A New Approach for Improving the Antibacterial and Tumor Cytotoxic Activities of Pipemidic Acid by Including It in Trimethyl-β-cyclodextrin

Different Drug Mobilities in Hydrophobic Cavities of Host-Guest Complexes between β-Cyclodextrin and 5-Fluorouracil at Different Stoichiometries: A Molecular Dynamics Study in Water

Cyclodextrins (CDs) are cyclic oligosaccharides able to form noncovalent water-soluble complexes useful in many different applications for the solubilization, delivery, and greater bioavailability of hydrophobic drugs. The complexation of 5-fluorouracil (5-FU) with natural or synthetic cyclodextrins permits the solubilization of this poorly soluble anticancer drug. In this theoretical work, the complexes between β-CD and 5-FU are investigated using molecular mechanics (MM) and molecular dynamics (MD) simulations in water. The inclusion complexes are formed thanks to the favorable intermolecular interactions between β-CD and 5-FU. Both 1:1 and 1:2 β-CD/5-FU stoichiometries are investigated, providing insight into their interaction geometries and stability over time in water. In the 1:2 β-CD/5-FU complexes, the intermolecular interactions affect the drug's mobility, suggesting a two-step release mechanism: a fast release for the more exposed and hydrated drug molecule, with greater freedom of movement near the β-CD rims, and a slow one for the less-hydrated and well-encapsulated and confined drug. MD simulations study the intermolecular interactions between drugs and specific carriers at the atomistic level, suggesting a possible release mechanism and highlighting the role of the impact of the drug concentration on the kinetics process in water. A comparison with experimental data in the literature provides further insights.

Host-Guest Interaction Study of Olmesartan Medoxomil with β-Cyclodextrin Derivatives

Olmesartan medoxomil (OLM) is a selective angiotensin II receptor antagonist used in the treatment of hypertension. Its therapeutic potential is limited by its poor water solubility, leading to poor bioavailability. Encapsulation of the drug substance by two methylated cyclodextrins, namely randomly methylated β-cyclodextrin (RM-β-CD) and heptakis(2,3,6-tri-O-methyl)-β-cyclodextrin (TM-β-CD), was carried out to overcome the limitation related to OLM solubility, which, in turn, is expected to result in an improved biopharmaceutical profile. Supramolecular entities were evaluated by means of thermoanalytical techniques (TG-thermogravimetry; DTG-derivative thermogravimetry), spectroscopic methods including powder X-ray diffractometry (PXRD), universal-attenuated total reflectance Fourier-transform infrared (UATR-FTIR) and UV spectroscopy, saturation solubility studies, and by a theoretical approach using molecular modeling. The phase solubility method reveals an AL-type diagram for both inclusion complexes, indicating a stoichiometry ratio of 1:1. The values of the apparent stability constant indicate the higher stability of the host-guest system OLM/RM-β-CD. The physicochemical properties of the binary systems are different from those of the parent compounds, emphasizing the formation of inclusion complexes between the drug and CDs when the kneading method was used. The molecular encapsulation of OLM in RM-β-CD led to an increase in drug solubility, thus the supramolecular adduct can be the subject of further research to design a new pharmaceutical formulation containing OLM, with improved bioavailability.

Characterization of Complexes between Imidacloprid and β-Cyclodextrin: Evaluation of the Toxic Activity in Algae and Rotifers

The development of new formulations can be driven by the knowledge of host–guest complexes using cyclodextrins which have the ability to include guest molecules within their hydrophobic cavities, improving the physicochemical properties of the guest. To rationally explore new pesticide formulations, the effects of cyclodextrins on the properties of such guest molecules need to be explored. Imidacloprid is a neonicotinoid systemic insecticide used worldwide. In this study, the inclusion complexes of Imidacloprid (IMI) with β-cyclodextrin (β-CD) were prepared in the solid state by co-precipitation and the physical mixing method, with a stoichiometry of 1:1 and 1:2 molar ratios. The obtained products, Imidacloprid:β-cyclodextrin inclusion complex (IMI:β-CD), were characterized in the solid state by Fourier transform-infrared (FT-IR) spectroscopy and X-ray powder diffractometry (XRD). In solution, the 1:1 stoichiometry for the inclusion complexes was established by the Job plot method, and the binding constant of IMI:β-CD was determined by UV–vis titration. The toxicity was determined in producers and primary consumers of the freshwater trophic chain, the green alga Raphidocelis subcapitata and the rotifer Brachionus calyciflorus, respectively. The results indicated that Imidacloprid forms inclusion complexes with CDs showing improved physicochemical properties compared to free Imidacloprid. The formation of the inclusion complex reduced the chronic toxicity in rotifers when IMI concentrations were close to those of environmental concern (tenths/hundredths of micromoles/L). Therefore, CD inclusion complexes could provide important advantages to be considered for the future industrial production of new formulations.

