A highly sensitive LC-MS/MS method for simultaneous determination of glycyrrhizin and its active metabolite glycyrrhetinic acid: Application to a human pharmacokinetic study after oral administration

Green Synthesis of Gold Nanoparticles Using Liquiritin and Other Phenolics from Glycyrrhiza glabra and Their Anti-Inflammatory Activity

Phenolic compounds are the main phytochemical constituents of many higher plants. They play an important role in synthesizing metal nanoparticles using green technology due to their ability to reduce metal salts and stabilize them through physical interaction/conjugation to the metal surface. Six pure phenolic compounds were isolated from licorice (Glycyrrhiza glabra) and employed in synthesizing gold nanoparticles (AuNPs). The isolated compounds were identified as liquiritin (1), isoliquiritin (2), neoisoliquiritin (3), isoliquiritin apioside (4), liquiritin apioside (5), and glabridin (6). The synthesized AuNPs were characterized using UV, zeta sizer, HRTEM, and IR and tested for their stability in different biological media. The phenolic isolates and their corresponding synthesized NP conjugates were tested for their potential in vitro cytotoxicity. The anti-inflammatory effects were investigated in both normal and inflammation-induced settings, where inflammatory biomarkers were stimulated using lipopolysaccharides (LPSs) in the RAW 264.7 macrophage cell line. LPS, functioning as a mitogen, promotes cell growth by reducing apoptosis, potentially contributing to observed outcomes. Results indicated that all six pure phenolic isolates inhibited cell proliferation. The AuNP conjugates of all the phenolic isolates, except liquiritin apioside (5), inhibited cell viability. LPS initiates inflammatory markers by binding to cell receptors and setting off a cascade of events leading to inflammation. All the pure phenolic isolates, except isoliquiritin, neoisoliquiritin, and isoliquiritin apioside inhibited the inflammatory activity of RAW cells in vitro.

Inactivated vaccine with glycyrrhizic acid adjuvant elicits potent innate and adaptive immune responses against foot-and-mouth disease

Background

Foot-and-mouth disease (FMD) is an extremely contagious viral disease that is fatal to young animals and is a major threat to the agricultural economy by reducing production and limiting the movement of livestock. The currently commercially-available FMD vaccine is prepared using an inactivated viral antigen in an oil emulsion, with aluminum hydroxide [Al(OH)3] as an adjuvant. However, oil emulsion-based options possess limitations including slow increases in antibody titers (up to levels adequate for defense against viral infection) and risks of local reactions at the vaccination site. Further, Al(OH)3 only induces a T helper 2 (Th2) cell response. Therefore, novel adjuvants that can address these limitations are urgently needed. Glycyrrhizic acid (extracted from licorice roots) is a triterpenoid saponin and has great advantages in terms of price and availability.

Methods

To address the limitations of the currently used commercial FMD vaccine, we added glycyrrhizic acid as an adjuvant (immunostimulant) to the FMD bivalent (O PA2 + A YC) vaccine. We then evaluated its efficacy in promoting both innate and adaptive (cellular and humoral) immune reactions in vitro [using murine peritoneal exudate cells (PECs) and porcine peripheral blood mononuclear cells (PBMCs)] and in vivo (using mice and pigs).

Results

Glycyrrhizic acid has been revealed to induce an innate immune response and enhance early, mid-, and long-term immunity. The studied bivalent vaccine with glycyrrhizic acid increased the expression of immunoregulatory genes such as pattern-recognition receptors (PRRs), cytokines, transcription factors, and co-stimulatory molecules.

Conclusion

Collectively, glycyrrhizic acid could have utility as a novel vaccine adjuvant that can address the limitations of commercialized FMD vaccines by inducing potent innate and adaptive immune responses.

The unique activity of saponin: Induction of cytotoxicity in HTLV-1 infected cells

Infection with the retrovirus human T-cell leukemia virus type 1 (HTLV-1) sometimes causes diseases that are difficult to cure. To find anti-HTLV-1 natural compounds, we opted to screen using the HTLV-1-infected T-cell line, MT-2. Based on our results, an extract of the pulp/seeds of Akebia quinata Decaisne fruit killed MT-2 cells but did not affect the Jurkat cell line that was not infected with virus. To determine the active ingredients, seven saponins with one-six sugar moieties were isolated from A. quinata seeds, and their activities against the two cell lines were examined. Both cell lines were killed in a similar manner by Akebia saponins A and B. Further, Akebia saponins D, E, PK and G did not exhibit cytotoxicity. Akebia saponin C had a similar activity to the extract found in the screening. This compound was found to enhance Gag aggregation, induce the abnormal cleavage of Gag, suppress virion release, and preferentially kill HTLV-1 infected cells; however, their relationship remains elusive. Our findings may lead to the development of new therapies for infectious diseases based on the removal of whole-virus-infected cells.

