Potent Antibacterial Activity Research Articles

Antibacterial Properties of Peptide and Protein Fractions from Cornu aspersum Mucus.

The discovery and investigation of new natural compounds with antimicrobial activity are new potential strategies to reduce the spread of antimicrobial resistance. The presented study reveals, for the first time, the promising antibacterial potential of two fractions from Cornu aspersum mucus with an MW < 20 kDa and an MW > 20 kDa against five bacterial pathogens-Bacillus cereus 1085, Propionibacterium acnes 1897, Salmonella enterica 8691, Enterococcus faecalis 3915, and Enterococcus faecium 8754. Using de novo sequencing, 16 novel peptides with potential antibacterial activity were identified in a fraction with an MW < 20 kDa. Some bioactive compounds in a mucus fraction with an MW > 20 kDa were determined via a proteomic analysis on 12% sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and bioinformatics. High homology with proteins and glycoproteins was found, with potential antibacterial activity in mucus proteins named aspernin, hemocyanins, H-lectins, and L-amino acid oxidase-like protein, as well as mucins (mucin-5AC, mucin-5B, mucin-2, and mucin-17). We hypothesize that the synergy between the bioactive components determined in the composition of the fraction > 20 kDa are responsible for the high antibacterial activity against the tested pathogens in concentrations between 32 and 128 µg/mL, which is comparable to vancomycin, but without cytotoxic effects on model eukaryotic cells of Saccharomyces cerevisiae. Additionally, a positive effect, by reducing the levels of intracellular oxidative damage and increasing antioxidant capacity, on S. cerevisiae cells was found for both mucus extract fractions of C. aspersum. These findings may serve as a basis for further studies to develop a new antibacterial agent preventing the development of antibiotic resistance.

Synthesis of 4-(3-(1-substituted/unsubstituted-phenyl-1H-1,2,3-triazole-4-yl)propoxy)benzaldehydes: In vitro antimicrobial, antimalarial activities and In silico docking study

In this work, we have developed new derivatives of 4-(3-(1-substituted/unsubstituted phenyl-1H-1,2,3-triazol-4-yl)propoxy)benzaldehydes 3(a-o) in good to excellent yield through the click reaction catalyzed by Copper(II) sulfate pentahydrate. 5-chloropent-1‑yne was used as an alkynylation reagent for 4-hydroxybenzaldehyde, whereas the aromatic azides were prepared from the corresponding diazonium salt by diazotization. All the newly synthesized derivatives were well characterized by FT-IR, 1H/ 13C NMR, high-resolution mass spectrometry and elemental analyses. These compounds were evaluated for their in vitro anti-microbial against six pathogenic strains as well as two pathogenic strains as anti-fungal activities using the broth dilution method. The activity results show that most of the compounds exhibit moderate to very good antibacterial and antifungal activities compared to the reference drugs. Furthermore, the in vitro antimalarial assay of synthesized compounds was screened against P. falciparum strain and then compared to Quinine and Chloroquine as the reference drugs. The results from the activity evaluation revealed that three out of fifteen compounds presented moderate efficacy when compared to Quinine. The structure-activity relationship (SAR) study indicated that substituted compounds with deactivating groups have potent antibacterial, antifungal, and antimalarial activities. Moreover, in silico molecular docking assay shows that 3 m is the most potent amongst 3(a-o) with a binding energy of -8.1 kcal/mol and -8.9 kcal/mol in the binding pocket of the receptor for bacterial and fungal infections, respectively compared to the standard drugs. The molecule 3 m has been studied in details for its ADMET properties and showed the most promise as a drug candidate.

Rapid in vitro activity of telavancin against Bacillus anthracis and in vivo protection against inhalation anthrax infection in the rabbit model.

