From the multitude of materials currently available on the market that can be used in the development of microparticles, sodium alginate has become one of the most studied natural anionic polymers that can be included in controlled-release pharmaceutical systems alongside other polymers due to its low cost, low toxicity, biocompatibility, biodegradability and gelatinous die-forming capacity in the presence of Ca2+ ions. In this review, we have shown that through coacervation, the particulate systems for the dispensing of drugs consisting of natural polymers are nontoxic, allowing the repeated administration of medicinal substances and the protection of better the medicinal substances from degradation, which can increase the capture capacity of the drug and extend its release from the pharmaceutical form.

The aim of this study was to determine the potential pharmaceutical applications of quercetin—a natural flavonoid compound with a polyphenolic structure—following its encapsulation in polymeric microspheres resistant to degradation. The microspheres were prepared from natural polymeric compounds (chitosan and sodium alginate) via a complex coacervation method, with the goal of protecting quercetin from the degradation reactions that can affect its bioactivity. After the microspheres were prepared, they were characterized using various analytical methods. The encapsulation efficiency (EE (%)), swelling index (idxSWL%), roughness (measured using confocal laser scanning microscopy—CLSM), and surface morphology (measured using scanning electron microscopy—SEM) were all analyzed. In addition, the release capacity of quercetin from the microspheres (mQrel%) and the antimicrobial activity of the microspheres were evaluated in vitro. Finally, a multivariate statistical analysis (MANOVA, p = 0.05, PCA, and AHC) was conducted. This analysis showed that chitosan–sodium alginate–quercetin microspheres (CAQ-Ms) entrap 86.91 ± 1.10–93.11 ± 0.72% quercetin; in vitro, 71.46 ± 0.25–91.06 ± 0.15% quercetin was released, and the swelling index was higher (6701.29 ± 0.39–10,009.30 ± 1.11%) in the phosphate-buffered solution with a pH of 7.4. The CLSM and SEM analyses showed that the polymer concentration in CAQ-Ms was increased, and the roughness and smoothness of the microspheres were also increased. SEM also showed that the external layer of CAQ-Ms was formed from chitosan and the internal layer was formed from sodium alginate. Antimicrobial tests showed that CAQ-Ms had antibacterial and antifungal effects on the analyzed strains and produced larger inhibition zones between 15.3 and 14.4 mm on Escherichia coli and between 13.3 and 14.2 mm on Candida albicans, and smaller inhibition zones, between 12.4 and 13.6 mm, on Staphylococcus aureus. According to the obtained results, after the multivariate statistical analysis, it can be observed that the best performance was presented by samples P1, P2, and P3. In conclusion, the method used for the formulation of CAQ-Ms was efficient because it enabled an increase in the solubility of quercetin in water and its protection against external and internal degradation in the gastrointestinal tract. This system can be further used to produce new pills for oral administration that are able to reach the small intestine, where they can then release loaded active drugs.

Five new complexes with metal cations (Mn2+, Fe3+, Co2+, Ni2+, and Cu2+) of monolacunary Keggin monovanado-deca-tungstophosphate, K8[PVW10O39]·15H2O, have been synthesised. The molar ratio of the combination between metal cations and K8[PVW10O39]·15H2O has been established to be 1:1, and its general molecular formulas were found to be: Kn[MPVW10O39(H2O)]·xH2O (n = 5 for M = Fe3+ and n = 6 for M = Mn2+, Co2+, Ni2+, and Cu2+). Optimal conditions for complexes’ synthesis (pH, temperature, and reaction time) have been determined. The characterisation of K8[PVW10O39]·15H2O and of its compounds Kn[MPVW10O39(H2O)]·xH2O have been performed using AAS, TG-DTA-DTG, UV-VIS, IR, Raman, and powder XRD methods. In UV spectra, two maximums of absorption were obtained, at 200 and 250 nm, characteristic of Keggin polycondensate compounds. The coordination of cations Ni2+, Co2+, and Cu2+ through oxygen atoms from K8[PVW10O39]·15H2O in an octahedron system has been reflected with VIS spectroscopy. All these methods have proved the compositions and structures of K8[PVW10O39]·15H2O and Kn[MPVW10O39(H2O)]·xH2O, their similarity with other vanadotungstophosphates, and their achievements in the Keggin class. Additionally, all analysis methods have shown an increase in the degree of structural symmetry and the thermal stability of a polyoxoanion complex after attaching metal cations compared to the monolacunary, K8[PVW10O39]·15H2O.

Study objectives: were evaluation of the content in bioactive compounds with antioxidant properties of the species Viola x wittrockiana Gams flowers, cultivated in the Bihor region of Romania. Materials and Methods: Viola x wittrockiana Gams flowers were harvested, dried, then prepared for to evaluate the phenolic and flavonoid contents and for determined antioxidant capacity by the following methods: DPPH and FRAP. Results – after determined the total polyphenolic compounds content the concentration found was contained between 2.5-4.52 mg GAE/100 g dry flowers and flavonoids were contained between 46.75-54.49 mg QE/100 g dry flowers garden pansies. Conclusions: strong correlation between the polyphenols and flavonoids content and antioxidant properties which have been evaluated at the extracts obtained from the pansy flowers have shown that the plant has inhibition capacity on DPPH reagent contained between 62.644 – 92.241% and antioxidant capacity which varies between 494.588-889.882 made by FRAP method.