Inclusions of Pesticides by β-Cyclodextrin in Solution and Solid State: Chlorpropham, Monuron, and Propanil

Persistence and degradation are important factors in determining the safe use of such synthetic products, and numerous studies have been addressed to develop pesticide remediation methods aimed at ameliorating these features. In this frame, the use of different cyclodextrins (CDs) molecules has attracted considerable attention due to their well-known non-toxic nature, limited environmental impact, and capability to reduce the environmental and health risks of pesticides. CDs appear to be a valuable tool for the elimination of pesticides from polluted areas as well as for better pesticide formulations that positively influence their hydrolysis or degradation. The present work investigates the interaction between β-cyclodextrins and three commonly used pesticides (i.e., chlorpropham, monuron, and propanil) both in solution and in the solid state by means of UV-Vis, FT-IR, and X-ray powder diffractometry. We show that such interactions result in all three cases in the formation of inclusion complexes with a 1:1 stoichiometry and binding constants (K_b) of 369.9 M^-1 for chlorpropham, 292.3 M^-1 for monuron, and 298.3 M^-1 for propanil. We also report the energy-minimized structures in silico for each complex. Our data expand and complement the available literature data in indicating CDs as a low-cost and very effective tool capable of modulating the properties that determine the environmental fate of pesticides.

Cyclodextrin-Based Nanosponges as Perse Antimicrobial Agents Increase the Activity of Natural Antimicrobial Peptide Nisin

At present, antibiotic resistance is considered a real problem. Therefore, for decades scientists have been looking for novel strategies to treat bacterial infections. Nisin Z, an antimicrobial peptide (AMP), can be considered an option, but its usage is mainly limited by the poor stability and short duration of its antimicrobial activity. In this context, cyclodextrin (CD)-based nanosponges (NSs), synthesized using carbonyldiimidazole (CDI) and pyromellitic dianhydride (PMDA), were chosen for nisin Z loading. To determine the minimum inhibitory of nisin Z loaded on CD-NS formulations, agar well diffusion plates were used. Then, the bactericide concentrations of nisin Z loaded on CD-NS formulations were determined against Gram-positive (Staphylococcus aureus) and -negative (Escherichia coli) bacteria, using microdilution brain heart infusion (BHI) and tetrazolium salt 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT). The minimum and bactericide inhibitory values of the nisin complex with NSs were potentially decreased against both bacteria, compared with the nisin-free sample, while the nisin complex with β-CD showed lower antibacterial activity. The antimicrobial effect was also demonstrated by free NSs. Furthermore, the total viable counts (TVCs) antibacterial experiment indicated that the combination of nisin Z in both PMDA and CDI β-CD-based NSs, especially CDI, can provide a better conservative effect on cooked chicken meat. Generally, the present study outcomes suggest that the cross-linked β-CD-based NSs can present their own antimicrobial potency or serve as promising carriers to deliver and enhance the antibacterial action of nisin Z.

Synthesis of Mono-Amino Substituted γ-CD: Host–Guest Complexation and In Vitro Cytotoxicity Investigation

Cyclodextrins (CDs) are cyclic oligosaccharides which can trap hydrophobic molecules and improve their chemical, physical, and biological properties. γ-CD showed the highest aqueous solubility with the largest cavity diameter among other CD types. The current study describes a direct and easy method for nucleophilic mono-aminos to be substituted with γ-CD and tested for their ability to host the guest curcumin (CUR) as a hydrophobic drug model. The mass spectrometry and NMR analyses showed the successful synthesis of three amino-modified γ-CDs: mono-6-amino-6-deoxy-cyclodextrine (γ-CD-NH₂), mono-6-deoxy-6-ethanolamine-γ-cyclodextrine (γ-CD-NHCH₂CH₂OH), and mono-6-deoxy-6-aminoethylamino)-γ-cyclodextrin (γ-CD-NHCH₂CH₂NH₂). These three amino-modified γ-CDs were proven to be able to host CUR as native γ-CDs with formation constants equal to 6.70 ± 1.02, 5.85 ± 0.80, and 8.98 ± 0.90 mM⁻¹, respectively. Moreover, these amino-modified γ-CDs showed no significant toxicity against human dermal fibroblast cells. In conclusion, the current work describes a mono-substitution of amino-modified γ-CDs that can still host guests and showed low toxicity in human dermal fibroblasts cells. Therefore, the amino-modified γ-CDs can be used as a carrier host and be conjugated with a wide range of molecules for different biomedical applications, especially for active loading methods.

