Molecular mechanisms underlying the anticancer activities of licorice flavonoids

ETHNOPHARMACOLOGICAL RELEVANCE

Licorice has been commonly used in traditional Chinese medicine for treatment of gastric, liver, and respiratory disease conditions for more than two thousand years. It is a major component of several Chinese patent medicines certificated by National Medical Products Administration that possess great anticancer activities.

AIM OF THE STUDY

To comprehensively summarize the anticancer activities of licorice flavonoids, explain the underlying molecular mechanisms, and assess their therapeutic potentials and side-effects.

METHODS

PubMed, Research Gate, Web of Science, Google Scholar, academic journals, and Science Direct were used as information sources, with the key words of "anticancer", "licorice", "flavonoids", and their combinations, mainly from 2000 to 2019.

RESULTS

Sixteen licorice flavonoids are found to possess anticancer activities. These flavonoids inhibit cancer cells through blocking cell cycle and regulating multiple signaling pathways. The major pathways targeted by licorice flavonoids include: the MAPK pathway, PI3K/AKT pathway, NF-κB pathway, death receptor - dependent extrinsic signaling pathway, and mitochondrial apoptotic pathway.

CONCLUSION

Licorice flavonoids are a group of versatile molecules that have pleiotropic effects on cell growth, survival and cell signaling. Many of the flavonoids possess inhibitory activities toward cancer cell growth and hence have a great therapeutic potential in cancer treatment. However, additional preclinical studies are still needed to assess their in vivo efficacy and possible toxicities. It is also imperative to evaluate the effects of licorice flavonoids on the metabolism of other drugs and explore the potential synergistic mechanism.

[Toxicokinetics of bakuchiol, hepatic and renal toxicity in rats after single oral administration of Psoraleae Fructus and combination with Glycyrrhizae Radix et Rhizoma]

To study the toxicokinetics of bakuchiol, hepatic and renal toxicity in rats after single oral administration of Psoraleae Fructus and combined with Glycyrrhizae Radix et Rhizoma, in order to provide scientific evidences for clinical safe medication use. A total of 35 SD rats were randomly divided into seven groups: vehicle (distilled water) control group, Glycyrrhizae Radix et Rhizoma group, positive control (aristolochic acid A) group, Psoraleae Fructus (40 g x kg(-1)) group( both male and female rats), Psoraleae Fructus and Glycyrrhizae Radix et Rhizoma (40 +20) g x kg(-1) group (both male and female rats). HPLC-UV method was used to determine the concentration of bakuchiol in rat plasma at different time points after single oral administration. Plasma alanine transaminase (ALT), aspartate aminotransferase (AST), blood urea nitrogen (BUN), plasma creatinine (Cr), N-acetyl-β-D-glucosaminidase (NAG) and kidney injury molecule 1 (Kim-1) were measured after administration for 24 h. The main toxicokinetics parameters of bakuchiol in rats exert significantly gender difference. When Psoraleae Fructus combination with Glycyrrhizae Radix et Rhizoma, the total area under the plasma concentration-time curve( AUC), C(max), and plasma clearance (CL) of bakuchiol were increased, respectively; CL, half-life (t½) were decreased, and T(max) were prolonged. The biochemical indicators (including ALT, AST, BUN, Cr and KIM-1 level) in different dose of Psoraleae Fructus groups, were found no statistically significant difference when compared with vehicle control group. The level of NAG in both Psoraleae Fructus and compatibility with Glycyrrhizae Radix et Rhizoma groups were significant increased (P < 0.05). There are obvious effects on toxicokinetics of bakuchiol in rats when Psoraleae Fructus combined with Glycyrrhizae Radix et Rhizoma. Renal toxicity induced by Psoraleae Fructus at high dose was observed after single oral administration and no liver damage in rats was found.

[Investigating mechanism of toxicity reduction by combination of Glycyrrhizae Radix et Rhizoma and Aconiti Lateralis Radix Preparata on terms of proteins self-assembly]

