Gülcan Özkan

Antibacterial activity and composition of essential oils from Origanum, Thymbra and Satureja species with commercial importance in Turkey

The antibacterial activity of essential oils and their derivatives has been recognized for a long time. In the present study, the chemical composition and the antibacterial properties of the essential oils obtained from the aerial parts of the four Lamiaceae species, wild oregano (Origanum minutiflorum) (endemic in Turkey), oregano (Origanum onites), black thyme (Thymbra spicata) and wild savory (Satureja cuneifolia), with commercial importance in Turkey, were evaluated. The major constituent of the oils determined by GC was cavracrol (86.9% in O. onites, 84.6% in O. minutiflorum, 75.5% in T. spicata and 53.3% in S. cuneifolia). Four essential oils were investigated for activity against Aeromonas hydrophila, Bacillus amyloliquefaciens, B. brevis, B. cereus, B. subtilis, Corynebacterium xerosis, Enterococcus faecalis, Escherichia coli, Klebsiella pneumoniae, Listeria monocytogenes, Micrococcus luteus, Mycobacterium smegmatis, Proteus vulgaris, Staphylococcus aureus and Yersinia enterocolitica, using a paper disc diffusion method. All essential oils inhibited all bacteria at concentrations of <1/100 (v/v). The essential oil of T. spicata was the most active. B. amyloliquefaciens was the most sensitive. The results of this study confirmed the possibility of using these four essential oils in food systems to prevent the growth of foodborne bacteria and extend the shelf life of processed foods. 2003 Elsevier Ltd. All rights reserved.

Total phenolic contents and antibacterial activities of grape (Vitis vinifera L.) extracts

Powdered grape seeds and bagasse were extracted with petroleum ether to remove fatty material and then re-extracted with different solvent mixtures to determine their total phenolics and antibacterial activities. In the grape seeds extracts the content of total phenolic compounds was found to be 627.98 mg gallic acid equivalent (GAE)/g with acetone:water:acetic acid (90:9.5:0.5) and 667.87 mg GAE/g with ethyl acetate:methanol:water (60:30:10). The bagasse extracts contained 45.44 mg GAE/g and 29.55 mg GAE/g with ethyl acetate:methanol:water (60:30:10) and ethanol:water (95:5), respectively. These extracts at 1%, 2%, 4% and 20% concentrations were tested for their antibacterial effects by using the paper disc diffusion method against some food spoilage and pathogenic bacteria including Aeromonas hydrophila ATCC 7965, Bacillus amyloliquefaciens ATCC 3842, Bacillus brevis FMC 3, Bacillus cereus FMC 19, Bacillus megaterium DSM 32, Bacillus subtilis IMG 22, Enterobacter aerogenes CCM 2531, Enterococcus feacalis ATCC 15753, Escherichia coli DM, Klebsiella pneumoniae FMC 5, Listeria monocytogenes Scott A, Mycobacterium smegmatis RUT, Proteus vulgaris FMC 1, Pseudomonas aeruginosa ATCC 27853 and Staphylococcus aureus COWAN 1. The grape seed extracts at 20% concentration inhibited all the bacteria except B. amyloliquefaciens. The acetone:water:acetic acid (90:9.5:0.5) extract was found to be more effective than the other one, whose extracts at 4% concentration were inactive against A. hydrophila, B. amyloliquefaciens, B. megaterium and B. subtilis, while the acetone:water:acetic acid (90:9.5:0.5) extract at 4% was effective against most of the test bacteria. The grape bagasse extracts and methanol (control) had no inhibitory effects on the fifteen bacteria tested. The grape seed extracts at 1% and 2% concentrations were also ineffective. Consequently, grape seed extracts at 4% and 20% may be useful as antibacterial agents to prevent the deterioration of food products.

