Evaluation of novel compounds as anti-bacterial or anti-virulence agents

Therapeutic effect and concomitant toxicity of hydrargyrum chloratum compositum on chronic difficult-to-heal wounds in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Hydrargyrum chloratum compositum(Hcc) is a traditional Chinese medicine for external use, with the efficacy of 'transforming corrosion and pulling out toxins, removing corrosion and regenerating muscles'. The main components are mercuric chloride (HgCl2) and mercurous chloride (Hg2Cl2), which have antibacterial, corrosive and tissue repairing effects. However, the therapeutic mechanism and toxicity risk of its topical application for treating difficult-to-heal wounds have not been clearly explained.

AIMS OF THE STUDY

To investigate the therapeutic mechanism of Baishuidan on chronic non-healing wounds in rats and to assess the risk of mercury toxicity.

METHODS

The antimicrobial activity of Hcc against Staphylococcus aureus, Candida albicans, Pseudomonas aeruginosa, and Streptococcus-β haemolyticus was assessed by the circle of inhibition assay, Minimum inhibitory concentration(MIC) and Minimum bactericidal concentration(MBC) assay and 24-h inhibition curve. SD rats were used to establish a chronic difficult-to-heal wound model. The efficacy of C. albicans and its effects on inflammatory and angiogenic factors were assessed by wound healing rate, histopathological analysis, immunohistochemical staining, and Elisa assay. The pathological effects of Hcc on the principal organs of rats and the accumulation of mercury ions were detected by hematoxylin-eosin (H&E) staining and atomic absorption spectrophotometry (AAS).

RESULTS

Hcc showed different degrees of bacteriostatic effects on Staphylococcus aureus, Streptococcus-β haemolyticus, Pseudomonas aeruginosa, and Candida albicans. Among them, the most significant inhibitory effect was on S. aureus (MIC 4 μg/mL, MBC 8 μg/mL). Hcc significantly promoted the healing of skin wounds in rats, with the best effect in the middle-dose group. Pathological analysis showed that collagen fibre production and neocapillary formation increased and inflammatory cell infiltration decreased in the treatment group. Hcc improved the microenvironment of wounds by decreasing the level of the pro-inflammatory factor IL-6 and increasing the level of the anti-inflammatory factor IL-10. By activating the Pi3k - Akt and Notch1 - Vegfa signalling pathways, Hcc promotes cell proliferation and angiogenesis, accelerating wound healing. Hcc did not cause significant pathological damage to the major organs of rats at the therapeutic dose. However, a significant accumulation of mercury ions was detected in the kidneys, suggesting that long-term use may cause damage to renal function.

CONCLUSION

This study is the first to systematically investigate the multi-target, multi-pathway mechanism of action of Hydrargyrum Chloratum Compositum (Hcc) in treating chronic hard-to-heal wounds and to comprehensively assess its potential mercury toxicity risk. Through in vitro antimicrobial assays, animal models, histopathological analyses, protein expression and mercury ion accumulation assays, the present study revealed the unique mechanisms of Hcc in promoting wound healing, including inhibition of bacterial growth, modulation of immune-inflammatory responses, promotion of angiogenesis, and activation of key signalling pathways (Pi3k-Akt and Notch1-Vegfa pathways). In addition, this study is the first to evaluate the accumulation of mercury ions in Hcc in different organs, especially the significant accumulation in the kidney, which provides important safety data for clinical application. Compared with the existing literature, the present study verified the antimicrobial activity of Hcc, and revealed its specific mechanism in promoting wound healing, providing a scientific basis for the clinical use of Hcc.

New Methodologies as Opportunities in the Study of Bacterial Biofilms, Including Food-Related Applications

Traditional food technologies, while essential, often face limitations in sensitivity, real-time detection, and adaptability to complex biological systems such as microbial biofilms. These constraints have created a growing demand for more advanced, precise, and non-invasive tools to ensure food safety and quality. In response to these challenges, cross-disciplinary technological integration has opened new opportunities for the food industry and public health, leveraging methods originally developed in other scientific fields. Although their industrial-scale implementation is still evolving, their application in research and pilot settings has already significantly improved our ability to detect and control biofilms, thereby strengthening food safety protocols. Advanced analytical techniques, the identification of pathogenic species and their virulence markers, and the screening of "natural" antimicrobial compounds can now be conceptualized as interconnected elements within a virtual framework centered on "food" and "biofilm". In this short review, starting from the basic concepts of biofilm and associated microorganisms, we highlight a selection of emerging analytical approaches-from optical methods, microfluidics, Atomic Force Microscopy (AFM), and biospeckle techniques to molecular strategies like CRISPR, qPCR, and NGS, and the use of organoids. Initially conceived for biomedical and biotechnological applications, these tools have recently demonstrated their value in food science by enhancing our understanding of biofilm behavior and supporting the discovery of novel anti-biofilm strategies.