Natural Products as a Potential Source of Promising Therapeutics for COVID-19 and Viral Diseases

Background

A global pandemic has recently been observed due to the new coronavirus disease, caused by SARS-CoV-2. Since there are currently no antiviral medicines to combat the highly contagious and lethal COVID-19 infection, identifying natural sources that can either be viricidal or boost the immune system and aid in the fight against the disease can be an essential therapeutic support.

Methods

This review was conducted based on published papers related to the herbal therapy of COVID-19 by search on databases including PubMed and Scopus with herbal, COVID-19, SARS-CoV-2, and therapy keywords.

Results

To combat this condition, people may benefit from the therapeutic properties of medicinal plants, such as increasing their immune system or providing an antiviral impact. As a result, SARS-CoV-2 infection death rates can be reduced. Various traditional medicinal plants and their bioactive components, such as COVID-19, are summarized in this article to assist in gathering and debating techniques for combating microbial diseases in general and boosting our immune system in particular.

Conclusion

The immune system benefits from natural products and many of these play a role in activating antibody creation, maturation of immune cells, and stimulation of innate and adaptive immune responses. The lack of particular antivirals for SARS-CoV-2 means that apitherapy might be a viable option for reducing the hazards associated with COVID-19 in the absence of specific antivirals.

Chemical analysis of the Chinese herbal medicine licorice (Gan-Cao): An update review

ETHNOPHARMACOLOGICAL RELEVANCE

Licorice, called Gan-Cao in China, is one of the most popular traditional herbal medicines. It is derived from the dried roots and rhizomes of Glycyrrhiza uralensis, G. glabra, and G. inflata. Licorice is recorded in the pharmacopoeias of China, Japan, US, and Europe.

AIM

This review updates research progress of licorice from the perspectives of chemical analysis, quality evaluation, drug metabolism, and pharmacokinetic studies from 2009 to April 2022.

MATERIALS AND METHODS

Both English and Chinese literatures were collected from databases including PubMed, Elsevier, Web of Science, and CNKI (Chinese). Licorice, extraction, structural characterization/identification, quality control, metabolism, and pharmacokinetics were used as keywords.

RESULTS

Newly developed analytical methods, including LC/UV, 2DLC, LC/MS, GC/MS, and mass spectrometry imaging (MSI) for chemical analysis of licorice were summarized.

CONCLUSION

This review provides a comprehensive summary on chemical analysis of licorice.

Physiology-Based Pharmacokinetic Study on 18β-Glycyrrhetic Acid Mono-Glucuronide (GAMG) Prior to Glycyrrhizin in Rats

To understand that 18β-Glycyrrhetic acid 3-O-mono-β-D-glucuronide (GAMG) showed better pharmacological activity and drug-like properties than 18β-Glycyrrhizin (GL); a rapid and sensitive HPLC-MS/MS method was established for the simultaneous determination of GAMG and its metabolite 18β-Glycyrrhetinic acid (GA) in rat plasma and tissues after oral administration of GAMG or GL. This analytical method was validated by linearity, LLOQ, specificity, recovery rate, matrix effect, etc. After oral administration, GAMG exhibited excellent C_max (2377.57 ng/mL), T_max (5 min) and AUC_0-T (6625.54 mg/L*h), which was much higher than the C_max (346.03 ng/mL), T_max (2.00 h) and AUC_0-T (459.32 mg/L*h) of GL. Moreover, GAMG had wider and higher tissue distribution in the kidney, spleen, live, lung, brain, etc. These results indicated that oral GAMG can be rapidly and efficiently absorbed and be widely distributed in tissues to exert stronger and multiple pharmacological activities. This provided a physiological basis for guiding the pharmacodynamic study and clinical applications of GAMG.

Synthesis and In Vitro Study of Antiviral Activity of Glycyrrhizin Nicotinate Derivatives against HIV-1 Pseudoviruses and SARS-CoV-2 Viruses

