The Herbal Compound Thymol Targets Multiple Salmonella Typhimurium Virulence Factors for Lon Protease Degradation

In vitro and in vivo activities of scutellarein, a novel polyphosphate kinase 1 inhibitor against Acinetobacter baumannii infection

BACKGROUND

Inorganic polyphosphate (polyP)-targeted polyphosphate kinase 1 (PPK1) has attracted much attention by virtue of its importance in bacterial pathogenicity and persistence, as well as its exclusive presence in microorganisms. However, only very few drugs have been found to be efficacious in inhibiting the Acinetobacter baumannii (A. baumannii) PPK1 protein.

RESULTS

In this study, we identified Scutellarein (Scu), a potent PPK1 inhibitor that could significantly influence PPK1-regulated motility, biofilm formation, and bacterial persistence, which was further validated by the results of transcriptome analysis. Mechanistic explorations revealed that Scu achieved its enzyme inhibitory activity predominantly through direct engagement with the active center of PPK1. Moreover, the survival rate of Galleria mellonella larvae was increased by about 35% with 20 mg/kg of Scu treatment. The remarkable therapeutic benefits of Scu were also observed in the mouse pneumonia model, shown mainly by reduced bacterial colonization, pathological lesions, and inflammatory factors.

CONCLUSION

Our results revealed that Scu could attenuate the pathogenicity and persistence of A. baumannii by interfering with its important kinase PPK1.

Plant-Derived Antimicrobials and Their Crucial Role in Combating Antimicrobial Resistance

Antibiotic resistance emerged shortly after the discovery of the first antibiotic and has remained a critical public health issue ever since. Managing antibiotic resistance in clinical settings continues to be challenging, particularly with the rise of superbugs, or bacteria resistant to multiple antibiotics, known as multidrug-resistant (MDR) bacteria. This rapid development of resistance has compelled researchers to continuously seek new antimicrobial agents to curb resistance, despite a shrinking pipeline of new drugs. Recently, the focus of antimicrobial discovery has shifted to plants, fungi, lichens, endophytes, and various marine sources, such as seaweeds, corals, and other microorganisms, due to their promising properties. For this review, an extensive search was conducted across multiple scientific databases, including PubMed, Elsevier, ResearchGate, Scopus, and Google Scholar, encompassing publications from 1929 to 2024. This review provides a concise overview of the mechanisms employed by bacteria to develop antibiotic resistance, followed by an in-depth exploration of plant secondary metabolites as a potential solution to MDR pathogens. In recent years, the interest in plant-based medicines has surged, driven by their advantageous properties. However, additional research is essential to fully understand the mechanisms of action and verify the safety of antimicrobial phytochemicals. Future prospects for enhancing the use of plant secondary metabolites in combating antibiotic-resistant pathogens will also be discussed.

Polyphenols and CRISPR as Quorum Quenching Agents in Antibiotic-Resistant Foodborne Human Pathogens (Salmonella Typhimurium, Campylobacter jejuni and Escherichia coli 0157:H7)

Antibiotic resistance in foodborne pathogens is an increasing threat to global human health. Among the most prevalent antibiotic-resistant bacteria are Salmonella enterica serovar Typhimurium, Campylobacter jejuni and E. coli 0157:H7. Control of these and other pathogens requires innovative approaches, i.e., discovering new molecules that will inactivate them, or render them less virulent without inducing resistance. Recently, several polyphenol molecules have been shown to possess such characteristics. Also, the use of CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) approaches has recently been proposed for such purpose. This review summarizes the main findings regarding the application of both approaches to control the above-mentioned foodborne pathogens by relying on Quorum Sensing interference (Quorum Quenching) mechanisms and highlights the avenues needed for further research.

