This work aimed to describe the synthesis and characterisation of two anionic Ru(III) complexes of the general formula Na[Ru - Cl 2 ( N -4-Cl-Ph-salim) 2 ] and Na[RuCl 2 ( N -3-Br-Ph-salim) 2 , their associated ligands, and determine their antioxidant activity. The ligands N- 4-Cl-phenylsalicylidenimine ( N -4-Cl-Ph-salimH, HL a ) and N- 3-Br-phenylsalicylidenimine ( N -3-Br-Ph-salimH, HL b ), Schiff bases, were synthesised from salicylaldehyde and chloroaniline or bromoaniline. The compounds were characterised us - ing IR spectroscopy and ESI ToF mass spectrometry. The following was confirmed: coordination of ligands on the Ru(III) centre, the molecular formulas, and the corresponding M − ions: [C 26 H 18 N 2 O 2 Cl 4 Ru] − ion, (m/z: 631.9173) and [C 26 H 18 N 2 O 2 Cl 2 Br 2 Ru] − ion, (m/z: 719.8283). The antioxidant activity was determined by the ABTS (2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) and DPPH (1,1-diphenyl-2-picrylhydrazyl) assays. In contrast to the ligands, both complexes proved to be strong scaven - gers of the ABTS and DPPH radicals with IC 50 (half maximal inhibitory concentration) values comparable to those of Trolox. As such, they present valuable candidates for further research related to their biological properties.

The samples of stinging nettle were collected during June in the Tuzla region. Aqueous extracts were prepared from fresh and dried leaves in order to determinate and compare content of bioactive components and antioxidant potential. Conventional soxhlet, ultrasound assisted extraction and traditional maceration extraction were used as extraction methods. Quantitative determination of phenols and flavonoids was carried out using spectrophotometric methods. Antioxidant activity of nettle aqueous extracts was determined using ferric reducing antioxidant power and DPPH free radical scavenging activity. Extracts obtained by Soxhlet extraction showed the highest total phenolic and flavonoid content and expected the highest antioxidant capacity, while extracts obtained by maceration gave the lowest results. KEYWORDS:stinging nettle extract;bioactive components;extraction;antioxidant

In this research, the possibility of using Ca(OH)2 in the form of commercial hydrated lime as a catalyst for the methanolysis of refined rapeseed oil was evaluated. Characterization of unused catalyst was performed by SEM-EDS, laser diffraction, XRF, BET, XRD and TG/DTG methods, and vegetable oil was analyzed for physicochemical characteristics. Within methanolysis, the effects of catalyst loading, reaction temperature and reaction time on methyl ester yield, density and viscosity of biodiesel, as well as the possibility of catalyst reuse were investigated. The obtained results showed that hydrated lime is an efficient catalyst for transesterification of vegetable oil, whereby the use of 3 wt% of catalyst relative to oil weight, at temperature 60℃ and mixing rate 1000 rpm after 120 min of transesterification reaction achieved a yield of methyl esters 98.76%. With three reuses of hydrated lime, without intermediate washing and regeneration procedures, the yield of rapeseed oil methyl ester remained above 90%.