The antioxidant activity ofwater, ethanol and methanol Hieracium pilosella L.extracts is reported. The antioxidative activity was tested by spectrophotometrically measuring their ability to scavenge a stable DPPH^· free radical and a reactive hydroxyl radical trapped by DMPO during the Fenton reaction, using the ESR spectroscopy. Total phenolic content and total flavonoid content were evaluated according to the Folin-Ciocalteu procedure, and a colorimetric method, respectively. A HPLC method was used for identification of some phenolic compounds (chlorogenic acid, apigenin-7-O-glucoside and umbelliferone). The antioxidant activity of the investigated extracts slightly differs depending on the solvent used. The concentration of 0.30 mg/mL of water, ethanol and methanol extract is less effective in scavenging hydroxyl radicals (56.35, 58.73 and 54.35%, respectively) in comparison with the DPPH^· radical scavenging activity (around 95% for all extracts). The high contents of total phenolic compounds (239.59–244.16 mg GAE/g of dry extract) and total flavonoids (79.13–82.18 mg RE/g of dry extract) indicated that these compounds contribute to the antioxidative activity.

The subject of this study is to determine chemical composition, antioxidant and antimicrobial activity of essential oil obtained from chamomile flowers (Matricaria chamomilla L.). The essential oil has been obtained by hydrodistillation process on semi industrial production conditions. Qualitative and quantitative composition of the oil was determined by GC-MS and GC-FID analysis. The antioxidative and antimicrobial activity of chamomile essential oil was investigated in terms of their possible application as natural antioxidants and antimicrobial agents. The obtained results proved the presence of 52 components, wherein the highest content of β-farnesene (29.8 %), α-farnesene (9.3 %), α-bisabolol and its oxide (15.7 %), chamazulene (6.4 %), germacrene D (6.2 %) and spiroether (5.6 %) is determined. The antioxidant activity was investigated by DPPH assay. Chamomile essential oil has shown the best antioxidant properties after 90 minutes of incubation with EC₅₀ value of 2.07 mg/ml. The antimicrobial activity of chamomile essential oil was tested using the agar diffusion method wherein the essential oil has shown notably antibacterial effect with the inhibition zone in diameter from 13.33 mm (on Listeria monocytogenes) to 40.00 mm (on Staphylococcus aureus). There was no antimicrobial activity of chamomile oil on the Pseudomonas aeruginosa bacteria. Chemical composition, antioxidant and antimicrobial activity of the tested chamomile essential oil, obtained from plant material from the northwestern Republic of Srpska, indicate a significant phytomedical potential.

Essential oils, as sources of natural products, represent an alternative to synthetic antioxidants and antimicrobial agents in food and pharmaceutical industry, alternative medicine and natural therapy. Basil (Ocimum basilicum L.) belongs to the Lamiaceae family of herbs, which in addition to being used as a spice, is also medicinally known as a powerful antibacterial, antimutagenic and chemopreventive agent. The aim of the present study was to determine chemical composition, antioxidant and antimicrobial activity of essential oil obtained from basil aerial parts (grown in the northwestern Republic of Srpska) by hydrodistillation on semi-industrial level of production. Qualitative and quantitative composition of the oil was determined by GC-MS and GC-FID spectrometry. The antioxidant activity of essential oil was investigated spectrophotometrically by DPPH assay and antimicrobial activity using the agar diffusion method on the following microorganisms: Escherichia coli, Listeria monocytogenes, Salmonella enterica, Staphylococcus aureus, Pseudomonas aeruginosa, Bacillus cereus, Providencia stuartii, coagulase-positive Staphylococcus, Streptococcus group D, Salmonella spp. and Candida albicans. The results obtained proved the presence of 65 components, with the highest content of linalool (31.6%) and methyl chavicol (23.8%). Essential oil has shown the best antioxidant properties after 90 minutes of incubation with EC₅₀ value of 2.38mg/ml. The oil has shown the best antimicrobial activity on coagulase-positive Staphylococcus. Chemical composition, antioxidant and antimicrobial activity of the investigated basil essential oil indicate a significant phytomedical potential.

In the present work, essential oil has been obtained by Clevenger-type hydrodestillation from grounded curcuma rhizome (Rhizoma Curcumae) (Turkey) with hydromodulus 1:5 m/V during 180 minutes. The qualitative and quantitative composition of the oil was determined by GC-MS and GC-FID spectrometry. The antioxidant activity of the obtained oil was determined using DPPH assay just after adding DPPH radical and after 20 min, 30 min and 45 min incubation with radical. The antimicrobial activity was determined using a discdiffusion method. The yield of the essential oil was 0.3 cm3/ 100 g plant material. Eight compounds were identified. The major ones were ar-turmerone (22.7%), turmerone (26%) and curlone (16.8%). The best antioxidant activity showed the oil incubated for 45 minutes with DPPH radical. EC50 values for the obtained oil were 1.784 mg/cm3 (without incubation), 0.098 mg/cm3 (after 20 minutes), 0.072 mg/cm3 (after 30 minutes) and 0.045 mg/cm3 (after 45 minutes incubation with radical). The oil showed the best antimicrobial activity against Candida albicans. The results indicate that turmeric essential oil is an extremely strong antioxidant and antimicrobial (antifungal) agent with potential application in the food and pharmaceutical industries as a safer alternative to the synthetic antioxidants and antimicrobial agents.