The combination of Glycyrrhizae Radix et Rhizoma and Aconiti Lateralis Radix Preparata can increase efficacy and decrease toxicity. This study started from the phenomena of protein self-assembly in the mixed decoction of Glycyrrhizae Radix et Rhizoma with Aconiti Lateralis Radix Preparata. The attenuated mechanism was explored between the combination of Glycyrrhizae Radix et Rhizoma and Aconiti Lateralis Radix Preparata by using the protein of Glycyrrhizae Radix et Rhizoma and aconitine which was the major toxic component of Aconiti Lateralis Radix Preparata. Glycyrrhizae Radix et Rhizoma protein with aconitine could form stable particles which particle mean diameter was (206.2 ± 2.02) nm and (238.20 ± 1.23) nm at pH 5.0 in normal temperature. Through the mouse acute toxicity experiment found that injection of aconitine monomer all mice were killed, and injection of Glycyrrhizae Radix et Rhizoma protein-aconitine particles with the same content of aconitine all mice survived. Survey the stability of Glycyrrhizae Radix et Rhizoma protein-aconitine shows that the colloid particles is stable at room temperature, and it has the possibility to candidate drug carrier. Glycyrrhizae Radix et Rhizoma protein can reduce the toxicity of aconitine through self-assembly.

Toxic potentials of ten herbs commonly used for aphrodisiac effect in Turkey

BACKGROUND/AIM

Sexual dysfunction is a serious problem worldwide. In Turkey, herbal products are used by some people suffering from sexual dysfunction. Despite their therapeutic advantages, some constituents of herbs are potentially toxic and pose health risks because they can be bought from the market without a prescription. Therefore, we aimed to determine the safety of herbs possessing aphrodisiac effects, chosen on the basis of their frequency of medicinal use and commercial importance in Turkey.

MATERIALS AND METHODS

Ten herbs (Anethum graveolens, Carthamus tinctorius, Citrus aurantium, Cocos nucifera, Glycyrrhiza glabra, Melissa officinalis, Nigella arvensis, Pinus pinea, Prunus mahaleb, and Zingiber officinale) were extracted with water, methanol, and chloroform. The cyto- and genotoxic potentials of the extracts were assessed using an MTT test on a rat kidney cell line and an Ames assay in Salmonella typhimurium strains, respectively.

RESULTS

In the cytotoxic evaluation, IC50 values were 1.51-31.4 mg/mL for the methanol and chloroform extracts, while the water extracts were not cytotoxic. In the genotoxic evaluation, it was revealed that the water extracts had more mutagenic activity than the chloroform and methanol extracts. Water extract of M. officinalis was shown to have the most genotoxic activities to TA100 (±S9) and TA98 (-S9).

CONCLUSION

These results might be useful in determining the toxic effects of herbs and lead to precautions being taken in regards to their consumption.

Liquorice, a unique "guide drug" of traditional Chinese medicine: a review of its role in drug interactions

ETHNOPHARMACOLOGICAL RELEVANCE

Liquorice is the root of Glycyrrhiza uralensis Fisch. or Glycyrrhiza glabra L., Leguminosae. It is a widely used herbal medicine native to southern Europe and parts of Asia and has beneficial applications in both the medicinal and the confectionery sectors. Unlike its usage in Europe, liquorice in traditional Chinese medicine is commonly combined with other herbs in a single prescription, as a unique "guide drug" to enhance the effectiveness of other ingredients, to reduce toxicity, and to improve flavor in almost half of Chinese herbal formulas. A review on phytochemical and pharmacological research to explain this unique "guide" effect is suggested for future investigations.

MATERIALS AND METHODS

The information was collected from scientific journals, books, and pharmacopeia. The studies about the traditional uses, randomized controlled trials, chemical, pharmacological and pharmacokinetic data related to liquorice-herb/drug interaction or combination were included in the review.

RESULTS

According to recent reports, the "guide" effect of liquorice is partially through components transformed in liquorice-drug interaction; altering enzyme activity of P450 isoforms, as evidenced by induction of model probe substrates; and modulation of drug transporter proteins such as intestinal P-glycoprotein.

CONCLUSION

The overview and comparison of traditional uses of liquorice with recent pharmacological studies and randomized controlled trials provide new insights into this ancient drug for future investigations and clinical use, especially in drug combination.

