Rifampicin (RIF) is a kind of semi-synthetic antibiotic with broad-spectrum antibacterial action, which has remarkable antibacterial activity against many pathogenic microorganisms. The World Health Organization classifies RIF as critically important for human medicine, especially for tuberculosis treatment. The polymorphic nature of RIF contributes to the complexity of the impurities of the drug. Lack of systematic and comparative studies on its impurities in different crystal forms may affect the efficiency of this drug and increase the incidence of adverse reactions. Current methods in pharmacopoeias and literature can only separate a limited number of known impurities, and the process of preparing the mobile phase is highly cumbersome. In this work, response surface methodology was employed to optimize the conditions of one-dimensional liquid chromatography (LC) as an alternative approach to pharmacopoeia methods. This method demonstrated high accuracy and sensitivity, enabling the quantification of impurities as low as 0.25 μg/mL. The proposed method provided satisfactory linearity, percentage of recovery from 88 to 101 % with relative standard, deviations (RSD) lower than 5 %, indicating good precision. Additionally, the parallel determination of 6 sample solutions showed that the content changes of the relevant components were within an acceptable range, demonstrating method repeatability. A detection method based on high-resolution two-dimensional LC-mass spectrometry (2D-LC-MS/MS) was developed to analyze. A total of 25 impurities were identified and the impurity profiles were systematically investigated for the first time, providing experimental basis for the quality control of the drug.

Rapid and precise identification of the pathogens causing sepsis remains a significant diagnostic challenge. Blood culture is time-consuming and insensitive, while molecular diagnostic techniques, such as the polymerase chain reaction (PCR), are fast but greatly influenced by template quality. Here, we present a new approach to separate trace amounts of pathogen DNA from blood, which utilizes lysozyme to destroy bacteria and release DNA, followed by enrichment and purification using magnetic nanoparticles (MNPs) modified with kanamycin (Kan) or tobramycin (TM). We demonstrate that the prepared Kan@MNPs and TM@MNPs can efficiently adsorb DNA, with the mechanism involving interaction with the minor groove of DNA. Notably, the adoption of lysozyme ensures bacterial lysis while avoiding damage to blood cells, minimizing the interference from human genomic DNA background and inhibitory components, thereby obtaining relatively pure bacterial DNA. For artificially infected whole blood samples, our method shortens the sample processing time to 35 min and achieves a 10-fold improvement in PCR sensitivity compared to a commercial kit. Through clinical evaluation of blood samples collected from suspected infected patients, we identified positive samples that were 100% consistent with the clinical practice. Therefore, this method holds promising potential for clinical application in advancing rapid sepsis diagnosis and earlier interventions.

DNA, vital for biological processes, encodes hereditary data for protein synthesis, shaping cell structure and function. Since revealing its structure, DNA has become a target for various therapeutically vital molecules, spanning antidiabetic to anticancer drugs. These agents engage with DNA-associated proteins, DNA-RNA hybrids, or bind directly to the DNA helix, triggering diverse downstream effects. These interactions disrupt vital enzymes and proteins essential for maintaining cell structure and function. Analysing drug-DNA interactions has significantly advanced our understanding of drug mechanisms. Glipizide, an antidiabetic drug, is known to cause DNA damage in adipocytes. However, its extract mechanism of DNA interaction is unknown. This study delves into the interaction between glipizide and DNA utilizing various biophysical tools and computational technique to gain insights into the interaction mechanism. Analysis of UV-visible and fluorescence data reveals the formation of complex between DNA and glipizide. The binding affinity of glipizide to DNA was of moderate strength. Examination of thermodynamic parameters at different temperatures suggests that the binding was entropically spontaneous and energetically favourable. Various experiments such as thermal melting assays, viscosity measurement, and dye displacement assays confirmed the minor grove nature of binding of glipizide with DNA. Molecular dynamics studies confirmed the glipizide forms stable complex with DNA when simulated by mimicking the physiological conditions. The binding was mainly favoured by hydrogen bonds and glipizide slightly reduced nucleotide fluctuations of DNA. The study deciphers the mechanism of interaction of glipizide with DNA at molecular levels.