When developing drugs against SARS-CoV-2, it is important to consider the characteristics of patients with different co-morbidities. People infected with HIV-1 are a particularly vulnerable group, as they may be at a higher risk than the general population of contracting COVID-19 with clinical complications. For such patients, drugs with a broad spectrum of antiviral activity are of paramount importance. Glycyrrhizinic acid (Glyc) and its derivatives are promising biologically active compounds for the development of such broad-spectrum antiviral agents. In this work, derivatives of Glyc obtained by acylation with nicotinic acid were investigated. The resulting preparation, Glycyvir, is a multi-component mixture containing mainly mono-, di-, tri- and tetranicotinates. The composition of Glycyvir was characterized by HPLC-MS/MS and its toxicity assessed in cell culture. Antiviral activity against three strains of SARS-CoV-2 was tested in vitro on Vero E6 cells by MTT assay. Glycyvir was shown to inhibit SARS-CoV-2 replication in vitro (IC502-8 μM) with an antiviral activity comparable to the control drug Remdesivir. In addition, Glycyvir exhibited marked inhibitory activity against HIV pseudoviruses of subtypes B, A6 and the recombinant form CRF63_02A (IC50 range 3.9-27.5 µM). The time-dependence of Glycyvir inhibitory activity on HIV pseudovirus infection of TZM-bl cells suggested that the compound interfered with virus entry into the target cell. Glycyvir is a promising candidate as an agent with low toxicity and a broad spectrum of antiviral action.

Development of a xylosyltransferase-I-selective UPLC MS/MS activity assay using a specific acceptor peptide

Xylosyltransferases-I and -II (XT-I and -II) play an important role regarding the homeostasis of the extracellular matrix. Both enzymes catalyze the initial step of the proteoglycan (PG) biosynthesis by the transfer of xylose from their natural substrate uridine diphosphate (UDP) -xylose to a PG-core protein. The subsequent addition of further sugars, catalyzed by different glycosyltransferases, leads to the formation of a tetrasaccharide linker, which connects the PG-core protein and glycosaminoglycans. The reason for the appearance of two XT isoforms in all higher organisms is not known and remarkable, as both enzymes are able to initiate PG biosynthesis. The determination of the XT-I activity is of clinical importance because it can be used as a biomarker of several PG-associated fibrotic diseases. Since previous assays did not adequately differentiate between both XT-isoforms, the aim of this study was to develop an XT-I selective mass spectrometric (MS) assay. For this purpose, we initially used isoform-specific supernatants to successfully identify a synthetic acceptor peptide which was xylosylated much more selectively by the XT-I when compared to the XT-II isoform. The assay was further optimized concerning methodical parameters such as the injection volume and the incubation time of the reaction-mixture. By using samples covering a broad XT-activity spectrum, we successfully validated the assay to be used not only for the quantification of cell culture samples but also human serum specimens. Compared to previously used XT-activity assays, our newly developed test is more selective and sensitive, less expensive and easier to perform in high throughput.

Natural Products as Modulators of CES1 Activity

Carboxylesterase (CES) 1 is the predominant esterase expressed in the human liver and is capable of catalyzing the hydrolysis of a wide range of therapeutic agents, toxins, and endogenous compounds. Accumulating studies have demonstrated associations between the expression and activity of CES1 and the pharmacokinetics and/or pharmacodynamics of CES1 substrate medications (e.g., methylphenidate, clopidogrel, oseltamivir). Therefore, any perturbation of CES1 by coingested xenobiotics could potentially compromise treatment. Natural products are known to alter drug disposition by modulating cytochrome P450 and UDP-glucuronosyltransferase enzymes, but this issue is less thoroughly explored with CES1. We report the results of a systematic literature search and discuss natural products as potential modulators of CES1 activity. The majority of research reports reviewed were in vitro investigations that require further confirmation through clinical study. Cannabis products (Δ ⁹-tetrahydrocannabinol, cannabidiol, cannabinol); supplements from various plant sources containing naringenin, quercetin, luteolin, oleanolic acid, and asiatic acid; and certain traditional medicines (danshen and zhizhuwan) appear to pose the highest inhibition potential. In addition, ursolic acid, gambogic acid, and glycyrrhetic acid, if delivered intravenously, may attain high enough systemic concentrations to significantly inhibit CES1. The provision of a translational interpretation of in vitro assessments of natural product actions and interactions is limited by the dearth of basic pharmacokinetic data of the natural compounds exhibiting potent in vitro influences on CES1 activity. This is a major impediment to assigning even potential clinical significance. The modulatory effects on CES1 expression after chronic exposure to natural products warrants further investigation. SIGNIFICANCE STATEMENT: Modulation of CES1 activity by natural products may alter the course of treatment and clinical outcome. In this review, we have summarized the natural products that can potentially interact with CES1 substrate medications. We have also noted the limitations of existing reports and outlined challenges and future directions in this field.

Glycyrrhizin: An alternative drug for the treatment of COVID-19 infection and the associated respiratory syndrome?