Polyphenols and CRISPR as Quorum Quenching Agents in Antibiotic-Resistant Foodborne Human Pathogens (Salmonella Typhimurium, Campylobacter jejuni and Escherichia coli 0157:H7)

Antibiotic resistance in foodborne pathogens is an increasing threat to global human health. Among the most prevalent antibiotic-resistant bacteria are Salmonella enterica serovar Typhimurium, Campylobacter jejuni and E. coli 0157:H7. Control of these and other pathogens requires innovative approaches, i.e., discovering new molecules that will inactivate them, or render them less virulent without inducing resistance. Recently, several polyphenol molecules have been shown to possess such characteristics. Also, the use of CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) approaches has recently been proposed for such purpose. This review summarizes the main findings regarding the application of both approaches to control the above-mentioned foodborne pathogens by relying on Quorum Sensing interference (Quorum Quenching) mechanisms and highlights the avenues needed for further research.

Investigation of the inhibitory effect and mechanism of epigallocatechin-3-gallate against Streptococcus suis sortase A

AIMS

Streptococcus suis seriously harms people and animals, and importantly, causes great economic losses in the pig industry. Similar to most Gram-positive pathogenic bacteria, sortase A (SrtA) of S. suis can mediate the anchoring of a variety of virulence factors that contain specific sorting sequences to the surface of the bacterial cell wall envelope and participate in pathogenicity. The purpose of this study is to clarify the molecular mechanism of epigallocatechin-3-gallate (EGCG) inhibiting S. suis SrtA and provide more evidence for the development of novel anti-S. suis infections drugs.

METHODS AND RESULTS

Through the SrtA substrate cleavage experiment, we found that the main component of green tea, EGCG, can effectively inhibit the enzyme activity of S. suis SrtA. Further, molecular docking and molecular dynamics simulation were used to clarify the molecular mechanism of its inhibitory effect, demonstrating that EGCG mainly interacts with amino acids at 113 and 115 to exert its inhibitory function. It was previously found that EGCG can inhibit the growth of S. suis and reduce the activity of suilysin and inhibit its expression. Our research reveals a new function of EGCG in S. suis infection.

CONCLUSIONS

Our research proves that EGCG can effectively inhibit the transpeptidase activity of SrtA. We also clarify the accompanying molecular mechanism, providing more sufficient evidence for the use of EGCG as a potential lead compound against S. suis infection.

Quercitrin Is a Novel Inhibitor of Salmonella enterica Serovar Typhimurium Type III Secretion System

The purpose was to screen type III secretory system (T3SS) inhibitors of Salmonella enterica serovar Typhimurium (S. Typhimurium) from natural compounds. The pharmacological activities and action mechanisms of candidate compounds in vivo and in vitro were systematically studied and analyzed. Using a SipA-β-lactamase fusion reporting system, we found that quercitrin significantly blocked the translocation of SipA into eukaryotic host cells without affecting the growth of bacteria. Adhesion and invasion assay showed that quercitrin inhibited S. Typhimurium invasion into host cells and reduced S. Typhimurium mediated host cell damage. β-galactosidase activity detection and Western blot analysis showed that quercitrin significantly inhibited the expression of SPI-1 genes (hilA and sopA) and effectors (SipA and SipC). The results of animal experiments showed that quercitrin significantly reduced colony colonization and alleviated the cecum pathological injury of the infected mice. Small molecule inhibitor quercitrin directly inhibited the function of T3SS and provided a potential antibiotic alternative against S. Typhimurium infection. Importance: T3SS plays a crucial role in the bacterial invasion and pathogenesis of S. Typhimurium. Compared with conventional antibiotics, small molecules could inhibit the virulence factors represented by S. Typhimurium T3SS. They have less pressure on bacterial vitality and a lower probability of producing drug resistance. Our results provide strong evidence for the development of novel inhibitors against S. Typhimurium infection.

Targeting bacterial pathogenesis by inhibiting virulence-associated Type III and Type IV secretion systems

Infections caused by Gram-negative pathogens pose a major health burden. Both respiratory and gastrointestinal infections are commonly associated with these pathogens. With the increase in antimicrobial resistance (AMR) over the last decades, bacterial infections may soon become the threat they have been before the discovery of antibiotics. Many Gram-negative pathogens encode virulence-associated Type III and Type IV secretion systems, which they use to inject bacterial effector proteins across bacterial and host cell membranes into the host cell cytosol, where they subvert host cell functions in favor of bacterial replication and survival. These secretion systems are essential for the pathogens to cause disease, and secretion system mutants are commonly avirulent in infection models. Hence, these structures present attractive targets for anti-virulence therapies. Here, we review previously and recently identified inhibitors of virulence-associated bacterial secretions systems and discuss their potential as therapeutics.

