Antimicrobial agents from higher plants. Antimicrobial isoflavanoids and related substances from Glycyrrhiza glabra L. var. typica

Antibacterial phenolic compounds from the flowering plants of Asia and the Pacific: coming to the light

CONTEXT

The emergence of pan-resistant bacteria requires the development of new antibiotics and antibiotic potentiators.

OBJECTIVE

This review identifies antibacterial phenolic compounds that have been identified in Asian and Pacific Angiosperms from 1945 to 2023 and analyzes their strengths and spectra of activity, distributions, molecular masses, solubilities, modes of action, structures-activities, as well as their synergistic effects with antibiotics, toxicities, and clinical potential.

METHODS

All data in this review was compiled from Google Scholar, PubMed, Science Direct, Web of Science, and library search; other sources were excluded. We used the following combination of keywords: 'Phenolic compound', 'Plants', and 'Antibacterial'. This produced 736 results. Each result was examined and articles that did not contain information relevant to the topic or coming from non-peer-reviewed journals were excluded. Each of the remaining 467 selected articles was read critically for the information that it contained.

RESULTS

Out of ∼350 antibacterial phenolic compounds identified, 44 were very strongly active, mainly targeting the cytoplasmic membrane of Gram-positive bacteria, and with a molecular mass between 200 and 400 g/mol. 2-Methoxy-7-methyljuglone, [6]-gingerol, anacardic acid, baicalin, vitexin, and malabaricone A and B have the potential to be developed as antibacterial leads.

CONCLUSIONS

Angiosperms from Asia and the Pacific provide a rich source of natural products with the potential to be developed as leads for treating bacterial infections.

Natural products - Dawn of keloid treatment

Keloids are prevalent pathological scars, often leading to cosmetic deformities and hindering joint mobility.They cause discomfort, including burning and itching, while gradually expanding and potentially posing a risk of cancer.Developing effective drugs and treatments for keloids has been a persistent challenge in the medical field. Natural products are an important source of innovative drugs and a breakthrough for many knotty disease.Herein, keywords of "natural, plant, compound, extract" were combined with "keloid" and searched in PubMed and Google Scholar, respectively. A total of 32 natural products as well as 9 extracts possessing the potential for treating keloids were ultimately identified.Current research in this field faces a significant challenge due to the lack of suitable animal models, resulting in a predominant reliance on in vitro studies.In vivo and clinical studies are notably scarce as a result.Moreover, there is a notable deficiency in research focusing on the role of nutrients in keloid formation and treatment.The appropriate dosage form (oral, topical, injectable) is crucial for the development of natural product drugs. Finally, the conclusion was hereby made that natural products, when used as adjuncts to other treatments, hold significant potential in the management of keloids.By summarizing the natural products and elucidating their mechanisms in keloid treatment, the present study aims to stimulate further discoveries and research in drug development for effectively addressing this challenging condition.

Qualitative and Quantitative Analysis of Chemical Components in Yinhua Pinggan Granule with High-Performance Liquid Chromatography Coupled with Q-Exactive Mass Spectrometry

Yinhua Pinggan Granule (YPG) is an approved compounded traditional Chinese medicine (TCM) prescription for the treatment of cold, cough, viral pneumonia, and related diseases. Due to its complicated chemical composition, the material basis of YPG has not been systematically investigated. In this study, an analytical method based on high-performance liquid chromatography (HPLC) coupled with Q-Exactive mass spectrometry was established. Together with the help of a self-built compound database and Compound Discoverer software 3.1, the chemical components in YPG were tentatively identified. Subsequently, six main components in YPG were quantitatively characterized with a high-performance liquid chromatography-diode array detector (HPLC-DAD) method. As a result, 380 components were annotated, including 19 alkaloids, 8 organic acids, 36 phenolic acids, 27 other phenols, 114 flavonoids, 75 flavonoid glycoside, 72 terpenes, 11 anthraquinones, and 18 other compounds. Six main components, namely, chlorogenic acid, puerarin, 3'-methoxypuerarin, polydatin, glycyrrhizic acid, and emodin, were quantified simultaneously. The calibration curves of all six analytes showed good linearity (R2 > 0.9990) within the test ranges. The precision, repeatability, stability, and recovery values were all in acceptable ranges. In addition, the total phenol content and DPPH scavenging activity of YPG were also determined. The systematic elucidation of the chemical components in YPG in this study may provide clear chemical information for the quality control and pharmacological research of YPG and related TCM compounded prescriptions.

MAO inhibiting phytochemicals from the roots of Glycyrrhiza glabra L

Glycyrrhizin, a natural compound that is substantially present in Glycyrrhiza glabra L. (Gg) root. Monoamine oxidase B (MAOB) inhibitor is used for the treatment of several important neuropsychological diseases like Parkinson's disease. Gg is known to possess psychoactive properties which relates to its MAO inhibitory potential. This study sought to determine the MAO inhibition property of glycyrrhizin from Gg root extract. The Aqueous extract containing glycyrrhizin was isolated from the root of Gg and characterized using TLC, HPLC, and LC-MS techniques. In silico docking was conducted using Extra precision Glide 2018, Schrödinger docking suite. In addition, the pharmacokinetic properties of the compounds were predicted using SwissADME. The binding energies of the glycyrrhizin correlated well with their in vitro MAO inhibitory potential. Glycyrrhizin exhibited potent inhibitory activity towards MAOB whereas, an aqueous extract of Gg root inhibits both A and B forms of MAO enzyme. Further, molecular docking and molecular dynamics simulation showed that liquiritigenin and methoxyglabridin showed higher stability than other inhibitor compounds from the Gg root extract. These observations suggest that the phytochemicals from the Gg root extract have potent MAO inhibition properties, which can be exploited for the treatment of neurodegenerative disorders.Communicated by Ramaswamy H. Sarma.