Safe and efficient drugs to combat the current COVID-19 pandemic are urgently needed. In this context, we have analyzed the anti-coronavirus potential of the natural product glycyrrhizic acid (GLR), a drug used to treat liver diseases (including viral hepatitis) and specific cutaneous inflammation (such as atopic dermatitis) in some countries. The properties of GLR and its primary active metabolite glycyrrhetinic acid are presented and discussed. GLR has shown activities against different viruses, including SARS-associated Human and animal coronaviruses. GLR is a non-hemolytic saponin and a potent immuno-active anti-inflammatory agent which displays both cytoplasmic and membrane effects. At the membrane level, GLR induces cholesterol-dependent disorganization of lipid rafts which are important for the entry of coronavirus into cells. At the intracellular and circulating levels, GLR can trap the high mobility group box 1 protein and thus blocks the alarmin functions of HMGB1. We used molecular docking to characterize further and discuss both the cholesterol- and HMG box-binding functions of GLR. The membrane and cytoplasmic effects of GLR, coupled with its long-established medical use as a relatively safe drug, make GLR a good candidate to be tested against the SARS-CoV-2 coronavirus, alone and in combination with other drugs. The rational supporting combinations with (hydroxy)chloroquine and tenofovir (two drugs active against SARS-CoV-2) is also discussed. Based on this analysis, we conclude that GLR should be further considered and rapidly evaluated for the treatment of patients with COVID-19.

A simple method for evaluation pharmacokinetics of glycyrrhetinic acid and potential drug-drug interaction between herbal ingredients

A simple validated high performance liquid chromatography method was developed for the evaluation of the effect of three kinds of active ingredients in traditional Chinese medicine (TCM) on the pharmacokinetics of glycyrrhetinic acid (GA),a kind of active component from the most commonly used TCM licorice. Our results revealed that all of the calibration curves displayed good linearity. Intra- and inter-day precision for GA ranged from 2.54 to 3.98% and from 4.95 to 7.08%, respectively. The recovery rates for GA were determined to be 96.3–106.4%. All the samples showed satisfactory precision and accuracy in various stability tests. Plasma pharmacokinetic parameters including area under the concentration-time curve (AUC), elimination half-life (t_1/2), time to peak concentration(T_max) and peak concentration C_max were calculated. No significant difference was found as compared the groups administrating GA with and without other ingredients from TCM.

Selective and competitive inhibition of kynurenine aminotransferase 2 by glycyrrhizic acid and its analogues

The enzyme kynurenine aminotransferase (KAT) catalyses the conversion of kynurenine (KYN) to kynurenic acid (KYNA). Although the isozymes KAT1–4 have been identified, KYNA is mainly produced by KAT2 in brain tissues. KNYA is an antagonist of N-methyl-D-aspartate and α-7-nicotinic acetylcholine receptors, and accumulation of KYNA in the brain has been associated with the pathology of schizophrenia. Therefore, KAT2 could be exploited as a therapeutic target for the management of schizophrenia. Although currently available KAT2 inhibitors irreversibly bind to pyridoxal 5′-phosphate (PLP), inhibition via this mechanism may cause adverse side effects because of the presence of other PLP-dependent enzymes. Therefore, we identified novel selective KAT2 inhibitors by screening approximately 13,000 molecules. Among these, glycyrrhizic acid (GL) and its analogues, glycyrrhetinic acid (GA) and carbenoxolone (CBX), were identified as KAT2 inhibitors. These compounds were highly selective for KAT2 and competed with its substrate KYN, but had no effects on the other 3 KAT isozymes. Furthermore, we demonstrated that in complex structures that were predicted in docking calculations, GL, GA and CBX were located on the same surface as the aromatic ring of KYN. These results indicate that GL and its analogues are highly selective and competitive inhibitors of KAT2.

Validation of an LC-MS/MS method for simultaneous detection of diverse components of Qinxing Qingre Zhike Granule in rat plasma and its application to pharmacokinetic study after oral administration to rats

A sensitive and validated method of liquid chromatography-tandem mass spectrometry (LC-MS/MS) was established to test the plasma concentrations of active ingredients in Qinxing Qingre Zhike Granule, namely geniposide, liquiritin, isoliquiritin, baicalin, wogonoside, baicalein, liquiritigenin, isoliquiritigenin and glycyrrhetinic acid. The analysis was performed on an Ultimate XB-C₁₈ column at the flow rate of 0.4 mL min^-1 in a single run of 18 min. The mobile phase was composed of 0.05% formic acid in water and acetonitrile with gradient elution. Positive and negative scanning and selected multiple reaction monitoring modes were applied for quantization. The proposed method showed good linearity in the given ranges from 0.6800-340.0 to 3.920-1960 ng mL^-1 with r²  > 0.9917 for all the analytes. The precision (RSD) was no more than 12%, and the accuracy (RE) was less than ±11% for intra- and inter-day. The extract recovery and matrix effect were acceptable for the requirements of biological sample analysis. Moreover, the developed method was effectively applied to the pharmacokinetic investigation of Qinxing Qingre Zhike Granule after oral administration in rats.