Complexation of norfloxacin with DNA in the presence of caffeine

Phytochemicals: A Promising Weapon in the Arsenal against Antibiotic-Resistant Bacteria

The extensive usage of antibiotics and the rapid emergence of antimicrobial-resistant microbes (AMR) are becoming important global public health issues. Many solutions to these problems have been proposed, including developing alternative compounds with antimicrobial activities, managing existing antimicrobials, and rapidly detecting AMR pathogens. Among all of them, employing alternative compounds such as phytochemicals alone or in combination with other antibacterial agents appears to be both an effective and safe strategy for battling against these pathogens. The present review summarizes the scientific evidence on the biochemical, pharmacological, and clinical aspects of phytochemicals used to treat microbial pathogenesis. A wide range of commercial products are currently available on the market. Their well-documented clinical efficacy suggests that phytomedicines are valuable sources of new types of antimicrobial agents for future use. Innovative approaches and methodologies for identifying plant-derived products effective against AMR are also proposed in this review.

The theory of interceptor-protector action of DNA binding drugs

The review discusses the theory of interceptor-protector action (the IPA theory) as the new self-consistent biophysical theory establishing a quantitative interrelation between parameters measured in independent physico-chemical experiment and in vitro biological experiment for the class of DNA binding drugs. The elements of the theory provide complete algorithm of analysis, which may potentially be applied to any system of DNA targeting aromatic drugs. Such analytical schemes, apart from extension of current scientific knowledge, are important in the context of rational drug design for managing drug's response by changing the physico-chemical parameters of molecular complexation.

Comparative study of binding interactions between porphyrin systems and aromatic compounds of biological importance by multiple spectroscopic techniques: A review

The specific spectroscopic and redox properties of porphyrins predestine them to fulfill the role of sensors during interacting with different biologically active substances. Monitoring of binding interactions in the systems porphyrin-biologically active compound is a key question not only in the field of physiological functions of living organisms, but also in environmental protection, notably in the light of the rapidly growing drug consumption and concurrently the production of drug effluents. Not always beneficial action of drugs on natural porphyrin systems induces to further studies, with commercially available porphyrins as the model systems. Therefore the binding process between several water-soluble porphyrins and a series of biologically active compounds (e.g. caffeine, guanine, theophylline, theobromine, xanthine, uric acid) has been studied in different aqueous solutions analyzing their absorption and steady-state fluorescence spectra, the porphyrin fluorescence lifetimes and their quantum yields. The magnitude of the binding and fluorescence quenching constants values for particular quenchers decreases in a series: uric acid > guanine > caffeine > theophylline > theobromine > xanthine. In all the systems studied there are characters of static quenching, as a consequence of the π-π-stacked non-covalent and non-fluorescent complexes formation between porphyrins and interacting compounds, accompanied simultaneously by the additional specific binding interactions. The porphyrin fluorescence quenching can be explain by the photoinduced intermolecular electron transfer from aromatic compound to the center of the porphyrin molecule, playing the role of the binding site. Presented results can be valuable for designing of new fluorescent porphyrin chemosensors or monitoring of drug traces in aqueous solutions. The obtained outcomes have also the toxicological and medical importance, providing insight into the interactions of the water-soluble porphyrins with biologically active substances.

Non-covalent interactions between thio-caffeine derivatives and water-soluble porphyrin in ethanol-water environment

To determine the binding interactions and ability to form the non-covalent systems, the association process between 5,10,15,20-tetrakis[4-(trimethylammonio)phenyl]-21H,23H-porphine tetra-p-tosylate (H₂TTMePP) and a series of five structurally diverse thio-caffeine analogues has been studied in ethanol and ethanol-water solutions, analyzing its absorption and steady-state fluorescence spectra. The porphyrin fluorescence lifetimes in the systems studied were established as well. During the titration with thio-caffeine compounds the slight bathochromic effect and considerable hypochromicity of the porphyrin Soret band maximum can be noted. The fluorescence quenching effect observed for interactions in H₂TTMePP - thio-caffeine derivative systems, as well as the order of binding and fluorescence quenching constants (of 10⁵-10³mol^-1) suggest the existence of the mechanism of static quenching due to the formation of non-covalent and non-fluorescent stacking complexes. In all the systems studied the phenomenon of the fractional accessibility of the fluorophore for the quencher was observed as well. Additionally, the specific binding interactions, due to the changes in reaction environment polarity, can be observed. It was found that thio-caffeine compounds can quench the porphyrin fluorescence according to the structure of thio-substituent in caffeine molecule. The obtained results can be potentially useful from scientific, therapeutic or environmental points of view.