Mineralocorticoid effects due to cortisol inactivation overload explain the beneficial use of hydrocortisone in septic shock

The role of corticosteroids in septic shock remains controversial despite their use for over 50 years. Large prospective trials of their use continue with the aim of resolving the controversy. These may well remain indecisive if basic endocrine principles are ignored. Review of the available evidence suggests that use of synthetic glucocorticoids is harmful but hydrocortisone beneficial. Consideration of the basic properties of the corticosteroids used and their receptors suggest an explanation for their differing therapeutic effects. The harmful synthetic glucocorticoids have no or reduced mineralocorticoid effects in contrast with the significant mineralocorticoid effects of hydrocortisone at the doses which have been found to be beneficial. The potent synthetic mineralocorticoid fludrocortisone is well recognised to raise peripheral resistance by sensitising the resistance vessels to endogenous or exogenous catecholamines and also causes metabolic alkalosis. We provide evidence to support our hypothesis that at the doses of hydrocortisone used, cortisol inactivation overload is the basis of the beneficial effect. The consequent mineralocorticoid effects result in increased sensitivity of the resistance vessels to endogenous and exogenous catecholamines with an increase in peripheral resistance correcting shock. In addition the metabolic alkalotic component of mineralocorticoid effect would tend to correct the prevailing metabolic acidosis. Hydrocortisone also has an attenuating, as opposed to the suppressing effect of synthetic glucocorticoids on the immune response which is also regarded as beneficial.

Risk and safety assessment on the consumption of Licorice root (Glycyrrhiza sp.), its extract and powder as a food ingredient, with emphasis on the pharmacology and toxicology of glycyrrhizin

Licorice (or 'liquorice') is a plant of ancient origin and steeped in history. Licorice extracts and its principle component, glycyrrhizin, have extensive use in foods, tobacco and in both traditional and herbal medicine. As a result, there is a high level of use of licorice and glycyrrhizin in the US with an estimated consumption of 0.027-3.6 mg glycyrrhizin/kg/day. Both products have been approved for use in foods by most national and supranational regulatory agencies. Biochemical studies indicate that glycyrrhizinates inhibit 11beta-hydroxysteroid dehydrogenase, the enzyme responsible for inactivating cortisol. As a result, the continuous, high level exposure to glycyrrhizin compounds can produce hypermineralocorticoid-like effects in both animals and humans. These effects are reversible upon withdrawal of licorice or glycyrrhizin. Other in vivo and clinical studies have reported beneficial effects of both licorice and glycyrrhizin consumption including anti-ulcer, anti-viral, and hepatoprotective responses. Various genotoxic studies have indicated that glycyrrhizin is neither teratogenic nor mutagenic, and may possess anti-genotoxic properties under certain conditions. The pharmacokinetics of glycyrrhizin have been described and show that its bioavailability is reduced when consumed as licorice; this has hampered attempts to establish clear dose-effect levels in animals and humans. Based on the in vivo and clinical evidence, we propose an acceptable daily intake of 0.015-0.229 mg glycyrrhizin/kg body weight/day.

Cytotoxic allyl retrochalcone from the roots of Glycyrrhiza inflata

Two known retrochalcones, licochalcone A (1) and licochalcone C (2), and one new retrochalcone, licochalcone E (4) were isolated by cytotoxicity-guided fractionation from the roots of Glycyrrhiza inflata along with an ordinary chalcone, isoliquiritigenin (3). The structure of the new retrochalcone was elucidated through a spectroscopic analysis.

Toxicologic evaluation of licorice extract as a cigarette ingredient

Licorice extract (block, powder or liquid) may be applied to cigarette tobacco at levels of about 1-4% to enhance and harmonize the flavor characteristics of smoke, improve moisture holding characteristics of tobacco, and act as a surface active agent for ingredient application. Neat material pyrolysis studies, and smoke chemistry and biological activity studies (bacterial mutagenicity, cytotoxicity, micronucleus, and sub-chronic inhalation) with mainstream smoke, or mainstream smoke preparations from cigarettes containing various target levels (1.5-12%) of the licorice extracts were performed to provide data for an assessment of the use of licorice extract as a cigarette tobacco ingredient. At simulated tobacco burning temperatures up to 900 degrees C all forms of neat licorice extract pyrolyzed extensively, yielding small amounts of benzene, toluene, phenol and acetaldehyde with no indication that licorice extracts would transfer intact to mainstream smoke. As a single ingredient added to cigarette tobacco, block licorice extract at a target level of 12.5% increased smoke constituents including selected PAH, arsenic, lead, phenol and formaldehyde (on a TPM basis), while licorice extract powder (target level of 8% tobacco) increased select PAH, phenol and formaldehyde (on a TPM basis). Lower target application levels (including typical application levels) of block, powder or liquid licorice extract did not significantly alter the smoke chemistry profile. Biological tests indicated no relevant difference in the genotoxic or cytotoxic potential of either mainstream smoke (or smoke preparations) from cigarettes with added licorice extracts compared to control cigarettes. In sub-chronic 90-day rat inhalation studies, the mainstream smoke from cigarettes with 12.5% added block and 8% added powder licorice extract contained higher formaldehyde concentrations compared to control cigarette smoke. Female rats in the 12.5% block licorice extract exposure group displayed an increased incidence and severity of epithelial hyperplasia in the nose (level 2), with no relevant respiratory tract changes in the 8% powder licorice extract exposed rats. At the lower licorice extract application levels (1.25-5%), there was no indication of increased formaldehyde concentration in the smoke atmosphere and no relevant changes in respiratory tract tissues. Mineralcorticoid-like effects which have been associated with excess licorice ingestion were not found in any of the smoke inhalation studies. The results of these studies with various forms of licorice extract applied to cigarette tobacco suggest that adding licorice extract to cigarette tobacco at levels of < or =5% does not discernibly alter the smoke chemistry or biological effects normally associated with mainstream cigarette smoke.

