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

Photodegradation of indomethacin and naproxen contained within commercial products for skin - RAP

Patient can be exposed to the photodegradation products of a drug after skin application of topical formulations. NSAIDs, with analgesic and anti-inflammatory properties, are known for the potential photoinstability, and are applied often in the form of creams, gels or liquids, commonly used among athletes, elderly people, geriatric patients and patients treated with multidrug therapies. Susceptibility to photodegradation hazard of those group arises the need for development of a new approach, with the ability to evaluate the patient safety. We planned to use a rapid assessment procedure (RAP) of safety by testing the photostability of popular skin medicinal products. This method, proposed many years ago by WHO, is now reintroduced to analytical applications in industry, when emergency drugs (e.g. for Covid) are implemented to the market in accelerated procedures. In the health care system, qualitative evaluation of drugs is extremely valuable, therefore we have planned to identify photodegradation using the FTIR method - infrared spectroscopy and DSC - differential scanning calorimetry, whilst the risk of formation of genotoxic products using the Ames test. We have successfully demonstrated that changes in the chemical structure and physical form of both pure APIs and drug products containing the API be assessed in a short time. Another advantage of our work is the combination of the developed results from FTIR/NIR spectra with statistical analysis. As a result, full and quick qualitative assessment of the effects of photoexposure of selected NSAIDs is performed, fortunately showing no mutagenicity. Due to the popularity of NSAIDs applied to the skin, a gel containing naproxen and spray with indomethacin were selected for testing. The analysis carried out for various formulations of both preparations allows us to demonstrate the universality of the applied RAP methods in assessing the risk of hazard to the patient, thus we present research results that expand or widen the knowledge and assessment of risks related to the use of drugs on the skin.

Synergistic Effects of Caffeine in Combination with Conventional Drugs: Perspectives of a Drug That Never Ages

Plants have been known since ancient times for their healing properties, being used as preparations against human diseases of different etiologies. More recently, natural products have been studied and characterized, isolating the phytochemicals responsible for their bioactivity. Most certainly, there are currently numerous active compounds extracted from plants and used as drugs, dietary supplements, or sources of bioactive molecules that are useful in modern drug discovery. Furthermore, phytotherapeutics can modulate the clinical effects of co-administered conventional drugs. In the last few decades, the interest has increased even more in studying the positive synergistic effects between plant-derived bioactives and conventional drugs. Indeed, synergism is a process where multiple compounds act together to exert a merged effect that is greater than that of each of them summed together. The synergistic effects between phytotherapeutics and conventional drugs have been described in different therapeutic areas, and many drugs are based on synergistic interactions with plant derivatives. Among them, caffeine has shown positive synergistic effects with different conventional drugs. Indeed, in addition to their multiple pharmacological activities, a growing body of evidence highlights the synergistic effects of caffeine with different conventional drugs in various therapeutic fields. This review aims to provide an overview of the synergistic therapeutic effects of caffeine and conventional drugs, summarizing the progress reported to date.

New Life of an Old Drug: Caffeine as a Modulator of Antibacterial Activity of Commonly Used Antibiotics

With the rapid and continuous emergence of antimicrobial resistance, bacterial infections became a significant global healthcare concern. One of the proposed strategies to combat multidrug-resistant pathogens is to use additional compounds, such as natural biologically active substances, as adjuvants for existing antibiotics. In this study, we investigated the potential of caffeine, the widely consumed alkaloid, to modulate the antibacterial effects of antibiotics commonly used in clinical practice. We used disc diffusion assay to evaluate the effects of caffeine on 40 antibiotics in two Staphylococcus aureus strains (methicillin-resistant and methicillin-sensitive). Based on the results of this step, we selected five antibiotics for which the greatest caffeine-induced improvements in antibacterial activity were observed, and further analyzed their interactions with caffeine using a checkerboard approach. Caffeine at concentrations of 250 µg/mL or higher halved the MIC values of ticarcillin, cefepime, gentamycin, azithromycin, and novobiocin for all gram-negative species investigated (Pseudomonas aeruginosa, Klebsiella pneumoniae, and Acinetobacter baumannii). At the highest caffeine concentrations tested (up to 16 mg/mL), decreases in MIC values were 8- to 16-fold. The obtained results prove that caffeine modulates the activity of structurally diverse antibiotics, with the most promising synergistic effects observed for cefepime and azithromycin toward gram-negative pathogens.

