Imperatorin inhibits the expression of alpha-hemolysin in Staphylococcus aureus strain BAA-1717 (USA300)

A review of the ethnomedicinal, phytochemical, and pharmacological properties of the Ferulago genus based on Structure-Activity Relationship (SAR) of coumarins

BACKGROUND

The Ferluago W.D.J. Koch genus includes 48 accepted perennial herbs that are distributed in the Mediterranean region, Southeast Europe, Central and Middle East of Asia. These plants are widely used in folk and conventional medicine due to their biological benefits such as anti-microbial, anti-inflammatory, anti-cancer, and immunomodulatory properties. Conducting a comprehensive review based on the structure activity relationships (SARs) of the coumarins, which has not been previously documented, can lead to a better insight into the genus Ferulago and its beneficial therapeutic activities.

METHODS

This review covers literature from 1969 to 2023, were collected from various scientific electronic databases to review phytochemical, pharmacological, and ethnopharmacological data of Ferulago species, as well as latest information on the SAR of reported coumarins from this genus.

RESULTS

Phytochemical studies showed that the biological actions of this genus are mediated by the reported specialized metabolites, such as coumarins and flavonoids. Simple coumarins, prenylated coumarins, furanocoumarins, and pyranocoumarins are the largest subclasses of coumarins found in diverse Ferulago species, which have discussed the biological effects of them with a focus on the Structure-Activity Relationship (SAR). For example, prenylated coumarins have shown potential leishmanicidal and anti-neuropsychiatric effects when substituted with a prenyl group at the 7-hydroxy, as well as the C6 and C8 positions in their scaffold. Similarly, furanocoumarins exhibit varied biological activities such as anti-inflammatory, anti-proliferative, and anti-convulsant effects. Modifying substitutions at the C5 and C6 positions in furanocoumarins can enhance these activities.

CONCLUSION

This study conducted a comprehensive review of all available information on the phytochemical and pharmacological characteristics of Ferulago species. Given the high occurrence of coumarins in this genus, which exhibit potential anti-Alzheimer and anti-microbial properties, it presents promising new therapeutic avenues for addressing these common issues. Further investigation is needed to understand the molecular-level mechanisms of action and to explore their clinical applications.

Inhibitory Effect of Jingfang Mixture on Staphylococcus aureus α-Hemolysin

Staphylococcus aureus (S. aureus) is a kind of gram-positive bacteria, and its virulence factors can cause many kinds of infections. Traditional antibiotics can not only kill bacteria, but also easily lead to bacterial resistance. Jingfang Mixture (JFM) is commonly used in clinic to prevent and treat epidemic diseases and infectious diseases. The main purpose of this study is to explore the inhibitory effect of JFM on alpha-hemolysin (Hla) of S. aureus and to alleviate the damage caused by Hla. We found that JFM could inhibit the hemolytic activity, gene and protein level and neutralizing activity of Hla in a dose-dependent manner at the concentrations of 125, 250 and 500 μg/mL, without affecting the growth of bacteria. In addition, JFM reduced the damage of Hla to A549 cells and the release of lactate dehydrogenase (LDH). We also observed that in the S. aureus - induced pneumonia mouse model, JFM could significantly prolong the life of mice, reduce the bacterial load in the lungs, significantly improve the pathological state of the lungs and alleviate the damage caused by inflammatory factors, and the pathogenicity of gene deletion strain DU 1090 of S. aureus to pneumonia mice was also significantly reduced. In conclusion, this study proved that JFM is a potential drug against S. aureus infection, and this study provided a preliminary study for better guidance of clinical drug use.

