Antibacterial Activity of Caffeic Acid Combined with UV-A Light against Escherichia coli O157:H7, Salmonella enterica Serovar Typhimurium, and Listeria monocytogenes

Evaluation of Antioxidant, Xanthine Oxidase-Inhibitory, and Antibacterial Activity of Syzygium cumini Linn. Seed Extracts

Syzygium cumini (L.) Skeels, commonly known as the Jamun or Indian blackberry, is a tropical evergreen tree native to the Indian subcontinent, and it belongs to the Myrtaceae family. This research aimed to assess the antibacterial properties of the extracts derived from S. cumini seed kernels and evaluate their total flavonoid content, total phenol content, total carbohydrate content, antioxidant capacity, and inhibitory effects on xanthine oxidase. Cold maceration was chosen for its ability to preserve thermolabile compounds and efficiently extract bioactive constituents with minimal energy and equipment requirement, with hexane and methanol employed as extraction solvents. The methanolic seed kernel extract of S. cumini showed the highest flavonoid (127.78 μg quercetin equivalent/mg dried extract vs. 21.24 μg quercetin equivalent/mg in hexane dried extract) and polyphenol content (153.81 μg gallic acid equivalent/mg dried extract vs. 38.89 μg gallic acid equivalent/mg in hexane dried extract), along with significant carbohydrate content (475.61 μg glucose equivalent/mg dried extract vs. 5.57 μg GE/mg in hexane dried extract). It also demonstrated potent antioxidant activity (IC50: 9.23 μg/mL; ascorbic acid: 5.10 μg/mL) and xanthine oxidase inhibition (IC50: 14.88 μg/mL), comparable to the standard drug allopurinol (IC50: 6.54 μg/mL), suggesting its therapeutic potential. Moreover, the methanolic extract of seed kernels exhibited strong antibacterial activity, with inhibition zones of 19.00 mm against S. epidermidis, higher than the standard antibiotic (gentamicin: 18.33 mm) against K. pneumonia (ciprofloxacin: 33.66 mm). The lowest minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of 0.32 mg/mL and 0.52 mg/mL, respectively, were observed for the same extract against S. epidermis. In conclusion, this study demonstrated the remarkable antibacterial effects of S. cumini methanolic seed kernel extract against various pathogenic microorganisms as well as significant inhibitory effects on xanthine oxidase and antioxidant activity.

Natural Antimicrobial Compounds as Promising Preservatives: A Look at an Old Problem from New Perspectives

Antimicrobial compounds of natural origin are of interest because of the large number of reports regarding the harmfulness of food preservatives. These natural products can be derived from plants, animal sources, microorganisms, algae, or mushrooms. The aim of this review is to consider known antimicrobials of natural origin and the mechanisms of their action, antimicrobial photodynamic technology, and ultrasound for disinfection. Plant extracts and their active compounds, chitosan and chitosan oligosaccharide, bioactive peptides, and essential oils are highly potent preservatives. It has been experimentally proven that they possess strong antibacterial capabilities against bacteria, yeast, and fungi, indicating the possibility of their use in the future to create preservatives for the pharmaceutical, agricultural, and food industries.

Synergistic antimicrobial action of chlorogenic acid and ultraviolet-A (365 nm) irradiation; mechanisms and effects on DNA integrity

