Inhibitory effects of herbal constituents on P-glycoprotein in vitro and in vivo: herb-drug interactions mediated via P-gp.

Modulation of drug transporters via herbal medicines which have been widely used in combination with conventional prescription drugs may result in herb-drug interactions in clinical practice. The present study was designed to investigate the inhibitory effects of 50 major herbal constituents on P-glycoprotein (P-gp) in vitro and in vivo as well as related inhibitory mechanisms. Among these herbal medicines, four constituents, including emodin, 18ß-glycyrrhetic acid (18ß-GA), dehydroandrographolide (DAG), and 20(S)-ginsenoside F1 [20(S)-GF1] exhibited significant inhibition (>50%) on P-gp in MDR1-MDCKII and Caco-2 cells. Emodin was the strongest inhibitor of P-gp (IC50=9.42 µM), followed by 18ß-GA (IC50=21.78 µM), 20(S)-GF1 (IC50=76.08 µM) and DAG (IC50=77.80 µM). P-gp ATPase activity, which was used to evaluate the affinity of substrates to P-gp, was stimulated by emodin and DAG with Km and Vmax values of 48.61, 29.09 µM and 71.29, 38.45 nmol/min/mg protein, respectively. However, 18ß-GA and 20(S)-GF1 exhibited significant inhibition on both basal and verapamil-stimulated P-gp ATPase activities at high concentration. Molecular docking analysis (CDOCKER) further elucidated the mechanism for structure-inhibition relationships of herbal constituents with P-gp. When digoxin was co-administered to male SD rats with emodin or 18ß-GA, the AUC(0₋t) and Cmax of digoxin were increased by approximately 51% and 58%, respectively. Furthermore, 18ß-GA, DAG, 20(S)-GF1 and Rh1 at 10 µM significantly inhibited CYP3A4/5 activity, while emodin activated the metabolism of midazolam in human liver microsomes. In conclusion, four herbal constituents demonstrated inhibition of P-gp to specific extents in vitro and in vivo. Taken together, our findings provided the basis for the reliable assessment of the potential risks of herb-drug interactions in humans.

18ß-Glycyrrhetinic acid from licorice root impairs dendritic cells maturation and Th1 immune responses.

18ß-Glycyrrhetinic acid (ß-GA) is a natural triterpenoid compound derived from licorice root. ß-GA has been demonstrated to exert antiviral and antitumor effects. However, the effects of the maturation and immunostimulatory functions of dendritic cells (DCs) remain to be clearly elucidated. In this study, we attempted to determine whether ß-GA could influence DCs surface molecule expression, antigen uptake capacity, cytokine production and capacity to induce T-cell differentiation. The DCs used in this study were derived from murine bone marrow cells, and were used as immature or lipopolysaccharide (LPS)-stimulated mature DCs. The DCs were then assessed with regard to surface molecules expression, cytokine production, capacity to induce T-cell differentiation and proliferation. ß-GA was shown to significantly suppress the expression of surface molecules CD80, CD86, major histocompatibility complex (MHC) class I and MHC class II as well as the levels of interleukin-12 production in LPS-stimulated DCs. Moreover, ß-GA-treated DCs showed an impaired induction of the T helper type 1 immune response. These findings provide important understanding of the immunopharmacological functions of ß-GA and have ramifications for the development of therapeutic adjuvants for the treatment of DCs-related acute and chronic diseases.

[Adverse effects of licorice consumed as food: An update]. / Toxicités de l'exposition alimentaire à la réglisse : mise au point.