Note: Antioxidant and Antibacterial Activities of Rosa Damascena Flower Extracts

Rosa damascena Mill. is one of the most important Rosa species for the flavour and fragrance industries. The high amount of residues of spent flowers after steam distillation and the potential use of their essential oils as natural antioxidants and antimicrobials lead to determine the antioxidant and antibacterial activities of fresh and spent Rosa damascena flower extracts. The total phenolic contents were 276.02±2.93mg gallic acid equivalent (GAE)/g in FF (fresh flower) extract and 248.97±2.96mg GAE/g in SF (spent flower) extract. FF and SF extracts showed 74.51±1.65 and 75.94±1.72% antiradical activities at 100ppm. The antioxidant activity of FF extract (372.26±0.96mg/g) was higher than that of SF extract (351.36± 0.84mg/g). Antibacterial activity of the extracts was determined by the agar diffusion method against 15 species of bacteria: Aeromonas hydrophila, Bacillus cereus, Enterobacter aerogenes, Enterococcus feacalis, Escherichia coli, Escherichia coli O157:H7, Klebsiella pneumoniae, Mycobacterium smegmatis, Proteus vulgaris, Pseudomonas aeruginosa, Pseudomonas fluorescens, Salmonella enteritidis, Salmonella typhimurium, Staphylococcus aureus and Yersinia enterocolitica. Statistical differences among bacteria were significant at p 0.05. Both extracts were effective against all the bacteria except E. coli O157:H7, although the FF extract was more effective than the SF extract. FF and SF extracts showed the strongest effects against S. enteritidis and M. smegmatis, respectively.

Note: Effect of Some Spice Extracts on Bacterial Inhibition

Eighteen extracts of spices commonly consumed worldwide and grown naturally in Turkey were tested against twenty three bacterial strains to compare their antibacterial effects with eleven antibiotics. Eight pathogens and fifteen lactobacilli isolated from chick intestine were used as the test microorganisms. Pathogens (six different Staphylococcus aureus strains, Escherichia coli ATCC 25922 and Yersinia enterocolitica ATCC 1501) were grown in Nutrient broth and lactobacilli in MRS broth. Hop extracts formed inhibition zones against S. aureus strains of upto 36 mm. Inhibitory effects of hop extracts against S. aureuswere generally higher than that of erythromycin as antibiotic. Helichrysum compactum extract produced an inhibition zone of 23mm to E. coli ATCC 25922 and 26mm to Y. enterocolitica ATCC 1501. Helichrysum compactum extract inhibited the growth of Y. enterocolitica ATCC 1501 more than other spice extracts. While inhibition zones of these extracts against lactobacilli were found smaller than on S. aureus strains, inhibition zones of the same extracts against lactobacilli were found similar to those of E. coli ATCC 25922 and Y. enterocolitica ATCC 1501.

RP-HPLC–DAD analysis of phenolic compounds in pomace extracts from five grape cultivars: Evaluation of their antioxidant, antiradical and antifungal activities in orange and apple juices

Phenolic compounds, related to antioxidative and antifungal properties of ethanolic extracts from five commercial grape cultivars (three red and two white) grown in Turkey were determined. A reversed-phase high performance liquid chromatography (RP-HPLC) procedure was developed, and a total 18 different phenolic compounds were identified. Total phenolic contents of the extracts were determined using Folin-Ciocalteau method. Antioxidant activities of the extracts were evaluated by using DPPH radical scavenging and phosphomolybdenum methods. All extracts exhibited strong antioxidant and antiradical activity. Phenolic compounds and antioxidant activities of the extracts were variety dependent. Antifungal activities of the pomaces and extracts were screened by both in vitro agar-well diffusion assay and antifungal activity in apple and orange juices in situ using Zygosaccharomyces rouxii and Z. bailii. Antifungal activities revealed that the pomaces and extracts of Gamay and Kalecik karasi could be more effective antifungal agents than those of Emir, Narince and Okuzgozu grape cultivars.

Note: Inhibition of Pathogenic Bacteria by Essential Oils at Different Concentrations:

The antimicrobial effect of 11 selected Turkish spice essential oils was investigated against seventeen pathogenic bacteria. The antimicrobial activity of the essential oils of six spices (cumin, fennel, laurel, mint, marjoram, oregano, pickling herb, sage, savory, thyme (black) and thyme) was tested at four concentrations (0.2, 0.4, 1 and 2%) on various microorganisms (E. aerogenes, E. coli, E. coli O157:H7, K. pneumoniae, P. vulgaris, S. enteritidis, S. gallinarum, S. typhimurium, S. aureus, Y. enterocolitica, A. hydrophila, C. xerosis, M. luteus, M. smegmatis, E. feacalis, P. aeruginosa and P. fluorescens). All preparations showed antibacterial activity against at least one or more bacteria. The inhibitory effect of the essential oils was evaluated through paper disc diffusion method. In general, the essential oils at 1 and 2% levels were effective. The most active essential oils were marjoram, thyme and oregano. According to the results, the studied essential oils potentially might be used as antibacterial agents to prevent the spoilage of food products, although further research is needed.

