Recently, the demand for supplements based on natural products has grown and they are now part of the daily life of the general population. Studies suggest that supplements with high antioxidant activity have a vital role in the prevention of various diseases, such as hypercholesterolemia, a disease characterised by high blood cholesterol. Currently, the drugs available to treat hypercholesterolemia have some adverse side effects related to their chronic use. Therefore, food supplements are a viable alternative.

In this work, an aqueous avocado extract was studied to assess its potential in treating hypercholesterolaemia. Initially, the extract was characterised by HPLC-DAD and LC-HRMS/MS, where phenolic compounds such as chlorogenic acid, epicatechin and catechin were identified. Catechin was quantified as the major compound (12 mg catechin/100 mg dry extract). The antioxidant activity of the extract was also determined with an EC50 of 5.8 ± 0.2 µg/mL. To use this extract as a supplement, a delivery nanosystem was selected, namely albumin nanoparticles (NPs). NPs with 5, 10 and 15 mg of extract were formulated and characterised. NPs with 15 mg of extract were the largest (401 ± 4 nm). Whereas NPs with 5 mg of extract presented a higher encapsulation efficiency (81 ± 5 %). Finally, to assess the safety of the extract, toxicity tests were performed on an intestinal and hepatic cell line model, where the IC50 was 0.240 mg/mL and 0.165 mg/mL, respectively. The subsequent phase consists of evaluating the extract effect on the cholesterol permeability through a gastrointestinal barrier model.

Natural products are an essential source for obtaining versatile building blocks for various purposes. Many of these molecules are present in plant extracts and essential oils, which give them interesting physicochemical properties and relevant biological activities. From a chemical point of view, essential oils are synergistic volatile mixtures based essentially on phenolic compounds, terpenes and phenylpropanoids. Phenylpropanoids are an extremely promising class of lead compounds, into which eugenol, the major constituent of clove essential oil, fits perfectly.

Harnessing the potential of secondary metabolites provides an encouraging avenue for diverse research areas. For example, eugenol is a reasonable siderophore, capable of forming complexes with ferrous ions. From this perspective, it is possible to implement structural alterations to the respective molecules through synthetic processes, in order to enhance their ability to form complexes with other metal cations, namely by incorporating functional groups that have donor atoms that facilitate the formation of complexes.

In this way, it was possible to evaluate eugenol's ability to complex with various metal cations, by UV-vis spectroscopy, and to construct a series of azo dyes through the coupling reaction with diazonium salts of different aromatic amines. The new eugenol-based azo dyes as potential colored chelating agents were full characterized by the usual analytical techniques. The UV-vis properties with emphasis in solvent effects were studied and will be discussed.

Non-fluorescent azo dyes are extensively employed in advanced optical bioprobes, particularly those utilizing the Förster resonance energy transfer (FRET) mechanism. These probes find widespread application in protease activity assays, nucleic acid hybridization, and real-time PCRs, effectively quenching the fluorescence of energy donors. The unique photochemical properties of these dyes, such as the isomerization of the -N=N- moiety upon UV-vis irradiation, render them weakly or non-fluorescent, thereby enabling their use as fluorescence quenchers. Common examples of such quenchers include DABCYL and members of the Black Hole Quencher (BHQ) family, covering the spectrum from 480 nm to the near-infrared (NIR) region. Among them, BHQ-3, with a maximal absorbance at 672 nm, effectively overlaps the emission of the pentamethine cyanine (Cy5) fluorophore. Consequently, the Cy5/BHQ-3 FRET pair has been employed in various protease activity assays. Its effectiveness in deep tissue imaging is notable due to Cy5's far-red excitation and emission wavelengths (Exc. 650 nm, Em. 670 nm).

Following our research interests in developing nanoconstructed FRET-labeled peptide probes for real-time monitoring of proteases activity in therapy and medical imaging, we present the synthesis and characterization of the fluorescence quencher BHQ-3. It was synthesized via an azo-coupling reaction between an aryl-phenazonium salt and an N,N-substituted aniline functionalized with a primary amine, enabling its further conjugation to the C-terminal of a specific peptide via amide bond formation. Additionally, we investigated the quenching mechanism of the Cy5/BHQ-3 FRET pair through photometric and fluorimetric studies.

In this study, the ultrasound-assisted biosorption of Bemacid Red dye (BR) from an aqueous system using Casuarina Equisetifolia needles (CEP); an inexpensive, environmentally friendly, and efficient biosorbent, was evaluated. The biosorbent was characterized by the Fourier-transform infrared spectroscopy (FTIR), Scanning electronic microscopy (SEM), X-ray diffraction analysis (XRD), thermogravimetric analysis (TGA), and the point of zero charge (pHpzc). The effects of different analytical parameters; including contact time, initial dye concentration, biosorbent dosage, pH, and temperature, were investigated to optimize the biosorption process. Kinetic, thermodynamic, and isothermal biosorption studies were performed to elucidate the mechanisms and efficiency.