The word "licorice" refers to the plant, its root, and its aromatic extract. From a commercial point of view, Glycyrrhiza glabra is the most important species with a wide range of uses (herbal medicine, tobacco industry, cosmetics, food and pharmaceutical). Glycyrrhizin is one of the main constituents of licorice. Glycyrrhizin is hydrolyzed in the intestinal lumen by bacterial ß-glucuronidases to 3ß-monoglucuronyl-18ß-glycyrrhetinic acid (3MGA) and 18ß-glycyrrhetinic acid (GA), which are metabolized in the liver. Plasma clearance is slow due to enterohepatic cycling. 3MGA and GA can bind to mineralocorticoid receptors with very low affinity, and 3MGA induces apparent mineralocorticoid excess syndrome through dose-dependent inhibition of 11ß-hydroxysteroid dehydrogenase type 2 in renal tissue. The cases of apparent mineralocorticoid excess syndrome reported in the literature are numerous and sometimes severe, even fatal, most often in cases of chronic high dose consumption. Glycyrrhizin poisonings are characterized by hypertension, fluid retention, and hypokalemia with metabolic alkalosis and increased kaliuresis. Toxicity depends on the dose, the type of product consumed, the mode of consumption (acute or chronic) and a very large inter-individual variability. The diagnosis of glycyrrhizin-induced apparent mineralocorticoid excess syndrome is based on the history, clinical examination, and biochemical analysis. Management is primarily based on symptomatic care and stopping licorice consumption.

[The old man and the syrup]. / Le vieil homme et le sirop.

Intoxication by glycyrrhizin is a rare cause of hypokalemia. We describe a patient with severe hypokalemia caused by long-term consumption of syrup containing liquorice. The physiopathological mechanism of the intoxication and the differential diagnosis are presented.

Prevention of D-GalN/LPS-induced ALI by 18ß-glycyrrhetinic acid through PXR-mediated inhibition of autophagy degradation.

Acute liver injury (ALI) has multiple causes and results in liver dysfunction. Severe or persistent liver injury eventually leads to liver failure and even death. Pregnane X receptor (PXR)-null mice present more severe liver damage and lower rates of autophagy. 18ß-glycyrrhetinic acid (GA) has been proposed as a promising hepatoprotective agent. We hypothesized that GA significantly alleivates D-GalN/LPS-induced ALI, which involved in PXR-mediated autophagy and lysosome biogenesis. We found that GA can significantly decrease hepatocyte apoptosis and increase the hepatic autophagy marker LC3-B. Ad-mCherry-GFP-LC3 tandem fluorescence, RNA-seq and real-time PCR indicated that GA may stabilize autophagosomes and lysosomes and inhibit autophagosome-lysosome fusion. Simultaneously, GA markedly activates PXR, even reversing the D-GalN/LPS-induced reduction of PXR and its downstream genes. In contrast, GA has a weak protective effect in pharmacological inhibition of PXR and PXR-null mice, which significantly affected apoptosis- and autophagy-related genes. PXR knockout interferes with the stability of autophagosomes and lysosomes, preventing GA reducing the expression of lysosomal genes such as Cst B and TPP1, and suppressing autophagy flow. Therefore, we believe that GA increases autophagy by inhibiting autophagosome-lysosome fusion and blocked autophagy flux via activation of PXR. In conclusion, our results show that GA activates PXR to regulate autophagy and lysosome biogenesis, represented by inhibiting autophagosome-lysosome fusion and stabilization of lysosome. These results identify a new mechanism by which GA-dependent PXR activation reduces D-GalN/LPS-induced acute liver injury.

[Acute myocardial infarction and severe hypokalaemia due to liquorice consumption during COVID-19 confinement]. / Infarto agudo de miocardio e hipopotasemia severa por consumo de regaliz durante el confinamiento por COVID-19.

Liquorice is one of the oldest known herbs with medicinal properties and comprises up to 300 active compounds. It has been used for millennia for its digestive, anti-inflammatory and anti-infective properties. However, its possible toxic effects were described only a few years ago and there is growing interest in the side effects associated with chronic consumption. The main active component of liquorice is the prodrug glycyrrhizin and its active metabolite glycyrrhetic acid. It is a rare cause of hypokalaemia due to suppression of the renin-angiotensin-aldosterone axis, causing pseudohyperaldostenonism (PHA). We describe a rare case of secondary acute myocardial infarction in a patient with chronic consumption of liquorice.