Pentoxifylline as a modulator of anticancer drug doxorubicin. Part I: Reduction of doxorubicin DNA binding

Pentoxifylline--biologically active aromatic compound--has a well established capability to sequester aromatic ligands, such as an anticancer drug--doxorubicin--in mixed stacking aggregates. Formation of such hetero-complexes may influence biological activity of secluded drug. Presented work shows assessment of pentoxifylline influence on doxorubicin direct interactions with DNA employing biophysical methods. Achievement of this goal required statistical-thermodynamical model allowing numerical four-parameter analysis of experimental mixture--an issue that was successfully tackled by merging McGhee--von Hippel and Kapuscinski--Kimmel models. Results obtained with new model are well in agreement with data obtained with separate experiments with each of these two models and show reduction of doxorubicin in free (monomeric, dimeric) and complexed with DNA forms in favor of doxorubicin-pentoxifylline complexes with increasing pentoxifylline concentration. Developed model appears to be a universal tool allowing numerical analysis of mixtures containing self-aggregating ligand, DNA, and modulating agent.

Caffeine and other methylxanthines as interceptors of food-borne aromatic mutagens: inhibition of Trp-P-1 and Trp-P-2 mutagenic activity

Caffeine is one of the most important biologically active food components. In this article, we demonstrate that caffeine and other methylxanthines significantly reduce the mutagenic activity of two food-derived heterocyclic aromatic amines, Trp-P-1 and Trp-P-2 in the Salmonella typhimurium TA98 strain. Moreover, protection against Trp-P-1-induced mutagenicity was independent of liver S9 enzymatic fraction, suggesting that mechanisms other than modulation of mutagen bioactivation can contribute to the observed protective effects. UV-vis spectroscopy and computational studies revealed that methylxanthines intercept Trp-P-1 and Trp-P-2 in noncovalent molecular complexes, with association constants (KAC) in the 10(2) M(-1) range. Enthalpy values (ΔH about -30 kJ·mol(-1)) of mutagen-methylxanthine heterocomplexation obtained microcalorimetrically correspond to stacking (π-π) interactions. Finally, we demonstrated that the biological activity of Trp-P-1 and Trp-P-2 is strictly dependent on the presence of the mutagen in a free (unbound with methylxanthine) form, suggesting that mutagen sequestration in stacking heterocomplexes with methylxanthines can decrease its bioavailability and diminish its biological effects.

Heterocyclic Aromatic Amines Heterocomplexation with Biologically Active Aromatic Compounds and Its Possible Role in Chemoprevention

Food-borne heterocyclic aromatic amines (HCAs) are known mutagens and carcinogens present especially in Western population diet, which contains large amount of meat and its products. HCAs are capable of interacting with DNA directly through the formation of covalent adducts, however this process requires biological activation in liver, mainly by cytochrome P450 enzymes. This process may produce mutations and in consequence may contribute to the development of cancer. However, there are many studies showing that several biologically active aromatic compounds (BACs) may protect against genotoxic effects of HCAs. Direct interactions and noncovalent heterocomplexes formation may be one of the most important mechanisms of such protection. This work describes several BACs present in human diet, which are capable of molecular complexes formation with HCAs and protect cells as well as whole organisms against HCAs action.

Physicochemical Mechanisms of Synergistic Biological Action of Combinations of Aromatic Heterocyclic Compounds

The mechanisms of synergistic biological effects observed in the simultaneous use of aromatic heterocyclic compounds in combination are reviewed, and the specific biological role of heteroassociation of aromatic molecules is discussed.