Natural isoflavone glabridin targets PI3Kγ as an adjuvant to increase the sensitivity of MDA-MB-231 to tamoxifen and DU145 to paclitaxel

Glabridin is a natural isoflavone with estrogen receptor agonism and significant anti-tumor activity. Additionally, glabridin has a regulation effect on PI3K/AKT/mTOR pathway, but its exact target remains unclear. In this study, we evaluated the antitumor activity of glabridin against breast cancer and prostate cancer cells, and further clarified its targeting to PI3K. We found that glabridin could significantly inhibit the cell viability of human breast cancer and prostate cancer cell lines. It induced caspase activation cascade and cell apoptosis through decreasing the mitochondrial transmembrane potential and increasing the intracellular reactive oxygen species (ROS). Moreover, glabridin could attenuate epithelial-mesenchymal transition (EMT) progression by inhibiting cell migration. PharmMapper calculation showed that PI3Kγ might be the most potential target protein because of the highest Normal Fit score (0.9735) and z'-score (0.9797). Molecular docking and bio-layer interferometry (BLI) analysis further demonstrated the PI3Kγ targeting of glabridin. In vivo experiments showed that glabridin can effectively inhibit the tumor growth of breast cancer xenograft model, and does not show obvious hepatorenal toxicity. Moreover, glabridin could effectively promote the anti-proliferation and pro-apoptotic effects of tamoxifen on MDA-MB-231 cell and taxol on DU145 cell. Elucidating the targeting of glabridin to PI3K may lay a theoretical foundation for the structural derivatization of glabridin, which is expected to greatly promote the application and development of glabridin in the field of cancer therapy.

A virtual screening investigation to identify bioactive natural compounds as potential inhibitors of cyclin-dependent kinase 9

Cyclin-dependent kinase 9 (CDK9) is a transcription-associated protein involved in controlling the cell cycle and is often deregulated in stress conditions. CDK9 is being studied as a well-known druggable target for developing effective therapeutics against a wide range of cancer, cardiac dysfunction and inflammatory diseases. Owing to the significance of CDK9 in the etiology of hematological and solid malignancies, its structure, biological activity, regulation and its pharmacological inhibition are being explored for therapeutic management of cancer. We employed a structure-based virtual high-throughput screening of bioactive compounds from the IMPPAT database to discover potential bioactive inhibitors of CDK9. The preliminary results were obtained from the Lipinski criteria, ADMET parameters and sorting compounds without any PAINS patterns. Subsequently, binding affinity and selectivity analyses were used to find effective CDK9 hits. This screening resulted in the identification of two natural compounds, Glabrene and Guggulsterone with high affinity and specificity for the CDK9 binding site. Both compounds exhibit drug-like characteristics, as projected by ADMET analysis, physicochemical data and PASS evaluation. Both compounds preferentially bind to the ATP-binding pocket of CDK9 and interact with functionally important residues. Further, the dynamics and consistency of CDK9 interaction with Glabrene and Guggulsteron were evaluated through all-atom molecular dynamic (MD) simulations which suggested the stability of both complexes. The results might be deployed to introduce novel CDK9 inhibitors that may treat life-threatening diseases, including cancer.Communicated by Ramaswamy H. Sarma.

4-Dimethylaminopyridine (DMAP), A Superior Mediator for Morita-Balylis-Hillman Reaction-Triggered Annulative Condensation of Salicylaldehydes and Acrylonitrile to Form 3-Cyano-2H-chromenes

We unveiled superior base mediators for the annulative condensation of salicylaldehydes and acrylonitrile to give 3-cyano-2H-chromenes, which has been mediated only by 1,4-diazabicyclo[2.2.2]octane (DABCO) over the past two decades. The reactions were most efficiently mediated by 4-dimethylaminopyridine (DMAP), which yielded 3-cyano-2H-chromenes in higher yields than DABCO in most cases. We also confirmed that the reaction remained high yielding in a decagram-scale experiment with a catalytic amount of DMAP. The utility of this reaction was also exemplified by derivatization of an obtained 3-cyano-2H-chromene into a known 2H-chromene-3-carboxylic acid, which was previously synthesized with a non-readily available reagent.