Nanoenabling MbtI Inhibitors for Next-Generation Tuberculosis Therapy

The urgent need for safer and innovative antitubercular agents remains a priority for the scientific community. In pursuit of this goal, we designed and evaluated novel 5-phenylfuran-2-carboxylic acid derivatives targeting Mycobacterium tuberculosis (Mtb) salicylate synthase (MbtI), a key enzyme, absent in humans, that plays a crucial role in Mtb virulence. Several potent MbtI inhibitors demonstrating significant antitubercular activity and a favorable safety profile were identified. Structure-guided optimization yielded 5-(3-cyano-5-isobutoxyphenyl)furan-2-carboxylic acid (1e), which exhibited strong MbtI inhibition (IC50 = 11.2 μM) and a promising in vitro antitubercular activity (MIC99 = 32 μM against M. bovis BCG). Esters of 1e were effectively loaded into poly(2-methacryloyloxyethyl phosphorylcholine)-poly(2-(diisopropylamino)ethyl methacrylate) (PMPC-PDPA) polymersomes (POs) and delivered to intracellular mycobacteria, resulting in reduced Mtb viability. This study provides a foundation for the use of POs in the development of future MbtI-targeted therapies for tuberculosis.

VFDB 2025: an integrated resource for exploring anti-virulence compounds

With the escalating crisis of bacterial multidrug resistance, anti-virulence therapeutic strategies have emerged as a highly promising alternative to conventional antibiotic treatments. Anti-virulence compounds are specifically designed to target virulence factors (VFs), disarming pathogens without affecting bacterial growth and thus reduce the selective pressure for resistance development. However, due to the complexity of bacterial pathogenesis, no anti-virulence small molecules have been approved for clinical use thus far, despite the documentation of hundreds of potential candidates. To provide valuable reference resources for drug design, repurposing, and target selection, the virulence factor database (VFDB, http://www.mgc.ac.cn/VFs/) has systematically collected public data on anti-virulence compounds through extensive literature mining, and further integrated this information with its existing knowledge of bacterial VFs. To date, the VFDB has curated a comprehensive dataset of 902 anti-virulence compounds across 17 superclasses reported by 262 studies worldwide. By cross-linking the current knowledge of bacterial VFs with information on relevant compounds (e.g. classification, chemical structure, molecular targets and mechanisms of action), the VFDB aims to bridge the gap between chemists and microbiologists, providing crucial insights for the development of innovative and effective antibacterial therapies to combat bacterial infections and address antibiotic resistance.

Toward Mycobacterium tuberculosis Virulence Inhibition: Beyond Cell Wall

Mycobacterium tuberculosis (Mtb) is one of the most successful bacterial pathogens in human history. Even in the antibiotic era, Mtb is widespread and causes millions of new cases of tuberculosis each year. The ability to disrupt the host's innate and adaptive immunity, as well as natural persistence, complicates disease control. Tuberculosis traditional therapy involves the long-term use of several antibiotics. Treatment failures are often associated with the development of resistance to one or more drugs. The development of medicines that act on new targets will expand treatment options for tuberculosis caused by multidrug-resistant or extensively drug-resistant Mtb. Therefore, the development of drugs that target virulence factors is an attractive strategy. Such medicines do not have a direct bacteriostatic or bactericidal effect, but can disarm the pathogen so that the host immune system becomes able to eliminate it. Although cell wall-associated targets are being actively studied for anti-TB drug development, other virulence factors important for adaptation and host interaction are also worth comprehensive analysis. In this review, specific Mtb virulence factors (such as secreted phosphatases, regulatory systems, and the ESX-1 secretion system) are identified as promising targets for novel anti-virulence drug development. Additionally, models for the search of virulence inhibitors are discussed, such as virtual screening in silico, in vitro enzyme inhibition assay, the use of recombinant Mtb strains with reporter constructs, phenotypic analysis using in vitro cell infection models and specific environments.