The licorice flavonoid isoliquiritigenin suppresses phorbol ester-induced cyclooxygenase-2 expression in the non-tumorigenic MCF-10A breast cell line

Chemical composition, antifungal and antibiofilm activities of essential oils from Glycyrrhiza foetida (Desf.) growing in Tunisia

This study was designated to investigate the chemical composition, the antifungal activity and antibiofilm properties of Glycyrrhiza foetida (Desf.) growing in Tunisia and recognized for its pharmacological and therapeutic effects. The chemical analysis of essential oil samples prepared via hydrodistillation of the aerial parts was performed by gas chromatography-mass spectrometry (GC-MS). Moreover, the antifungal activity of G. foetida essential oil was developed against three dermatophyte strains, two molds and Candida spp. yeasts using the broth microdilution assay. According to the percentages, the main constituents are δ-cadinene (13.9%), (E)-caryophyllene (13.2%) and γ-cadinene (8.3%). The efficiency of the essential oil in inhibiting Candida albicans biofilms formation was also evaluated in terms of inhibitory percentages. The results showed that C. albicans and Microsporum canis were the most sensitive to G. foetida essential oil with a complete inhibition at 0.4 and 0.2 mg ml^-1 , respectively. Candida albicans biofilm development was reduced by 80% by the volatile oil at a concentration of 0.8 mg ml^-1 . The essential oil of G. foetida has a promising role in the control of fungal agents with medical interest and in inhibition of Candida biofilm development.

Liquorice for pain?

Liquorice has a long history of use in traditional Chinese, Ayurvedic and herbal medicine. The liquorice plant contains numerous bioactive compounds, including triterpenes, flavonoids and secondary metabolites, with glycyrrhizin being the main active compound. Liquorice constituents have been found to have anti-inflammatory, antioxidant, antiviral, anticancer, hepatoprotective and neuroprotective properties. In addition, they appear to have antidepressant actions and effects on morphine tolerance. Glycyrrhizin, its metabolite glycyrrhetic (glycyrrhetinic) acid and other liquorice-derived compounds such as isoflavonoids and trans-chalcones, exert potent anti-inflammatory effects via a wide range of mechanisms including high mobility group box 1 protein (HMGB1) inhibition, gap junction blockade and α_2A-adrenoceptor antagonism. These properties, together with an increasing body of preclinical studies and a long history of use in herbal medicine, suggest that liquorice constituents may be useful for pain management. Glycyrrhizin is used widely in the confectionary, food and tobacco industries, but has documented adverse effects that may limit clinical use. Whether liquorice plant-derived compounds represent a novel class of analgesics is yet to be established. Having a host of bioactive compounds with a broad range of mechanisms of effect, liquorice is a plant that, in the future, may give rise to new therapies for pain.

Perspectives on the Role of Isoliquiritigenin in Cancer

Isoliquiritigenin (2',4',4-trihydroxychalcone, ISL), one of the most important bioactive compounds with a chalcone structure, is derived from licorice root. Licorice is commonly known as Glycyrrhiza, including Glycyrrhiza uralensis, Glycyrrhiza radix, and Glycyrrhiza glabra, which are generally available in common foods and Chinese herbal medicines based on a wide variety of biological functions and pharmacological effects, and its derivative (ISL) is utilized as a food additive and adjunct disease treatment. In this review, we summarized the progress over the last 10 years in the targeted pathways and molecular mechanisms of ISL that are involved in the regulation of the onset and progression of different types of cancers.

Long-Lasting Anti-Inflammatory and Antinociceptive Effects of Acute Ammonium Glycyrrhizinate Administration: Pharmacological, Biochemical, and Docking Studies

The object of the study was to estimate the long-lasting effects induced by ammonium glycyrrhizinate (AG) after a single administration in mice using animal models of pain and inflammation together with biochemical and docking studies. A single intraperitoneal injection of AG was able to produce anti-inflammatory effects in zymosan-induced paw edema and peritonitis. Moreover, in several animal models of pain, such as the writhing test, the formalin test, and hyperalgesia induced by zymosan, AG administered 24 h before the tests was able to induce a strong antinociceptive effect. Molecular docking studies revealed that AG possesses higher affinity for microsomal prostaglandin E synthase type-2 compared to type-1, whereas it seems to locate better in the binding pocket of cyclooxygenase (COX)-2 compared to COX-1. These results demonstrated that AG induced anti-inflammatory and antinociceptive effects until 24-48 h after a single administration thanks to its ability to bind the COX/mPGEs pathway. Taken together, all these findings highlight the potential use of AG for clinical treatment of pain and/or inflammatory-related diseases.