Efficacy and safety of intravenous stronger neo-minophagen C and S-adenosyl-L-methionine in treatment of pregnant woman with chronic hepatitis B: a pilot study.

BACKGROUND: There have been no studies evaluating the efficacy and potential risks of stronger neo-minophagen C (SNMC) in pregnant women with chronic hepatitis B CHB. MATERIAL/METHODS: A total of 36 pregnant women with CHB, but without severe complications, were randomized to intravenously receive SNMC or S-adenosyl-L-methionine (SAM) daily for 4 weeks or until birth. Normalization of serum alanine transaminase (ALT) and aspartate transaminase (AST) levels and changes in ALT and AST levels from baseline were determined. All neonates were regularly examined for up to 1 year. RESULTS: Treatment with SNMC and SAM resulted in normalization of ALT levels at 4 weeks in 64.3% and 21.4% of patients, respectively (OR=6.60, 95% CI: 1.23-35.44, P=0.0540). SNMC and SAM significantly decreased ALT (from 558.28+/-390.24 to 47.07+/-24.94 IU/L, P<0.0001 and from 525.61+/-483.87 to 117.43+/-85.44 IU/L, P=0.0041, respectively) and AST (from 419.72+/-409.49 to 38.14+/-18.87 IU/L, P=0.0016, and from 510.78+/-621.58 to 79.93+/-63.25 IU/L, P=0.0152, respectively) at 4 weeks relative to baseline values. Hypokalemia was observed in 4 SNMC-treated patients and in 2 SAM-treated patients and hypernatremia in 3 SNMC-treated and in 3 SAM-treated patients. Hypertension was observed in 1 SNMC-treated patient. There was no significant difference in the volume of amniotic fluid or meconium between SNMC-treated and SAM-treated groups. All the neonates were physically normal at birth and at the 1-year follow-up examination. CONCLUSIONS: Both SNMC and SAM improve liver function, with SNMC appearing more effective, in pregnant women with chronic hepatitis B without impact on fetal development.

A Review of the Pharmacological Efficacy and Safety of Licorice Root from Corroborative Clinical Trial Findings.

Since ancient times, licorice, the root of Glycyrrhiza glabra, has been known to have a wide spectrum of therapeutic effects. Glycyrrhizin is cleaved to glycyrrhizic acid, which is subsequently converted to glycyrrhetic acid by human intestinal microflora. Glycyrrhetic acid is a potent inhibitor of 11ß-hydroxysteroid dehydrogenase (11ß-HSD) and performs a range of corticosteroid-like activities. The pharmacologic effects of licorice contribute to its anti-inflammatory, antioxidative, anti-allergenic, and antimicrobial properties. Licorice has been used to treat liver disease, gastrointestinal disorders, oral disease, and various skin disorders and has been used in gum, candy, herbs, alcoholic beverages, and food supplements. Licorice and its extracts, especially glycyrrhizin, can be taken orally, through the skin (in the form of gels and oils), and intravenously. Licorice demonstrates mineralocorticoid-like activity not only by inhibiting 11ß-HSD2, but also by binding to a mineralocorticoid receptor, leading to potentially adverse risks of mineralocorticoid-like overactivity. Chronic use of licorice can lead to hypokalemia and hypertension, and some people are more sensitive to licorice exposure. Based on clinical trials, this review summarizes the positive effects of licorice and other reported side effects.

Licorice: a sweet alternative to prevent hyperkalemia in dialysis patients?

In patients on hemodialysis, Farese et al. report that inhibition of the enzyme 11beta-hydroxysteroid dehydrogenase type 2 by glycyrrhetinic acid, the active compound of licorice, reduces serum potassium concentration and the frequency of hyperkalemia, possibly by enhancing intestinal potassium loss. This finding could be an important tool to maintain predialysis [K(+)] within safe limits in some dialysis patients at risk of hyperkalemic arrhythmias.

Glycyrrhetinic acid food supplementation lowers serum potassium concentration in chronic hemodialysis patients.

