Prepulse inhibition (PPI) disrupting effects of Glycyrrhiza glabra extract in mice: A possible role of monoamines

Quantitative determination of the antibacterial activity of licorice (Glycyrrhiza glabra) and tetracycline gel against Aggregatibacter actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg) and Prevotella intermedia (Pi) - a microbiological in vitro study

OBJECTIVES

The aim of this study was to evaluate and compare the antibacterial efficacy of licorice gel and tetracycline gel against Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis and Prevotella intermedia.

METHODS

An indigenously prepared 50 μL licorice and tetracycline gel was subjected to antibacterial sensitivity test (thrice) against Aa, Pg, Pi by agar well diffusion method using Brain Heart Infusion media. Colonies of Aa, Pg, Pi was transferred into broth and incubated at 37 °C for 24 h and diameter of inhibition zone was measured.

RESULTS

The drug release profile of licorice gel at six regular intervals was higher when compared to tetracycline. MIC of licorice gel (50 μg/mL) against Aa (14 mg), Pg (7 mg), Pi (7 mg) respectively. The diameter of inhibition zone of licorice gel was significant against Aa when compared to tetracycline gel. However, tetracycline gel exhibited significant diameter of inhibition zone against Pg and Pi when compared to licorice gel. There was a statistical significance difference between licorice and tetracycline gel against Aa (p=0.043*), Pg (p=0.037*), Pi (p=0.046*) while assessing antibacterial sensitivity test.

CONCLUSIONS

Licorice gel has anti-inflammatory and anti-microbial properties which can act against periodontal pathogens and can be considered in treating periodontal disease at low concentrations. Therefore, it can be used as an adjunctive local drug delivery agent to non-surgical periodontal therapy (NSPT) in treating periodontal disease.

Revisiting Licorice as a functional food in the management of neurological disorders: Bench to trend

Traditional and scientific evidence attribute numerous bioactivities of Licorice (Glycyrrhiza glabra Linn.) in aging-related disorders. In this state-of-art review, an extensive search in several databases was conducted to collect all relevant literature and comprehensively analyze Licorice's pharmacological attributes, neuroprotective properties, safety, and its mechanistic role in treating various neurological conditions. Network pharmacology was employed for the first time exploring the mechanistic role of Licorice in neurological disorders. Its neuroprotective role is attributed to phytoconstituents, including liquiritin, glycyrrhizic acid, liquiritigenin, glabridin, 18ß-glycyrrhetinic acid, quercetin, isoliquiritigenin, paratocarpin B, glycyglabrone, and hispaglabridin B, as evident from in vitro and in vivo studies. Network pharmacology analysis reveals that these compounds protect against long-term depression, aging-associated diseases, Alzheimer's disease, and other addictions through interactions with cholinergic, dopaminergic, and serotonergic proteins, validated in animal studies only. Future clinical trials are warranted as Licorice administration has a limiting factor of mild hypertension and hypokalemia. Hopefully, scientific updates on Licorice will propagate a paradigm shift in medicine, research propagation, and development of the central nervous system phytopharmaceuticals.

Licorice as a herbal extract in periodontal therapy

Periodontal disease is caused by specific pathogens which results in inflammation of the tooth-supporting structures and subsequently causes the continued breakdown of alveolar bone and periodontal ligament. Licorice (Glycyrrhiza glabra) is a perennial herb with substantial medicinal value. Licorice extract is derived from dried, unpeeled stolons and roots of Glycyrrhiza uralensis and G. glabra. The bioactive ingredients in licorice extract such as glycyrrhizin, licoricidin, glabridin, licochalcone A, and licorisoflavan A have anti-inflammatory, antimicrobial, and anti-adherence effects that are beneficial against periodontal disease. Since periodontal disease has a complex etiology that includes the host response and microorganisms, licorice phytochemicals offer a therapeutic advantage due to their dual functionality. The aim of this review was to enumerate the bioactive compounds present in herbal licorice extract and to elucidate the beneficial effects of licorice and its derivatives in periodontal therapy. Literature review and clinical trials evaluating the effect of licorice on periodontopathogens and periodontal disease are included in this article.

Licorice as a herbal extract in periodontal therapy

Periodontal disease is caused by specific pathogens which results in inflammation of the tooth-supporting structures and subsequently causes the continued breakdown of alveolar bone and periodontal ligament. Licorice (Glycyrrhiza glabra) is a perennial herb with substantial medicinal value. Licorice extract is derived from dried, unpeeled stolons and roots of Glycyrrhiza uralensis and G. glabra. The bioactive ingredients in licorice extract such as glycyrrhizin, licoricidin, glabridin, licochalcone A, and licorisoflavan A have anti-inflammatory, antimicrobial, and anti-adherence effects that are beneficial against periodontal disease. Since periodontal disease has a complex etiology that includes the host response and microorganisms, licorice phytochemicals offer a therapeutic advantage due to their dual functionality. The aim of this review was to enumerate the bioactive compounds present in herbal licorice extract and to elucidate the beneficial effects of licorice and its derivatives in periodontal therapy. Literature review and clinical trials evaluating the effect of licorice on periodontopathogens and periodontal disease are included in this article.