Ingenol-3-Angelate Suppresses Growth of Melanoma Cells and Skin Tumor Development by Downregulation of NF-κB-Cox2 Signaling

Background

A recent focus in skin cancer prevention intervenes though modulating molecular links between inflammation and cell growth signaling, such as NF-κB. This study elucidates the effect of a non-tumor promoting phorbol ester, ingenol-3-angelate (I3A), on the growth of human melanoma cells and on the 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced skin inflammation and 7,12-Dimethylbenz(a)anthracene (DMBA)-induced skin carcinoma in mice.

Material/Methods

Cell viability was assessed by MTT assay, cell proliferation by clonogenic assay, apoptosis and cell cycle arrest was analyzed by flow cytometry, protein expression was studied by IHC and Western blotting, and gene expression by qPCR.

Results

I3A suppressed the survival and proliferation of human melanoma cells with estimated IC50 values around 38 and 46 μM for A2058 and HT144 cell, respectively. I3A activated the protein levels of PKCδ and PKCɛ, which induced apoptosis by activating caspase-9 and caspace-3 followed by lowering of mitochondrial membrane potential and enhancing DNA fragmentation. I3A induced G1 phase cell cycle arrest as well as G2/M phase arrest in both cell lines. I3A inhibited the levels of NF-κB p65 protein as well as phosphorylation of p65 and its nuclear translocation. I3A suppressed the gene expression of NF-κB, COX-2 and iNOS. I3A inhibited TPA-induced inflammation and epidermal hyperplasia in female ICR mice by downregulating NF-κB and iNOS. I3A suppressed the growth of skin tumor in DMBA-induced mice in dose-dependent manner.

Conclusions

The mechanism of I3A induces apoptosis in human melanoma cells and suppresses skin inflammation and carcinoma via downregulation of NF-κB-iNOS-COX-2 signaling.

Can active components of licorice, glycyrrhizin and glycyrrhetinic acid, lick rheumatoid arthritis?

OBJECTIVES

This review stated the possible application of the active components of licorice, glycyrrhizin (GL) and glycyrrhetinic acid (GA), in rheumatoid arthritis (RA) treatment based on the cyclooxygenase (COX)-2/thromboxane A2 (TxA2) pathway.

METHODS

The extensive literature from inception to July 2015 was searched in PubMed central, and relevant reports were identified according to the purpose of this study.

RESULTS

The active components of licorice GL and GA exert the potential anti-inflammatory effects through, at least in part, suppressing COX-2 and its downstream product TxA2. Additionally, the COX-2/TxA2 pathway, an auto-regulatory feedback loop, has been recently found to be a crucial mechanism underlying the pathogenesis of RA. However, TxA2 is neither the pharmacological target of non-steroidal anti-inflammatory drugs (NSAIDs) nor the target of disease modifying anti-rheumatic drugs (DMARDs), and the limitations and side effects of those drugs may be, at least in part, attributable to lack of the effects on the COX-2/TxA2 pathway. Therefore, GL and GA capable of targeting this pathway hold the potential as a novel add-on therapy in therapeutic strategy, which is supported by several bench experiments.

CONCLUSIONS

The active components of licorice, GL and GA, could not only potentiate the therapeutic effects but also decrease the adverse effects of NSAIDs or DMARDs through suppressing the COX-2/TxA2 pathway during treatment course of RA.