Inhalation anthrax is the most severe form of Bacillus anthracis infection, often progressing to fatal conditions if left untreated. While recommended antibiotics can effectively treat anthrax when promptly administered, strains engineered for antibiotic resistance could render these drugs ineffective. Telavancin, a semisynthetic lipoglycopeptide antibiotic, was evaluated in this study as a novel therapeutic against anthrax disease. Specifically, the aims were to (i) assess in vitro potency of telavancin against 17 B. anthracis isolates by minimum inhibitory concentration (MIC) testing and (ii) evaluate protective efficacy in rabbits infected with a lethal dose of aerosolized anthrax spores and treated with human-equivalent intravenous telavancin doses (30 mg/kg every 12 hours) for 5 days post-antigen detection versus a humanized dose of levofloxacin and vehicle control. Blood samples were collected at various times post-infection to assess the level of bacteremia and antibody production, and tissues were collected to determine bacterial load. The animals' body temperatures were also recorded. Telavancin demonstrated potent bactericidal activity against all strains tested (MICs 0.06-0.125 μg/mL). Further, telavancin conveyed 100% survival in this model and cleared B. anthracis from the bloodstream and organ tissues more effectively than a humanized dose of levofloxacin. Collectively, the low MICs against all strains tested and rapid bactericidal in vivo activity demonstrate that telavancin has the potential to be an effective alternative for the treatment or prophylaxis of anthrax infection.

Alirocumab boosts antioxidant status and halts inflammation in rat model of sepsis-induced nephrotoxicity via modulation of Nrf2/HO-1, PCSK9/HMGB1/NF-ᴋB/NLRP3 and Fractalkine/CX3CR1 hubs

Acute kidney injury (AKI) is a devastating consequence of sepsis, accompanied by high mortality rates. It was suggested that inflammatory pathways are closely linked to the pathogenesis of lipopolysaccharide (LPS)-induced AKI. Inflammatory signaling, including PCSK9, HMGB1/RAGE/TLR4/MYD88/NF-κB, NLRP3/caspase-1 and Fractalkine/CX3CR1 are considered major forerunners in this link. Alirocumab, PCSK9 inhibitor, with remarkable anti-inflammatory features. Accordingly, this study aimed to elucidate the antibacterial effect of alirocumab against E. coli in vitro. Additionally, evaluation of the potential nephroprotective effects of alirocumab against LPS-induced AKI in rats, highlighting the potential underlying mechanisms involved in these beneficial actions. Thirty-six adult male Wistar rats were assorted into three groups (n=12). Group I; was a normal control group, whereas sepsis-mediated AKI was induced in groups II and III through single-dose intraperitoneal injection of LPS on day 16. In group III, animals were given alirocumab. The results revealed that LPS-induced AKI was mitigated by alirocumab, evidenced by amelioration in renal function tests (creatinine, cystatin C, KIM-1, and NGAL); oxidative stress biomarkers (Nrf2, HO-1, TAC, and MDA); apoptotic markers and renal histopathological findings. Besides, alirocumab pronouncedly hindered LPS-mediated inflammatory response, confirmed by diminishing HMGB1, TNF-α, IL-1β, and caspase-1 contents; the gene expression of PCSK9, RAGE, NF-ᴋB and Fractalkine/CX3CR1, along with mRNA expression of TLR4, MYD88, and NLRP3. Regarding the antibacterial actions, results showed that alirocumab displayed potential anti-bacterial activity against pathogenic gram-negative E. coli. In conclusion, alirocumab elicited nephroprotective activities against LPS-induced AKI via modulation of Nrf2/HO-1, PCSK9, HMGB1/RAGE/TLR4/MYD88/NF-ᴋB/NLRP3/Caspase-1, Fractalkine/CX3R1 and apoptotic axes.

Quantum sized blue light emitting ZnO nanoparticles: Synthesis, characterization and biomedical applications

The synthesis of zinc oxide nanoparticles via the hydrolysis and condensation method is described in this study. Characterization of the synthesized nanoparticles through X-ray diffraction, optical absorption, photoluminescence, and transmission electron microscopy discloses highly stable particles with an exceptionally small and uniform size distribution, showing a discrete quantum size effect. These nanoparticles show robust blue emission and demonstrate potent antibacterial activity against a spectrum of pathogenic bacteria, making them capable candidates for combating infectious diseases. Additionally, they display noteworthy anti-cancer properties against HT-29 colon cancer cell lines. This dual functionality of the ZnO nanoparticles holds significant promise for the development of affordable therapies in biomedical applications, as well as for potential applications in electronics.