Foodborne diseases caused by Staphylococcus aureus contamination on meat and meat products has gained increasing attention in recent years, while the pathogenicity of S. aureus is mainly attributed to its virulence factors production, which is primarily regulated by quorum sensing (QS) system. Herein, we aimed to uncover the inhibitory effects and mechanisms of citral (CIT) on virulence factors production by S. aureus, and further explore its potential application in pork preservation. Susceptibility test confirmed the antibacterial properties of CIT against S. aureus, the minimal inhibitory concentration (MIC) was 0.25 mg/mL. Treatment with sub-MICs of CIT reduced the hemolytic activity by inhibiting the production of α-hemolysin, and staphylococcal enterotoxins (SEs) production was significantly inhibited by CIT in both culture medium and pork without affecting bacterial growth. Transcriptomic analysis indicated that the differentially expression genes encoding α-hemolysin, SEs, and other virulence factors were down-regulated after treatment with 1/2MIC CIT. Moreover, the genes related to QS including agrA and agrC were also down-regulated, while the global transcriptional regulator sarA was up-regulated. Data here demonstrated that CIT could inhibited S. aureus virulence factors production through disturbing QS systems. In a challenge test, the addition of CIT caused a remarkable inhibition of S. aureus population and delay in lipid oxidation and color change on pork after 15 days incubation at 4 °C. These findings demonstrated that CIT could not only efficiently restrain the production of S. aureus virulence factors by disturbing QS, but also exhibit the potential application on the preservation of meat products.

This study aimed to prepare sodium alginate-linalool emulsion (SA-LE) to overcome the low solubility of linalool and explore its inhibitory activity against Shigella sonnei. The results indicated that linalool significantly reduced the interfacial tension between SA and oil phase (p < 0.05). Droplet sizes of fresh emulsions were uniform with sizes from 2.54 to 2.58 μm. The ζ-potential was between -23.94 and -25.03 mV, and the viscosity distribution was 973.62 to 981.03 mPa·s at pH 5-8 (near neutral pH) without significant difference. In addition, linalool could be effectively released from SA-LE in accordance with the Peppas-Sahlin model, mainly described by Fickian diffusion. In particular, SA-LE can inhibit S. sonnei with a minimum inhibitory concentration of 3 mL/L, which was lower than free linalool. The mechanism can be described as damaging the membrane structure and inhibiting respiratory metabolism accompanied by oxidative stress based on FESEM, SDH activity, ATP and ROS content. These results suggest that SA is an effective encapsulation strategy to enhance the stability of linalool and its inhibitory effect on S. sonnei at near neutral pH. Moreover, the prepared SA-LE has the potential to be developed as a natural antibacterial agent to address the growing food safety challenges.

This review summarizes the literature data reported from 2000 up to the present on the development of various electrochemical (voltammetric, amperometric, potentiometric and photoelectrochemical), optical (UV-Vis and IR) and luminescence (chemiluminescence and fluorescence) methods and the corresponding sensors for rifamycin antibiotics analysis. The discussion is focused mainly on the foremost compound of this class of macrocyclic drugs, namely rifampicin (RIF), which is a first-line antituberculosis agent derived from rifampicin SV (RSV). RIF and RSV also have excellent therapeutic action in the treatment of other bacterial infectious diseases. Due to the side-effects (e.g., prevalence of drug-resistant bacteria, hepatotoxicity) of long-term RIF intake, drug monitoring in patients is of real importance in establishing the optimum RIF dose, and therefore, reliable, rapid and simple methods of analysis are required. Based on the studies published on this topic in the last two decades, the sensing principles, some examples of sensors preparation procedures, as well as the performance characteristics (linear range, limits of detection and quantification) of analytical methods for RIF determination, are compared and correlated, critically emphasizing their benefits and limitations. Examples of spectrometric and electrochemical investigations of RIF interaction with biologically important molecules are also presented.

The thalidomide-DNA interactions have been investigated in detail by numerous biophysical techniques such as UV-vis, dye displacement assay, viscosity, cyclic voltammetry, circular dichroism, molecular docking, molecular dynamic simulation, FT-IR and ¹H NMR spectroscopy. CD spectroscopy, thermal denaturation and viscosity measurement explained that thalidomide is groove binder. Molecular docking analysis highlighted that thalidomide binds trough minor groove of calf thymus DNA which also confirmed from dye displacement experiment. To our knowledge, this is the first instance thalidomide was shown to binds with calf thymus DNA. Molecular dynamic simulation indicated that the thalidomide-DNA system was stabilized by electrostatic attraction as the main interaction and mode of binding is minor groove. Our study provides a better understanding to the DNA-thalidomide binding affinity and it mechanism. Overall, all these in formations can be used for further understanding the pharmacological effects of thalidomide.