Isolation, Characterization, Pharmacology and Biopolymer Applications of Licorice Polysaccharides: Review

Licorice is known as "Gan-Cao" in traditional Chinese Medicine (TCM), belonging to the genus Glycyrrhiza (Family: Fabaceae/Leguminosae). It has a long medicinal history and wide applications in China. Polysaccharides of licorice (LPs) are one of the key bioactive components. As herbal polysaccharides attracted increasing interest in the past several decades, their extraction, isolation, structural characterization, pharmacological activities, and medicinal application have been explored extensively. It is worth heeding that the method of extraction and purification effects LPs, apart from specie and origin specificity. This review evaluates the method of extraction and purification and demonstrates its performance in gaining specific composition and its structure-activity relationship, which might lead the readers to a fresh horizon for developing advanced treatment strategies. It is recently reported that the conformation of LPs plays a vital role as biopolymers, such as selenized modification, microencapsulation, nanocomposite, liposome formulation, drug/hydrogel combinations, biosensor device, and synergistic effect with a vaccine. In addition, LPs showed a good thermodynamics profile, as these properties enable them to interact with additional supramolecular interaction by chemical modifications or copolymerization. Functional polymers that are responsive to various external stimuli, such as physical, chemical, and biological signals, are a promising study topic. Thus, LPs are emerging as a new biomaterial that can enhance intended formulation along exerting its inherent medicinal effects. It is hoped that this review will provide a basis for the utilization and further developments of licorice polysaccharides in the vast medium.

Advances in Pharmacological Activities and Mechanisms of Glycyrrhizic Acid

Licorice (Glycyrrhiza glabra L.) is widely regarded as an important medicinal plant and has been used for centuries in traditional medicine because of its therapeutic properties. Studies have shown that metabolites isolated from licorice have many pharmacological activities, such as antiinflammatory, anti-viral, participation in immune regulation, anti-tumor and other activities. This article gives an overview of the pharmacological activities and mechanisms of licorice metabolites and the adverse reactions that need attention. This review helps to further investigate the possibility of licorice as a potential drug for various diseases. It is hoped that this review can provide a relevant theoretical basis for relevant scholars' research and their own learning.

Synergistic effect of tolfenamic acid and glycyrrhizic acid on TPA-induced skin inflammation in mice

Tolfenamic acid (TA) and glycyrrhizic acid (GA) are well-known components with anti-inflammatory properties. However, their combined effects on inflammation have not been well studied. The present study aimed to investigate the in vivo anti-inflammatory effects of TA combined with GA using a 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced mouse ear edema model, as well as the underlying mechanisms thereof. The results indicated that TA combined with GA led to a stronger inhibition on TPA-induced mouse ear edema compared to the singular treatments. In addition, the combined treatment significantly alleviated subcutaneous tissue inflammation caused by TPA. Further mechanistic investigations demonstrated that TA combined with GA decreased the levels of TPA-induced interleukin-1β (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α). Furthermore, the combined treatment effectively inhibited nuclear factor-κB (NF-κB), extracellular signal-regulated kinase (ERK1/2), c-Jun N-terminal kinase (JNK), phosphor-ERK1/2 and phosphor-JNK, which was accompanied by blocking of the activation and the phosphorylation in mitogen-activated protein kinase (MAPK) and phosphoinositide 3-kinase (PI3K)/Akt signaling pathways. Collectively, our findings revealed that different anti-inflammatory components used in combination lead to enhanced inhibitory effects against inflammation.

Glycyrrhizic acid from licorice down-regulates inflammatory responses via blocking MAPK and PI3K/Akt-dependent NF-κB signalling pathways in TPA-induced skin inflammation

Glycyrrhizinic acid (GA), a principal component derived from licorice which is used extensively as a natural sweetener and traditional folk herbal medicine, is attracting considerable attention because of its broad range of bioactivities. However, the anti-inflammatory mechanism of GA on 12-O-tetradecanoylphorbol-13-acetate (TPA)-mediated skin inflammation has not been elucidated. Herein, we investigated the anti-inflammatory activity of GA by using a TPA-induced mouse ear model. It was indicated that GA, applied topically onto mouse ears, effectively inhibited the TPA-mediated expressions of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in a dose-dependent manner, respectively. Mechanistic investigations demonstrated that GA down-regulated the expressions of IκBα and p65 and blocked the phosphorylation of IκBα and p65 in TPA-induced mouse skin. Moreover, GA significantly inhibited the TPA-mediated activation of extracellular signal-regulated kinase (ERK1/2), p38 mitogen-activated protein kinase (MAPK), and phosphatidylinositol 3-kinase (PI3K)/Akt, which are upstream of nuclear factor-kB (NF-κB). Taken together, these results indicated that GA, being of natural origin, may be a potential agent for preventing inflammatory diseases.

