In this study, the efficacy of different extraction techniques (maceration, ultrasound-assisted and Soxhlet extraction) on the content of biologically active components in extracts from fresh and dried nettle leaves, and their antioxidant activity were analyzed. Methanol was used as the solvent. Total phenolic content and antioxidant capacity were determined by Folin-Ciocalteu, DPPH and FRAP methods, respectively. High content of total phenolic compounds and high antioxidant activity were recorded in extracts of dried nettle. Extracts obtained from fresh nettle samples showed significantly lower content of analyzed bioactive components and lower antioxidant activity. In the case of all extracts, Soxhlet extraction proved to be the most efficient, and maceration the least efficient extraction technique for isolation of bioactive components from nettle leaves.

In this work, four silver(I) complexes with Schiff bases derived from ninhydrin and selected amino acids (methionine, histidine, cysteine, and phenylalanine) were synthesized. The aim of this study is to determine the potential biological activity of these complexes. FTIR and UV/VIS spectroscopy were used for structural characterization of the products. Antioxidant activity was examined in vitro using DPPH method. Antimicrobial screening was performed by diffusion technique on reference bacterial strains from the ATCC collection. Interaction with bovine serum albumin (BSA) was examined using UV/VIS spectroscopy. Based on the obtained spectral data, it is assumed that all Schiff bases coordinate the Ag(I) ion as a tridentate ONO donor ligand. The antioxidant activity of the synthesized compounds is extremely high, with a range of IC50 values of 0.023-0.06 mg/mL. Antimicrobial screening determined the inhibitory ability of almost all complexes for concentrations of 1 and 2 mg/mL, with zones of inhibition in the range of 9-19 mm. Examination of the interaction of BSA with Ag(I) complexes revealed the same change in the absorption maximum (hyperchromic shift) in the region of about 205 nm, which indicates that the interaction of BSA and the complex results in conformational changes of BSA.

Extracts obtained from plant material have widely applied in the chemical and pharmaceutical industries because they contain significant concentrations of biologically active substances. Commercial daisy extract (Bellis perennis) was used in this paper for in vitro testing of tyrosinase enzyme inhibition, and antioxidant and antimicrobial activity. Inhibition of the tyrosinase enzyme was determined by monitoring dopachrome formation at a wavelength of 492 nm. Antioxidant activity was tested using FRAP and DPPH methods, while antibacterial activity was tested by diffusion technique on reference strains from the ATCC collection. The results showed that daisy extract inhibits tyrosinase enzyme in a dose-dependent manner. The extract effectively neutralized DPPH radicals and also showed good reducing ability. Bacterial strains used for in vitro antimicrobial activity testing did not show sensitivity to the extract concentrations used in this study.

No abstract

In this study, metal complex of Copper(II) with a Schiff base derived from 2,2-dihydroxyindane-1,3-dione and 2-aminoethanoic acid were synthesized. The product are characterized by spectral methods. The antimicrobial activity was tested on reference bacterial strains and the antioxidant capacity was analyzed by using the DPPH and FRAP methods. The spectral data indicates that the Schiff base coordinates the Copper(II) as a tridentate ONO donor ligand. The compounds showed weaker antimicrobial activity on certain tested microorganisms. In vitro testing of antioxidant activity showed a significant reducing ability of the complex, as well as inhibitory activity against DPPH radicals.