Chlorogenic acid (CGA) is abundant in various plants and notably in coffee beans. This study investigated the bactericidal activity of CGA combined with ultraviolet-A light (UVA, 365 nm) (CGA + UVA) against Escherichia coli DH5α, with the aim of developing novel strategies for food preservation and healthcare. CGA + UVA treatment was superiorin reducing bacterial survival than either treatment alone. At 20 J/cm2 and pH 7, CGA (0.3%) + UVA treatment resulted in only about a 3-log reduction in bacterial survival, whereas at 15 J/cm2 and pH 3, no surviving bacteria could be detected, demostrating that the treatment was more effective at acidic pH. CGA + UVA treatment was also bactericidal in green plum juice, confirming that its low pH-dependent property could be effective in acidic food products. To elucidate the bactericidal mechanism of CGA + UVA treatment, its effects on reactive oxygen species (ROS) generation, membrane integrity, and enzyme activity were measured. ROS generated via the type-1 reaction, such as hydrogen peroxide (H2O2) and hydroxyl radicals (·OH), were mainly detected. CGA + UVA disrupted the bacterial cell membrane, causing the leakage of cellular components, particularly proteins. CGA + UVA treatment also led to deoxyribonucleic acid (DNA) degradation and reduced succinate-coenzyme Q reductase activity by approximately 72 %. Furthermore, CGA + UVA treatment decreased β-lactamase activity and plasmid transforming efficacy with maximal reductions of 68 % and 98 %, respectively, highlighting its potential for increasing antibiotic susceptibility and preventing the spread of antimicrobial resistance. The results demonstrate that CGA + UVA treatment could be used to effectively combat antibiotic-resistant bacteria and prevent the spoilage of preserved foods or food poisoning.

Molecular Insights on Coffee Components as Chemical Antioxidants

Coffee is not only a delicious beverage but also an important dietary source of natural antioxidants. We live in a world where it is impossible to avoid pollution, stress, food additives, radiation, and other sources of oxidants that eventually lead to severe health disorders. Fortunately, there are chemicals in our diet that counteract the hazards posed by the reactive species that trigger oxidative stress. They are usually referred to as antioxidants; some of them can be versatile compounds that exert such a role in many ways. This review summarizes, from a chemical point of view, the antioxidant effects of relevant molecules found in coffee. Their mechanisms of action, trends in activity, and the influence of media and pH in aqueous solutions, are analyzed. Structure-activity relationships are discussed, and the protective roles of these compounds are examined. A particular section is devoted to derivatives of some coffee components, and another one to their bioactivity. The data used in the analysis come from theoretical and computational protocols, which have been proven to be very useful in this context. Hopefully, the information provided here will pro-mote further investigations into the amazing chemistry contained in our morning coffee cup.   Resumen. El café no solo es una bebida deliciosa, sino también una importante fuente dietética de antioxidantes naturales. Vivimos en un mundo donde es imposible evitar la contaminación, el estrés, los aditivos alimentarios, la radiación y otras fuentes de oxidantes que eventualmente conducen a trastornos de salud graves. Afortunadamente, existen sustancias químicas en nuestra dieta que contrarrestan los peligros planteados por las especies reactivas que desencadenan el estrés oxidativo. Por lo general, se les denomina antioxidantes; algunos de ellos pueden ser compuestos versátiles que ejercen dicho papel de muchas maneras. Este artículo de revisión resume, desde un punto de vista químico, los efectos antioxidantes de moléculas relevantes encontradas en el café. Se analizan sus mecanismos de acción, tendencias en la actividad y la influencia del medio y el pH en soluciones acuosas. Se discuten las relaciones estructura-actividad, y se examinan los roles protectores de estos compuestos. Se dedica una sección particular a los derivados de algunos componentes del café, y otra a su bioactividad. Los datos utilizados en el análisis provienen de protocolos teóricos y computacionales, que han demostrado ser muy útiles en este contexto. Se espera que la información proporcionada aquí promueva investigaciones futuras sobre la química contenida en nuestra taza de café matutina.

Antibacterial Activity of Plants in Cirsium: A Comprehensive Review

As ethnic medicine, the whole grass of plants in Cirsium was used as antimicrobial. This review focuses on the antimicrobial activity of plants in Cirsium, including antimicrobial components, against different types of microbes and bacteriostatic mechanism. The results showed that the main antimicrobial activity components in Cirsium plants were flavonoids, triterpenoids and phenolic acids, and the antimicrobial ability varied according to the species and the content of chemicals. Among them, phenolic acids showed a strong antibacterial ability against Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterococcus faecium. The antibacterial mechanisms include: (1) damaging the cell membrane, cell walls, mitochondria and nucleus of bacteria; (2) inhibiting the synthesis of proteins and nucleic acids; (3) suppressing the synthesis of enzymes for tricarboxylic acid cycle pathways and glycolysis, and then killing the bacteria via inhibition of energy production. Totally, most research results on antimicrobial activity of Cirsium plants are reported based on in vitro assays. The evidence from clinical data and comprehensive evaluation are needed.