Sepsis-induced AKI: From pathogenesis to therapeutic approaches

Sepsis is a heterogenous and highly complex clinical syndrome, which is caused by infectious or noninfectious factors. Acute kidney injury (AKI) is one of the most common and severe complication of sepsis, and it is associated with high mortality and poor outcomes. Recent evidence has identified that autophagy participates in the pathophysiology of sepsis-associated AKI. Despite the use of antibiotics, the mortality rate is still at an extremely high level in patients with sepsis. Besides traditional treatments, many natural products, including phytochemicals and their derivatives, are proved to exert protective effects through multiple mechanisms, such as regulation of autophagy, inhibition of inflammation, fibrosis, and apoptosis, etc. Accumulating evidence has also shown that many pharmacological inhibitors might have potential therapeutic effects in sepsis-induced AKI. Hence, understanding the pathophysiology of sepsis-induced AKI may help to develop novel therapeutics to attenuate the complications of sepsis and lower the mortality rate. This review updates the recent progress of underlying pathophysiological mechanisms of sepsis-associated AKI, focuses specifically on autophagy, and summarizes the potential therapeutic effects of phytochemicals and pharmacological inhibitors.

Natural phytochemicals that affect autophagy in the treatment of oral diseases and infections: A review

Autophagy is a critical factor in eukaryotic evolution. Cells provide nutrition and energy during autophagy by destroying non-essential components, thereby allowing intracellular material conversion and managing temporary survival stress. Autophagy is linked to a variety of oral disorders, including the type and extent of oral malignancies. Furthermore, autophagy is important in lymphocyte formation, innate immunity, and the regulation of acquired immune responses. It is also required for immunological responses in the oral cavity. Knowledge of autophagy has aided in the identification and treatment of common oral disorders, most notably cancers. The involvement of autophagy in the oral immune system may offer a new understanding of the immune mechanism and provide a novel approach to eliminating harmful bacteria in the body. This review focuses on autophagy creation, innate and acquired immunological responses to autophagy, and the status of autophagy in microbial infection research. Recent developments in the regulatory mechanisms of autophagy and therapeutic applications in oral illnesses, particularly oral cancers, are also discussed. Finally, the relationship between various natural substances that may be used as medications and autophagy is investigated.

Lysionotin Induces Ferroptosis to Suppress Development of Colorectal Cancer via Promoting Nrf2 Degradation

Extensive use of substances derived from natural sources has been documented in the treatment of colorectal cancer (CRC). Lysionotin (Lys) is a flavonoid present in the flowers and leaves of Gesneriaceae family plants. Despite its various pharmacological properties, which include neuroprotective, pro, antimalarial, and anticancer effects, the therapeutic advantages of Lys for CRC remain uncertain. In this present study, we demonstrated that Lys treatment successfully inhibited cell proliferation, migration, and invasion in HCT116 and SW480 CRC cells in vitro. Intriguingly, significant ferroptosis and reactive oxygen species (ROS) accumulation in CRC cells were induced by Lys treatment, whereas antagonism of ferroptosis by Liproxstatin-1 (Lip1) pretreatment retarded the anti-CRC effects of Lys. In addition, Lys reduced the amount of Nrf2 protein in CRC cells by increasing the rate at which it is degraded. Overexpression of Nrf2 rescued Lys reduced ferroptosis, suggesting the Nrf2 signaling is a crucial determinant of whether Lys induces ferroptosis in CRC cells. We also revealed that Lys suppressed tumor growth in vivo without obvious adverse effects on the main organs of mice. In conclusion, our results discovered that Lys treatment induced ferroptosis to exert antitumor effects in HCT116 and SW480 CRC cells by modulating Nrf2 signaling, providing a potential therapeutic approach for the prevention of colorectal cancer.