Botanicals and Their Bioactive Phytochemicals for Women's Health

Botanical dietary supplements are increasingly popular for women's health, particularly for older women. The specific botanicals women take vary as a function of age. Younger women will use botanicals for urinary tract infections, especially Vaccinium macrocarpon (cranberry), where there is evidence for efficacy. Botanical dietary supplements for premenstrual syndrome (PMS) are less commonly used, and rigorous clinical trials have not been done. Some examples include Vitex agnus-castus (chasteberry), Angelica sinensis (dong quai), Viburnum opulus/prunifolium (cramp bark and black haw), and Zingiber officinale (ginger). Pregnant women have also used ginger for relief from nausea. Natural galactagogues for lactating women include Trigonella foenum-graecum (fenugreek) and Silybum marianum (milk thistle); however, rigorous safety and efficacy studies are lacking. Older women suffering menopausal symptoms are increasingly likely to use botanicals, especially since the Women's Health Initiative showed an increased risk for breast cancer associated with traditional hormone therapy. Serotonergic mechanisms similar to antidepressants have been proposed for Actaea/Cimicifuga racemosa (black cohosh) and Valeriana officinalis (valerian). Plant extracts with estrogenic activities for menopausal symptom relief include Glycine max (soy), Trifolium pratense (red clover), Pueraria lobata (kudzu), Humulus lupulus (hops), Glycyrrhiza species (licorice), Rheum rhaponticum (rhubarb), Vitex agnus-castus (chasteberry), Linum usitatissimum (flaxseed), Epimedium species (herba Epimedii, horny goat weed), and Medicago sativa (alfalfa). Some of the estrogenic botanicals have also been shown to have protective effects against osteoporosis. Several of these botanicals could have additional breast cancer preventive effects linked to hormonal, chemical, inflammatory, and/or epigenetic pathways. Finally, although botanicals are perceived as natural safe remedies, it is important for women and their healthcare providers to realize that they have not been rigorously tested for potential toxic effects and/or drug/botanical interactions. Understanding the mechanism of action of these supplements used for women's health will ultimately lead to standardized botanical products with higher efficacy, safety, and chemopreventive properties.

Dietary compound isoliquiritigenin prevents mammary carcinogenesis by inhibiting breast cancer stem cells through WIF1 demethylation

Breast cancer stem cells (CSCs) are considered as the root of mammary tumorigenesis. Previous studies have demonstrated that ISL efficiently limited the activities of breast CSCs. However, the cancer prevention activities of ISL and its precise molecular mechanisms remain largely unknown. Here, we report a novel function of ISL as a natural demethylation agent targeting WIF1 to prevent breast cancer. ISL administration suppressed in vivo breast cancer initiation and progression, accompanied by reduced CSC-like populations. A global gene expression profile assay further identified WIF1 as the main response gene of ISL treatment, accompanied by the simultaneous downregulation of β-catenin signaling and G0/G1 phase arrest in breast CSCs. In addition, WIF1 inhibition significantly relieved the CSC-limiting effects of ISL and methylation analysis further revealed that ISL enhanced WIF1 gene expression via promoting the demethylation of its promoter, which was closely correlated with the inhibition of DNMT1 methyltransferase. Molecular docking analysis finally revealed that ISL could stably dock into the catalytic domain of DNMT1. Taken together, our findings not only provide preclinical evidence to demonstrate the use of ISL as a dietary supplement to inhibit mammary carcinogenesis but also shed novel light on WIF1 as an epigenetic target for breast cancer prevention.

Differential Effects of Glycyrrhiza Species on Genotoxic Estrogen Metabolism: Licochalcone A Downregulates P450 1B1, whereas Isoliquiritigenin Stimulates It

