Synthesis, spectroscopic and theoretical studies of new quasi-podands from bile acid derivatives linked by 1,2,3-triazole rings

Quasi-Podands with 1,2,3-Triazole Rings from Bile Acid Derivatives: Synthesis, and Spectroscopic and Theoretical Studies

An innovative approach to producing derivatives of bile acids has been devised, utilizing the principles of "click" chemistry. By employing intermolecular [3 + 2] cycloaddition between the newly developed acyl propiolic esters of bile acids and the azide groups of 1,3,5-tris(azidomethyl)benzene, a novel class of quasi-podands featuring 1,2,3-triazole rings has been synthesized. Identifying and characterizing these six compounds involved comprehensive analysis through spectral techniques (1H NMR, 13C NMR, and FT-IR), mass spectrometry, and the PM5 semiempirical method. The synthesized compounds' pharmacotherapeutic potential has been evaluated, employing the Prediction of Activity Spectra for Substances (PASS) methodology. Additionally, molecular docking was performed for all molecules.

Efficient Antimicrobial Effect of Alginate-Catechol/Fe2+ Coating on Hydroxyapatite toward Oral Care Application

Reducing the formation of oral bacterial biofilms is critical to prevent common dental diseases. Though many strategies for restricting bacterial adhesion on tooth surfaces have been reported, a simple method for efficient oral bacteriostasis is still highly expected. Herein, we have proved a soft gel made of an alginate-catechol conjugate (SA-DA) and the ferrous cation (Fe²⁺) as an effective antibacterial coating on hydroxyapatite (HAP, a tooth model). As suggested by quartz crystal microbalance (QCM) measurements, SA-DA/Fe²⁺ coating possessed a high binding affinity to HAP without destruction by either immersion in artificial saliva or simulated tooth brushing. Significantly less protein (bovine serum albumin) and Streptococcus mutans (S. mutans, an oral bacterial model) could be found on HAP after coating with SA-DA/Fe²⁺, indicating that the prepared gel could resist well the adhesion of biofouling and microbes due to its hydrophilicity. Notably, such an antibacterial effect (around 70% S. mutans was inhibited) could be maintained for 3 d, which resulted from the extremely good stability of SA-DA/Fe²⁺ coating, as confirmed by QCM analysis. Our results may offer possibilities for developing applications in order to further improve oral hygiene.

Design, synthesis, spectral and theoretical study of new bile acid-sterol conjugates linked via 1,2,3-triazole ring

New four steroid conjugates have been prepared from bile acids and sterol derivatives using click chemistry method. The azide-alkyne Huisgen cycloaddition (intermolecular 1,3-dipolar cycloaddition) of the propargyl ester of lithocholic, deoxycholic, cholic acid as well as dehydrocholic acids and azide derivatives of cholesterol gave a new bile acid-sterol conjugates linked with a 1,2,3-triazole ring. Previously, bile acids were converted into bromoacetyl substituted derivatives by the reaction of propargyl esters of lithocholic, deoxycholic, cholic with bromoacetic acid bromide in toluene with TEBA and sodium hydride. All conjugates were obtained in good yields using an efficient synthesis method. The structures of all products were confirmed by spectral (¹H- and ¹³C NMR, and FT-IR) analysis, mass spectrometry (ESI-MS), as well as PM5 semiempirical methods. Estimation of the pharmacotherapeutic potential has been accomplished for the synthesized compounds on the basis of Prediction of Activity Spectra for Substances (PASS).

In vitro studies on the interactions of blood lipid level-related biological molecules with gallic acid and tannic acid

BACKGROUND

To provide the scientific evidence for a possible new mechanism of hypolipidemic effects of gallic acid (GA) and tannic acid (TA), the binding capacity of GA and TA with blood lipid level-related biological molecules, including fat, cholesterol and cholates, were investigated in vitro. Additionally, we attempted to study the interactions of cholates with GA and TA by spectroscopic methods, high-performance liquid chromatography electrospray-ionization mass spectrometry (HPLC-ESI-MS) analysis and molecular modeling studies.

RESULTS

Our results demonstrated that both GA and TA were capable of binding with the blood lipid level-related biological molecules in vitro. The fat-binding capacity of TA was 122.1% that of GA when the addition of polyphenol was 90 mg. The inhibitory effects of GA and TA on the cholesterol solubility in mixed micelles and liquid egg yolk exhibited a dose-dependent relationship (0.5-2.0 mg mL^-1 ). In cholate-binding tests, TA showed higher affinity for sodium cholate than GA at a concentration of 2.0 mg mL^-1 , while no significant difference in the affinity for sodium deoxycholate was found between GA and TA. Moreover, the data of spectroscopic methods, HPLC-ESI-MS analysis and molecular modeling studies indicated that GA and TA might precipitate cholates through hydrophobic interactions and intermolecular hydrogen bonds rather than covalent bonds.

CONCLUSION

The findings of the present study suggested that the binding capacity of GA and TA with blood lipid level-related biological molecules might play a crucial role in their hypolipidemic effects in animals. © 2019 Society of Chemical Industry.