6 ′ -O-Galloylpaeoniflorin Exerts Inhibitory Bioactivities in Human Neuroblastoma Cells via Modulating AMPK/miR-489/XIAP Pathway

Although therapies against neuroblastoma (NBM) have advanced, the patients still suffer from poor prognoses due to distal metastasis or the occurrence of multidrug resistance. Accumulating evidence has proved that chemicals derived from natural products possess potent anti-NBM properties or can be used as adjuvants for chemotherapy. In the present study, we demonstrated that 6′-O-galloylpaeoniflorin (GPF), a galloylated derivative of paeoniflorin isolated from the roots of Paeonia lactiflora Pall, exerted significant inhibitory effects on proliferation and invasion of SH-SY5Y cells (an NBM cell line) and enhanced the sensitivity of SH-SY5Y cells to cisplatin in vitro. Further studies showed that GPF treatment upregulated miR-489 in NBM cells via activating AMP-activated protein kinase (AMPK). We also demonstrated that similar to GPF treatment, miR-489 exhibited a significant anti-NBM capacity. Further studies showed that miR-489 directly targeted the X-linked inhibitor of apoptosis protein (XIAP). Overall, our results indicated that GPF possessed an evident anti-NBM capacity dependent on AMPK/miR-489/XIAP pathway, providing an emerging strategy for clinical treatment of NBM.

Effects of Traditional Chinese Medicine Anticancer Decoction Combined with Basic Chemotherapy and Nursing Intervention on Oral Cancer Patients after Surgery and Its Effect on Tumor Markers and Immune Function

Objective

To prospectively study the application effect of traditional Chinese medicine (TCM) anticancer decoction with basic chemotherapy and nursing intervention on oral cancer patients after surgery and the effect on tumor markers and immune function.

Methods

Eighty-four postoperative oral cancer patients in our hospital from May 2017 to February 2019 were selected and divided into observation group (42 cases) and control group (42 cases). The control group was treated with basic chemotherapy combined with basic nursing care, and the observation group was treated with TCM anticancer decoction and comprehensive nursing intervention on the basis of the control group. The clinical efficacy, the occurrence of adverse reactions, the satisfaction of nursing care, and the two-year cumulative survival rate of the two groups were compared. The immune function, tumor marker level, VAS score, QoR40 score, and survival quality score of the two groups were compared before and after nursing care.

Results

The total clinical treatment efficiency of the observation group (88.10%) was significantly higher than that of the control group (69.05%), and the differences between the two groups in oral cleanliness, aspiration frequency, and oral comfort were statistically significant (P < 0.05). The differences in the occurrence of halitosis, oral fungal infection, leukopenia, gastrointestinal reaction, and fever in the observation group were statistically significant compared with the control group (P < 0.05). The nursing satisfaction rate in the observation group (95.24%) was significantly higher than that in the control group (78.57%). The two-year cumulative survival rate of the observation group (92.86%) was significantly higher than that of the control group (73.81%). After nursing care, CD4+, CD4+/CD8+, VAS scores, QoR40 scores, and quality of survival scores in both groups all increased, and CD8+, CD56+, CEA level, NSE level, and CA19-9 level all decreased (all P < 0.05).

Conclusion

The clinical efficacy of TCM anticancer decoction with basic chemotherapy and nursing interventions in the treatment of postoperative oral cancer patients was remarkable, which could significantly improve patients' oral cleanliness and comfort, reduce the frequency of sputum aspiration, improve patients' immunity, reduce tumor marker levels, inhibit tumor activity, improve patients' nursing satisfaction, further improve patients' treatment compliance, reduce patients' pain level, improve patients' survival quality, and prolong patients' survival time with high safety. It could be used as a theoretical basis for subsequent clinical research.

A natural compound hyperoside targets Salmonella Typhimurium T3SS needle protein InvG

The antimicrobial actions of natural compounds derived from medicinal plants have been well documented. However, their detailed mechanism underlying the action against microorganisms remains largely unexplored. Salmonella enterica is a...