Comparative assessment of antimicrobial, antiradical and cytotoxic activities of cannabidiol and its propyl analogue cannabidivarin

Cannabidiol and cannabidivarin are phytocannabinoids produced by Cannabis indica and Cannabis sativa. Cannabidiol has been studied more extensively than its propyl analogue cannabidivarin. Therefore, we performed a battery of in vitro biological assays to compare the cytotoxic, antiradical and antibacterial activities of both cannabinoids. Potential mitochondrial metabolism alterations, DNA synthesis inhibition, and plasma membrane damage were studied by MTT assay, BrdU-ELISA and LDH assay of cancer and normal human cells exposed to cannabinoids. ABTS and DPPH assays were performed to observe the effects of the cannabinoids on free radicals. Microbial susceptibility tests were performed to study the activity of the cannabinoids in two bacterial species implicated in human infections, Escherichia coli and Staphylococcus aureus. The results showed that the cannabinoids induced medium levels of cytotoxicity in cancer and normal cells at concentrations ranging from 15.80 to 48.63 and from 31.89 to 151.70 µM, respectively, after 72 h of exposure. Cannabinoids did not exhibit a strong antioxidant capacity in scavenging ABTS or DPPH radicals. No evident differences were observed between the two cannabinoids in antimicrobial activity, except with respect to S. aureus, which showed greater susceptibility to cannabidiol than to cannabidivarin after 72 h of exposure.

Antibacterial Activities and Molecular Docking of Novel Sulfone Biscompound Containing Bioactive 1,2,3-Triazole Moiety

In this study, a new synthetic 1,2,3-triazole-containing disulfone compound was derived from dapsone. Its chemical structure was confirmed using microchemical and analytical data, and it was tested for its in vitro antibacterial potential. Six different pathogenic bacteria were selected. MICs values and ATP levels were determined. Further, toxicity performance was measured using MicroTox Analyzer. In addition, a molecular docking study was performed against two vital enzymes: DNA gyrase and Dihydropteroate synthase. The results of antibacterial abilities showed that the studied synthetic compound had a strong bactericidal effect against all tested bacterial strains, as Gram-negative species were more susceptible to the compound than Gram-positive species. Toxicity results showed that the compound is biocompatible and safe without toxic impact. The molecular docking of the compound showed interactions within the pocket of two enzymes, which are able to stabilize the compound and reveal its antimicrobial activity. Hence, from these results, this study recommends that the established compound could be an outstanding candidate for fighting a broad spectrum of pathogenic bacterial strains, and it might therefore be used for biomedical and pharmaceutical applications.

Natural Methoxyphenol Compounds: Antimicrobial Activity against Foodborne Pathogens and Food Spoilage Bacteria, and Role in Antioxidant Processes

The antibacterial and antioxidant activities of three methoxyphenol phytometabolites, eugenol, capsaicin, and vanillin, were determined. The in vitro antimicrobial potential was tested on three common foodborne pathogens (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus) and three food spoilage bacteria (Shewanella putrefaciens, Brochothrix thermosphacta, and Lactobacillus plantarum). The antioxidant assays were carried out for studying the free radical scavenging capacity and the anti-lipoperoxidant activity. The results showed that eugenol and capsaicin were the most active against both pathogens and spoilage bacteria. S. aureus was one of the most affected strains (median concentration of growth inhibition: IC50 eugenol = 0.75 mM; IC50 capsaicin = 0.68 mM; IC50 vanillin = 1.38 mM). All phytochemicals slightly inhibited the growth of L. plantarum. Eugenol was the most active molecule in the antioxidant assays. Only in the oxygen radical absorbing capacity (ORAC) test did vanillin show an antioxidant activity comparable to eugenol (eugenol ORAC value = 2.12 ± 0.08; vanillin ORAC value = 1.81 ± 0.19). This study, comparing the antimicrobial and antioxidant activities of three guaiacol derivatives, enhances their use in future applications as food additives for contrasting both common pathogens and spoilage bacteria and for improving the shelf life of preserved food.

Synthesis and antibiofilm activity of 1,2,3-triazole-pyridine hybrids against methicillin-resistant Staphylococcus aureus (MRSA)

Antibiotic-resistant bacteria are emerging at an alarming rate, posing a potential threat to human health. A series of 1,2,3-triazole-pyridine hybrids were synthesised as promising antibiofilm agents against planktonic and sessile MRSA.

Inspiration for revival of old drugs: improving solubility and avoiding hygroscopicity of pipemidic acid by forming two pharmaceutical salts based on charge-assisted hydrogen bond recognitions

Improving solubility and avoiding hygroscopicity of pipemidic acid by forming pharmaceutical salts based on CAHBs.

From pipemidic acid molecular salts to metal complexes and BioMOFs using mechanochemistry

Mechanochemistry has proven to be an excellent sustainable, efficient and fast tool for the discovery of new crystal forms of old drugs.