Development of a natural product optimization strategy for inhibitors against MraY, a promising antibacterial target

MraY (phospho-N-acetylmuramoyl-pentapeptide-transferase) inhibitory natural products are attractive molecules as candidates for a new class of antibacterial agents to combat antimicrobial-resistant bacteria. Structural optimization of these natural products is required to improve their drug-like properties for therapeutic use. However, chemical modifications of these natural products are painstaking tasks due to complex synthetic processes, which is a bottleneck in advancing natural products to the clinic. Here, we develop a strategy for a comprehensive in situ evaluation of the build-up library, which enables us to streamline the preparation of the analogue library and directly assess its biological activities. We apply this approach to a series of MraY inhibitory natural products. Through construction and evaluation of the 686-compound library, we identify promising analogues that exhibit potent and broad-spectrum antibacterial activity against highly drug-resistant strains in vitro as well as in vivo in an acute thigh infection model. Structures of the MraY-analogue complexes reveal distinct interaction patterns, suggesting that these analogues represent MraY inhibitors with unique binding modes. We further demonstrate the generality of our strategy by applying it to tubulin-binding natural products to modulate their tubulin polymerization activities.

Enhancing Selective Antimicrobial and Antibiofilm Activities of Melittin through 6-Aminohexanoic Acid Substitution.

Leucine residues are commonly found in the hydrophobic face of antimicrobial peptides (AMPs) and are crucial for membrane permeabilization, leading to the cell death of invading pathogens. Melittin, which contains four leucine residues, demonstrates broad-spectrum antimicrobial properties but also significant cytotoxicity against mammalian cells. To enhance the cell selectivity of melittin, this study synthesized five analogs by replacing leucine with its structural isomer, 6-aminohexanoic acid. Among these analogs, Mel-LX3 exhibited potent antibacterial activity against both Gram-positive and Gram-negative bacteria. Importantly, Mel-LX3 displayed significantly reduced hemolytic and cytotoxic effects compared to melittin. Mechanistic studies, including membrane depolarization, SYTOX green uptake, FACScan analysis, and inner/outer membrane permeation assays, demonstrated that Mel-LX3 effectively permeabilized bacterial membranes similar to melittin. Notably, Mel-LX3 showed robust antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) and multidrug-resistant Pseudomonas aeruginosa (MDRPA). Furthermore, Mel-LX3 effectively inhibited biofilm formation and eradicated existing biofilms of MDRPA. With its improved selective antimicrobial and antibiofilm activities, Mel-LX3 emerges as a promising candidate for the development of novel antimicrobial agents. We propose that the substitution of leucine with 6-aminohexanoic acid in AMPs represents a significant strategy for combating resistant bacteria.

Emerging 2D Nanomaterials-Integrated Hydrogels: Advancements in Designing Theragenerative Materials for Bone Regeneration and Disease Therapy.

This review highlights recent advancements in the synthesis, processing, properties, and applications of 2D-material integrated hydrogels, with a focus on their performance in bone-related applications. Various synthesis methods and types of 2D nanomaterials, including graphene, graphene oxide, transition metal dichalcogenides, black phosphorus, and MXene are discussed, along with strategies for their incorporation into hydrogel matrices. These composite hydrogels exhibit tunable mechanical properties, high surface area, strong near-infrared (NIR) photon absorption and controlled release capabilities, making them suitable for a range of regeneration and therapeutic applications. In cancer therapy, 2D-material-based hydrogels show promise for photothermal and photodynamic therapies, and drug delivery (chemotherapy). The photothermal properties of these materials enable selective tumor ablation upon NIR irradiation, while their high drug-loading capacity facilitates targeted and controlled release of chemotherapeutic agents. Additionally, 2D-materials -infused hydrogels exhibit potent antibacterial activity, making them effective against multidrug-resistant infections and disruption of biofilm generated on implant surface. Moreover, their synergistic therapy approach combines multiple treatment modalities such as photothermal, chemo, and immunotherapy to enhance therapeutic outcomes. In bio-imaging, these materials serve as versatile contrast agents and imaging probes, enabling their real-time monitoring during tumor imaging. Furthermore, in bone regeneration, most 2D-materials incorporated hydrogels promote osteogenesis and tissue regeneration, offering potential solutions for bone defects repair. Overall, the integration of 2D materials into hydrogels presents a promising platform for developing multifunctional theragenerative biomaterials.