Estrogen chemical carcinogenesis involves 4-hydroxylation of estrone/estradiol (E1/E2) by P450 1B1, generating catechol and quinone genotoxic metabolites that cause DNA mutations and initiate/promote breast cancer. Inflammation enhances this effect by upregulating P450 1B1. The present study tested the three authenticated medicinal species of licorice [Glycyrrhiza glabra (GG), G. uralensis (GU), and G. inflata (GI)] used by women as dietary supplements for their anti-inflammatory activities and their ability to modulate estrogen metabolism. The pure compounds, liquiritigenin (LigF), its chalcone isomer isoliquiritigenin (LigC), and the GI-specific licochalcone A (LicA) were also tested. The licorice extracts and compounds were evaluated for anti-inflammatory activity by measuring inhibition of iNOS activity in macrophage cells: GI ≫ GG > GU and LigC ≅ LicA ≫ LigF. The Michael acceptor chalcone, LicA, is likely responsible for the anti-inflammatory activity of GI. A sensitive LC-MS/MS assay was employed to quantify estrogen metabolism by measuring 2-MeOE1 as nontoxic and 4-MeOE1 as genotoxic biomarkers in the nontumorigenic human mammary epithelial cell line, MCF-10A. GG, GU, and LigC increased 4-MeOE1, whereas GI and LicA inhibited 2- and 4-MeOE1 levels. GG, GU (5 μg/mL), and LigC (1 μM) also enhanced P450 1B1 expression and activities, which was further increased by inflammatory cytokines (TNF-α and IFN-γ). LicA (1, 10 μM) decreased cytokine- and TCDD-induced P450 1B1 gene expression and TCDD-induced xenobiotic response element luciferase reporter (IC50 = 12.3 μM), suggesting an antagonistic effect on the aryl hydrocarbon receptor, which regulates P450 1B1. Similarly, GI (5 μg/mL) reduced cytokine- and TCDD-induced P450 1B1 gene expression. Collectively, these data suggest that, of the three licorice species that are used in botanical supplements, GI represents the most promising chemopreventive licorice extract for women's health. Additionally, the differential effects of the Glycyrrhiza species on estrogen metabolism emphasize the importance of standardization of botanical supplements to species-specific bioactive compounds.

MicroRNA-25 regulates chemoresistance-associated autophagy in breast cancer cells, a process modulated by the natural autophagy inducer isoliquiritigenin

Recent findings have revealed that dysregulated miRNAs contribute significantly to autophagy and chemoresistance. Pharmacologically targeting autophagy-related miRNAs is a novel strategy to reverse drug resistance. Here, we report a novel function of isoliquiritigenin (ISL) as a natural inhibitor of autophagy-related miR-25 in killing drug-resistant breast cancer cells. ISL induced chemosensitization, cell cycle arrest and autophagy, but not apoptosis, in MCF-7/ADR cells. ISL also promoted the degradation of the ATP-binding cassette (ABC) protein ABCG2 primarily via the autophagy-lysosome pathway. More importantly, miRNA 3.0 array experiments identified miR-25 as the main target of ISL in triggering autophagy flux. A mechanistic study validated that miR-25 inhibition led to autophagic cell death by directly increasing ULK1 expression, an early regulator in the autophagy induction phase. miR-25 overexpression was demonstrated to block ISL-induced autophagy and chemosensitization. Subsequent in vivo experiments showed that ISL had chemosensitizing potency, as revealed by an increase in LC3-II staining, the downregulation of ABCG2, a reduction in miR-25 expression and the activation of the miR-25 target ULK1. Overall, our results not only indicate that ISL acts as a natural autophagy inducer to increase breast cancer chemosensitivity, but also reveal that miR-25 functions as a novel regulator of autophagy by targeting ULK1.

Chemopreventive Effects of Licorice and Its Components

Cancer is still a major health issue worldwide and identifying novel but safe compounds for prevention and treatment is a high priority. Licorice (Glycyrrhiza) is a perennial plant that is cultivated in many countries and has been reported to exert antioxidant, anti-inflammatory and anticancer effects. However, some components of licorice exert unwanted side effects and therefore identifying safer licorice components would be ideal. The anticancer activities of many of the licorice components appear to include cycle arrest, apoptosis induction, and general antioxidant effects. Commonly reported indirect protein targets important in tumorigenesis include many cell cycle-related proteins, apoptosis-associated proteins, MMP proteins, COX-2, GSK-β, Akt, NF-κB, and MAP kinases. Importantly, several licorice components were reported to directly bind to and inhibit the activities of PI3-K, MKK4, MKK7, JNK1, mTOR, and Cdk2, resulting in decreased carcinogenesis in several cell and mouse models with no obvious toxicity. This review focuses on specific components of licorice for which a direct protein target has been identified.