Encapsulation of Risperidone by Methylated β-Cyclodextrins: Physicochemical and Molecular Modeling Studies

Risperidone (RSP) is an atypical antipsychotic drug which acts as a potent antagonist of serotonin-2 (5TH2) and dopamine-2 (D2) receptors in the brain; it is used to treat schizophrenia, behavioral and psychological symptoms of dementia and irritability associated with autism. It is a poorly water soluble benzoxazole derivative with high lipophilicity. Supramolecular adducts between drug substance and two methylated β-cyclodextrins, namely heptakis(2,6-di-O-methyl)-β-cyclodextrin (DM-β-CD) and heptakis(2,3,6-tri-O-methyl)-β-cyclodextrin (TM-β-CD) were obtained in order to enhance RSP solubility and improve its biopharmaceutical profile. The inclusion complexes were evaluated by means of thermoanalytical methods (TG—thermogravimetry/DTG—derivative thermogravimetry/HF—heat flow), powder X-ray diffractometry (PXRD), universal-attenuated total reflectance Fourier transform infrared (UATR-FTIR), UV spectroscopy and saturation solubility studies. Job’s method was employed for the determination of the stoichiometry of the inclusion complexes, which was found to be 2:1 for both guest–host systems. Molecular modeling studies were carried out for an in-depth characterization of the interaction between drug substance and cyclodextrins (CDs). The physicochemical properties of the supramolecular systems differ from those of RSP, demonstrating the inclusion complex formation between drug and CDs. The RSP solubility was enhanced as a result of drug encapsulation in the CDs cavity, the higher increase being obtained with DM-β-CD as host; the guest–host system RSP/DM-β-CD can thus be a starting point for further research in developing new formulations containing RSP, with enhanced bioavailability.

Simultaneous improvement of ketoconazole solubility, antifungal and antibiofilm activity by multicomponent complexation

Background: A novel multicomponent complex (MC) of ketoconazole (KET) with β-cyclodextrin (β-CD) and N-acetylcysteine (NAC) was developed with the purpose of improving the solubility as well as the antifungal and antibiofilm activity of KET against Candida albicans. Results & methodology: The interactions among the components were studied using nuclear magnetic resonance, thermal analysis, powder x-ray diffraction, infrared spectroscopy and scanning electron microscopy. Phase-solubility studies demonstrated a considerable increase in the solubility of the MC. An enhancement in antibiofilm and antifungal activity of MC was determined against C. albicans by XTT assay and microbiological studies. Conclusion: This MC, with improvements in the drug pharmaceutical performance, might have an important potential in the development of new pharmaceutical formulations of KET.

M. Antunes A, André V. Bioactivity of Isostructural Hydrogen Bonding Frameworks Built from Pipemidic Acid Metal Complexes

We report herein three novel complexes whose design was based on the approach that consists of combining commercially available antibiotics with metals to attain different physicochemical properties and promote antimicrobial activity. Thus, new isostructural three-dimensional (3D) hydrogen bonding frameworks of pipemidic acid with manganese (II), zinc (II) and calcium (II) have been synthesised by mechanochemistry and are stable under shelf conditions. Notably, the antimicrobial activity of the compounds is maintained or even increased; in particular, the activity of the complexes is augmented against Escherichia coli, a representative of Gram-negative bacteria that have emerged as a major concern in drug resistance. Moreover, the synthesised compounds display similar general toxicity (Artemia salina model) levels to the original antibiotic, pipemidic acid. The increased antibacterial activity of the synthesised compounds, together with their appropriate toxicity levels, are promising outcomes.

Antimicrobial and antileukemic effects: in vitro activity of Calyptranthes grandifolia aqueous leaf extract

Natural products are still a promising source of bioactive molecules. Food and Drug Administration data showed that approximately 49% of the approved molecules originate naturally or chemically-resemble these substances, of which more than 70% are being used in anticancer therapy. It is noteworthy that at present there are no scientific studies to prove the effectiveness and safety of a number of plants used in folk medicine such as in the case of Calyptranthes grandifolia O. Berg (Myrtaceae) originally from South America. The aim of the present study was to determine the biological potential and toxicological effects of the aqueous leaf extract of C. grandifolia. The main detected phytoconstituents were condensed tannins and flavonoids and a high quantity of polyphenols. Regarding the antimicrobial potential, the extract exerted inhibitory activity against Pseudomonas aeruginosa. The results also revealed the extract induced DNA damage in a concentration-dependent manner in RAW 264.7 cells. In addition, C. grandifolia produced cytotoxicity in leukemia cell lines (HL60 and Kasumi-1) without affecting isolated human lymphocytes but significantly inhibited JAK3 and p38α enzyme activity. Taken together, these findings add important information on the biological and toxicological effects of C. grandifolia, indicating that aqueous extract may be a source of natural antimicrobial and antileukemic constituents.