Bektas Tepe
Cumhuriyet University
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Featured researches published by Bektas Tepe.
Journal of Ethnopharmacology | 2003
Ferda Candan; Mehmet Ünlü; Bektas Tepe; Dimitra Daferera; Moschos G. Polissiou; Atalay Sokmen; H. Askin Akpulat
The in vitro antimicrobial and antioxidant activities of the essential oil and methanol extracts of Achillea millefolium subsp. millefolium Afan. (Asteraceae) were investigated. GC-MS analysis of the essential oil resulted in the identification of 36 compounds constituting 90.8% of the total oil. Eucalyptol, camphor, alpha-terpineol, beta-pinene, and borneol were the principal components comprising 60.7% of the oil. The oil strongly reduced the diphenylpicrylhydrazyl radical (IC(50)=1.56 micro g/ml) and exhibited hydroxyl radical scavenging effect in the Fe(3+)-EDTA-H(2)O(2) deoxyribose system (IC(50)=2.7 micro g/ml). It also inhibited the nonenzymatic lipid peroxidation of rat liver homogenate (IC(50)=13.5 micro g/ml). The polar phase of the extract showed antioxidant activity. The oil showed antimicrobial activity against Streptococcus pneumoniae, Clostridium perfringens, Candida albicans, Mycobacterium smegmatis, Acinetobacter lwoffii and Candida krusei while water-insoluble parts of the methanolic extracts exhibited slight or no activity. This study confirms that the essential oil of Achillea millefolium possesses antioxidant and antimicrobial properties in vitro.
Food Chemistry | 2004
Bektas Tepe; Erol Dönmez; Mehmet Ünlü; Ferda Candan; Dimitra Daferera; Gülhan Vardar-Ünlü; Moschos G. Polissiou; Atalay Sokmen
Abstract The essential oils and methanolic extracts of Salvia cryptantha and Salvia multicaulis were examined for their potential antimicrobial and radical scavenging activities. No, or slight, activity was observed when the polar and non-polar subfractions of the extracts were tested, whereas essential oils exhibited antimicrobial activity. The essential oils isolated from S. cryptantha and S. multicaulis were analysed by GC–MS and 53 and 47 constituents were identified, respectively. Antioxidant activities of the polar subfraction and the essential oil were examined using 2,2-diphenyl-1-picrylhydrazyl (DPPH), hydroxyl radical-scavenging and lipid peroxidation assays. The essential oils, in particular, and the non-polar subfractions of methanol extracts, showed antioxidant activity. In conclusion, the results indicate that the oils of S. cryptantha and S. multicaulis have the capacity to scavenge free radicals and to inhibit the growth of pathogenic microorganisms. Therefore they could be suitable for using as antimicrobial and antioxidative agents in the food industry.
Food and Chemical Toxicology | 2009
Cengiz Sarikurkcu; Kadir Arısoy; Bektas Tepe; Ahmet Cakir; Gulsah Abali; Ebru Mete
This study is designed to examine the chemical composition and antioxidant activity of the essential oil and different solvent extracts of Vitexagnuscastus. GC and GC-MS analysis was resulted in the detection of 27 components, representing 94.5% of the oil. Major components of the oil were 1,8-cineole (24.98%), sabinene (13.45%), alpha-pinene (10.60%), alpha-terpinyl acetate (6.66%), and (Z)-beta-farnesene (5.40%). Antioxidant activities of the samples were determined by three different test systems, DPPH, beta-carotene/linoleic acid and reducing power assays. In all systems, water extract exhibited excellent activity potential than those of other extracts (hexane, dichloromethane, ethyl acetate and methanol) and the oil. As expected, amount of total phenolics was very high in this extract (112.46+/-1.22mugGAEs/mgextract). Dichloromethane extract has been found to be rich in flavonoids. A positive correlation was observed between the antioxidant activity potential and total phenolic and flavonoid levels of the extracts.