The influence of harvest time on essential oil composition, phenolic constituents and antioxidant properties of Turkish oregano (Origanum onites L.)

BACKGROUND The aim of this research was to determine essential oil composition, phenolic constituents and antioxidant properties of Turkish oregano (Origanum onites L.) leaves harvested during the months of June to September. RESULT The maximum essential oil yield in the leaves appeared in the middle of July. The main components of oregano oil were carvacrol, thymol, gamma-terpinene, p-cymene, alpha-terpinene and alpha-pinene. Carvacrol was highest in the July harvest. The maximum extract yield was found in September. Oil distilled from early-season (June) harvested leaves had the highest antioxidant ability, expressed as low concentration providing 50% inhibition of free radical scavenging activity and high levels of reducing/antioxidant capacity. Twelve phenolic compounds of oregano extract were identified and the main components were found to be rosmarinic acid and acecetin. The maximum rosmarinic acid and acecetin were found in harvests of July and June, respectively. Total phenolic contents, free radical scavenging activities and reducing/antioxidant capacities were found to be highest in the July harvest. DISCUSSION All yields, chemical compositions, free radical scavenging activities and reducing/antioxidant capacities of extracts and essential oils of Turkish oregano changed importantly depending on vegetative periods of growing season.

Glycyrrhiza flavescens subsp. antalyensis exerts antiproliferative effects on melanoma cells via altering TNF-α and IFN-α levels

Glycyrrhiza species possess preventive and therapeutic potentials against various cancers. In the present study, we have evaluated regulation of apoptotic cell death by aqueous extracts of leaf and flower of an endemic Glycyrrhiza species; Glycyrrhiza flavescens subsp. antalyensis, in mouse melanoma cell lines. Both leaf and flower extracts induced apoptosis in terms of induction of caspase-3 activity, TNF-α and IFN-γ release. Concentrations of both TNF-α and IFN-γ in extract-treated groups were significantly and dose dependently exalted as compared to their relative controls. The effects of extracts on caspase-3, TNF-α and IFN-γ processes mediate the plausible mechanism of apoptosis induction of G. flavescens subsp. antalyensis.

Characteristics of grains and oils of four different oats (Avena sativa L.) cultivars growing in Turkey

Some physical and chemical properties of four oat (Avena sativa L.) varieties (BDMY-6, BDMY-7, Che-Chois and Y-2330) harvested from Konya in Turkey were investigated. The weight of the grain, moisture, crude protein, crude ash, crude fibre, crude energy, crude oil and water-soluble extract contents of all oat variety grains were analysed. Contents of aluminium, calcium, cadmium, phosphorus, magnesium, zinc, lead, potassium and manganese were also determined in the oat grains. The specific gravity, refractive index, free fatty acids, peroxide value, saponification number and unsaponifiable matter were determined in the grain oil. Tocopherol contents of these four oat grain oils were measured. Palmitic acid (15.72%), oleic acid (33.97–51.26%) and linoleic acid (22.80–35.90%) were found to be rich in protein, oil, fibre, unsaturated fatty acids and minerals, suggesting that they may be valuable for food uses. Due to high nutritive values, it is recommended to process for healthy food products.

Determination of the volatile constituents and total phenolic contents of some endemic Stachys taxa from Turkey

The total phenolic contents and the essential oil compositions of the previously unknown Stachys taxa (Labiatae), including Stachys pinardii Boiss, Stachys cretica L. subsp. mersinaea (Boiss.) Rech., and Stachys aleurites Boiss. & Heldr., all endemic to Turkey, were studied. Their essential oil compositions were investigated by GC-MS. It was found that the main constituents were α-curcumene (34.10%) for S. cretica, cedrandiol (25.26%) and caryophyllene dioxide (22.15%) for S. pinardii, and (Z)-β-caryophyllene (31.60%) for S. aleurites. The total phenolic contents, by the Folin-Ciocalteu colorimetric method, of the S. pinardii, S. cretica subsp. mersinaea, and S. aleurites methanolic extract were found to be 600.74±0.23, 1200.94±0.11, and 900.61±0.06 mg gallic acid equivalent (GAE)/100 g in dried herb, respectively.