Spectroscopic study of porphyrin-caffeine interactions

The association between water-soluble porphyrins: 4,4′,4″,4‴-(21 H,23 H-porphine-5,10,15,20-tetrayl)tetrakis-(benzoic acid) (H₂TCPP), 5,10,15,20-tetrakis(4-sulfonatophenyl)-21 H,23 H-porphine (H₂TPPS₄), 5,10,15,20-tetrakis[4-(trimethylammonio)phenyl]-21 H,23 H-porphine tetra-p-tosylate (H₂TTMePP), 5,10,15,20-tetrakis(1-methyl-4-pyridyl)-21 H,23 H-porphine tetra-p-tosylate (H₂TMePyP), the Cu(II) complexes of H₂TTMePP and H₂TMePyP, as well as chlorophyll a with caffeine (1,3,7-trimethylxanthine) has been studied analysing their absorption and emission spectra in aqueous (or acetone in case of chlorophyll a) solution. During the titration by caffeine the porphyrins absorption spectra undergo the evolution – the bathochromic effect can be observed as well as the hypochromicity of the Soret maximum. The association constants were calculated using curve-fitting procedure (K_AC of the order of magnitude of 10³ mol^-1). Whereas the emission spectra point at the presence of the fluorescence quenching effect testifying for the partial inactivation of the porphyrin molecule. The fluorescence quenching constants were calculated from Stern-Volmer plots. The results obtained show that caffeine can interact with water-soluble porphyrins and through formation of stacking complexes is able to quench their ability to emission.

General analysis of competitive binding in drug-interceptor-DNA systems

A general model of competitive binding in drug-interceptor-DNA systems has been developed in order to quantify both the interceptor and protector mechanisms. The model involves full parameterization of the basic equations governing the mutual competition between drugs binding to DNA and incorporates as partial cases various similar models existing in the literature. The generality of the model results from strict accounting of the statistical effects of the binding of the drug and interceptor with DNA according to the McGhee-von Hippel formalism, and to the strict treatment of hetero-association between the drug and interceptor, which includes formation of all possible types of self- and hetero-complexes in solution. Indirect experimental evidence is provided for the importance of the protector mechanism in drug-caffeine-DNA systems, which is sometimes ignored in the literature because of the small magnitude of the CAF-DNA binding constant.

Surface functionalization of polypropylene devices with hemocompatible DMAAm and NIPAAm grafts for norfloxacin sustained release

To improve the hemocompatibility and elution of antimicrobial agents for medical devices, N,N′-dimethylacrylamide (DMAAm) and N-isopropylacrylamide (NIPAAm) were sequentially grafted onto polypropylene (PP) films. Various (PP-g-DMAAm)-g-NIPAAm grafts were prepared using different time periods of irradiation while keeping the radiation dose constant. The hydrogel layer that formed on the surface of the PP was temperature-responsive (shifted from 32°C for NIPAAm to 37°C for the copolymer). The (PP-g-DMAAm)-g-NIPAAm films adsorbed serum albumin but not fibrinogen and had significantly lower hemolytic and thrombogenic activity. The DMAAm promoted the loading of norfloxacin (13.3 μg cm—2) when the hydrogel layer was swollen; as the NIPAAm shrank, a sustained delivery (∼6 h) occurred at body temperature. These functionalized PP films have potential as hemo- and cyto-compatible materials for medical devices and drug delivery products.

Quantification of the interceptor action of caffeine on the in vitro biological effect of the anti-tumour agent topotecan

Using published in vitro data on the dependence of the percentage of apoptosis induced by the anti-cancer drug topotecan in a leukaemia cell line on the concentration of added caffeine, and a general model of competitive binding in a system containing two aromatic drugs and DNA, it has been shown to be possible to quantify the relative change in the biological effect just using a set of component concentrations and equilibrium constants of the complexation of the drugs. It is also proposed that a general model of competitive binding and parameterization of that model may potentially be applied to any system of DNA-targeting aromatic drugs under in vitro conditions. The main reasons underpinning the proposal are the general feature of the complexation of aromatic drugs with DNA and their interaction in physiological media via hetero-association.