Hyperkalemia is a common life-threatening problem in hemodialysis patients. Because glycyrrhetinic acid (GA) inhibits the enzyme 11beta-hydroxy-steroid dehydrogenase II and thereby increases cortisol availability to the colonic mineralocorticoid receptor, it has the potential to lower serum potassium concentrations. To test this, 10 patients in a 6 month prospective, double-blind, placebo-controlled crossover study were given cookies or bread rolls supplemented with glycyrrhetinic acid or placebo. Twenty-four-hour blood pressure measurements were performed at baseline and week 6 and 12 of each treatment period. The ratio of plasma cortisol/cortisone was significantly increased in all patients on GA as compared to baseline or placebo, indicating appropriate enzyme inhibition. Nine of the 10 patients had a persistent decrease in predialysis serum potassium concentration. On GA, mean predialysis serum potassium was significantly lower than at baseline or on placebo. On placebo, serum potassium was significantly elevated above the upper limit of normal in 76% compared to 30% of measurements during GA treatment. Furthermore, on this treatment the frequency of severe hyperkalemia significantly decreased from 9% to 0.6%. No differences were found in parameters reflecting sodium retention. Although these studies show that prolonged GA supplementation persistently lowers serum potassium in dialysis patients, a long-term toxicity study will be mandatory before we recommend the routine use of this treatment.

Treatment of pruritus in mild-to-moderate atopic dermatitis with a topical non-steroidal agent.

Atopiclair (Zarzenda) is a topical non-steroidal anti-inflammatory agent for the treatment of allergic diseases of the skin. Three main ingredients are contained in this product: glycyrrhetinic acid, telmesteine and Vitis vinifera extracts. Other ingredients include: allantoin, alpha-bisabolol, capryloyl glycine, hyaluronic acid, shea butter and tocopheryl acetate. Two previous randomized, double-blind, vehicle-controlled clinical studies provided evidence that Atopiclair is effective in the treatment of atopic dermatitis. This article presents an open, multicenter, sponsor-free, study on the anti-pruritic activity of this product in adult patients with mild-to-moderate atopic dermatitis. The Median Visual Analogue Scale (VAS) values were: at the start of the study (TO), median VAS was 48.5 mm; three weeks later (T1), median VAS was 34.1 mm (-14.4 mm from baseline); six weeks later (T2), median VAS was 24.6 mm (-23.9 mm from baseline). Statistical analysis revealed that differences between TO versus T1, TO versus T2 and T1 versus T2 were highly significant (p<0.001). Side effects (local burning) were relatively common, although mild in severity. On the basis of the results of this study, Atopiclair showed efficacy in relief of pruritus in adult patients with mild-to-moderate atopic dermatitis.

A double-blind, randomized, vehicle-controlled clinical study to evaluate the efficacy and safety of MAS063DP (ATOPICLAIR) in the management of atopic dermatitis in paediatric patients.

A multicenter, randomized, double-blind, vehicle-controlled clinical study was conducted to evaluate the efficacy and safety of MAS063DP in 60 paediatric patients affected by atopic dermatitis (AD), aged between 2 and 17 years. Using the Investigator's Global Assessment (IGA) score for AD, patients with a score of 2 (mild) or 3 (moderate) were enrolled in the study. Patients were randomly selected to receive MAS063DP (20 patients), MAS060 (20 patients, a similar formulation with lower key ingredients' concentration and no preservatives) or vehicle (20 patients).The study consisted in a treatment period of 43 days, with clinical evaluations at baseline (day 1), days 8, 15, 22, 29 and 43, at which time the treatment was stopped. MAS063DP showed nearly 80% improvement in IGA score at day 22, compared with 16.6% and 26.3% with the MAS060 and vehicle respectively. A statistically significant difference was found by comparing MAS063DP with MAS060 (p < 0.0001); a similar result was evidenced comparing MAS063DP and vehicle (p = 0.001). By contrast, no significant difference was found between MAS060 and vehicle. A statistically significant difference was sustained until the end of the study. MAS063DP may therefore be considered as one of the available regimens effective in the treatment of mild-to-moderate AD in children and adolescents.

