inhibition. Basal and forskolin-stimulated syntheses of deoxycorticosterone and dehydroepiandrosterone conjugates were also inhibited in a dose-dependent manner; glycyrrhetinic acid inhibited the conjugation of deoxycorticosterone and dehydroepiandrosterone with IC50 values of 7 μM. Inhibition of deoxycorticosterone and dehydroepiandrosterone conjugation was apparent within 4 h of starting glycyrrhetinic acid treatment and was not associated with changes in the expression of SULT 2A1 mRNA. SULT2A1 encodes the enzyme sulfotransferase 2A1 which is responsible for the sulfonation of deoxycorticosterone and dehydroepiandrosterone as well as pregnenolone and 17-hydroxypregnenolone in human adrenal glands. We suggest that the glycyrrhetinic acid constituent of liquorice increases circulating and thereby, salivary levels of unconjugated deoxycorticosterone and dehydroepiandrosterone by inhibiting their conjugation at source within the adrenal cortex. This effect may contribute to the mineralocorticoid actions of glycyrrhetinic acid and gives substance to claims that liquorice also has androgenic properties.

Isoangustone A suppresses mesangial fibrosis and inflammation in human renal mesangial cells

Development of diabetic nephropathy with fibrosis is associated with hypereglycemia-linked inflammation. Increased levels of proinflammatory factors have been found in diabetic patients with nephropathy. The present study was to test the hypothesis that isoangustone A, a novel compound present in licorice, can inhibit renal fibrosis and inflammation inflamed by high glucose (HG) in human mesangial cells through disturbing transforming growth factor β (TGF- β) and nuclear facor κB (NF- κB) pathways. Serum-starved mesangial cells were cultured in 33 mmol/L glucose media. Cells were treated with 1–20 μmol/L isoangustone A isolated from Glycyrrhiza uralensis licorice for three days. Exposure of cells to HG elevated connective tissue growth factor and collagen production, which was dose-dependently reversed by isoangustone A. Isoangustone A boosted HG-plummeted membrane type matrix metalloproteinase (MMP)-1 expression and diminished HG-elevated tissue inhibitor of MMP-2 expression. HG activated mesangial TGF- β1-SMAD-responsive signaling, which was repealed by ≥10 μmol/L isoangustone A. Furthermore, HG upregulated intracellular cell adhesion molecule-1 (ICAM-1) level and monocyte chemoattractant protein-1 (MCP-1) mRNA expression, and such increases were dose-dependently suppressed by isoangustone A most likely through hampering TGF- β signaling pathways. Blockade of NF- κB signaling appeared to be responsible for attenuating HG-triggered induction of ICAM-1 and MCP-1. Our findings provide the first evidence that isoangustone A dampens mesangial sclerosis associated with inflammation in response to HG through hindering TGF- β and NF- κB signaling.