Computational Tools to Expedite the Identification of Potential PXR Modulators in Complex Natural Product Mixtures: A Case Study with Five Closely Related Licorice Species

The genus Glycyrrhiza, comprising approximately 36 spp., possesses complex structural diversity and is documented to possess a wide spectrum of biological activities. Understanding and finding the mechanisms of efficacy or safety for a plant-based therapy is very challenging, yet it is crucial and necessary to understand the polypharmacology of traditional medicines. Licorice extract was shown to modulate the xenobiotic receptors, which might manifest as a potential route for natural product-induced drug interactions. However, different mechanisms could be involved in this phenomenon. Since the induced herb-drug interaction of licorice supplements via Pregnane X receptor (PXR) is understudied, we ventured out to analyze the potential modulators of PXR in complex mixtures such as whole extracts by applying computational mining tools. A total of 518 structures from five species of Glycyrrhiza: 183 (G. glabra), 180 (G. uralensis), 100 (G. inflata), 33 (G. echinata), and 22 (G. lepidota) were collected and post-processed to yield 387 unique compounds. Visual inspection of top candidates with favorable ligand-PXR interactions and the highest docking scores were identified. The in vitro testing revealed that glabridin (GG-14) is the most potent PXR activator among the tested compounds, followed by licoisoflavone A, licoisoflavanone, and glycycoumarin. A 200 ns molecular dynamics study with glabridin confirmed the stability of the glabridin-PXR complex, highlighting the importance of computational methods for rapid dereplication of potential xenobiotic modulators in a complex mixture instead of undertaking time-consuming classical biological testing of all compounds in a given botanical.

Glycyrrhiza glabra (Licorice): A Comprehensive Review on Its Phytochemistry, Biological Activities, Clinical Evidence and Toxicology

There are more than 30 species of Glycyrrhiza genus extensively spread worldwide. It was the most prescribed herb in Ancient Egyptian, Roman, Greek, East China, and the West from the Former Han era. There are various beneficial effects of licorice root extracts, such as treating throat infections, tuberculosis, respiratory, liver diseases, antibacterial, anti-inflammatory, and immunodeficiency. On the other hand, traditional medicines are getting the attraction to treat many diseases. Therefore, it is vital to screen the medicinal plants to find the potential of new compounds to treat chronic diseases such as respiratory, cardiovascular, anticancer, hepatoprotective, etc. This work comprehensively reviews ethnopharmacological uses, phytochemistry, biological activities, clinical evidence, and the toxicology of licorice, which will serve as a resource for future clinical and fundamental studies. An attempt has been made to establish the pharmacological effect of licorice in different diseases. In addition, the focus of this review article is on the molecular mechanism of licorice extracts and their four flavonoids (isoliquiritigenin, liquiritigenin, lichalocone, and glabridin) pharmacologic activities. Licorice could be a natural alternative for current therapy to exterminate new emerging disorders with mild side effects. This review will provide systematic insights into this ancient drug for further development and clinical use.

Biologically guided isolation and ADMET profile of new factor Xa inhibitors from Glycyrrhiza glabra roots using in vitro and in silico approaches

Selective factor Xa inhibitors effectively block coagulation cascade with a broader therapeutic window than multitargeted anticoagulants. They have evolved as a crucial part of prevention and treatment of thromboembolic diseases and in therapeutic protocols involved in many clinical trials in coronavirus disease 2019 (COVID-19) patients. Biologically-guided isolation of specific FXa inhibitors from licorice (Glycyrrhiza glabra) root extract furnished ten flavonoids. By detailed analysis of their 1H, 13C NMR and MS data, the structures of these flavonoids were established as 7,4'-dihydroxyflavone (1), formononetin (2), 3-R-glabridin (3), isoliquiritigenin (4), liquiritin (5), naringenin 5-O-glucoside (6), 3,3',4,4'-tetrahydroxy-2-methoxychalcone (7), liquiritinapioside (8) and the two isomers isoliquiritigenin-4'-O-β-d-apiosylglucoside (9) and isoliquiritigenin-4-O-β-d-apiosylglucoside (10). All the isolated compounds were assessed for their FXa inhibitory activity using in vitro chromogenic assay for the first time. Liquirtin (5) showed the most potent inhibitory effects with an IC50 of 5.15 μM. The QikProp module was implemented to perform ADMET predictions for the screened compounds.

Glycyrrhiza glabra L. (Fabaceae/Leguminosae)

Liquorice is a perennial, temperate-zone herb or subshrub, native of India, Pakistan and southern Europe; also cultivated in England, Belgium, France, Germany, Spain, Italy, Greece, Turkey, Russia, South Africa, Egypt, Syria and Iraq. It has also been grown experimentally in the United States. Ancient historical manuscripts from China, India and Greece mention its use for symptoms of viral respiratory tract infections and hepatitis. The plant has also been described by Theophrastus. Licorice from Egypt has been described to be the best, followed by from Iraq and Syria; the root should be decorticated before use. It concocts viscid humours in diseases of liver, bladder and lungs, and expectorates them. It has been used in Iranian herbal medicine for skin eruptions, including dermatitis, eczema, pruritus and cysts, and for treatment of stomach disorders including peptic ulcers. The herb extract inhibits gastric motility in vivo, which is regarded to be an important aspect for its antiulcer activity. Licorice possesses both anti-inflammatory and antiulcer activities; whereas most anti-inflammatory agents are ulcerogenic. Former German Commission E believed it to be effective in the treatment of atopic dermatitis. Licorice root has been used for years to regulate gastrointestinal function in TCM, has been used for generations as an antidote, demulcent, and elixir in folk medicine of China, and is the most commonly used crude drug in Kampo Medicines, the Japanese form of modified TCM, for the treatment of peptic ulcer. Roots contain glycyrrhizin, the main water-soluble constituent that is 50× sweeter than sugar, 2-β-glucuronosyl glucuronic acid, and isoliquiritigenin-4-glucoside. Glycyrrhizin is a nonhemolytic saponin with foaming property, and one of the most potent hydroxyl radical scavengers. No significant effect of deglycyrrhizinised liquorice was observed on gastric ulcer in an RCT of British patients. Treatment of healthy men with licorice for one-week decreased salivary testosterone values by 26% but no significant decrease in free testosterone, and nine healthy women treated with licorice daily for two cycles, had their mean total serum testosterone decreased by 37% at the end of 2nd month. This property could be useful as an adjunct therapy of hirsutism and PCOS.