In vitro and in vivo evaluation of novel anticancer agents in triple negative breast cancer models

Triple negative breast cancer (TNBC) is subtype of breast disease devoid of the estrogen, progesterone, and Her2/neu receptors which are targets for pharmacological intervention. There is a need for novel anti-breast cancer agents that target TNBC. Therefore, novel isochalcone DJ52 was evaluated using the alamar blue dye exclusion assay, the luciferase colony assay, and xenograft models to determine its efficacy and potency. DJ52 significantly decreased proliferation of cells measured by using the alamar blue dye method and produced IC50 values of DJ52, DJ56, and DJ82 at 10-6M, 10-5M, and 10-5M, respectively. In vivo studies were conducted by injecting MDA-MB-231 cells into SCID mice to determine tumor regression was measured over 20 days. DJ52 at 50 mg/kg caused significant decrease in tumor volume (p value <.05) by nearly 50% compared with the control with vehicle alone. These data suggest that DJ52 has merit for further evaluation as a novel anticancer agent.

Novel plant-derived target drugs: a step forward from licorice?

Isoliquiritigenin (ISL) is a chalcone compound with valuable pharmacological properties such as antioxidant, anti-inflammatory, anticancer and anti-allergic activities. With regard to anticancer property, ISL was able to suppress HIF-1α level, VEGF expression and secretion, cell migration and to decrease the expression and secretion of MMP-9/-2. These effects may be mediated through inhibition of p38, PI3K/Akt and NF-κB signaling pathways. Thus, low concentration of ISL may have therapeutic potential in the treatment of aggressive breast carcinoma and other neoplasms.

Isoliquiritigenin inhibits proliferation and induces apoptosis of U87 human glioma cells in vitro

Isoliquiritigenin (ISL), a member of the flavonoids, has been demonstrated to possess antitumor activity in various cancer cell lines in vitro and in vivo. In this study, we investigated the antitumor effects of ISL on U87 glioma cells in vitro. As determined by MTT assay, ISL inhibited the proliferation of U87 cells in a time-dependent and dose-dependent manner. The results of fluorescence-activated cell sorting (FACS) analysis suggested that ISL induced the apoptosis of the U87 cells and blocked cell cycle progression at the S and G2/M phases. Moreover, it was identified that ISL induced the apoptosis of the U87 cells in a caspase-dependent manner. Although treatment with the pan-caspase inhibitor Z-VAD-FMK efficiently blocked the ISL-induced caspase activation, it did not eliminate the ISL-induced cell death. Further examination using western blot analysis revealed that ISL upregulated p21/WAF1 and p27. These results indicate that cell cycle arrest and the caspase-mediated apoptosis pathway may participate in the antiproliferative activity of ISL in U87 cells by regulating the expression of specific molecules.

Butein downregulates phorbol 12-myristate 13-acetate-induced COX-2 transcriptional activity in cancerous and non-cancerous breast cells

Butein is a flavonoid isolated from the bark of Rhus verniciflua Stokes and the flowers of Butea monosperma, and is known to be a potential therapeutic drug for treating inflammation and cancer. Cyclooxygenase (COX) converts arachidonic acid to prostanoids, and increased expression of its isoform COX-2 has been observed in breast cancer tissues. It has been suggested that COX inhibitors can be used as chemopreventive agents against breast carcinogenesis. This study examined the potential suppressive effect of the flavonoid on phorbol 12-myristate 13-acetate (PMA)-induced COX-2 expression in the non-tumorigenic MCF-10A and cancerous MCF-7 breast cells. Immunoblot and mRNA analyses revealed that butein at or below 10 μM significantly inhibited PMA-induced COX-2 expression in these breast cells. The blocking of the PKC signaling pathway appeared to be the underlying mechanism. Butein treatment reduced the amount of phospho-mitogen activated protein kinase (MAPK) ERK-1/2, and the total activity of PKC. Activated ERKs might trigger the transcriptional activation of COX-2. Reporter gene assays as well as electrophoretic mobility shift assays (EMSA) illustrated that butein inhibited transcription of this gene. This study showed that butein down-regulated PMA-induced COX-2 expression in both cancerous and non-cancerous breast cells, and such findings could provide the basis for pharmaceutical development of butein.