Interceptor potential of C60 fullerene aqueous solution: a comparative analysis using the example of the antitumor antibiotic mitoxantrone

We performed a qualitative and quantitative analysis of intermolecular interactions in aqueous solution between the antitumor antibiotic mitoxantrone and C₆₀ fullerene in comparison with interactions between the antibiotic and well-known aromatic molecules such as caffeine and flavin mononucleotide, commonly referred to as interceptor molecules. For these purposes, we obtained equilibrium hetero-association constants of these interactions using a UV/Vis titration experiment. Special attention was paid to the interaction of C₆₀ fullerene with mitoxantrone, which has been quantified for the first time. Based on the theory of interceptor-protector action and using a set of measured equilibrium constants we managed to estimate the relative biological effect of these mixtures in a model living system, taking human buccal epithelium cells as an example. We demonstrated that C₆₀ fullerene is able to restore the functional activity of the buccal epithelium cell nucleus after exposure to mitoxantrone, which makes it possible to use C₆₀ fullerene as regulator of medico-biological activity of the antibiotic.

Interaction of ionic liquids with human serum albumin in the view of bioconcentration: a preliminary study

Bioaccumulation potential is critical in PBT and risk assessment of chemicals. However, for ionic liquids (ILs), this aspect remains neglected. It is especially important to fill this gap, because for this group of compounds, existing data confirm their risk of being environmentally persistent and toxicity. Moreover, considering preliminary reports on the interactions of ILs with lipids, it may be assumed that ILs have a higher potential for bioaccumulation than indicated by previous estimations built upon octanol–water partition coefficients. Moreover, the bioconcentration of ionizable chemical compounds may also be strongly related to plasma protein contents. Therefore, in this work, the affinity of a set of imidazolium cations and organic anions, and their combination to human serum albumin (HSA) was determined. The obtained results reveal that both cations and anions can be strongly bound to HSA, and blood proteins might play an important role in overall bioaccumulation. Furthermore, it was observed that HSA binding properties towards IL cations depend on the hydrophobicity of cations. The obtained data also provide indication that cation–anion interaction may affect ILs ions affinity to HSA.

Cytogenetic effect of caffeine in the micronucleus test

Relevance. The consumption of caffeine-containing food in the modern world must necessarily be safe for humans, including should not affect the hereditary material of the body. Objective: to determine the possible effect of caffeine at the cytogenetic level by the micronucleus method on erythrocytes. Materials and Methods. The objects for the study were non-linear mice, which were divided into 6 groups - one control group and 5 experimental groups. The first experimental group and the second in the experiment received caffeine in doses of 40 mg/kg and 100 mg/kg.The control group received saline. Caffeine was administered orally. The mutagen (dioxidine) was injected intraperitoneally. On the 5th day of the experimental study, we performed blood sampling for cytogenetic analysis. Results and Discussion. Our study of the caffeine preparation made it possible to determine the following patterns. Firstly, when administered within 5 days, caffeine at a dose of 40 and 100 mg/kg did not cause an increase in the number of micronuclei in erythrocytes in mice. Secondly, the combined use of caffeine (both at a dose of 40mg/kgand at a dose of 100 mg / kg) and dioxidine significantly increased the level of micronuclei in comparison with the control group. Thirdly, caffeine at a dose of 40mg/kgdid not increase the mutagenic activity of dioxidine, but a dose of caffeine of 100mg/kgwhen combined with a mutagen led to a significant increase in the level of cytogenetic damage. Conclusion. According to our data, caffeine in the experimental study was not a mutagen, but at a dose of 100 mg/kg it represented a comutagenic effect.

Modulatory Effects of Caffeine and Pentoxifylline on Aromatic Antibiotics: A Role for Hetero-Complex Formation

Antimicrobial resistance is a major healthcare threat globally. Xanthines, including caffeine and pentoxifylline, are attractive candidates for drug repurposing, given their well-established safety and pharmacological profiles. This study aimed to analyze potential interactions between xanthines and aromatic antibiotics (i.e., tetracycline and ciprofloxacin), and their impact on antibiotic antibacterial activity. UV-vis spectroscopy, statistical-thermodynamical modeling, and isothermal titration calorimetry were used to quantitatively evaluate xanthine-antibiotic interactions. The antibacterial profiles of xanthines, and xanthine-antibiotic mixtures, towards important human pathogens Staphylococcus aureus, Enterococcus faecium, Escherichia coli, Acinetobacter baumannii, Klebsiella pneumoniae, and Enterobacter cloacae were examined. Caffeine and pentoxifylline directly interact with ciprofloxacin and tetracycline, with neighborhood association constant values of 15.8-45.6 M^-1 and enthalpy change values up to -4 kJ·M^-1. Caffeine, used in mixtures with tested antibiotics, enhanced their antibacterial activity in most pathogens tested. However, antagonistic effects of caffeine were also observed, but only with ciprofloxacin toward Gram-positive pathogens. Xanthines interact with aromatic antibiotics at the molecular and in vitro antibacterial activity level. Given considerable exposure to caffeine and pentoxifylline, these interactions might be relevant for the effectiveness of antibacterial pharmacotherapy, and may help to identify optimal treatment regimens in the era of multidrug resistance.