Photochemical Strategies toward Precision Targeting against Multidrug-Resistant Bacterial Infections

Infectious diseases pose a serious threat and a substantial economic burden on global human and public health security, especially with the frequent emergence of multidrug-resistant (MDR) bacteria in clinical settings. In response to this urgent need, various photobased anti-infectious therapies have been reported lately. This Review explores and discusses several photochemical targeted antibacterial therapeutic strategies for addressing bacterial infections regardless of their antibiotic susceptibility. In contrast to conventional photobased therapies, these approaches facilitate precise targeting of pathogenic bacteria and/or infectious microenvironments, effectively minimizing toxicity to mammalian cells and surrounding healthy tissues. The highlighted therapies include photodynamic therapy, photocatalytic therapy, photothermal therapy, endogenous pigments-based photobleaching therapy, and polyphenols-based photo-oxidation therapy. This comprehensive exploration aims to offer updated information to facilitate the development of effective, convenient, safe, and alternative strategies to counter the growing threat of MDR bacteria in the future.

Novel MAXPOWER biological antibacterial liquid for eradicating oral Helicobacter pylori

BACKGROUND

Eradication of oral Helicobacter pylori (H. pylori) not only reduces the infection rate from the transmission route but also improves the success rate of intragastric eradication. MAXPOWER Biological Bacteriostatic Liquid, developed in our previous work, is a composite biological preparation with strong antibacterial ability and unique antibacterial mechanism. The present study evaluated the efficacy of the MAXPOWER biocontrol solution on H. pylori and its success rate in eradicating oral H. pylori in clinical patients.

METHODS

Live-dead cell staining and hemolysis test were used to evaluate the cellular safety of MAXPOWER biocontrol solution; plate spreading, live-dead bacterial staining, and scanning electron microscopy methods were used to evaluate its antimicrobial effect against H. pylori. Transcriptomics was used to analyze the changes in H. pylori genes before and after treatment. After seven days of gavage treatment, H&E staining and mice feces were collected for 16SrDNA sequencing to evaluate the animals' safety. Oral H. pylori-positive patients were randomized to be given a placebo and MAXPOWER Bio-Bacteriostatic Liquid gargle for seven days to evaluate the effect on oral H. pylori eradication.

RESULTS

In vitro tests demonstrated that this product has excellent biocompatibility and hemocompatibility and can effectively eradicate oral H. pylori. In vivo tests further showed that it has good biosafety and virtually no adverse effect on intestinal microflora. Transcriptomics analysis revealed that it kills H. pylori cells mainly by disrupting their cell membranes and metabolism. Additionally, the results of randomized controlled trials on humans disclosed that the oral H. pylori eradication rates achieved by MAXPOWER Biological Antibacterial Liquid were 71.4% and 78.9% according to the intention-to-treat and the per-protocol analysis, respectively.

CONCLUSION

MAXPOWER Biological Antibacterial Liquid is both safe and efficacious in the eradication of oral H. pylori.

TRIAL REGISTRATION

This study was retrospectively registered in the ClinicalTrials.gov Trial Registry on 21/09/2023 (NCT06045832).