Inhibitory effect of Jingfang mixture on Staphylococcus aureus α-hemolysin

Staphylococcus aureus is a gram-positive bacteria, and its virulence factors can cause many kinds of infections, such as pneumonia, sepsis, enteritis and osteomyelitis. Traditional antibiotics can not only kill bacteria, but also easily lead to bacterial resistance. Jingfang Mixture (JFM) has the effects of inducing sweating and relieving the exterior, dispelling wind and eliminating dampness, and is commonly used in clinic to prevent and treat epidemic diseases and infectious diseases. The main purpose of this study is to explore the inhibitory effect of JFM on alpha-hemolysin (Hla) of S. aureus and to alleviate the damage caused by Hla. We found that JFM could inhibit the hemolytic activity, transcription level and neutralizing activity of Hla in a dose-dependent manner at the concentrations of 125, 250 and 500 µg/mL, without affecting the growth of bacteria. In addition, JFM reduced the damage of Hla to A549 cells and the release of lactate dehydrogenase (LDH). We also observed that in the S. aureus - induced pneumonia mouse model, JFM could significantly prolong the life of mice, reduce the bacterial load in the lungs, significantly improve the pathological state of the lungs and alleviate the damage caused by inflammatory factors, and the pathogenicity of gene deletion strain DU 1090 of S. aureus to pneumonia mice was also significantly reduced. In conclusion, this study proved that JFM is a potential drug against S. aureus infection, and this study provided a preliminary study for better guidance of clinical drug use.

Discovery and mechanistic study of Imperatorin that inhibits HBsAg expression and cccDNA transcription

Chronic hepatitis B virus (HBV) infection remains a significant global health challenge due to its link to severe conditions like HBV-related cirrhosis and hepatocellular carcinoma (HCC). Although current treatments effectively reduce viral levels, they have limited impact on certain HBV elements, namely hepatitis B surface antigen (HBsAg) and covalently closed circular DNA (cccDNA). This highlights the urgent need for innovative pharmaceutical and biological interventions that can disrupt HBsAg production originating from cccDNA. In this study, we identified a natural furanocoumarin compound, Imperatorin, which markedly inhibited the expression of HBsAg from cccDNA, by screening a library of natural compounds derived from Chinese herbal medicines using ELISA assay and qRT-PCR. The pharmacodynamics study of Imperatorin was explored on HBV infected HepG2-NTCP/PHHs and HBV-infected humanized mouse model. Proteome analysis was performed on HBV infected HepG2-NTCP cells following Imperatorin treatment. Molecular docking and bio-layer interferometry (BLI) were used for finding the target of Imperatorin. Our findings demonstrated Imperatorin remarkably reduced the level of HBsAg, HBV RNAs, HBV DNA and transcriptional activity of cccDNA both in vitro and in vivo. Additionally, Imperatorin effectively restrained the actions of HBV promoters responsible for cccDNA transcription. Mechanistic study revealed that Imperatorin directly binds to ERK and subsequently interfering with the activation of CAMP response element-binding protein (CREB), a crucial transcriptional factor for HBV and has been demonstrated to bind to the PreS2/S and X promoter regions of HBV. Importantly, the absence of ERK could nullify the antiviral impact triggered by Imperatorin. Collectively, the natural compound Imperatorin may be an effective candidate agent for inhibiting HBsAg production and cccDNA transcription by impeding the activities of HBV promoters through ERK-CREB axis.

An inhibitory effect of schisandrone on α-hemolysin expression to combat methicillin-resistant staphylococcus aureus infections

Due to increasing antibiotic resistance, targeting bacterial virulence factors is now gaining further interest as an alternative strategy to develop novel classes of anti-infective agents. The critical role of α-hemolysin (Hla), an indispensable virulence determinant, in the pathogenicity of Staphylococcus aureus renders this virulence factor an appealing target for effective therapeutic applications. Herein, we identified a natural compound schisandraone, as an effective Hla inhibitor, which could inhibit Hla production and thus hemolytic activity in a dose-dependent manner without affecting the growth of S. aureus. We also found that the addition of schisandrone could down-regulate the transcriptional levels of the hla, agrA and RNAIII and significantly alleviated Hla-mediated injury of A549 cells co-cultured with S. aureus. In vivo studies further suggested that schisandrone combined with antibiotic ceftiofur exhibited a significant therapeutic effect on S. aureus infection. These findings revealed the role of schisandrone in inhibiting the activity of Hla and we believe that it is a promising anti-virulence candidate to combat MRSA pneumonia.