Synthesis and biological evaluation of 2-(2-hydrazinyl) thiazole derivatives with potential antibacterial and antioxidant activity

Heterocyclic systems containing 2-(2-hydrazinyl) thiazole moieties were synthesized by heterocyclization of thiosemicarbazones with arylglyoxals and Meldrum's acid in ethanol and water 1:1 (v/v) under reflux conditions. The paper reports an efficient, facile, and environmentally friendly protocol via a novel one-pot three-component reaction to access a broad range of 2-(2-Hydrazinyl) thiazole derivatives. Products were isolated by plate chromatography and their structures were established from their spectroscopic data, then the antibacterial and antioxidant activity of synthesized 2-(2-hydrazinyl) thiazole derivatives were evaluated, and demonstrated encouraging antibacterial activity against Staphylococcus aureus as a gram positive bacteria and Escherichia coli as a gram negative bacteria. Furthermore, when representative products were assessed for radical scavenging activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH0), high antioxidant effects were observed, indicating their potential safety for use in pharmacological studies.

Effects of ciprofloxacin and levofloxacin on initial colonization of intestinal microbiota in Bufo gargarizans at embryonic stages

Ciprofloxacin (CIP) and levofloxacin (LEV) are broad-spectrum antibiotics with potent antibacterial activity. Although many studies have shown that antibiotics can lead to gut microbiota disruption, the effects of CIP and LEV on gut microbial colonization at the embryonic stage remain poorly characterized. Here, we evaluated the response of Bufo gargarizans embryos in terms of gut microbiota colonization, growth and developmental stages to CIP and LEV exposure. Embryos treated with 100 μg/L CIP and LEV exhibited significantly reduced diversity and richness of the gut microbiota, as well as altered community structure. Both CIP and LEV treatments resulted in an increase in the pathogenic bacteria Bosea and Aeromonas, and they appeared to be more resistant to CIP than LEV. Additionally, CIP exposure caused reduced total length and delayed the development in B. gargarizans embryos, while LEV increased the total length and promoted embryonic development. The present study revealed the adverse effects of CIP and LEV exposure on host gut microbiota, growth and development during the embryonic stage, and contributed new perspectives to the evaluation of early aquatic ecological risk under CIP and LEV exposure.

Probiotic potential of Streptomyceslevis strain HFM-2 isolated from human gut and its antibiofilm properties against pathogenic bacteria

BackgroundAntimicrobial resistance (AMR) is a serious worldwide public health concern that needs immediate action. Probiotics could be a promising alternative for fighting antibiotic resistance, displaying beneficial effects to the host by combating diseases, improving growth, and stimulating the host immune responses against infection. This study was conducted to evaluate the probiotic, antibacterial, and antibiofilm potential of Streptomyces levis strain HFM-2 isolated from the healthy human gut.ResultsIn vitro antibacterial activity in the cell-free supernatant of S. levis strain HFM-2 was evaluated against different pathogens viz. K. pneumoniae sub sp. pneumoniae, S. aureus, B. subtilis, VRE, S. typhi, S. epidermidis, MRSA, V. cholerae, M. smegmatis, E. coli, P. aeruginosa and E. aerogenes. Further, the ethyl acetate extract from S. levis strain HFM-2 showed strong biofilm inhibition against S. typhi, K. pneumoniae sub sp. pneumoniae, P. aeruginosa and E. coli. Fluorescence microscopy was used to detect biofilm inhibition properties. MIC and MBC values of EtOAc extract were determined at 500 and 1000 µg/mL, respectively. Further, strain HFM-2 showed high tolerance in gastric juice, pancreatin, bile, and at low pH. It exhibited efficient adhesion properties, displaying auto-aggregation (97.0%), hydrophobicity (95.71%, 88.96%, and 81.15% for ethyl acetate, chloroform and xylene, respectively), and showed 89.75%, 86.53%, 83.06% and 76.13% co-aggregation with S. typhi, MRSA, S. pyogenes and E. coli, respectively after 60 min of incubation. The S. levis strain HFM-2 was susceptible to different antibiotics such as tetracycline, streptomycin, kanamycin, ciprofloxacin, erythromycin, linezolid, meropenem, amikacin, gentamycin, clindamycin, moxifloxacin and vancomycin, but resistant to ampicillin and penicillin G.ConclusionThe study shows that S. levis strain HFM-2 has significant probiotic properties such as good viability in bile, gastric juice, pancreatin environment, and at low pH; proficient adhesion properties, and antibiotic susceptibility. Further, the EtOAc extract of Streptomyces levis strain HFM-2 has a potent antibiofilm and antibacterial activity against antibacterial-resistant clinical pathogens.