Ultrasonically functionalized chitosan-gallic acid films inactivate Staphylococcus aureus through envelope-disruption under UVA light exposure

The significant threat of foodborne pathogens contamination has continuously promoted the development of efficient antimicrobial food packaging materials. Here, an antimicrobial film was prepared with gallic acid-grafted-chitosan (CS/GA) that obtained by a two-step ultrasound method. The resultant films exhibited good transparency, improved UV barrier performance, and enhanced mechanical strength. Specifically, with the grafting of 1.2 % GA, the UV blocking ability of CS/GA film at 400 nm was significantly increased by 19.7 % and the tensile strength was nearly two times higher than that of CS film. Moreover, the CS/GA films exhibited an inspiring photoactivated bactericidal ability under 400 nm UVA light irradiation that eradicated almost 99.9 % of Staphylococcus aureus (S. aureus) cells within 60 min. To gain more insights into the antibacterial mechanism, the treated S. aureus cells were further investigated by visualizing bacterial ultrastructure and analyzing membrane properties. The results pointed to the peptidoglycan layer as the primary action target when bacteria come into contact with CS/GA films. Afterward, the intracellular oxidative lesions, disrupted bacterial integrity, and disordered membrane functional properties collectively resulted in eventual cell death. The findings revealed the unique peptidoglycan targeting and membrane disruptive mechanisms of CS/GA films, confirming the application values in controlling foodborne pathogens.

A new acridine-based photosensitizer with ultra-low light requirement efficiently inactivates carbapenem-resistant Acinetobacter baumannii and methicillin-resistant Staphylococcus aureus and degrades their antibiotic resistance genes

The spread of antibiotic resistant pathogens and antibiotic resistance genes (ARGs) in the environment poses a serious threat to public health. However, existing methods are difficult to effectively remove antibiotic resistant pathogens and ARGs from the environment. In this study, we synthesized a new acridine-based photosensitizer, 2,7-dibromo-9-mesityl-10-methylacridinium perchlorate (YM-3), by the heavy atom effect, which could photodynamically inactivate antibiotic resistant pathogens and reduce ARGs by generating singlet oxygen (¹O₂) in an aqueous environment. The ¹O₂ yield of YM-3 was 4.9 times that of its modified precursor. YM-3 could reduce the culturable number and even the viable counts of methicillin-resistant Staphylococcus aureus and carbapenem-resistant Acinetobacter baumannii to 0 (inactivation rate > 99.99999%) after 2 and 8 h of low-intensity blue light (15 W/m²) irradiation, respectively. After 20 h of light exposure, the copy numbers of ARGs in both bacteria were reduced by 5.80 and 4.48 log, respectively, which might indicate that ARGs had been degraded. In addition, YM-3 still had an efficient bactericidal effect after five inactivation cycle. These characteristics of ultra-low light intensity requirement and efficient bactericidal ability make YM-3 have good application prospects for disinfection in indoor and sunlight environment.

Chemical Characterization and Antimicrobial Properties of the Hydroalcoholic Solution of Echinacea purpurea (L.) Moench. and Propolis from Northern Italy

In this study, for the first time, the chemical composition of Echinacea purpurea (L.) Moench. and propolis (EAP) hydroalcoholic solution from the Trentino Alto Adige region of northern Italy was investigated by using SPME-GC-MS to describe the volatile content and GC-MS after silylation to detect the non-volatile compounds in the extractable organic matter. The antimicrobial activity of EAP hydroalcoholic solution was evaluated by Minimum Inhibitory Concentration (MIC) determination on 13 type strains, food and clinical isolates. Time Kill Kinetics (TKK) assays and the determination on swimming and swarming motility for 48 h gave more details on the mode of action of EAP solution. The results highlighted the presence of some terpenes and a large number of compounds belonging to different chemical classes. Among these, sugars and organic acids excelled. The EAP hydroalcoholic solution exhibited a strong antimicrobial activity in terms of MIC, with a clear decrease in the cellular load after 48 h. However, the bacterial motility may not be affected by the EAP treatment, displaying a dynamic swarming and swimming motility capacity over time. Given the complexity of chemical profile and the strong antimicrobial effectiveness, the EAP hydroalcoholic solution can be considered a source of bioactive molecules, deserving further investigation for the versatility of application.