Antimicrobial activities and mechanisms of extract and components of herbs in East Asia

Antibacterial drugs face increasing challenges due to drug resistance and adverse reactions, which has created a pressing need for the discovery and development of novel antibacterial drugs. Herbs have played an important role in the treatment of infectious diseases. This review aims to summarize, analyze and evaluate the antibacterial activities and mechanisms of components from popular herbs in East Asia. In this review, we have searched and summarized the scientific papers published during the past twenty-year period from electronic databases such as PubMed, ScienceDirect, and Web of Science. These herbs and their components, including alkaloids, flavonoids, essential oils, terpenes, organic acids, coumarins and lignans, display potential antimicrobial effects. Herbal medicine formulas (HMFs) usually show stronger antibacterial activity than single herbs. Herbs and HMFs bring forth antibacterial activities by damaging cell membranes and walls, inhibiting nucleic acid and protein synthesis, and increasing intracellular osmotic pressure. These herbs and their components can be developed as potential and promising novel antibacterial herbal products.

Epigallocatechin gallate (EGCG) attenuates staphylococcal alpha-hemolysin (Hla)-induced NLRP3 inflammasome activation via ROS-MAPK pathways and EGCG-Hla interactions

Alpha-hemolysin (Hla), the virulence factor secreted by Staphylococcus aureus (S. aureus), plays a critical role in infection and inflammation, which is a severe health burden worldwide. Therefore, it is necessary to develop a drug against Hla. Epigallocatechin gallate (EGCG), a polyphenol extracted from green tea, has excellent anti-inflammatory activity. In this study, we investigated the inhibitory effect of EGCG on Hla-induced NLRP3 inflammasome activation in vitro and in vivo and elucidated the potential molecular mechanism. We found that EGCG attenuated the hemolysis of Hla by inhibiting its secretion. Besides, EGCG significantly decreased overproduction of ROS and activation of MAPK signaling pathway induced by Hla, thereby markedly attenuating the expression of NLRP3 inflammasome-related proteins in THP-1 cells. Notably, EGCG could spontaneously bind to Hla with affinity constant of 1.71 × 10-4 M, thus blocking the formation of the Hla heptamer. Moreover, Hla-induced expression of NLRP3, ASC and caspase-1 protein and generation of IL-1β and IL-18 in the damaged liver tissue of mice were also significantly suppressed by EGCG in a dose-dependent manner. Collectively, EGCG could be a promising candidate for alleviating Hla-induced the activation of NLRP3 inflammasome, depending on ROS mediated MAPK signaling pathway, and inhibition of Hla secretion and heptamer formation. These findings will enlighten the applications of EGCG to reduce the S. aureus infection by targeting Hla in food and related pharmaceutical fields.

Imperatorin: A review of its pharmacology, toxicity and pharmacokinetics

As a naturally occurring furanocoumarin, the medicinal value of imperatorin has been studied more and more. We hope to provide useful information for the further development of imperatorin by analyzing the literature of imperatorin in recent years. By collating the literature on the pharmacology of imperatorin, we found that the pharmacological activity of imperatorin is wide and imperatorin can be used for anti-cancer, neuroprotection, anti-inflammatory, anti-hypertension and antibacterial. In addition, we found that some researchers confirmed the toxicity of imperatorin. Pharmacokinetic studies demonstrated that oxidation metabolism is the main metabolic pathways of imperatorin. At present, the shortcomings of research on imperatorin mainly include: most pharmacological studies are concentrated in vitro, lacking enough in vivo experimental data; more and more studies showed that imperatorin has synergistic effect with other drugs in anticancer and other aspects, but lacking the detailed explanation of the mechanism of the synergistic effect; imperatorin has side effect, but it lacks enough experimental conclusions. Based on the above defects, we believe that more in vivo experiments of imperatorin should be carried out in the future; future research need to explore synergistic mechanisms of imperatorin with other drugs, especially in anticancer; the dose affects both the pharmacological activity and the side effect of imperatorin. The relationship between the dose and the two aspects need to be further studied in order to reduce the side effect. In addition, through structural modification of imperatorin, it is possible to improve the treatment effect and reduce side effect.