The Antibacterial Efficacy of a Compound Extracted from Marine Sediment Bacterium Enterococcus Lactis (S-2): A Comparative Analysis Through In-Vitro and In-Silico Assessments.

Marine sediment bacteria have been generating considerable attention lately due to their potential as valuable reservoirs of novel antimicrobial agents. In vitro and in silico antibacterial activities of antibacterial compounds isolated from the marine sediment bacterium Enterococcus Lactis (S-2). Coastal sediment samples were collected from Rameswaram, Ramnathapuram District, Tamil Nadu, India. Bacteria were isolated using the crowded plate method, and their phenotypic and genotypic characteristics were studied. Purified bacteria were cultured in large volumes, secondary metabolites were extracted, and novel antibacterial agents were isolated from the aqueous extract. Novel compound antibacterial activity was studied through in-silico and invitro. The mechanism activity of antibacterial activity was confirmed by a high-resolution transmission electron microscope. Genotypic analysis confirmed that the isolated S-2 bacteria were Enterococcus lactis, and the aqueous extract showed antibacterial activity against Staphylococcus aureus (17 mm zone of inhibition) and Proteus mirabilis (12 mm zone of inhibition). A bioactive molecule, 13- hydroxy-9-(1-hydroxyethyl)-11-methoxy-2,4dioxapentacyclo[10.7.1.0³,⁴.0⁵,²¹.0¹³,¹⁶]icosa- 1(20),5,7,12,14(19), 16-hexane-18-one, was isolated from aqueous extracts of the S-2 bacterium. Chromatography and spectroscopic analysis confirmed the identity of the isolated compound. Novel compound potential antibacterial activity showing against S. aureus (18 mm zone of inhibition) and MIC 250 μg/mL, which was confirmed by tetrazolium staining. The antibacterial activity mechanism was confirmed by transmission electron microscopy. Molecular docking studies show good binding (-9.9 kcal/mol) of the compound with 3U2D, while molecular dynamic simulation studies confirm the conformationally stable structure of the complex between 3U2D and 13-hydroxy-9-(1-hydroxyethyl)-11-methoxy-2,4-dioxapentacyclo [10.7.1.0³,⁴.0⁵,²¹.0¹³,¹⁶]icosa-1(20),5,7,12,14(19), 16-hexane-18-one. It has been observed from the docking study of 3U2D with standard drug ciprofloxacin that the lower affinity is compared to the test ligand, which has a docking score of 7.3 kcal/mol. Out of interacting residues of protein 3U2D residue, Thr173 and Ile86 formed conventional hydrogen bonds. Marine bacterium E. lactis produces a novel antibacterial compound (13-hydroxy- 9-(1-hydroxyethyl)-11-methoxy-2,4-dioxapentacyclo[10.7.1.0³,⁴.0⁵,²¹.0¹³,¹⁶]icosa- 1(20),5,7,12,14(19),16-hexane-18-one), which shows antibacterial activity against clinical S. aureus, confirmed by in vitro and in silico analysis. This molecule can used as a lead molecule for antibacterial activity.

Neuroprotective Effects of Curcumin in Neurodegenerative Diseases.