Neocarzinostatin as a probe for DNA protection activity--molecular interaction with caffeine

Neocarzinostatin (NCS), a potent mutagen and carcinogen, consists of an enediyne prodrug and a protein carrier. It has a unique double role in that it intercalates into DNA and imposes radical-mediated damage after thiol activation. Here we employed NCS as a probe to examine the DNA-protection capability of caffeine, one of common dietary phytochemicals with potential cancer-chemopreventive activity. NCS at the nanomolar concentration range could induce significant single- and double-strand lesions in DNA, but up to 75 ± 5% of such lesions were found to be efficiently inhibited by caffeine. The percentage of inhibition was caffeine-concentration dependent, but was not sensitive to the DNA-lesion types. The well-characterized activation reactions of NCS allowed us to explore the effect of caffeine on the enediyne-generated radicals. Postactivation analyses by chromatographic and mass spectroscopic methods identified a caffeine-quenched enediyne-radical adduct, but the yield was too small to fully account for the large inhibition effect on DNA lesions. The affinity between NCS chromophore and DNA was characterized by a fluorescence-based kinetic method. The drug-DNA intercalation was hampered by caffeine, and the caffeine-induced increases in DNA-drug dissociation constant was caffeine-concentration dependent, suggesting importance of binding affinity in the protection mechanism. Caffeine has been shown to be both an effective free radical scavenger and an intercalation inhibitor. Our results demonstrated that caffeine ingeniously protected DNA against the enediyne-induced damages mainly by inhibiting DNA intercalation beforehand. The direct scavenging of the DNA-bound NCS free radicals by caffeine played only a minor role.

Caffeine, pentoxifylline and theophylline form stacking complexes with IQ-type heterocyclic aromatic amines

Methylxanthines (MTX), in particular caffeine (CAF), are known as the most widely consumed alkaloids worldwide. Many accumulated statistical data indicate the protective effect of CAF intake against several types of cancer. One of the possible explanations of this phenomenon is direct non-covalent interaction between CAF and aromatic mutagen/carcinogen molecules through stacking (π-π) complexes formation. Here we demonstrate that CAF and other MTX, pentoxifylline (PTX) and theophylline (TH), form stacking complexes with carcinogenic imidazoquinoline-type (IQ-type) food-borne heterocyclic aromatic amines (HCAs). We estimated neighborhood association constants (K(AC) of the order of magnitude of 10(2)M(-1)) in neutral and acidic environment and enthalpy changes (ΔH values between -15.1 and -39.8kJ/mol) for these interactions using UV-Vis spectroscopy, calculations based on thermodynamical model of mixed aggregation and titration microcalorimetry. Moreover, using Ames test with Salmonella typhimurium TA98 strain and recently developed mutagenicity assay based on bioluminescence of Vibrio harveyi A16 strain, we demonstrated a statistically significant reduction in HCAs mutagenic activity in the presence of MTX.

Interaction of an anthracycline disaccharide with ctDNA: Investigation by spectroscopic technique and modeling studies

This study was designed to examine the interaction of an anthracycline disaccharide, 4'-O-(beta-L-oleandrosyl) daunorubicin (DNR-D2), with calf thymus deoxyribonucleic acid (ctDNA) by UV-vis in combination with fluorescence spectroscopy and molecular modeling techniques under physiological conditions (Britton-Robinson buffer solutions, pH 7.4). By the analysis of UV-vis and fluorescence spectrum, it was observed that the binding mode between DNR-D2 and ctDNA might be intercalation, and fluorescence quenching mechanism of DNR-D2 by ctDNA was a static quenching type. Upon binding to ctDNA, the anthraquinone chromophore of DNR-D2 could slide into the C-G rich region of ctDNA. Hydrogen bonding forces may play an essential role in the binding of DNR-D2 to ctDNA. Furthermore, the results obtained from computational modeling corroborated the experimental results obtained from spectroscopic investigations. These studies are valuable for a better understanding the datailed mode of DNR-D2-DNA interaction, which should be important in deeper insight into the therapeutic efficiency of DNR-D2.