The elimination of BR was fast and efficient, with an equilibrium time of 7 minutes. The removal efficiency of BR increased with higher biosorbent dosage, initial dye concentration, and ionic strength but decreased with increasing pH, temperature, and particle size of the biosorbent.

The kinetic study was best represented by the pseudo-second-order model (R² = 0.99). Experimental data on dye biosorption onto CEP corresponded to the Sips model (R² = 0.98); which combines the Langmuir and Freundlich hypotheses. For thermodynamic parameters, the negative value of ΔH (∆H = -18.3 kJ/mol) suggests that the biosorption process is exothermic and that BR biosorption onto CEP has a pure physical nature. CEP is a suitable biosorbent for practical applications and holds potential for the development of purification and extraction technologies.

Fungal infections represent a significant public health issue, especially due to the rising number of immunocompromised patients and the growing incidence of drug-resistant fungal strains. Although traditional antifungal treatments are effective, they often suffer from drawbacks such as toxicity, a narrow range of activity, and the potential for resistance. Consequently, there is a crucial need to discover new antifungal agents with innovative mechanisms of action. In this regard, benzo[a]phenoxazines have surfaced as promising candidates.

Benzo[a]phenoxazines are a class of heterocyclic compounds known for their diverse biological activities, including antimicrobial, anticancer, and antiviral properties. Their unique structure, characterized by a fused aromatic system, imparts distinctive electronic and photophysical properties, making them attractive for various biomedical applications.

Given the interest of our research team in this type of compounds, in this work we present the synthesis, photophysical characterization, and evaluation of the potential antifungal activity of a series of benzo[a]phenoxazines. The UV-Vis absorption and fluorescence data revealed notable strong absorbance and significant fluorescence emission superior than 650 nm in water, indicative of their potential applicability in fluorescent labelling. Furthermore, the antifungal activity of the synthesized benzo[a]phenoxazines was assessed against Saccharomyces cerevisiae and the results were promising and provide clues to direct further studies.

Nanoparticles are known to have high specific surface area that accounts for an increased probability of their interaction with bacterial cells. Therefore, the application of silver(I) nanoparticles (AgNPs) and their nanocomposites as antimicrobial agents against drug-resistant bacterial strains appears to be prospective. A critical point for the advancement of AgNPs into clinical practice is a fundamental understanding of their behavior in biological systems, including protein binding and interaction with blood components, which reflects their toxicity. The latter is primarily determined by the physicochemical properties of AgNPs, namely their size, shape, surface chemistry, etc. Therefore, nanotoxicity may be substantially reduced through the manipulation of certain physicochemical characteristics of AgNPs, increasing their biocompatibility and hence paving the way for possible biomedical applications. In this study we have focused on estimating the binding affinity of the synthesized Ag(I) complexes of 2-(4,6-di-tert-butyl-2,3-dihydroxyphenylsulfanyl)-acetic acid and 4,6-di-tert-butyl-2,3-dihydroxybenzaldehyde isonicotinoyl hydrazone, as well as AgNPs derived thereof to bovine serum albumin (BSA) and hemoglobin by the fluorimetric method. Furthermore, cellular toxicity of the AgNPs towards human erythrocytes was measured in a hemolysis assay. Organosols formed by the Ag(I) complexes upon their reduction to AgNPs in acetonitrile and DMSO were characterized by the trasmission electron microscopy (TEM) method and atomic force microscopy (AFM).

Protein-based hydrogels have gained considerable interest due to their properties such us biocompatibility, nontoxic, biodegradability, renewable, inexpensive and easy to obtain. Hydrogel properties depend on temperature, polymer concentration, pH, crosslinking levels, salt concentrations and aging. Casein is a natural protein present in the bovine milk (about 80%) which exists in the form of various micelles, it is composed of α-s1, α-s2, and β- and κ-casein and tends to self-assembly. Casein based hydrogels are suitable for use in biomedical applications. Considering their potential applications in the field of medicine, in this work, we have the objective to find the best conditions to development a casein hydrogel with tetracaine hydrochloride such active compound. The tetracaine hydrochloride has anesthetic properties so would allow a painless and comfortable treatment for the patient. So, different hydrogel formulations were proposed. The selected components were casein, glycerol, tetracaine hydrochloride, potassium carbonate and sodium alginate. Stability test, apparent density, pH, moisture content and swelling test were investigated. The formulation that allowed us to obtain a hydrogel with the desired properties was composed of tetracaine hydrochloride 1%, casein 2%, glycerol 50%, sodium alginate 4% and potassium carbonate solution 18% (The percentages are expressed on a casein basis). Casein hydrogel showed potential for use as anesthetic in medicine.