Mycobacterium leprae, the causative organism of leprosy, harbors many antigenic proteins, and one such protein is the 18-kDa antigen. This protein belongs to the small heat shock protein family and is commonly known as HSP18. Its chaperone function plays an important role in the growth and survival of M. leprae inside infected hosts. HSP18/18-kDa antigen is often used as a diagnostic marker for determining the efficacy of multidrug therapy (MDT) in leprosy. However, whether MDT drugs (dapsone, clofazimine, and rifampicin) do interact with HSP18 and how these interactions affect its structure and chaperone function is still unclear. Here, we report evidence of HSP18-dapsone/clofazimine/rifampicin interaction and its impact on the structure and chaperone function of HSP18. These three drugs interact efficiently with HSP18 (having submicromolar binding affinity) with 1 : 1 stoichiometry. Binding of these MDT drugs to the 'α-crystallin domain' of HSP18 alters its secondary structure and tryptophan micro-environment. Furthermore, surface hydrophobicity, oligomeric size, and thermostability of the protein are reduced upon interaction with these three drugs. Eventually, all these structural alterations synergistically decrease the chaperone function of HSP18. Interestingly, the effect of rifampicin on the structure, stability, and chaperone function of this mycobacterial small heat shock protein is more pronounced than the other two MDT drugs. This reduction in the chaperone function of HSP18 may additionally abate M. leprae survivability during multidrug treatment. Altogether, this study provides a possible foundation for rational designing and development of suitable HSP18 inhibitors in the context of effective treatment of leprosy.

Herein, we describe the synthesis, structural elucidation, and DNA interaction of newly synthesized Cu(II) and Zn(II) complexes, i.e., [Cu(SB)(L-trp)(H₂O)₂]NO₃ (1) and [Zn(SB)(L-trp)(H₂O)₂]NO₃ (2) (SB = Schiff base obtained from the reaction between o-vanillin and 2-amino-2-methylpropane-1,3-diol; L-trp = L-tryptophan). From the analysis, a six-coordinated environment around the Cu(II) or Zn(II) center is proposed. The ability of the complexes to bind with calf thymus DNA was examined by optical spectroscopy (UV-vis titrations and steady-state fluorescence emission) and viscosity measurements. The vivid experimental results revealed that complexes 1 and 2 avidly bind to DNA through surface and groove binding modes, albeit with dissimilar intrinsic binding constants (1.54 × 10⁴ and 1.36 × 10⁴ M^-1 for 1 and 2, respectively). Both complexes can displace ethidium bromide (EB) to some extent from the intercalated EB-DNA system, resulting in fluorescence quenching. Additional experiments such as [Fe(CN)₆]^4--induced quenching and thermal melting confirmed the electrostatic and groove binding mode. Furthermore, molecular docking studies verified that both complexes locate in the DNA minor groove by surface binding and were stabilized through weak intermolecular forces. The binding affinity of the lowest energy docked pose was found to be -5.37 kcal/mol for complex 1 and - 5.18 kcal/mol for complex 2. The present work is expected to pave the way for the synthesis of DNA-targeting Cu(II)/Zn(II) metal complexes for the development of chemotherapeutic agents.

The interactions of dsDNA with rifampicin (RF) or with rifampicin after encapsulation in phospholipid micelles (nanosome/rifampicin) (NRF) were studied electrochemically. Screen-printed electrodes (SPEs) modified by stable dispersions of multi-wolled carbon nanotubes (MWCNTs) in aqueous solution of poly(1,2-butadiene)-block-poly(2-(dimethylamino)ethyl methacrylate) (PB₂₉₀-b-PDMAEMA₂₄₀) diblock copolymer were used for quantitative electrochemical investigation of direct electrochemical oxidation of guanine at E = 0.591 V (vs. Ag/AgCl) and adenine at E = 0.874 V (vs. Ag/AgCl) of dsDNA and its change in the presence of RF or NRF. Due to RF or NRF interaction with dsDNA, the differential pulse voltammetry (DPV) peak currents of guanine and adenine decreased and the peak potentials shifted to more positive values with increasing drug concentration (RF or NRF). Binding constants (K_b) of complexes RF-dsDNA and NRF-dsDNA were calculated based on adenine and guanine oxidation signals. The K_b values for RF-dsDNA were 1.48 × 10⁴ M^-1/8.56 × 10⁴ M^-1, while for NRF-dsDNA were 2.51 × 10⁴ M^-1/1.78 × 10³ M^-1 (based on adenine or guanine oxidation signals, respectively). The values of K_b revealed intercalation mode of interaction with dsDNA for RF and mixed type of interaction (intercalation and electrostatic mode) for NRF. The estimated values of ΔG (Gibbs free energy) of the complex formation confirmed that drug-dsDNA interactions are spontaneous and favourable reactions.