In vitro antiproliferative activity of glabridin derivatives and their in silico target identification

Novel Mannich base derivatives of glabridin were synthesized and their antiproliferative activity were performed along with our previously reported glabridin-chalcone hybrids molecules (GCHMs) against various human cell lines MDA-MB-231 (breast adenocarcinoma), HEK-293 (embryonic kidney cell line), K562 (leukemia), MCF-7 (breast adenocarcinoma), HeLa (cervix adenocarcinoma), HepG2 (hepatocellular carcinoma) and WRL-68 (hepatic carcinoma). The result showed that the glabridin significantly reduced cell proliferation with IC₅₀ ranges from 3.67 to 58.30 µM against all the tested cell lines. The remarkable reduction in antiproliferative activity 2',4'-dimethoxyglabridin and GCHMs compounds with phenolic OH groups protected by methoxy (OCH₃) groups suggested that the free OH groups are essential factor for the antiproliferative activity of glabridin and its derivatives. The Mannich base derivatives of glabridin showed moderate activity IC₅₀ (2.20->95.78 µM). Furthermore, in silico target identification analysis revealed that AKT1, DECR1 and NOS1 are the potential targets for glabridin and their derivatives.

Glycyrrhiza glabra: Chemistry and Pharmacological Activity

Nature is an attractive source of new therapeutic candidate compounds as a tremendous chemical diversity is found in millions of species of plants, animals, marine organisms, and microorganisms as potential medicinal agents. This chapter of research is an effort to highlight the phytochemical/chemical constituents of an ancient medicinal plant G. glabra and their pharmacological importance. G. glabra is an old age medicinal plant that belongs to Leguminosae/Fabaceae/Papilionaceae family and commonly known as mulaithi in north India. The chemical composition of G. glabra is glycyrrhizin, glycyrrhetic acid, isoliquiritin, isoflavones, etc., and their derivatives have been reported for several pharmacological activities like, expectorant, antidemulcent, antiulcer, anticancer, anti-inflammatory, antidiabetic, etc. These phytochemicals hold strong promise for designing new herbal drugs, and derivatives of these compounds are being generated to evaluate their pharmacological purposes for future drug use. Natural products have been a prime source for the treatment of many forms of ailments, many of which are consumed daily with the diet. They provide significant protection against various diseases and disorders.

Discovery of anti-microbial and anti-tubercular molecules from Fusarium solani: an endophyte of Glycyrrhiza glabra

AIMS

Glycyrrhiza glabra is a high-value medicinal plant thriving in biodiversity rich Kashmir Himalaya. The present study was designed to explore the fungal endophytes from G. glabra as a source of bioactive molecules.

METHODS AND RESULTS

The extracts prepared from the isolated endophytes were evaluated for anti-microbial activities using broth micro-dilution assay. The endophytic strain coded as A2 exhibiting promising anti-bacterial as well as anti-tuberculosis activity was identified as Fusarium solani by ITS-5.8S ribosomal gene sequencing technique. This strain was subjected to large-scale fermentation followed by isolation of its bioactive compounds using column chromatography. From the results of spectral data analysis and comparison with literature, the molecules were identified as 3,6,9-trihydroxy-7-methoxy-4,4-dimethyl-3,4-dihydro-1H-benzo[g]isochromene-5,10-dione (1), fusarubin (2), 3-O-methylfusarubin (3) and javanicin (4). Compound 1 is reported for the first time from this strain. All the four compounds inhibited the growth of various tested bacterial strains with MIC values in the range of <1 to 256 μg ml^-1 . Fusarubin showed good activity against Mycobacterium tuberculosis strain H37Rv with MIC value of 8 μg ml^-1 , whereas compounds 1, 3 and 4 exhibited moderate activity with MIC values of 256, 64, 32 μg ml^-1 , respectively.

CONCLUSIONS

To the best of our knowledge, this is the first study that reports significant anti-tuberculosis potential of bioactive molecules from endophytic F. solani evaluated against the virulent strain of M. tuberculosis. This study sets background towards their synthetic intervention for activity enhancement experiments in anti-microbial drug discovery programme.

SIGNIFICANCE AND IMPACT OF THE STUDY

Due to the chemoprofile variation of same endophyte with respect to source plant and ecoregions, further studies are required to explore endophytes of medicinal plants of all unusual biodiversity rich ecoregions for important and or novel bioactive molecules.