Liquorice and hypertension

Glycyrrhetinic acid, the active constituent of liquorice, inhibits renal IIbeta-hydroxysteroid dehydrogenase. This allows cortisol to stimulate mineralocorticoid receptors, which can result in hypertension and hypokalaemia. Treatment options are based on pathophysiological understanding.

Severe hypokalaemic paralysis and rhabdomyolysis due to ingestion of liquorice

Chronic ingestion of liquorice induces a syndrome with findings similar to those in primary hyperaldosteronism. We describe a patient who, with a plasma K+ of 1.8 mmol/l, showed a paralysis and severe rhabdomyolysis after the habitual consumption of natural liquorice. Liquorice has become widely available as a flavouring agent in foods and drugs. It is important for physicians to keep liquorice consumption in mind as a cause for hypokalaemic paralysis and rhabdomyolysis.

The old lady who liked liquorice: hypertension due to chronic intoxication in a memory-impaired patient

The authors report an 85-year-old patient admitted because of cognitive impairment. During examination hypertension and hypokalaemia were found. After some time it was discovered that the patient was eating too much liquorice. The case demonstrates that liquorice intoxication should be considered as a cause of hypertension in old age. Furthermore the case demonstrates that missing an intoxication is a pitfall for medical history taking of patients with cognitive impairment.

[An unusual cause of cardiac arrest]

The long QT syndrome is characterized by the observed association of "torsade de pointes" and the prolongation of the QT interval on the electrocardiogram. Acquired long QT syndrome typically affects older individuals, being often associated with the action of some drugs. Hypokalemia is a frequent cause of QT lengthening on the electrocardiogram. Chronic assumption of licorice may be an unusual cause of hypokalemia, due to its mineralocorticoid-like action. In this paper we describe a case of cardiac arrest due to "torsade de pointes" resulting from a marked hypokalemia caused by the patient's habit of eating daily a not negligible quantity of licorice.

Liquorice (Glycyrrhiza glabra) and the adrenal-kidney-pituitary axis in rats

The effect of oral administration of a water freeze-dried extract of Glycyrrhiza glabra (liquorice) has been studied at doses of 100, 250 and 500 mg/kg in rats on the plasma concentration of cortisol, adrenocorticotrophic hormone (ACTH), aldosterone, renin, sodium (Na) and potassium (K). The results indicated that treatment induced dose-dependent and mostly significant decreases in the concentration of cortisol, ACTH, aldosterone and K. There were concomitant dose-dependent increases in the concentrations of renin and Na. The results suggest a strong and dose-dependent suppression of the adrenal-pituitary axis, accompanied by stimulation of renin production from the kidney.

Toxicological assessment of liquorice: biliary excretion in rats

Glycyrrhizin (G) and its aglycone, glycyrrhetic acid (GA) have been prescribed for several therapeutic purposes. However, side effects have pointed out the problem of the toxicity of G. On the contrary, it was recently shown that the pure aqueous liquorice extract (LE), which also contains G, produces reduced adverse effects in rat and human, as compared to pure G, this is likely be related to differences in G bioavailability and the resulting pharmacokinetics of G and GA. Using a sensitive HPLC procedure for the determination of G and GA in rat bile, pharmacokinetics of G and GA in bile have been determined. The results of the analysis showed significantly lower concentrations of G in bile samples from rats treated with LE compared to pure G. Furthermore, LE presented a significant choleretic effect after both oral and i.v. administration, which increases the excretion rate of G. In case of GA, all the concentrations were very low, often below the detection limit. The results prompted us to assess the risk associated with liquorice intake and to determine the daily amount of pure liquorice root extract that can be safely consumed.