Recently, natural essential oils have been extensively studied for anti-bacterial application in foods due to their safety and high biological activity. Herein, Litsea cubeba essential oil (LC-EO) was applied as a natural anti-bacterial agent for exploring its anti-bacterial mechanism against Enterohemorrhagic Escherichia coli O157:H7 (EHEC O157:H7). The LC-EO could effectively inhibit the growth of EHEC O157:H7 and the minimal inhibitory concentration (MIC) was 0.5 mg/mL. In the study of anti-bacterial mechanism, the LC-EO was proved with good membrane penetration ability, which could destroy bacterial cell structure and disorder membrane permeability, thereby causing the leakage of intracellular organic matters. Furthermore, the inhibitory effects of LC-EO on physiological metabolism of EHEC O157:H7, including respiratory metabolism, enzyme activity, the replication of nucleic acid and the transcription level of main virulence genes (stx1, stx2, ehxA, eae), were also demonstrated in this study. Specially, the possible action mechanism of different components of LC-EO on bacterial genetic material was revealed deeply on molecular level by the molecular docking technology. Finally, the results of application evaluation indicated that the addition of LC-EO at MIC in different vegetable juices could maintain anti-bacterial rate above 99.9% for 4 days without remarkable influence on foods sensory quality. The information in this study provides the necessary theoretical foundation for extending the application of LC-EO in food preservation.

Magnetic Fe₃O₄ nanoparticles were synthesized successfully by co-precipitation method and characterized using XRD, SEM and EDS analyses. Then doxorubicin (DOX, a known anticancer drug) was loaded onto nanoparticles. In vitro DNA interaction of free DOX and loaded DOX onto Fe₃O₄ nanoparticles (DOX-Fe₃O₄) was investigated by DNA-viscosity measurements, UV-visible and fluorescence spectroscopies. The obtained values for binding constant of DOX and DOX-Fe₃O₄ compounds from UV-visible spectroscopies were 0.04 × 10⁵ and 0.68 × 10⁵ L mol^-1, respectively, which confirms DOX-Fe₃O₄ compound have a stronger interaction with CT-DNA compared to DOX. Considerable changes on viscosity of the compounds recommended that their binding mode with CT-DNA is intercalative binding. Fluorescence intensity of DOX and DOX-Fe₃O₄ was quenched via static process by regular addition of CT-DNA. Thermodynamic parameters suggest that Van der Waals forces and hydrogen bonding for DOX and electrostatic forces for DOX-Fe₃O₄ are predominantly responsible for interaction with CT-DNA. Competition fluorescence studies were done by Hoechst 33258 as a well-known groove binder and ethidium bromide (EtBr) as a known intercalator probe. Percentage of displacement for EtBr-DNA complex with DOX and DOX-Fe₃O₄ was 39% and 61%, and for Hoechst-DNA complex was 9% and 5%, respectively. These results confirmed that both compounds are intercalator binders, although DOX-Fe₃O₄ with a further 22% displacement is a stronger intercalator binder than DOX. The stronger interaction of DOX-Fe₃O₄ compared to DOX suggests that the current system can be used as a new and effective way to targeted therapy of anticancer drugs.

Dapsone is a sulfone drug mainly used as anti-microbial and anti-inflammatory agent for the treatment of various diseases including leprosy. Recently, its interaction with protein (bovine serum albumin) is evidenced. But, the binding propensity of this anti-mycobacterial drug towards DNA is still unknown. Also, the mode of dapsone-DNA interaction (if any) is still an unknown quantity. In this study, we have taken a thorough attempt to understand these two unknown aspects using various biophysical and in silico molecular docking techniques. Both UV-visible and fluorescence titrimetric studies indicated that dapsone binds to CT-DNA with a binding constant in order of 10⁴ M^-1. Circular dichroism, thermal denaturation and viscosity experiments revealed that dapsone binds to the grooves of CT-DNA. Competitive DNA binding studies clearly indicated the minor groove binding property of this anti-mycobacterial drug. Molecular docking provided detailed information about the formation of hydrogen bonding in the dapsone-DNA complex. This in silico study further revealed that dapsone binds to the AT-rich region of the minor groove of DNA having a relative binding energy of -6.22 kcal mol^-1. Overall, all these findings evolved from this study can be used for better understanding the medicinal importance of dapsone.