Journal of Ethnopharmacology | 2002
Mehmet Ünlü; Dimitra Daferera; Erol Dönmez; Moschos G. Polissiou; Bektas Tepe; Atalay Sokmen
GC-MS analysis of the isolated essential oils from air-dried aerial parts of Achillea setacea and Achillea teretifolia, an endemic taxon, resulted in the identification of 51 constituents (79.8% of the total oil) and 42 constituents (87.1% of the total oil), respectively. Eucalyptol (1,8-cineole) was the major constituent of both oils studied (18.5 and 19.9%, respectively). The antimicrobial activities of the essential oils were individually evaluated against 14 microorganisms. Both oils exhibited inhibitory effects on Clostridium perfringens, Acinetobacter lwoffii and Candida albicans with a range of minimum inhibitory concentration values extended from 0.28 to 2.25 mg/ml. Camphor and their derivatives, borneol, terpinen-4-ol and eucalyptol (1,8-cineol) can be considered as the main antimicrobial constituents of the oils studied.
Bioresource Technology | 2008
Cengiz Sarikurkcu; Bektas Tepe; Mustafa Yamaç
The methanolic extracts of Lactarius deterrimus, Suillus collitinus, Boletus edulis, Xerocomus chrysenteron were analyzed for their antioxidant activities in different test systems namely beta-carotene/linoleic acid, DPPH free radical scavenging, reducing power and metal chelating activities in addition to their total phenolic and flavonoid contents. In beta-carotene/linoleic acid and DPPH systems, L. deterrimus and B. edulis showed the strongest activity patterns. Their activities were as strong as the positive controls. The reducing power of the species was excellent. Chelating capacity of the extracts was increased with the increasing concentration. On the other hand, B. edulis found to have the highest phenolic content. Total flavonoid content of S. collitinus found the superior to the other mushrooms.
Food and Chemical Toxicology | 2015
Kemal Sevgi; Bektas Tepe; Cengiz Sarikurkcu
In this study, ten different phenolic acids (caffeic, chlorogenic, cinnamic, ferulic, gallic, p-hydroxybenzoic, protocatechuic, rosmarinic, syringic, and vanillic acids) were evaluated for their antioxidant and DNA damage protection potentials. Antioxidant activity was evaluated by using four different test systems named as β-carotene bleaching, DPPH free radical scavenging, reducing power and chelating effect. In all test systems, rosmarinic acid showed the maximum activity potential, while protocatechuic acid was determined as the weakest antioxidant in β-carotene bleaching, DPPH free radical scavenging, and chelating effect assays. Phenolic acids were also screened for their protective effects on pBR322 plasmid DNA against the mutagenic and toxic effects of UV and H2O2. Ferulic acid was found as the most active phytochemical among the others. Even at the lowest concentration value (0.002 mg/ml), ferulic acid protected all of the bands in the presence of H2O2 and UV. It is followed by caffeic, rosmarinic, and vanillic acids. On the other hand, cinnamic acid (at 0.002 mg/ml), gallic acid (at 0.002 mg/ml), p-hydroxybenzoic acid (at 0.002 and 0.004 mg/ml), and protocatechuic acid (at 0.002 and 0.004 mg/ml) could not protect plasmid DNA.
Fitoterapia | 2011
Bektas Tepe; Serpil Degerli; Serdal Arslan; Erdogan Malatyali; Cengiz Sarikurkcu
This work deals with the evaluation of in vitro antioxidant, DNA preventing and antiamoebic activities of the water extracts of Teucrium polium and Stachys iberica. In all systems, T. polium extract exhibited excellent activity potential than that of S. iberica. The amount of total phenolics and flavonoids were high in this extract. In the presence of 40 mg/ml T. polium extract, a significant protection was observed for native super coiled DNA of pBR322 plasmid DNA. In the presence of 32 mg/ml of T. polium extract, no trophozoite was after the 24th hour.