Application of Mixture Analysis to Crude Materials from Natural Resources (V) [1]: Discrimination of Glycyrrhiza uralensis and G. glabra by EI mass spectrometry

The roots and stolons of some Glycyrrhiza species are used worldwide for traditional folk medicines and commercial pharmaceuticals. Phenolic constituents such as flavonoids and coumarins are medicinal and vary according to species. Therefore, species identification is important for quality analysis. In order to identify Glycyrrhiza species by chemical fingerprinting, methanol extracts of the root bark of Glycyrrhiza uralensis Fischer and G. glabra Linné were analyzed using EI-MS. Differences in kinds and quantity of components are reflected in complex EI-MS data and determining characteristic peaks for each species is straightforward. The characteristic peaks were determined statistically by volcano plot, a multivariate analysis method. EI-MS data of G. uralensis and G. glabra showed differential patterns, and the notable peaks in each pattern were identified. Peaks at m/z 153 and 221 are signature peaks of G. uralensis, and at m/z 173, 309, and 324 are those of G. glabra. In conclusion, we found species-specific patterns by EI-MS that distinguish G. uralensis and G. glabra. This method based on chemical constituent patterns can be applied to identify other Glycyrrhiza species and similar natural products.

Pharmacological Activities and Phytochemical Constituents

Glycyrrhiza glabra is one of the most popular medicinal plants and it has been used in traditional herbal remedy since ancient times (Blumenthal et al. in Herbal medicine: expanded commission E monographs. Integrative Medicine Communications, Newton, 2000; Parvaiz et al. in Global J Pharmocol 8(1):8–13, 2014; Altay et al. in J Plant Res 129(6):1021–1032, 2016). Many experimental, pharmacological and clinical studies show that liquorice has antimicrobial, antibacterial, antiviral, antifungal, antihepatotoxic, antioxidant, antiulcer, anti-hemorrhoid antihyperglycemic, antidiuretic, antinephritic, anticarcinogenic, antimutagenic, anticytotoxic, anti-inflammatory, and blood stopper activity.

Glabridin-chalcone hybrid molecules: drug resistance reversal agent against clinical isolates of methicillin-resistant Staphylococcus aureus

16 folds reduction in MICs with norfloxacin against various clinical isolates of MRSA (FICI range from 0.312–0.375).

Glycyrrhiza glabra

Liquorice foliage

Cardiovascular protective effect of glabridin: Implications in LDL oxidation and inflammation

Atherosclerosis is one of the most common causes of death in Western countries and now considered as a chronic inflammatory disease in broad outline. Glaridin, a flavonoid isolated from licorice root, has been shown to exert a variety of biological activities, including antimicrobial, antioxidant, anti-inflammatory and cardiovascular protective effects. Among these, the most extensive research area in the past two decades was a cardiovascular protection-related activity of glabridin. The protective effect of glabridin on LDL oxidation, which is one of the important processes involved in the development of atherosclerosis, was demonstrated in vitro and in vivo and the mechanisms involved in this process were established well. Structure-activity relationship of glabridin derivatives on LDL oxidation was also reported. In addition, the inhibitory effects of glabridin on early inflammatory processes, including the expression of adhesion molecules on endothelial cells and the activation of macrophages and dendritic cells, were also demonstrated previously. In this review, we summarized the cardiovascular protection-related activities of glabridin and the mechanism of action involved in these activities. Collectively, it is hoped that glabridin or glabridin derivatives might be used as a therapeutic agent for the treatment of cardiovascular diseases in the future.

A polyphenolic flavonoid glabridin: Oxidative stress response in multidrug-resistant Staphylococcus aureus

Glabridin a polyphenolic flavonoid from Glycyrrhiza glabra is known to possess several therapeutic properties. In the present study, we report for the first time the in vitro antibacterial activity (MIC values ranging from 3.12 to 25 μg/mL) of glabridin against multidrug-resistant clinical isolates of S. aureus by inducing oxidative stress. Increased levels of H2O2 and NO were observed in a dose-dependent manner after treatment of glabridin that further affected macromolecules such as DNA, lipids, and proteins. Surprisingly, glabridin was found to possess antioxidant properties when used at lower concentrations using three different methods including DPPH, FRAP, and SOD assays. These observations were further validated through the expression analysis of oxidative stress-responsive genes using qRT-PCR wherein glabridin was observed to up- and down-regulate these genes at lower and higher concentrations, respectively. In in vitro combination experiments, glabridin was found to reduce the MIC of different antibiotics such as norfloxacin, oxacillin, and vancomycin by up to 4-fold, while the MIC of glabridin itself was found to be reduced by up to 8-fold in the presence of antibiotics. A synergistic interaction was observed between norfloxacin and glabridin when used in combination against multidrug-resistant clinical isolate SA 4627 of Staphylococcus aureus at much lower concentrations, indicating the suitability of glabridin in combination therapy.

