Deep eutectic solvents (DESs), as an alternative to ionic liquids, have greener credentials than ionic liquids and have attracted increasing attention in many applications. Choline chloride-based DESs in combination with different hydrogen bond donors (organic acid, sugars and urea), showed a high extraction efficiency. The aim of this study was to examine the possible effects of choline chloride-based eutectic solvents on the antioxidant and antimicrobial activity of lemon and mandarin orange seed extracts. Lactic acid, glucose, urea and water were used to prepare choline chloride-based Natural Deep Eutectic Solvents (NADESs). Ferric-Reducing Antioxidant Power (FRAP) Assay and 2,2-diphenyl-1-picryl-hydrazyl (DPPH) method were used to determine Original Research Article Kolarević et al.; IRJPAC, 21(23): 120-128, 2020; Article no.IRJPAC.63470 121 antioxidant activity. Antibacterial activity was investigated by diffusion method on reference bacterial strains E. coli, E. faecalis, S. aureus, B. subtilis and L. monocytogenes. The analysis revealed a significant reduction potential of the eutectic solvent based on lactic acid as well as significant antioxidant activity of lemon and mandarin seed extracts. In general, mandarin extracts showed better antioxidant capacity. In vitro antibacterial activity assays showed a complete absence of bacterial growth inhibition of the extracts. However, eutectic solvents with lactic acid have shown a significant antimicrobial effect.

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 IC 50 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.

Schiff bases are organic compounds formed by the reaction of the primary amine with carbonyl compounds (aldehydes or ketones). These are mainly bi- or tridentate ligands capable of forming very stable complexes with transitional metals. They are used as catalysts in oxygenation, hydrolysis, electro-reduction and decomposition reactions. Many Shiff bases show significant anti-tumor and antimicrobial activity, which is why they are the subject of research by many scientists in the world. In this paper Schiff's base from benzidine and 1,3-diphenyl-1,3-propanedione was synthesized. To characterize the product, FTIR spectroscopy and stereo-microscopy were used. In order to determine biological activity, antibacterial, antifungal and antioxidant activity of the product was tested. The results showed that the interaction of benzidine and 1,3-diphenylpropandione results in a Schiff base showing antibacterial, antifungal and antioxidant activity. Keywords: Schiff base, benzidine, FTIR, UV/Vis, antimicrobial activity.

several microorganisms of Gram-negative of the monocytogenes,

Origanum compactum (O. compactum) is an endemic Moroccan medicinal herb. Numerous studies have shown that O. compactum organic extracts, essential oil and its main components possess a broader spectrum of pharmacological and therapeutic activities such as antibacterial, antifungal, antioxidant and antitumour activity. This research was designed to examine the antibacterial activity of O. compactum essential oil tested on clinical bacterial strains isolated from vaginal and cervical swabs. First, antibacterial activity was tested against standard bacterial cultures: Staphylococcus aureus ATCC 25923, Enterococcus faecalis ATCC 51299, Escherichia coli ATCC 25922, and after that on clinical strains. For testing the antibacterial activity, agar diffusion and microdilution methods were used. The inhibition zones (IZ) for standard bacterial cultures were from 31.0 ± 0.57 mm to 35.0 ± 1.15 mm. The minimum inhibitory concentracion (MIC) for essential oil was tested using the broth dilution method. The values were in the range of 0.098 mg/ml - 1.562 mg/ml. O. compactum essential oil provided strong antibacterial activity for all tested microorganisms. The antibacterial activity of essential oil depends largely on the main components: carvacrol and thymol. Clinical isolates, which are more resistant in comparison with laboratory strains, are almost equally sensible to O. compactum essential oil. This essential oil could be an ideal replacement for conventional antimicrobial products, especially if we consider the increasing resistance to implemented antibiotics. In the future, O. compactum essential oil could be an option in the treatment of gynecological infections.

Ciprofloxacin, CFL is a drug that belongs to the second generation of fluoroquinolone antibiotics with a wide range of effects on Gram-positive and Gram-negative bacteria. The aim of this work was to investigate the interaction of CFL as ligand with divalent biological cations (Mn2+, Ni2+ and Co2+) in approximate physiological conditions. Synthesized complexes were characterized using FTIR and stereo-microscopy. Antimicrobial screening was performed on bacterial strains of Escherichia coli, Salmonella Enteritidis, Enterococcus faecalis and Staphylococcus aureus. The results of FTIR spectroscopy showed that the M(II) complexes with CFL were formed through the oxygen donors of the carboxyl and carbonyl group of the ligand. Stereo-microscopic characterization revealed the difference in color and size of crystals of the ligand and metal complexes. Antimicrobial screening has shown that CFL and complexes have almost similar antimicrobial activity against investigated bacterial strains.

The aim of this study was to determine the total phenolic content, evaluate antioxidant propertie and antimicrobial potential, and identify phenolic compounds in alcoholic and aqueous extracts of the wild cherry (Prunus avium L.) stems collected in Bosnia and Herzegovina. Alcoholic extracts had higher contents of phenolic and flavonoid components, as well as the antioxidant and ferric reducing antioxidant capacity in comparison to aqueous extracts. All extracts were characterized by HPLC analysis. Furthermore, for the first time, the antimicrobial properties of wild cherry stem extracts were evaluated. Quercetin and (+)-catechin were the main compounds identified in the alcoholic extract, followed by chlorogenic acid and rutin. Quercetin was also the major component detected in aqueous extracts. Besides, alcoholic extract showed better antibacterial properties against Staphylococcus aureus as a representative gram-positive bacteria than infusion, whereas none of the samples showed antibacterial activity against Escherichia coli and fungus Candida albicans.

UDK: 574.5:579.68(285)(497.6) In the spring and summer season of 2014, the change in the number of coliform and heterotrophic bacteria in specific localities of lake Bistarac and lake Vidara were observed and analyzed. Lake Bistarac was formed after the cessation of surface mining in the open pit, while lake Vidara is the artificial lake in the area of Gradacac made in order to protect the industrial zone of flooding. Both of these lakes, placed in Tuzla Canton, are very attractive for tourist and frequently are used for swimming, fishing and recreation. Results of this study showed an increased number of coliform bacteria in both periods, and the presence of Escherichia coli as a direct indicator of fecal pollution, while, as an additional indicator of fecal pollution, Citrobacter and Enterobacter were identified. From the total number of analyzed water samples of the lake Bistarac, 60% of samples belonged into to the second class, and 40% into the first class of water quality. Lake Vidara showed poor quality as the 80% of the analysed samples belonged to the second class and only 20% into the first class of water quality. For the microbiological assessment of the water quality standard microbiological procedures and methods were used. One of the main reasons for poor hygienic state of these two lakes is unregulated sewage network of the villages, restaurants and camping areas placed near the lakes. The increased number of fecal bacteria was found in the water of both lakes, which can be highly dangerous for the human population. Since both lakes are used for recreational purposes it is necessary to establish an appropriate monitoring system on the basis of which is possible to take measures and to protect and improve water quality.