Characterization of the direct interaction between apple condensed tannins and cholesterol in vitro

To provide the scientific evidences for a possible new hypocholesterolemic mechanism of apple condensed tannins (ACT), the direct interaction of ACT with cholesterol (CH) was investigated in the present study. Our results suggested that the quenching of ACT fluorescence by CH was carried out according to a static mechanism, while the interaction between ACT and CH in vitro was a spontaneous process. ACT were capable of binding with CH directly, and the CH-binding capacity (35.9-43.9%) of ACT remarkably enhanced with the increase of ACT concentration (0.5-2.0 mg proanthocyanidin B₂ equivalent/mL). Besides, spectroscopic methods and morphological analysis were used to characterize the ACT-CH coprecipitates, the findings indicated that ACT were able to precipitate CH via ionic interactions, hydrophobic interactions and intermolecular hydrogen bonds rather than covalent bonds. In conclusion, the direct interaction of ACT with CH might play a role in their CH-lowering effects in humans and animals.

Food-borne nanocarriers from roast beef patties for iron delivery

Fluorescent nanoparticles (FNs) from roast beef patties were characterized and used as nanocarriers for ferrous ions.

Synthesis, Structure, Surface and Antimicrobial Properties of New Oligomeric Quaternary Ammonium Salts with Aromatic Spacers

New dimeric, trimeric and tetrameric quaternary ammonium salts were accomplished by reaction of tertiary alkyldimethyl amines with appropriate bromomethylbenzene derivatives. A series of new cationic surfactants contain different alkyl chain lengths (C4-C18), aromatic spacers and different numbers of quaternary nitrogen atoms. The structure of the products was confirmed by spectral analysis (FT-IR, ¹H-NMR, ¹³C-NMR and 2D-NMR), mass spectroscopy (ESI-MS), elemental analysis, as well as PM5 semiempirical methods. Compound (21) was also analyzed using X-ray crystallography. Critical micelle concentration (CMC) of 1,4-bis-[N-(1-alkyl)-N,N-dimethylammoniummethyl]benzene dibromides (3-9) was determined to characterize the aggregation behavior. The antimicrobial properties of novel QACs (Quaternary Ammonium Salts) were examined to set their minimal inhibitory concentration (MIC) values against fungi Aspergillus niger, Candida albicans, Penicillium chrysogenum and bacteria Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa.

Pd- and Cu-catalyzed approaches in the syntheses of new cholane aminoanthraquinone pincer-like ligands

Cu- and Pd-catalyzed arylation of aminocholanes has been described for the first time. While this Cu-catalyzed protocol provides high yields in reactions of aminocholanes with iodoarenes, Pd catalysis was found to be preferable for the reactions of aminocholanes with dichloroanthraquinones. UV-vis titration of bis(cholanylamino)anthraquinones with a series of cations demonstrated their high binding affinity to Cu²⁺, Al³⁺, and Cr³⁺.

(3R,5S,7R,8R,9S,10S,12S,13R,14S)-10,13-Dimethyl-17-[5-oxo-5-(prop-2-yn-1-yloxy)pentan-2-yl]hexadecahydro-1H-cyclopenta[a]phenanthrene-3,7,12-triyl triacetate

In the title compound, C33H48O8, four terminal H atoms of cholic acid are replaced by three acetyl and one terminal alkyne group. All the acetyl residues are twisted with respect to the rings (A, B and C) to which they are attached. The cyclopentane ring D adopts an envelope conformation with the methyl-substituted C atom as the flap. Rings A, B and C have chair conformations. The dihedral angle between the mean planes of rings C and D is 4.70 (11)°. In the crystal, molecules are linked by C—H...O hydrogen bonds, forming a three-dimensional structure.

Designing, synthesis, and antimicrobial action of oxazoline and thiazoline derivatives of fatty acid esters

In this study, a novel series of oxazoline and thiazoline were designed as inhibitors of cytochrome P450 14 alpha-sterol demethylase (CYP51) from Candida albicans and peptide deformylase (PDF) of Escherichia coli. The long chain dibromo derivative of fatty acid esters on reaction with urea and thiourea gave their corresponding oxazolines and thiazolines, respectively. All the compounds were characterized by their spectral data (IR, ¹H NMR, ¹³C NMR and MS) and tested for antibacterial and antifungal activity by disk diffusion assay and minimum inhibitory concentration by the broth microdilution method against gram-positive and gram-negative strains of bacteria as well as fungus strains. The investigation into antimicrobial screening revealed that all the compounds were found to be potent antimicrobial agents. After calculating likeness drug properties of the compounds by Prediction of Activity Spectra for Substances software, ADMET-related descriptors were computed to predict the pharmacokinetic properties for the active and bioavailable compounds by discovery studio 2.5. Molecular docking studies have been performed on PDF of E. coli and CYP 450-14DM of C. albicans to understand the mode of binding of the molecules in the active site of the receptor. Compounds (2-amino-5-(carbomethoxyoctyl)-1,3-oxazoline, 2-amino-5-(carbomethoxyoctyl)-1,3-thiazoline and 2-amino-4-pentyl-5-[(8'R)-8' hydroxy (carbomethoxydecyl)-1,3-oxazoline) showed excellent antimicrobial activity nearly equivalent to the control compounds and compounds, 2-amino-4-octyl-5-(carbomethoxyheptyl)-1,3-oxazolin, 2-amino-4-(2'R)(2'-hydroxy octyl)-5-(carbomethoxyheptyl)-1,3-oxazoline and 2-amino-4-pentyl-5-[(8'R)-8'-hydroxy(carbomethoxy decyl)-1,3-oxazolineshowed vasodilation and antihypertensive properties. Furthermore, a computational analysis of physicochemical parameters revealed that the most of the compounds possessed drug-like attributes. Using Bioinformatics approach, we found a correlation between the observed and predicted antimicrobial activities.