Curcumin, a hydrophobic polyphenol extracted from the rhizome of Curcuma longa, is now considered a candidate drug for the treatment of neurological diseases, including Parkinson's Disease (PD), Alzheimer's Disease (AD), Huntington's Disease (HD), Multiple Sclerosis (MS), Amyotrophic Lateral Sclerosis (ALS), and prion disease, due to its potent anti-inflammatory, antioxidant potential, anticancerous, immunomodulatory, neuroprotective, antiproliferative, and antibacterial activities. Traditionally, curcumin has been used for medicinal and dietary purposes in Asia, India, and China. However, low water solubility, poor stability in the blood, high rate of metabolism, limited bioavailability, and little capability to cross the blood-brain barrier (BBB) have limited the clinical application of curcumin, despite the important pharmacological activities of this drug. A variety of nanocarriers, including liposomes, micelles, dendrimers, cubosome nanoparticles, polymer nanoparticles, and solid lipid nanoparticles have been developed with great success to effectively deliver the active drug to brain cells. Functionalization on the surface of nanoparticles with brain-specific ligands makes them target-specific, which should significantly improve bioavailability and reduce harmful effects. The aim of this review is to summarize the studies on curcumin and/or nanoparticles containing curcumin in the most common neurodegenerative diseases, highlighting the high neuroprotective potential of this nutraceutical.

Photocatalytic, antimicrobial and antibiofilm activities of MgFe2O4 magnetic nanoparticles

This study reports the antibacterial and antibiofilm activities of Magnesium ferrite nanoparticles (MgFe2O4) against gram-positive and gram-negative bacteria. The photocatalytic degradation of Carbol Fuchsin (CF) dye (a class of dyestuffs that are resistant to biodegradation) under the influence of UV-light irradiation is also studied. The crystalline magnesium ferrite (MgFe2O4) nanoparticles were synthesized using the co-precipitation method. The morphology of the resulting nanocomposite was examined using scanning electron microscopy (SEM), while transmission electron microscopy (TEM) was employed for further characterization of particle morphology and size. Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) were utilized to analyze the crystalline structure, chemical composition, and surface area, respectively. Optical properties were evaluated using UV–Vis spectroscopy. The UV-assisted photocatalytic performance of MgFe2O4 nanoparticles was assessed by studying the decolorization of Carbol fuchsin (CF) azo dye. The crystallite size of the MgFe2O4 nanoparticles at the (311) plane, the most prominent peak, was determined to be 28.5 nm. The photocatalytic degradation of 10 ppm CF using 15 mg of MgFe2O4 nanoparticles resulted in a significant 96% reduction after 135 min at ambient temperature (25 °C) and a pH value of 9. Additionally, MgFe2O4 nanoparticles exhibited potent antibacterial activity against E. coli and S. aureus in a dose dependent manner with maximum utilized concentration of 30 µg/ml. Specifically, MgFe2O4 nanoparticles demonstrated substantial antibacterial activity via disk diffusion and microbroth dilution tests with zones of inhibition and minimum inhibitory concentrations (MIC) for E. coli (26.0 mm, 1.25 µg/ml) and S. aureus (23.0 mm, 2.5 µg/ml), respectively. Moreover, 10.0 µg/ml of MgFe2O4 nanoparticles elicited marked percent reduction in biofilm formation by E. coli (89%) followed by S. aureus (78.5%) after treatment. In conclusion, MgFe2O4 nanoparticles demonstrated efficient dye removal capabilities along with significant antimicrobial and antibiofilm activity against gram-positive and gram-negative bacterial strains suggesting their potential as promising antimicrobial and detoxifying agents.

Biological potential of eight medicinal plants collected in the restored landscape after mining in South Kalimantan