Antiblood Cell Adhesion of Mussel-Inspired Chondroitin Sulfate- and Caffeic Acid-Modified Polycarbonate Membranes

We fabricated a mussel-inspired hemocompatible polycarbonate membrane (PC) modified by the cross-linking of chondroitin sulfate and caffeic acid polymer using CA-CS via a Schiff base and Michael addition reaction and named it CA-CS-PC. The as-fabricated CA-CS-PC membrane shows excellent hydrophilicity with a water contact angle of 0° and a negative surface charge with a zeta potential of -32 mV. The antiadhesion property of the CA-CS-modified PC membrane was investigated by enzyme-linked immunosorbent assay (ELISA), using human plasma protein fibrinogen adsorption studies, and proved to have excellent antiadhesion properties, because of the lower fibrinogen adsorption. In addition, the CA-CS-PC membrane also shows enhanced hemocompatibility. Finally, blood cell attachment tests of the CA-CS-PC membrane were observed by CLSM and SEM, and the obtained results proved that CA-CS-PC effectively resisted cell adhesion, such as platelets and leucocytes. Therefore, this work disclosed a new way to design a simple and versatile modification of the membrane surface by caffeic acid and chondroitin sulfate and apply it for cell adhesion.

Dual-Species Biofilms Formed by Escherichia coli and Salmonella Enhance Chlorine Tolerance

Outbreaks of Escherichia coli and Salmonella in food might be associated with the cross-contamination of biofilms on food-contact surfaces. The knowledge of the sanitization of mono-species biofilm on the food-contact surface is well established, while mixed-species biofilm occurs more naturally, which could profoundly affect the efficacy of sanitizer.

Phytochemistry, Pharmacology and Quality Control of Xiasangju: A Traditional Chinese Medicine Formula

As a traditional Chinese herbal formula, Xiasangju (XSJ) is widely used in China for antipyresis and influenza treatment. However, XSJ still fails to have a comprehensive summary of the research progress in the last decade. This review summarizes the advanced research on the extraction process, phytochemistry, pharmacological activity, and quality control of XSJ. Current research mainly focuses on quality control and the pharmacological effects of single herbs and active ingredients, but many pharmacological mechanisms of the formula are unclear. The development of active ingredients reflects the active characteristics of triterpenes, phenolic acids and flavonoids, but the hepatotoxicity of Prunella vulgaris L. has not been taken into account. XSJ has extensive historical practical experiences, while systematic clinical trials remain lacking. Therefore, it is necessary to study the active ingredients and define the mechanisms of XSJ to develop multiple applications, and further studies on the dose range between its hepatoprotective activity and hepatotoxicity are necessary to improve the safety of the clinical application. In this review, the current problems are discussed to facilitate the reference basis for the subsequent research on the development of XSJ and future application directions.

Potential Antimicrobial Properties of Coffee Beans and Coffee By-Products Against Drug-Resistant Vibrio cholerae

Vibrio cholerae is the causative organism of the cholera epidemic, and it remains a serious global health problem, particularly the multidrug-resistant strain, despite the development of several generic drugs and vaccines over time. Natural products have long been exploited for the treatment of various diseases, and this study aimed to evaluate the in vitro antibacterial activity of coffee beans and coffee by-products against V. cholerae antimicrobial resistant strains. A total of 9 aqueous extracts were investigated, including light coffee (LC), medium coffee (MC), dark coffee (DC), dried green coffee (DGC), dried red coffee (DRC), fresh red coffee (FRC), Arabica leaf (AL), Robusta leaf (RL), and coffee pulp (CP). The influential coffee phytochemicals, i.e., chlorogenic acid (CGA), caffeic acid (CA), and caffeine, were determined using HPLC. The antibacterial properties were tested by agar well-diffusion techniques, and the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were further determined against 20 V. cholerae isolates. The results revealed that all tested strains were sensitive to coffee extracts, with MIC and MBC values in the range of 3.125-25.0 mg/mL and 12.5-50.0 mg/mL, respectively. With a MIC of 6.25 mg/mL, DGC, DRC, and CP appeared to be the most effective compounds against 65, 60, and 55% of clinical strains, respectively. The checkerboard assay revealed that the combination of coffee extract and tetracycline was greater than either treatment alone, with the fractional inhibitory concentration index (FICI) ranging from 0.005 to 0.258. It is important to note that CP had the lowest FICI (0.005) when combined with tetracycline at 60 ng/mL, which is the most effective dose against V. cholerae six-drug resistance strains (azithromycin, colistin, nalidixic acid, sulfamethoxazole, tetracycline, and trimethoprim), with a MIC of 47.5 μg/mL (MIC alone = 12.5 mg/mL). Time killing kinetics analysis suggested that CA might be the most effective treatment for drug-resistant V. cholerae as it reduced bacterial growth by 3 log10 CFU/mL at a concentration of 8 mg/mL within 1 h, via disrupting membrane permeability, as confirmed by scanning electron microscopy (SEM). This is the first report showing that coffee beans and coffee by-product extracts are an alternative for multidrug-resistant V. cholerae treatment.