Antimicrobial and antiinsectan phenolic metabolites of Dalea searlsiae

Continued interest in the chemistry of Dalea spp. led to investigation of Dalea searlsiae, a plant native to areas of the western United States. Methanol extractions of D. searlsiae roots and subsequent chromatographic fractionation afforded the new prenylated and geranylated flavanones malheurans A-D (1-4) and known flavanones (5 and 6). Known rotenoids (7 and 8) and isoflavones (9 and 10) were isolated from aerial portions. Structure determination of pure compounds was accomplished primarily by extensive 1D- and 2D-NMR spectroscopy. The absolute configurations of compounds 1-5, 7, and 8 were assigned using electronic circular dichroism spectroscopy. Antimicrobial bioassays revealed significant activity concentrated in the plant roots. Compounds 1-6 exhibited MICs of 2-8 μg/mL against Streptococcus mutans, Bacillus cereus, and oxacillin-sensitive and -resistant Staphylococcus aureus. Aerial metabolites 7-10 were inactive against these organisms, but the presence of 7 and 8 prompted investigation of the antiinsectan activity of D. searlsiae metabolites toward the major crop pest Spodoptera frugiperda (fall armyworm). While compounds 1-10 all caused significant reductions in larval growth rates, associated mortality (33-66%) was highest with flavanone 4 and rotenoids 7 and 8. These findings suggest a differential allocation of antimicrobial and antiinsectan plant resources to root and aerial portions of the plant, respectively.

Bioactivity and potential health benefits of licorice

Licorice is an herbal plant named for its unique sweet flavor. It is widely used in the food and tobacco industries as a sweetener. Licorice is also used in traditional Chinese medicine (TCM) and complementary medicine. Because the use of licorice has long been a part of TCM, the details of its therapeutic applications have been thoroughly established. In modern science, licorice is of interest because of its broad range of applications. Extracts of and compounds isolated from licorice have been well studied and biologically characterized. In this review, we discuss the nutraceutical and functional activities of licorice as well as those of the extracts of and the isolated compounds from licorice, including agents with anti-inflammatory activity, cell-protective abilities, and chemopreventive effects. The side effects of licorice are also enumerated. A comparison of the activities of licorice described by modern science and TCM is also presented, revealing the correspondence of certain characteristics.

Phytochemistry and biological properties of glabridin

Glabridin, a prenylated isoflavonoid of G. glabra L. roots (European licorice, Fabaceae), has been associated with a wide range of biological properties such as antioxidant, anti-inflammatory, anti-atherogenic, regulation of energy metabolism, estrogenic, neuroprotective, anti-osteoporotic, and skin-whitening. While glabridin is one of the most studied licorice flavonoids, a comprehensive literature survey linked to its numerous bioactivities is unavailable. The present review provides a comprehensive description of glabridin as a key chemical and biological marker of G. glabra, by covering both its phytochemical characterization and reported biological activities. Both glabridin and standardized licorice extracts have significant impact on food, dietary supplements (DSs) and cosmetic markets, as evidenced by the amount of available patents and scientific articles since 1976, when glabridin was first described. Nevertheless, a thorough literature survey also reveals that information about the isolation and chemical characterization of this important marker is scattered and less detailed than expected. Accordingly, the first part of this review gathers and provides all analytical and spectroscopic data required for the comprehensive phytochemical characterization of glabridin. The four most frequently described and most relevant bioactivities of glabridin are its anti-inflammatory, anti-atherogenic, estrogenic-like effects, and its capacity to regulate energy metabolism. While all bioactivities reported for glabridin belong to a wide array of targets, its principal biological properties are likely interconnected. To this end, the current state of the literature suggests that the biological activity of glabridin mainly results from its capacity to down-regulate intracellular reactive oxygen species, bind to antioxidant effectors, and act on estrogen receptors, potentially as a plant-based Selective Estrogen Receptor Modulator (phytoSERM).

A practical access to highly enantiomerically pure flavanones by catalytic asymmetric transfer hydrogenation

A surprisingly selective, non-enzymatic kinetic resolution of readily available, racemic β-chiral ketones enabled the title process, which was applied to a rapid synthesis of several bioactive flavanones in virtually enantiopure form (see scheme; MOM=methoxymethyl, Ts=p-toluenesulfonyl).

The anti-inflammatory effects of sanguinarine and its modulation of inflammatory mediators from peritoneal macrophages

The quaternary ammonium salt, sanguinarine (SANG), is of great practical and research interest because of its pronounced, widespread physiological effects, which promote anti-microbial and anti-inflammatory responses in experimental animals. Sanguinarine was originally shown to possess anti-inflammatory properties and it has been used to treat various inflammatory diseases. To gain insight into the anti-inflammatory effect of sanguinarine and its mechanisms of action, we used animal models of acute and chronic inflammation and lipopolysaccharide (LPS)-induced murine peritoneal macrophages to examine the anti-inflammatory function of sanguinarine. Sanguinarine displayed significant anti-inflammatory effects both in vitro and in vivo. Our findings further demonstrated that sanguinarine potently inhibited the expression of inflammatory mediators and inflammation in general. Additionally, our results demonstrated that sanguinarine inhibited the activation of mitogen-activated protein kinase (MAPK), which altered inflammatory mediator synthesis and release in vitro. This study extends our understanding of the anti-inflammatory activity of sanguinarine in acute and chronic inflammation. Furthermore, our findings provide clarification of the molecular mechanisms underlying the anti-inflammatory activity of sanguinarine, supporting the naturopathic use of sanguinarine for the treatment of various human inflammatory diseases.