Coumarins as Modulators of the Keap1/Nrf2/ARE Signaling Pathway

The Keap1/Nrf2/ARE system is a central defensive mechanism against oxidative stress which plays a key role in the pathogenesis and progression of many diseases. Nrf2 is a redox-sensitive transcription factor controlling a variety of downstream antioxidant and cytodefensive genes. Nrf2 has a powerful anti-inflammatory activity mediated via modulating NF-κB. Therefore, pharmacological activation of Nrf2 is a promising therapeutic strategy for the treatment/prevention of several diseases that are underlined by both oxidative stress and inflammation. Coumarins are natural products with promising pharmacological activities, including antioxidant, anticancer, antimicrobial, and anti-inflammatory efficacies. Coumarins are found in many plants, fungi, and bacteria and have been widely used as complementary and alternative medicines. Some coumarins have shown an ability to activate Nrf2 signaling in different cells and animal models. The present review compiles the research findings of seventeen coumarin derivatives of plant origin (imperatorin, visnagin, urolithin B, urolithin A, scopoletin, esculin, esculetin, umbelliferone, fraxetin, fraxin, daphnetin, anomalin, wedelolactone, glycycoumarin, osthole, hydrangenol, and isoimperatorin) as antioxidant and anti-inflammatory agents, emphasizing the role of Nrf2 activation in their pharmacological activities. Additionally, molecular docking simulations were utilized to investigate the potential binding mode of these coumarins with Keap1 as a strategy to disrupt Keap1/Nrf2 protein-protein interaction and activate Nrf2 signaling.

Erianin against Staphylococcus aureus Infection via Inhibiting Sortase A

With continuous emergence and widespread of multidrug-resistant Staphylococcus aureus infections, common antibiotics have become ineffective in treating these infections in the clinical setting. Anti-virulence strategies could be novel, effective therapeutic strategies against drug-resistant bacterial infections. Sortase A (srtA), a transpeptidase in gram-positive bacteria, can anchor surface proteins that play a vital role in pathogenesis of these bacteria. SrtA is known as a potential antivirulent drug target to treat bacterial infections. In this study, we found that erianin, a natural bibenzyl compound, could inhibit the activity of srtA in vitro (half maximal inhibitory concentration-IC₅₀ = 20.91 ± 2.31 μg/mL, 65.7 ± 7.2 μM) at subminimum inhibitory concentrations (minimum inhibitory concentrations-MIC = 512 μg/mL against S. aureus). The molecular mechanism underlying the inhibition of srtA by erianin was identified using molecular dynamics simulation: erianin binds to srtA residues Ile182, Val193, Trp194, Arg197, and Ile199, forming a stable bond via hydrophobic interactions. In addition, the activities of S. aureus binding to fibronectin and biofilm formation were inhibited by erianin, when co-culture with S. aureus. In vivo, erianin could improve the survival in mice that infected with S. aureus by tail vein injection. Experimental results showed that erianin is a potential novel therapeutic compound against S. aureus infections via affecting srtA.

Subinhibitory Concentrations of Prim-O-Glucosylcimifugin Decrease the Expression of Alpha-Hemolysin in Staphylococcus aureus (USA300)

Staphylococcus aureus (S. aureus), an important opportunistic pathogen in human and animal, causes a series of diseases in the impairing of immunity of host and even then death. Alpha-hemolysin (Hla), a primary virulence factor, plays a major role in the pathogenic progress of S. aureus, especially in pneumonia. Prim-O-glucosylcimifugin (POG), a nature chromone compound, is an active ingredient in many Chinese Medicines. In this study, POG investigated the inhibitory effect of the secretion of Hla in S. aureus strain USA300 at the subinhibitory concentrations. The hemolysis assays and western blotting assays showed that POG can decrease the production of Hla in the USA300 growth cell cultures in a dose-dependent manner. The results of RT-PCR revealed that reduction of Hla was related to inhibit the transcription of hla and RNAIII. In the cells experiment, POG was proved to protect A549 cells from Hla-medicated injury. In conclusion, POG was shown the capacity of decreased the production of S. aureus Hla. POG can be developed as a candidate agent to treat S. aureus infections against Hla.

CRISPR/dCas9-mediated inhibition of gene expression in Staphylococcus aureus

The understanding of the genetic mechanism of Staphylococcus aureus requires efficient tools, however, genetic manipulation in S. aureus is always laborious and time-consuming. Here we proposed a novel CRISPR/dCas9 interference method for the rapid knockdown of target genes. Furthermore, multiple genes can be repressed simultaneously by using this method.