Samples of stinging nettle or common nettle (Urtica dioica L.) were collected from the area of Banja Luka. To measure and evaluate the content of chlorophyll (a and b), carotenoids, and soluble proteins, as well as peroxidase activity (POD, EC 1.11.1.7.), fresh nettle leaves of different developmental stages were used. Dried nettle leaves were used to obtain ethanol extract. The dry residue of ethanol extract was dissolved in metha- nol and the obtained solution was used to determine the content of total phenols, flavo- noids, flavonols, as well as non-enzymatic antioxidant activity and antimicrobial activity. The non-enzymatic antioxidant activity was determined by different methods: FRAP, DPPH, and ABTS. The results were compared to those of standard substances like vitamin C, BHT, and BHA. Antimicrobial activity was screened by using macrodilution method. The obtained results showed insignificantly higher content of chlorophyll, caroteno- ids, and proteins in young nettle leaves as well as an increase in the soluble peroxidase activities. Native electrophoresis of the soluble fraction showed the presence of two pero- xidase isophorms in the soluble protein fraction of nettle leaves. The total phenolic content in nettle extracts amounted to 208.37 mg GAE/gdw,, the content of total flavonoids was 20.29 mg QE/gdw, and the content of total flavonols was 22.83 mg QE/gdw. The antioxidant activity determined by FRAP method was 7.50 mM Fe(II)/gdw, whereas the antioxidant activity measured by using DPPH and ABTS methods, with IC50 values, were 31.38 and 23.55 μg mL -1 , respectively. These results showed the weak and moderate an- tioxidant capacity of stinging nettle. Extract of Urtica dioica L. was tested for antibacterial acivity against various Gram- positive and Gram-negative bacteria: Bacillus subtilis IP 5832, Lactobacillus plantarum 299v (Lp299v), Pseudomonas aeruginosa, and Escherichia coli isolated from food and Escherichia coli isolated from urine samples. Ampicillin, erythromycin, ciprofloxacin, and gentamicin were used as positive control. The results showed that minimum inhibi- tory concentration (MIC) and minimum bactericidal concentration (MBC) of the extract ranged from 9.05 to more than 149.93 mg mL -1 .

This study is a continued investigation of the influence of ferrocene and its derivatives on trypsin activity. The goal was to examine the effect in vivo, by monitoring the growth of the bacteria Escherichia coli. The growth of the bacteria with the addition of ferrocene and derivatives of various concentrations was followed up spectrophotometrically, measuring changes in OD, correlating OD with the number of formed bacterial colonies and comparing the results as the mean generation time. The obtained results in relation to control experiments indicate a very strong inhibitory action of ferrocene and (dimethylaminomethyl) ferrocene, a medium or modest inhibitory effect of methyl 1'-acetamidoferrocene- 1-carboxylate and benzyl 1'-methoxycarbonyl-1-ferrocenecarbamate; influence of benzyl 1'-carboxy-1-ferrocenecarbamate is negligible, while 1'-acetamidoferrocene-1-carboxylic acid causes the increase in the growth of Escherichia coli.

Ethanolic (50%, v/v) extract of Reynoutria japonica Houtt. rhizome from the Banja Luka region was prepared. The dry extract was dissolved in methanol, and total phenols content, antimicrobial and antioxidative activities were determined. The total phenols content was determined using modified Folin-Ciocalteu method, the antimicrobial activity by monitoring the optical density, and antioxidative activity by the method of quenching stable free 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals by FRAP and ABTS metods. The antioxidative activity results were compared with control antioxidants: vitamin C, BHA and BHT. In order to determine the antimicrobial extract activity, E. coli, S. aureus and B. cereus were used as test microorganisms. The paper discusses the results of antimicrobial and antioxidative activeties of the R. japonica extract with respect to extract concentration as well as to total phenols content. The extract of R. japonica rhizome shows both, a significant overall antioxidant activity (29.84 mM (FeII)/g of extract) and high activity in quenching DPPH (IC50 = = 13.68 μg/mL) and ABTS+ (99.1%) radicals. It was found that the R. Japonica extract had greater impact on growth rate reduction of B. cereus, E. coli, than S. aureus, expressed in percentages of growth rate, L, 73.6, 59.3 and 52.1% respectively. The greatest decrease in total bacterial count, M, was observed in S. aureus (71.9%), while the decrease in E. coli and B. cereus was approximately equal (about 50%). The total phenols content, expressed as mg of galic acid equivalents/g of extract was 664±15. The high antioxidant and significant antimicrobial activity of the R. japonica extract determined in this work is associated with extremely high total phenols content.