The anti-inflammatory activity of licorice, a widely used Chinese herb

CONTEXT

Increasing incidence and impact of inflammatory diseases have encouraged the search of new pharmacological strategies to face them. Licorice has been used to treat inflammatory diseases since ancient times in China.

OBJECTIVE

To summarize the current knowledge on anti-inflammatory properties and mechanisms of compounds isolated from licorice, to introduce the traditional use, modern clinical trials and officially approved drugs, to evaluate the safety and to obtain new insights for further research of licorice.

METHODS

PubMed, Web of Science, Science Direct and ResearchGate were information sources for the search terms 'licorice', 'licorice metabolites', 'anti-inflammatory', 'triterpenoids', 'flavonoids' and their combinations, mainly from year 2010 to 2016 without language restriction. Studies were selected from Science Citation Index journals, in vitro studies with Jadad score less than 2 points and in vivo and clinical studies with experimental flaws were excluded.

RESULTS

Two hundred and ninety-five papers were searched and 93 papers were reviewed. Licorice extract, 3 triterpenes and 13 flavonoids exhibit evident anti-inflammatory properties mainly by decreasing TNF, MMPs, PGE2 and free radicals, which also explained its traditional applications in stimulating digestive system functions, eliminating phlegm, relieving coughing, nourishing qi and alleviating pain in TCM. Five hundred and fifty-four drugs containing licorice have been approved by CFDA. The side effect may due to the cortical hormone like action.

CONCLUSION

Licorice and its natural compounds have demonstrated anti-inflammatory activities. More pharmacokinetic studies using different models with different dosages should be carried out, and the maximum tolerated dose is also critical for clinical use of licorice extract and purified compounds.

Economic Importance

The beneficial effects of liquorice in treating chills, colds, and coughs have been fully discussed in Ayurveda, as well as in the texts of ancient Egyptians, Greeks, and Romans. The plant has been prescribed for dropsy during the period of famous Hippocrates. The reason being that it was quite helpful as thirst-quenching drugs (Biondi et al. in J Nat Prod 68:1099–1102, 2005; Mamedov and Egamberdieva in Herbals and human health-phytochemistry. Springer Nature Publishers, 41 pp, 2017). No doubt, the clinical use of liquorice in modern medicine started around 1930; Pedanios Dioscorides of Anazarba (Adana), first century AD-Father of Pharmacists, mentions that it is highly effective in the treatment of stomach and intestinal ulcers. In Ayurveda, people in ancient Hindu culture have used it for improving sexual vigor.

The tyrosine kinase inhibitor, sunitinib malate, induces cognitive impairment in vivo via dysregulating VEGFR signaling, apoptotic and autophagic machineries

Chemobrain refers to a cluster of cognitive deficits which affects almost 4-75% of chemotherapy-treated cancer patients. Sunitinib, an FDA-approved multityrosine kinase inhibitor, is currently used in treating different types of tumors. Despite being regarded as targeted therapy which blunts sustained angiogenesis in cancer milieu through inhibiting vascular endothelial growth factor receptor 2 (VEGFR2) signaling, the latter has a cardinal role in cognition. Recent clinical reports warned that sunitinib adversely affected memory processing in cancer patients. Nevertheless, the underlying mechanisms have not been investigated yet. Hence, we explored the impact of a clinically relevant dose of sunitinib on memory processing in vivo and questioned the implication of VEGFR2 signaling, autophagy and apoptosis. Strikingly, sunitinib preferentially impaired spatial cognition as evidenced in Morris water maze, T-maze and passive avoidance task. Consistently, sunitinib degenerated cortical and hippocampal neurons as assessed by histopathological examination and toluidine blue staining. Ultrastructural examination also depicted chromatin condensation, mitochondrial damage and accumulated autophagosomes. Digging deeper, central VEGF/VEGFR2/mTOR signaling was robustly suppressed. Besides, sunitinib boosted cortical and hippocampal p53 and executioner caspase-3 and decreased nuclear factor kappa B and Bcl-2 levels promoting apoptotic cell death. It also profoundly impeded neuronal autophagic flux as shown by decreased beclin-1 and Atg5 and increased p62/SQTSM1 levels. To our knowledge, this is the first study to provide molecular insights into sunitinib-induced chemofog where impeded VEGFR2 signaling and autophagic and hyperactivated apoptotic machineries act in neurodegenerative concert. Importantly, our findings shed light on potential therapeutic strategies to be exploited in the management of sunitinib-induced chemobrain.

Glycyrrhiza glabra

Liquorice foliage

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.