Land restoration is expected to enhance the supply of valuable ecosystem resources such as herbaceous bushes and weeds. This study aimed to determine the primary phytochemical constituents and bioactivities of methanol extracts from eight bushes and weeds collected from a restored post-mining landscape in South Kalimantan, Indonesia. Qualitative phytochemical analysis showed the presence of phenolic compounds, flavonoids, tannins, alkaloids, steroids, terpenoids and saponins in the methanol extracts of herbaceous plants. Their antioxidant activity was measured by using the 2,2-diphenyl-1-picryl-hydrazyl-hydrate assay. Their superoxide dismutase (SOD) activity was also measured. In addition, selected plant extracts were screened against the common human pathogens Staphylococcus aureus and Candida albicans. Phytochemical analysis showed that the methanol extracts contained all the bioactive compounds examined in this study except the one from Lycopodium cernuum, which lacked flavonoids and alkaloids. Further investigation revealed that all methanol extracts except the one from L. cernuum had promising antioxidant potential. The methanol extracts from Chromolaena odorata (stem), Trema micrantha, Melastoma malabathricum (flower and leaf) and Thypa angustifolia exhibited effective antibacterial activity. In addition, the methanol extracts from M. malabathricum (flower and leaf), T. micrantha, Scleria sumatrensis and Breynia cernua (leaf) exhibited effective antifungal activity. M. malabathricum (flower and leaf) has the greatest potential as a herbaceous plant since its methanol extract exhibits the most potent antioxidant, antibacterial and antifungal activities.

Functionalized chitosan based antibacterial hydrogel sealant for simultaneous infection eradication and tissue closure in ocular injuries

Management of infections at ocular injury often requires prolonged and high dose of antibiotic, which is associated with challenges of antibiotic resistance and bacterial biofilm formation. Tissue glues are commonly used for repairing ocular tissue defects and tissue regeneration, but they are ineffective in curing infection. There is a critical need for antibacterial ocular bio-adhesives capable of both curing infection and aiding wound closure. Herein, we present the development of an imine crosslinked N-(2-hydroxypropyl)-3-trimethylammonium chitosan chloride (HTCC)‑silver chloride nanocomposites (QAm1-Agx) and poly-dextran aldehyde (PDA) based bactericidal sealant (BacSeal). BacSeal exhibited potent bactericidal activity against a broad spectrum of bacteria including their planktonic and stationary phase within a short duration of 4 h. BacSeal effectively reduced biofilm-embedded MRSA and Pseudomonas aeruginosa by ∼99.99 %. In ex-vivo human cornea infection model, BacSeal displayed ∼99 % reduction of ocular infection. Furthermore, the hydrogel exhibited excellent sealing properties by maintaining ocular pressure up to 75 mm-Hg when applied to human corneal trauma. Cytotoxicity assessment and hydrogel-treated human cornea with a retained tissue structure, indicate its non-toxic nature. Collectively, BacSeal represents a promising candidate for the development of an ocular sealant that can effectively mitigate infections and may assist in tissue regeneration by sealing ocular wounds.

Rational design of Bacteria-Targeted and Photo-Responsive MOF gel with antibacterial and anti-inflammatory function for infected wound healing

Damaged skin is prone to recurrent bacterial infections, which hinder proper wound healing and exacerbate inflammation. Urgent attention is required to devise versatile dressings possessing antibacterial and anti-inflammatory attributes to facilitate wound recovery. In this study, we engineered a photo-responsive metal–organic frameworks (MOFs) gel, targeting bacteria, and endowed it with antibacterial and anti-inflammatory effects to address infected wound healing. On the one hand, the anionic MOF was choose to support cationic natural drug Berberine (BBR) to achieve slow release of anti-inflammatory drugs. On the other hand, the incorporation of Ag nanoparticles onto MOFs not only facilitates the generation of reactive oxygen species (ROS) via photocatalysis under visible light but also furnishes sites for boric acid group attachment to target bacteria and expedites ROS transfer. The resultant MOFs@Ag-B@BBR exhibited potent photodynamic antibacterial activity against Staphylococcus aureus and MRSA at a low concentration of 37.5 µg mL−1, surpassing the efficacy of most reported MOFs-based nano-antimicrobials. Upon application of the MOFs@Ag-B@BBR composite hydrogel to infected wounds, the released BBR, in conjunction with photodynamic antibacterial action, significantly mitigated inflammatory responses and fostered wound healing. This study provides a widely applicable approach for rational design of MOFs materials with enhance antibacterial and anti-inflammatory functions.