[Severe hypokalemia after holidays return]. / Hypokaliémie sévère au retour de vacances.

A 52-year old man is referred to our institution for hypertension (190/90 mmHg) and lower limb edema. An initial blood sample reveals severe hypokalemia (1.58 mEq/l) associated with metabolic alkalosis (pH: 7.63; total bicarbonates: 47.7 mEq/I), rhabdomyolysis (CPK: 1.776 UI/I) and ECG modifications. Primary aldosteronism is suspected and further diagnostic procedures are performed. A urine sample shows inappropriate potassium elimination associated with both low plasmatic renin and aldosterone levels, orienting the diagnosis toward a case of pseudohyperaldosteronism. A more detailed history reveals daily consumption of more than half a liter of licorice-based aperitif during the holiday period. This case illustrates the paramount importance of a detective-like questioning and reminds the physiopathologic role of glycyrrhetinic acid as a cause of hyperaldosteronism.

18α-Glycyrrhetinic acid lethality for neuroblastoma cells via de-regulating the Beclin-1/Bcl-2 complex and inducing apoptosis.

18α-Glycyrrhetinic acid (18-GA) is a known gap-junction inhibitor with demonstrated anticancer effects. However, the different modes of cell cytotoxicity for 18-GA remain to be characterized. In this study, 18-GA reduced the expression of cell-cell interaction proteins (N- and VE-cadherin), and led to a dose-dependent increase in cytotoxicity of the neuroblastoma cells tested, but was less toxic toward actively dividing human embryonic kidney cells. We found that 18-GA could induce both autophagy and apoptosis. 18-GA mediated autophagy was due to accumulation of Atg5, Atg7 and LC3II and degradation of p62. Individual siRNAs against Atg5 and Atg7 prevented autophagy and resulted in a further loss of viability with 18-GA. In addition, combination of 18-GA with autophagy inhibitor chloroquine produced a more significant cell death. This implied a pro-survival function for autophagy induction with 18-GA. 18-GA also led to the destabilization of Bcl-2/Beclin-1 interaction and cleavage of Beclin-1, a protein known to play role in apoptosis and autophagy induction. Treatment of cells by a pan-caspase inhibitor or a caspase-3 siRNA prevented a large portion of 18-GA mediated cytotoxicity, demonstrating that caspase-dependent apoptosis induction was responsible for most of the observed cytotoxicity. In terms of signaling, 18-GA led to reduced phosphorylation of all three classes of MAP kinases. Taken together, 18-GA or its pathways may lead to more effective, targeted therapeutics against neuroblastoma.

Glycyrrhetinic acid, the active principle of licorice, can reduce the thickness of subcutaneous thigh fat through topical application.

Cortisol is involved in the distribution and deposition of fat, and its action is regulated by the activity of 11beta-hydroxysteroid dehydrogenase. Glycyrrhetinic acid, the active principle of licorice root, blocks 11beta-hydroxysteroid dehydrogenase type 1, thus reducing the availability of cortisol at the level of adipocytes. We evaluated the effect of topical application of a cream containing glycyrrhetinic acid in the thickness of fat at the level of the thigh. Eighteen healthy women (age range 20-33 years) with normal BMI were randomly allocated to treatment, at the level of the dominant thigh, with a cream containing 2.5% glycyrrhetinic acid (n=9) or with a placebo cream containing the excipients alone (n=9). Before and after 1 month of treatment both the circumference and the thickness of the superficial fat layer of the thighs (by ultrasound analysis) were measured. The circumference and the thickness of the superficial fat layer were significantly reduced in comparison to the controlateral untreated thigh and to control subjects treated with the placebo cream. No changes were observed in blood pressure, plasma renin activity, plasma aldosterone or cortisol. The effect of glycyrrhetinic acid on the thickness of subcutaneous fat was likely related to a block of 11beta-hydroxysteroid dehydrogenase type 1 at the level of fat cells; therefore, glycyrrhetinic acid could be effectively used in the reduction of unwanted local fat accumulation.