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.

Hetero-association models of non-covalent molecular complexation

The present review discusses the current state-of-the-art in building models enabling the description of non-covalent equilibrium complexation of different types of molecules in solution, which results in the formation of supramolecular structures different in length and composition (hetero-association or supramolecular multicomponent co-polymerisation). The description is focused on standard physical and chemical quantities such as experimental observables and equilibrium parameters of interaction (equilibrium constants and concentrations). The major partial cases of the hetero-association models, such as finite and indefinite isodesmic and cooperative complexations, and Benesi-Hildebrand and Langmuir adsorption models are considered. Future challenges in the development of the hetero-association models are provided.

In vitro study of the anticancer activity of various doxorubicin-containing dispersions

Introduction: The aim of this research was to study the impact of various doxorubicin (Dox)-containing nanofluids, e.g. singlewalled carbon nanotube (SWCNT)+Dox, graphene oxide (GO)+Dox and DextranPNIPAM (copolymer)+Dox mixtures on HeLa cells (human transformed cervix epithelial cells, as a model for cancer cells) depending on their concentration. Methods: Structural analysis of GO+Dox complex was accomplished using Hartree-Fock level of theory in 6-31G** basis set in Gaussian. Dynamic light scattering (DLS), zeta-potential, scanning electron microscopy and confocal laser scanning microscopy were used. The cell viability was analyzed by the MTT assay. Results: The viability of HeLa cells was studied with the MTT assay after the incubation with various Dox-containing dispersions depending on their concentration. The size of the particles was determined by DLS. The morphology of the nanoparticles (NPs) was studied by scanning electron microscopy and their uptake into cells was visualized by confocal laser scanning microscopy. It was found that the Dextran-PNIPAM+Dox nanofluid in contrast to Dox alone showed higher toxicity towards HeLa cells up to 80% after 24 hours of incubation, whereas the SWCNT+Dox and GO+Dox nanofluids at the same concentrations protected cells from Dox. Conclusion: The importance of Dextran-PNIPAM copolymer as a universal platform for drug delivery was established, and the huge potential of Dextran-PNIPAM+Dox NPs as novel anticancer agents was noted. Based on the in vitro study of the SWCNT+Dox and GO+Dox nanofluids, it was concluded that SWCNT and GO NPs can be effective cytoprotectors against the highly toxic drugs.

Does C60 fullerene act as a transporter of small aromatic molecules?

C₆₀ fullerene is reported to directly interact with biomolecules, such as aromatic mutagens or anticancer drugs. Therefore, it is extensively studied for its potential application in the fields of drug delivery and chemoprevention. Understanding the nature of fullerene-drugs interactions might contribute to optimization and modification of the existing chemotherapy systems. Possible interactions between ICR-191, a model acridine mutagen, with well-established biophysical properties and mutagenic activity, and C₆₀ fullerene aqueous solution were investigated by broad range of biophysical methods, such as Dynamic Light Scattering, Isothermal Titration Calorimetry, and Atomic Force Microscopy. Additionally, to determine biological activity of ICR-191-C₆₀ fullerene mixtures, Ames mutagenicity test was employed. It was demonstrated that C₆₀ fullerene interacts non-covalently with ICR-191 and has strong affinity to bacterial membranes. The obtained results provide practical insight into C₆₀ fullerene interactions with aromatic compounds.

Structural self-organization of C60 and cisplatin in physiological solution

The specific features of structural self-organization of C60 fullerene and antitumor drug cisplatin (Cis) in physiological solution (0.9% NaCl) have been investigated by means of small-angle neutron scattering, scanning electron and atomic force microscopies, as well as isothermal titration calorimetry, dynamic light scattering and UV-Vis spectroscopy. The formation of C60 + Cis complexes, has been reported, unveiling the mechanism of medico-biological synergy observed during administration of the mixture of these drugs.