The Chemical Composition and Health-Promoting Effects of the Grewia Species-A Systematic Review and Meta-Analysis

Globally grown and organoleptically appreciated Grewia species are known as sources of bioactive compounds that avert the risk of communicable and non-communicable diseases. Therefore, in recent years, the genus Grewia has attracted increasing scientific attention. This is the first systematic review which focusses primarily on the nutritional composition, phytochemical profile, pharmacological properties, and disease preventative role of Grewia species. The literature published from 1975 to 2021 was searched to retrieve relevant articles from databases such as Google Scholar, Scopus, PubMed, and Web of Science. Two independent reviewers carried out the screening, selection of articles, and data extraction. Of 815 references, 56 met our inclusion criteria. G. asiatica and G. optiva were the most frequently studied species. We found 167 chemical compounds from 12 Grewia species, allocated to 21 categories. Flavonoids represented 41.31% of the reported bioactive compounds, followed by protein and amino acids (10.7%), fats and fatty acids (9.58%), ash and minerals (6.58%), and non-flavonoid polyphenols (5.96%). Crude extracts, enriched with bioactive compounds, and isolated compounds from the Grewia species show antioxidant, anticancer, anti-inflammatory, antidiabetic, hepatoprotective/radioprotective, immunomodulatory, and sedative hypnotic potential. Moreover, antimicrobial properties, improvement in learning and memory deficits, and effectiveness against neurodegenerative ailments are also described within the reviewed article. Nowadays, the side effects of some synthetic drugs and therapies, and bottlenecks in the drug development pathway have directed the attention of researchers and pharmaceutical industries towards the development of new products that are safe, cost-effective, and readily available. However, the application of the Grewia species in pharmaceutical industries is still limited.

Plant Bioactive Compounds as an Intrinsic and Sustainable Tool to Enhance the Microbial Safety of Crops

Outbreaks of produce-associated foodborne illness continue to pose a threat to human health worldwide. New approaches are necessary to improve produce safety. Plant innate immunity has potential as a host-based strategy for the deactivation of enteric pathogens. In response to various biotic and abiotic threats, plants mount defense responses that are governed by signaling pathways. Once activated, these result in the release of reactive oxygen and nitrogen species in addition to secondary metabolites that aim at tempering microbial infection and pest attack. These phytochemicals have been investigated as alternatives to chemical sanitization, as many are effective antimicrobial compounds in vitro. Their antagonistic activity toward enteric pathogens may also provide an intrinsic hurdle to their viability and multiplication in planta. Plants can detect and mount basal defenses against enteric pathogens. Evidence supports the role of plant bioactive compounds in the physiology of Salmonella enterica, Escherichia coli, and Listeria monocytogenes as well as their fitness on plants. Here, we review the current state of knowledge of the effect of phytochemicals on enteric pathogens and their colonization of plants. Further understanding of the interplay between foodborne pathogens and the chemical environment on/in host plants may have lasting impacts on crop management for enhanced microbial safety through translational applications in plant breeding, editing technologies, and defense priming.