Food and Chemical Toxicology | 2010
Cengiz Sarikurkcu; Bektas Tepe; Deniz Karslı Semiz; M. Halil Solak
This study is designed for the determination of metal concentrations, antioxidant activity potentials and total phenolics of Amanita caesarea, Clitocybe geotropa and Leucoagaricus pudicus. Concentrations of four heavy metals (Pb, Cd, Cr, Ni) and five minor elements (Zn, Fe, Mn, Cu, Co) are determined. In the case of A. caesarea, Cr and Ni concentrations are found in a high level. Concentrations of the metals are found to be within safe limits for C. geotropa. In beta-carotene/linoleic acid test, L. pudicus showed the highest activity potential. In DPPH system, A. caesarea showed 79.4% scavenging ability. Additionally, reducing power and chelating capacity of the mushrooms increased with concentration. The strongest super-oxide anion scavenger was A. caesarea. In the case of total phenolics, L. pudicus found to have the highest content.
Food and Chemical Toxicology | 2010
Cengiz Sarikurkcu; M. Sabih Özer; Mustafa Eskici; Bektas Tepe; Şendil Can; Ebru Mete
This study is designed to examine the chemical composition and in vitro antioxidant activity of the hydrodistillated essential oil and various extracts obtained from Thymus longicaulis subsp. longicaulis var. longicaulis. GC and GC-MS analysis of the essential oil were resulted in determination 22 different compounds, representing 99.61% of total oil. gamma-terpinene, thymol and p-cymene were determined as the major compounds of the oil (27.80, 27.65 and 19.38%, respectively). Antioxidant activities of the samples were determined by four different test systems namely beta-carotene/linoleic acid, DPPH, reducing power and chelating effect. Essential oil showed the highest antioxidant activity in beta-carotene/linoleic acid system among the experiments examined. In the case of other test systems, in general, methanol and water extracts exhibited the strongest activity profiles. Especially, reducing power of water extract was found superior than those of synthetic antioxidants. As well as the antioxidant activities of the extracts, they were evaluated in terms of their total phenolic and flavonoid contents. Hexane and water extracts were found to be rich-in phenolics. However, flavonoids were determined in the highest level in methanol extract.
Natural Product Research | 2007
Bektas Tepe; Atalay Sokmen
In this study, production and optimisation of rosmarinic acid, a phenolic acid and an economically important metabolite, was investigated in the callus cultures established from the mature seeds of Satureja hortensis L. (summer savory) plant. Gamborgs B5 basal medium, supplemented with indol butyric acid (IBA) (1.00 mg L−1), N6-benzyl aminopurine (6-BA) (1.00 mg L−1) and sucrose (2.5%, w/v), was employed for the establishment and maintenance of the callus cultures. Applications were individually prepared by preparing the media containing different IBA/6-BA combinations and sucrose concentrations. All of the applications were carried out in the continuous dark. In the applications, where the effects of IBA/6-BA combinations on the growth and rosmarinic acid accumulation were assayed (1–15 applications), the highest biomass yield was obtained from the medium supplemented with 1.00 mg L−1 IBA and 5.00 mg L−1 6-BA. In the case of the rosmarinic acid accumulation, an opposite relationship was determined between the growth and rosmarinic acid production. While the highest biomass yield was obtained from the medium containing 1.00 mg L−1 IBA and 5.00 mg L−1 6-BA, the highest rosmarinic acid accumulation was obtained from the medium supported with 1.00 mg L−1 IBA and 1.00 mg L−1 6-BA. In the applications where the effects of sucrose concentrations on the growth and rosmarinic acid accumulation were examined, the highest biomass yield was obtained from the medium which is supplemented with 5.0% (w/v) sucrose. In this category, the highest rosmarinic acid accumulation was obtained from the medium which is supported with 3.0% (w/v) sucrose. According to the experiments carried out with the wild S. hortensis, it is found to have 25.02 ± 1.21 mg g−1 rosmarinic acid. No differentiation was observed in any callus during the course of this study.