Tannin extracts from immature fruits of Terminalia chebula Fructus Retz. promote cutaneous wound healing in rats

BACKGROUND

Tannins extracted from immature fruits of Terminalia chebula Fructus Retz. are considered as effective components promoting the process of wound healing. The objective of this study is to explore the optimal extraction and purification technology (OEPT) of tannins, while studying the use of this drug in the treatment of a cutaneous wound of rat as well as its antibacterial effects.

METHODS

The content of tannin extracts was measured by the casein method, and antibacterial ability was studied by the micro-dilution method in vitro. In wound healing experiment, animals in group Ⅰ, Ⅱ and Ⅲ were treated with vaseline ointment, tannin extracts (tannin content: 81%) and erythromycin ointment, respectively (5 mg of ointment were applied on each wound). To evaluate the process of wound healing, selected pharmacological and biochemical parameters were applied.

RESULTS

After optimal extraction and purification, content of tannin extracts was increased to 81%. Tannin extracts showed the inhibition of Staphylococcus aureus and Klebsiella Pneumonia in vitro. After excision of wounds, on days 7 and 10, the percent of wound contraction of group Ⅱ was higher than that of group Ⅰ. After being hurt with wounds, on days 3, 7, and 10, the wound healing quality of group Ⅱ was found to be better than that of group Ⅰ in terms of granulation formation and collagen organization. After wound creation, on day 3, the vascular endothelial growth factor expression of group Ⅱ was higher than that of group Ⅰ.

CONCLUSION

The results suggest that tannin extracts from dried immature fruits of Terminalia chebula Fructus Retz. can promote cutaneous wound healing in rats, probably resulting from a powerful anti-bacterial and angiogenic activity of the extracts.

Inhibition of bone marrow-derived dendritic cell maturation by glabridin

Glabridin has multiple pharmacological activities including anti-microbial, anti-atherosclerotic, anti-nephritic, anti-inflammatory and cardiovascular protective activities. In this study, we investigated the effect of glabridin on dendritic cells, which play an essential role in innate and adaptive immune responses. Glabridin inhibited lipopolysaccharide-, poly (I:C)-, or zymosan-induced phenotypic maturation of dendritic cells (DCs), as proven by the decreased expression of CD40, CD80, CD86, MHC-I, and MHC-II. Glabridin decreased the functional maturation of DCs, in that glabridin attenuated pro-inflammatory cytokine production of IL-12, IL-1β, TNF-α, and IFN-α/β, enhanced antigen capture capacity, inhibited migration to SDF-1α and MIP-3β, and impaired induction of allogenic T cell activation. We also showed that glabridin inhibited zymosan-induced inflammation in mice. As a mode of action, we showed that glabridin inhibited degradation of IκΒα/β, nuclear translocation of NF-κB p65/p50, and phosphorylation of ERK, JNK, and p38 MAPKs. Taken together, the present results show that glabridin inhibits dendritic cell maturation by blocking NF-κB and MAPK signalings.

Phenolics from Glycyrrhiza glabra roots and their PPAR-gamma ligand-binding activity

Bioassay-guided fractionation of the EtOH extract of licorice (Glycyrrhiza glabra roots), using a GAL-4-PPAR-gamma chimera assay method, resulted in the isolation of 39 phenolics, including 10 new compounds (1-10). The structures of the new compounds were determined by analysis of their spectroscopic data. Among the isolated compounds, 5'-formylglabridin (5), (2R,3R)-3,4',7-trihydroxy-3'-prenylflavane (7), echinatin, (3R)-2',3',7-trihydroxy-4'-methoxyisoflavan, kanzonol X, kanzonol W, shinpterocarpin, licoflavanone A, glabrol, shinflavanone, gancaonin L, and glabrone all exhibited significant PPAR-gamma ligand-binding activity. The activity of these compounds at a sample concentration of 10microg/mL was three times more potent than that of 0.5microM troglitazone.

Antifungal activity of Glycyrrhiza glabra extracts and its active constituent glabridin

Glabridin, an active constituent of Glycyrrhiza glabra roots, was found to be active against both yeast and filamentous fungi. Glabridin also showed resistance modifying activity against drug resistant mutants of Candida albicans at a minimum inhibitory concentration of 31.25-250 microg/mL. Although the compound was reported earlier to be active against Candida albicans, but this is the first report of its activity against drug resistant mutants.

Antimicrobial potential of Glycyrrhiza glabra roots

The present study was aimed to investigate antimicrobial potential of Glycyrrhiza glabra roots. Antimycobacterial activity of Glycyrrhiza glabra was found at 500 microg/mL concentration. Bioactivity guided phytochemical analysis identified glabridin as potentially active against both Mycobacterium tuberculosis H(37)Ra and H(37)Rv strains at 29.16 microg/mL concentration. It exhibited antimicrobial activity against both Gram-positive and Gram-negative bacteria. Our results indicate potential use of licorice as antitubercular agent through systemic experiments and sophisticated anti-TB assay.

Clinical Safety of Licorice Flavonoid Oil (LFO) and Pharmacokinetics of Glabridin in Healthy Humans

OBJECTIVE

Licorice flavonoids have various physiological activities such as abdominal fat-lowering, hypoglycemic and antioxidant effects. Licorice flavonoid oil (LFO: Kaneka Glavonoid Rich Oil) is a new dietary ingredient containing licorice flavonoids dissolved in medium-chain triglycerides (MCT). Glabridin is one of the bioactive flavonoids included specifically in licorice Glycyrrhiza glabra L. and is the most abundant flavonoid in LFO. In this study, we assessed the safety of LFO in healthy humans and determined the plasma concentration profile of glabridin as a marker compound.