The DFO, a special hexadentate chelator with three hydroxamate moieties, is a bifunctional para-thiocyanatobenzyl-decafluorobenzoate (p-SCN-Bn-Df), a significant next-generation ligand. The presence of the thiocyanate (-SCN) group, which is capable of hydrolysis and protonation processes. The aim of this study is to determine the stability of 1-(4-isothiocyanatophenyl)-3-[6,17-dihydroxy-7,10,18,21-tetraoxo-27-(n-acetylhydroxylamino)-6,11,17,22-tetraazaheptaeicosine] thiourea (p-SCN-Bn-Df) via RP-HPLC method. A variety of mobile phases were tested in various ratios of methanol: water, acetonitrile: water and phosphate buffer at various pH levels. However, when employing a mobile phase consisting of water to acetonitrile containing 0.1% TFA (05:95, v/v) in an isocratic manner, satisfactory separation and symmetric peaks were observed. In this method utilized Eclipsed C-18 column (5μm, 4.6 × 250 mm) with a flow rate 0.5 mL/min. The maximum absorption wavelength of p-SCN-Bn-Df at 254 nm was selected as detection wavelength. The retention time (t_R) of p-SCN-Bn-Df was found at 5.205 min. The ICH guideline was used to evaluate linearity, accuracy, precision, limit of detection (LOD), limit of quantitation (LOQ), specificity and system appropriateness criteria to validate the optimized chromatographic and spectrophotometric procedures. For accurate compound separation in pharmaceutical and environmental analyses, this phase is adaptable and often used. This study is useful of p-SCN-Bn-Df for evaluating QC parameters and chelation rates with different radioisotopes e.g. Zr-89.

The antibiotics and antifungal agents currently used in practical medicine are losing their effectiveness as a result of the rapid development of multidrug resistance in pathogenic microorganisms. In the context of this problem, modern medicine and veterinary medicine urgently need to discover new drugs and new medical technologies for the treatment of bacterial infections. Biological studies of pentacyclic triterpene acids, including ursolic and corosolic acids, over the last few decades have shown that these available secondary metabolites are active against many human bacterial and fungal pathogens. However, their antibacterial activity is much weaker compared to known anibiotics produced by bacteria and fungi. In order to enhance the antibacterial potential of natural tritepenes, we synthesised a series of new derivatives of ursolic and corosolic acids bearing aminoguanidinium and biguanidinium end fragments in the C-28 side chain. Guanidinium and biguanidinium groups are known to determine the chemical and physicochemical properties of biologically active substances. Many compounds containing guanidinium and biguanidinium moieties constitute an important class of therapeutic agents, including antibacterial and antifungal drugs. The introduction of guanidinium and biguanidinium moieties into triterpene acid molecules was carried out by guanylation and biguanylation of pre-synthesised carboxyamides of ursolic and corosolic acids containing terminal primary amino groups at C-28 of the alkane side chain. We found optimal guanylating and biguanylating reagents, which provided relatively mild reaction conditions and high yields of the target products.

Juglans regia (walnut tree) belong to Juglandaceae family the Juglans Genus, that is widely used in traditional medicine for its therapeutic effects. The purpose of the present work was to evaluate the in-vitro antifungal and antioxidant activity of ethanolic extracts prepared from Juglans regia bark using maceration and soxhelt methods and to determine the total phenolic compounds of the prepared extract.

The antifungal activity was evaluated against three strains of Candida albicans. The antioxidant activity was investigated using the DPPH and FRAP methods. Total phenolic compounds was determined using the Folin-Ciocalteau method.

The results of the antifungal activity study showed that Juglans regia bark ethanolic extracts were active against the three tested Candida albicans yeast strains with interesting MICs values (0.078 mg/ml). For both extract under study, the obtained results revealed appreciable radical scavenging activity with IC₅₀ of less than 0.02mg/ml, which remains below that of BHT (1.16 mg/ml) and vitamin C (0.048 mg/ml). While for the total phenolic compounds determination, the obtained results revealed a remarkable richness of the various extracts in total polyphenols whose content varies between 258 and 285 mg EAG/g of extract.

The obtained data confirmed the correlation between the total phenolic compounds and biological activities of medicinal plants extract. In addition, Juglans regia bark extracts demonstrate notable antifungal activity, which explains their use in traditional medicine and making them suitable for use in pharmaceutical preparations.