Pentoxifylline as a modulator of anticancer drug doxorubicin. Part II: Reduction of doxorubicin DNA binding and alleviation of its biological effects

Anticancer drug doxorubicin is commonly used in cancer treatment. However, drug's severe side effects make toxicity reduction important matter. Another biologically active aromatic compound, pentoxifylline, can sequester aromatic compounds in stacking complexes reducing their bioactivity. This work deals with the problem of alleviating doxorubicin side effects by pentoxifylline. We employed a wide spectrum of prokaryotic and eukaryotic cellular assays. In addition, we used the doxorubicin-pentoxifylline mixed association constant to quantitatively assess pentoxifylline influence on the doxorubicin mutagenic activity. Obtained results indicate strong protective effects of pentoxifylline towards doxorubicin, observed on bacteria and human keratinocytes with no such effects observed on the cancer cells. It may be hypothesized that, considering much shorter half-life of pentoxifylline than doxorubicin, simultaneous administration of doxorubicin and pentoxifylline will lead to gradual release of doxorubicin from complexes with pentoxifylline to reach desired therapeutic concentration. Proposed results shed light on the possible doxorubicin chemotherapy modification and its side effects reduction without the loss of its therapeutic potential.

The stacking interactions of bipyridine complexes: the influence of the metal ion type on the strength of interactions

The strength of the stacking interactions in the bipy complexes of nickel, palladium, and platinum, [M(CN)2 bipy]2 (M = Ni, Pd, Pt), was calculated using the ωB97xD/def2-TZVP method. The results show that for all considered geometries, interactions are the strongest for platinum, and weakest for nickel complexes, as a result of higher dispersion contributions of platinum over the palladium and nickel complexes. It was also shown that strength of interactions considerably rises with an increase of the stacking overlap area. As a consequence of the favorable electrostatic term, the strength of interactions also rises when metal atom and cyano ligands are involved in the overlap with bipy ligand. The strongest interaction was calculated in the platinum complex, for the geometry that has overlap of metal and cyano ligands with bipy ligand with an energy of -39.80 kcal mol(-1). The energies for similar geometries of palladium and nickel complexes are -34.60 and -32.45 kcal mol(-1). These energies, remarkably, exceed the strength of the stacking interactions between organic aromatic molecules. These results can be of importance in all systems with stacking interactions, from materials to biomolecules.

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.

Characterization of C60 fullerene complexation with antibiotic doxorubicin

The aim of this paper was to provide the physico-chemical characterization of a key process leading to amplification of the antitumor effect of antibiotic Doxorubicin (Dox) in vivo and in vitro and occurring at the molecular level through complexation with C60 fullerene. A wide range of physico-chemical tools was used such as UV/Vis and NMR spectroscopies, atomic force microscopy, isothermal titration calorimetry and zeta-potential methods. The unusual thermodynamic behavior of the complexation process was reported, featuring unexpected and, to a certain extent, contradictory experimental observations. The explanation of the obtained results was proposed resulting in creation of a general view on aromatic drug binding with C60 fullerene. Based on these results some important practical outcomes for anticancer therapy were formulated.

Fine-tuning recA expression in Staphylococcus aureus for antimicrobial photoinactivation: importance of photo-induced DNA damage in the photoinactivation mechanism

Bacterial cell envelope is generally accepted as the primary target for a photo-induced oxidative stress. It is plausible that DNA damage occurs during the antimicrobial photoinactivation. Here we investigate the correlation between DNA damage and photoinactivation by evaluating the level of RecA-based DNA repair system in Staphylococcus aureus. By using exogenous photosensitizers (new methylene blue (NMB), toluidine blue O (TBO), 5,10,15,20-tetrakis(1-methyl-4-pyridinio)porphyrin tetra(p-toluenesulfonate) (TMPyP), zinc phthalocyanine (ZnPc), Rose Bengal (RB)) and ALA-induced endogenous porphyrin-dependent blue light (405 nm), several outcomes were observed: (i) an increase of DNA damage (from gel electrophoresis in DNA damage assay), (ii) an increase of recA expression (luminescence assay in recA-lux strain), and (iii) an increase of RecA protein level (Western blotting). When recA expression was repressed by novobiocin, or abolished by deleting the gene, S. aureus susceptibility towards photoinactivation was increased at approximately a hundred-fold. The absence of RecA increases DNA damage to yield bactericidal effect. In novobiocin-resistant mutant (gyrB), as opposed to wild type, neither RecA protein level nor cell’s susceptibility was affected by photoinactivation (when novobiocin is present). This is to suggest that GyrB-dependent inhibition mediated recA repression. Therefore, we have established the role of RecA in DNA damage during photoinactivation. With the use of rifampicin mutation frequency and Ames tests, we demonstrated that photoinactivation did not increase S. aureus mutagenesis and potentially is not mutagenic toward eukaryotic cells. The results suggest that the treatment is considered safe. In conclusion, we provide an evidence that recA inhibitor may serve as therapeutic adjuvant for antimicrobial photoinactivation. Clinical relevance of our findings warrants further investigations.