METHODS

A single-dose and two multiple-dose studies at low (300 mg), moderate (600 mg) and high (1200 mg) daily doses of LFO were carried out using a placebo-controlled single-blind design. In each study the safety of LFO and the pharmacokinetics of glabridin were assessed.

RESULTS

Pharmacokinetic analysis in the single-dose study with healthy male subjects (n = 5) showed that glabridin was absorbed and reached the maximum concentration (Cmax) after approximately 4 h (Tmax), and then eliminated relatively slowly in a single phase with a T1/2 of approximately 10 h at all doses. The Cmax and AUC(0-24 h) increased almost linearly with dose. The multiple-dose studies with healthy male and female subjects for 1 week and 4 weeks suggested that plasma glabridin reached steady state levels within 2 weeks with a single daily administration of 300 to 1200 mg/day LFO. In these human studies at three dose levels, there were no clinically noteworthy changes in hematological or related biochemical parameters. All clinical events observed were mild and considered to be unrelated to LFO administration even after repeated administration for 4 weeks.

CONCLUSION

These studies demonstrated that LFO is safe when administered once daily up to 1200 mg/day. This is the first report on the safety of licorice flavonoids in an oil preparation and the first report on the pharmacokinetics of glabridin in human subjects.

Anticandidal low molecular compounds from higher plants with special reference to compounds from essential oils

The most active low molecular weight compounds from higher plants against Candida species are compiled from a database of antimicrobials (Amicbase) to find out new hints on their mechanism of action. The selected compounds possess strong inhibitory activities in vitro against Candida species either in the agar diffusion test, bioautography, agar dilution test, serial dilution test, or activity in the vapour phase. The test conditions are listed thoroughly and aspects of the different methods and recent developments in the testing of anticandidal drugs are discussed. The anticandidal spectra of drugs, antiseptics, and disinfectants licensed on the major markets are given for comparison of activities with compounds from natural sources. So far known mechanisms of action are described and some new structure-activity relationships are deduced from relationships between biological activities and chemical and physical parameters. Main specific targets of natural anticandidals are the ergosterol pathway, respiratory chain, and chitin biosynthesis.

Effects of tannins and related polyphenols on methicillin-resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) often acquires multi-drug resistance and is involved in many cases of disease in hospitals. We investigated natural substances directly effective against MRSA or that influence antibiotic resistance. Aloe-emodin, an anthraquinone, and several licorice flavonoids showed potent antibacterial effects against MRSA. Like some hydrolysable tannins (corilagin and tellimagrandin I) and a tea polyphenol [(-)-epicatechin gallate], the licorice flavonoid licoricidin also restored the effects of oxacillin, a beta-lactam antibiotic against MRSA. Further study revealed that theasinensin A, a polyphenol formed from (-)-epigallocatechin gallate, proanthocyanidins obtained from fruits of Zizyphus jujuba var. inermis, and polymeric proanthocyanidins from fruit peels of Zanthoxylum piperitum also suppressed the antibiotic resistance of MRSA.

Estrogenic activity of glabridin and glabrene from licorice roots on human osteoblasts and prepubertal rat skeletal tissues

Data from both in vivo and in vitro experiments demonstrated that glabridin and glabrene are similar to estradiol-17beta in their stimulation of the specific activity of creatine kinase, although at higher concentrations, but differ in their extent of action and interaction with other drugs. In pre-menopausal human bone cells, the response to estradiol-17beta and glabridin (at higher concentration) was higher than in post-menopausal cells; whereas, glabrene (at higher concentration) was more effective in post-menopausal cells. At both ages, the response to estradiol-17beta and glabridin was enhanced by pretreatment with the less-calcemic Vitamin D analog CB 1093 (CB) and the demonstrably non-calcemic analog JK 1624 F(2)-2 (JKF). The response to glabrene was reduced by this pretreatment. Both glabridin and glabrene stimulated creatine kinase specific activity in diaphyseal bone and epiphyseal cartilage of prepubertal female rats. Daily feeding (3-14 days) of prepubertal female rats with glabridin, estradiol-17beta or their combination, also stimulated creatine kinase specific activity. Glabridine, similarly to estradiol-17beta, also stimulated creatine kinase specific activity in ovariectomized female rats. Raloxifene, in combination with glabridin or estradiol-17beta, demonstrated the phenomenon of mutual annihilation of stimulation of creatine kinase specific activity in both epiphysis and diaphysis. Glabrene activity was not inhibited by raloxifene. Therefore, glabridin shows greater similarity to estradiol-17beta and thus greater potential, with or without Vitamin D, to modulate bone disorders in post-menopausal women.

Variability in the content of active constituents and biological activity of Glycyrrhiza glabra

Nine samples of Glycyrrhiza glabra were collected in various sites of Calabria, Italy, with the aim to determine the variability in the confront of active constituents and in antibacterial and antifungal activities of the extracts. The samples showed remarkable differences in chemical composition and biological activity.