Antibacterial activity of 3D printed thermoplastic elastomers doped with carbon quantum dots for biomedical applications

3D printing provides a lot of varieties for the manufacturing of personalized biomedical devices. Incorporation of the nanoparticles with potential antibacterial activity to the printed materials is another added value. One example of such nanoparticles are hydrophobic carbon quantum dots (hCQDs), which are zero-dimensional redox-active materials with high chemical stability and low production costs. They produce singlet oxygen only when activated by a specific wavelength of visible blue light which allows for controlled antibacterial action and minimizes the chances of bacterial resistance emergence. We prepared and characterized polymer composites based on thermoplastic elastomers (TPE) doped with hCQDs (TPE/hCQDs). The composites were 3D printed using fused deposition modeling method. In the first set of samples, a filament of pure TPE was immersed in a solution of hCQDs (0.5 mg/mL), then 3D printed, and compared with unmodified TPE filament. The mechanical properties, swelling behavior, hardness, and thermal stability of TPE/hCQDs were compared with the pure TPE printed samples. The production of singlet oxygen was confirmed by the electron paramagnetic resonance method. The antibacterial activity of the samples was tested according to ISO 22196 against Staphylococcus aureus and Escherichia coli after one hour of exposure to blue light, which completely inhibited bacterial growth. Besides, the cytotoxicity of samples was evaluated by MTT assay, and no significant effect of the materials on cell viability was observed. 3D printed materials with antibacterial activity represent a perspective for the future, especially in the field of personalized medicine, as well as in products for other industries.

Synthesis of acylated derivatives of alginate oligosaccharides and evaluation of their potential antibacterial activities against Staphylococcus aureus

Alginate oligosaccharides (AOS) are crucial carbohydrate-based biomaterial used in the synthesis of potential drugs and biological agents, but their antibacterial activities are not significant. In this study, AOS acylated derivatives were synthesized by grafting maleic anhydride (MA) onto AOS at varying ratios. Additionally, their inhibitory effects against Staphylococcus aureus were thoroughly investigated. Characterization of the AOS acylated derivatives (AOS-MA-x, where x = 1, 5, 10, and 20) was conducted using Fourier-transformed infrared spectroscopy, 1H nuclear magnetic resonance spectroscopy, and X-ray diffraction, which confirmed the successful synthesis of these derivatives. The bacteriostatic activity of the AOS-MA derivatives was assessed using growth curves and plate coating method, demonstrating significant antibacterial effects against S. aureus, as compared with AOS. Among these derivatives, AOS-MA-20 exhibited the most potent bacteriostatic activity and was selected for further investigation of its inhibitory mechanism. Scanning electron microscopy analysis revealed that treatment with AOS-MA-20 led to the lysis and rupture of S. aureus cells, expelling their intracellular contents. Moreover, AOS-MA-20 disrupted the integrity of cell wall and cell membrane, impacted ATPase activity, and inhibited the formation of biofilm to some extent, ultimately resulting in bacterial death. These findings lay a foundational framework for the development of environmentally friendly antimicrobial agents.

The chromatographic determination of the lipophilicity of newly synthesized aromatic-heterocyclic carbohydrazone derivatives with potential antibacterial and antituberculosis activities

Hydrazones are a large group of compounds with antibacterial, antituberculosis, antifungal, anticonvulsant, antiviral, antiprotozoal, anticancer and anti-inflammatory properties. Ten newly synthesized hydrazones were tested for their antimicrobial and antituberculosis activities. Screening tests were performed using the disk diffusion method. Then, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration were determined for the most promising compounds. Synergy of the action of the tested substances with reference drugs was also tested. Drugs standardly used in the treatment of tuberculosis: rifampicin and isoniazid were used as reference substances. Based on the obtained results, fractional inhibitory concentration coefficients were calculated for individual combinations. The tested ones showed weak antimicrobial activity. They didn’t show either synergism of action with rifampicin and isoniazid. Then, experimental and theoretical lipophilicity parameters were determined for the obtained derivatives. The research was carried out using reversed-phase high-performance liquid chromatography (RP-HPLC), in which the mobile phase is a mixture of methanol and water. To confirm the validity of the chromatographic technique used, both experimental and calculated lipophilicity parameters were correlated. The correlation matrix of these relationships was subjected to principal component analysis (PCA).