De-intercalation of ethidium bromide and propidium iodine from DNA in the presence of caffeine

Caffeine (CAF) is capable of interacting directly with several genotoxic aromatic ligands by stacking aggregation. Formation of such hetero-complexes may diminish pharmacological activity of these ligands, which is often related to its direct interaction with DNA. To check these interactions we performed three independent series of spectroscopic titrations for each ligand (ethidium bromide, EB, and propidium iodine, PI) according to the following setup: DNA with ligand, ligand with CAF and DNA-ligand mixture with CAF. We analyzed DNA-ligand and ligand-CAF mixtures numerically using well known models: McGhee-von Hippel model for ligand-DNA interactions and thermodynamic-statistical model of mixed association of caffeine with aromatic ligands developed by Zdunek et al. (2000). Based on these models we calculated association constants and concentrations of mixture components using a novel method developed here. Results are in good agreement with parameters calculated in separate experiments and demonstrate de-intercalation of EB and PI molecules from DNA caused by CAF.

Caffeine: a potential complexing agent for solubility and dissolution enhancement of celecoxib

Complexation of caffeine with the drug celecoxib was used to enhance its solubility as well as in vitro dissolution in the present investigation. Caffeine was extracted from tea leaves using the sublimation method. A molecular complex (1:1) of caffeine-celecoxib was prepared using the solubility method. The solubility of celecoxib in distilled water and the caffeine complex was determined using a HPLC method at a wavelength of 250 nm. Dissolution studies of pure celecoxib, a marketed capsule (Celebrex), and the complex were performed using USP dissolution apparatus I for pure celecoxib and the complex and apparatus II for the capsule in distilled water. The highest solubility (48.32 mg/mL) as well as percent dissolution (90.54%) of celecoxib was obtained with the caffeine-celecoxib complex. The results for solubility and dissolution were highly significant as compared to pure celecoxib and the marketed capsule (p < 0.01). These results suggest that caffeine is a promising complexing agent for solubility as well as dissolution enhancement of the poorly soluble drug celecoxib.

Complexation of biologically active aromatic compounds with DNA in the presence of theophylline

(1)H NMR measurements (500 MHz) have been used to determine the equilibrium hetero-association constants of theophylline (THP) with various biologically active aromatic compounds (daunomycin, novantrone, ethidium bromide, proflavine, norfloxacin) and the complexation constants of THP with both single- and double-stranded oligonucleotides in solution. The results provide a quantitative estimation of the effect of THP on the binding of aromatic ligands with DNA, and a determination of the fraction of aromatic ligand removed from DNA on addition of THP.

Complexation of anthracycline drugs with DNA in the presence of caffeine

The competitive binding of anthracycline antitumour drugs, [daunomycin (DAU), doxorubicin (DOX) or nogalamycin (NOG)], with caffeine (CAF) to a model DNA oligomer has been investigated by 500 MHz 1H NMR spectroscopy under physiological solution conditions. The method depends on the stepwise analysis of one-component (self-association), two-component (hetero-association and DNA complexation) and three-component interactions, in order to de-convolute the overall binding of the anthracycline antibiotic and CAF to DNA into two competing processes, viz. hetero-association of the antibiotic-CAF ('interceptor' action of CAF) and CAF-DNA complexation ('protector' action of CAF). It is found that the complexation of DAU with DNA in the presence of CAF is mainly affected by the CAF-DNA complexation, whereas the binding of either DOX or NOG to DNA is affected approximately equally by both the CAF-DNA complexation and CAF-antibiotic hetero-association. Quantitative evaluation of the three-component mixture of drug-CAF-DNA has enabled the proportion of the antibiotic displaced from DNA on addition of CAF to be calculated over a large range of CAF concentration, which may provide a quantitative basis for the change in anthracycline-related toxicity on addition of CAF.