Dimitra Daferera

Agricultural University of Athens, Athens, Attiki, Greece

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Publications (20)26.09 Total impact

  • Article: Phenolic acid contents, essential oil compositions and antioxidant activities of two varieties of Salvia euphratica from Turkey.
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    ABSTRACT: This study was designed to evaluate the in vitro antioxidant activities of n-hexane (Hex), dichloromethane (DCM), methanol (MeOH) and essential oils (EO) extracts obtained from Salvia euphratica var. euphratica and Salvia euphratica var. leiocalycina and to determine their essential oil and phenolic acid compositions. The samples were screened for their antioxidant activity by using DPPH and β-carotene/linoleic acid assays. Methanol extracts of both varieties exhibited strong antioxidant activities. Our results showed that rosmarinic acid was dominant phenolic acid of MeOH extracts (39.4 and 55.8 µg mg(-1), respectively). The chemical compositions of essential oils of two varieties were analysed and their main components were determined as eucalyptol (18.4%) and trans-pinocarvyl acetate (24.9%), respectively. It can be said that these varieties could be used as natural antioxidant.
    Natural product research 10/2011; 26(19):1848-51. · 1.01 Impact Factor
  • Article: Studies on the antioxidant activity of the essential oil and methanol extract of Marrubium globosum subsp. globosum (lamiaceae) by three different chemical assays.
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    ABSTRACT: This study is designed to examine the chemical composition and in vitro antioxidant activity of the essential oil and sub-fractions of the methanol extract of Marrubium globosum subsp. globosum. The GC and GC-MS analysis of the essential oil were resulted in the determination of 84 components representing 88.2% of the oil. The major constituents of the oil were spathulenol (15.8%), beta-caryophyllene (9.0%), caryophyllene oxide (7.9%), germacrene D (6.5%), and bicyclogermacrene (3.1%). Antioxidant activities of the samples were determined by three different test systems namely DPPH, beta-carotene/linoleic acid and reducing power assay. In DPPH system, the weakest radical scavenging activity was exhibited by the essential oil (1203.38+/-7.18 microg ml(-1)). Antioxidant activity of the polar sub-fraction of methanol extract was superior to the all samples tested with an EC(50) value of 157.26+/-1.12 microg ml(-1). In the second case, the inhibition capacity (%) of the polar sub-fraction of methanol extract (97.39%+/-0.84) was found the strongest one, which is almost equal to the inhibition capacity of positive control BHT (97.44%+/-0.74). In the case of reducing power assay, a similar activity pattern was observed as given in the first two systems. Polar sub-fraction was the strongest radical reducer when compared with the non-polar one, with an EC(50) value of 625.63+/-1.02 microg ml(-1). The amount of the total phenolics was highest in polar sub-fraction (25.60+/-0.74 microg/mg). A positive correlation was observed between the antioxidant activity potential and total phenolic level of the extracts. On the other hand, total flavonoid content was found equal for the both sub-fractions.
    Bioresource Technology 08/2008; 99(10):4239-46. · 4.98 Impact Factor
  • Source
    Article: Bioactivities of the Various Extracts and Essential Oils of Salvia limbata CA Mey. and Salvia sclarea L.
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    ABSTRACT: The present study evaluated the in vitro antimicrobial, antioxidant, and antiviral activities of the essential oil and various extracts of Salvia limbata C.A.Mey. and Salvia sclarea L., as well as the content of its essential oil. The activities of essential oils were tested against a wide range of human-, plant-, and food-borne microorganisms. A total of 55 microbial organisms belonging to 35 bacteria and 19 fungi and yeast species were tested using disk diffusion, micro dilution, and micro-well dilution. The essential oils were found to possess antimicrobial activity against some of the tested fungi, while no activity was observed against the bacteria. The chemical compositions of the plant hydrodistilled essential oils were analyzed by means of GC-MS. The main compounds of Salvia species oils were spathulenol (29.30%) and germacrene D (24.72%). Other important components were sclareoloxide (14.08%) and β-caryophyllene (16.24%). The results showed that the compositions of the essential oils of these Salvia species varied significantly. Antioxidant activity was measured by 2 methods, namely scavenging of free radical DPPH and the inhibition of linoleic acid oxidation. In the β-carotene/linoleic acid system, values were 85.1% ± 1 and 76.6% ± 1, respectively, being comparable with that of the synthetic antioxidant BHT (96% ± 1). In antiviral activity assays, the MeOH extracts from Salvia species had a significant anti-influenza virus effect and limited antiherpetic activity. Salvia limbata C.A.Mey. ve Salvia sclarea L. Bitkilerinin Uçucu Yağ ve Çeşitli Özütlerinin Biyoaktiviteleri Özet: Bu çalışma, Salvia limbata C.A.Mey. ve Salvia sclarea L. bitkilerinin çeşitli özütleri ve uçucu yağının in vitro antimikrobiyal, antioksidan, antiviral aktivitelerinin ve uçucu yağ içeriğinin araştırılması için tasarlanmıştır. Uçucu yağ aktivitesi, insan, bitki ve gıda kaynaklı geniş bir mikroorganizma grubuna karşı test edilmiştir. 35 bakteri, 19 mantar ve maya türlerinden oluşan toplam 55 mikroorganizma disk difüzyon metodu, mikro-dilüsyon ve mikro-well dilüsyon yöntemleri kullanılarak test edilmiştir. Uçucu yağlar test edilen mantarlardan bazılarına karşı antimikrobiyal aktiviteye sahip iken bakterilerden hiçbirine karşı aktivite gözlenmemiştir. Hidrodistilasyon ile elde edilen uçucu yağların kimyasal bileşenleri GC-MS ile analiz edilmiştir. Salvia türlerinin yağının temel bileşenleri spathulenol (% 29,30) ve germacrene D (% 24,72) olarak belirlenmiştir. Diğer önemli bileşenler ise sırası ile sclareoloxide (% 14,08) ve β-caryophyllene (% 16,24) olarak belirlenmiştir. Sonuçlar bu Salvia türlerinin bitkisel yağ bileşenlerinde önemli derecede farklılıklar olduğunu göstermiştir. Antioksidan aktivite, serbest radikal giderici DPPH ve linoleik asit oksidasyonu olmak üzere iki metot kullanılarak çalışılmıştır. Kontrol olarak kullanılan sentetik antioksidan BHT (% 96 ± 1)'e karşı, β-karoten/linoleik asit sistem seviyeleri sırası ile % 85,1 ± 1 ve % 76,6 ± 1, olarak tespit edilmiştir. Antiviral aktivite çalışmalarında Salvia türlerinin MeOH özütleri önemli anti-influenza virus etkisi ve sınırlı antiherpetik etki göstermiştir.
    Turk J Biol. 01/2008; 32:181-192.
  • Article: The in vitro antioxidant and antimicrobial activities of the essential oil and various extracts of Origanum syriacum L var bevanii
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    ABSTRACT: The present work examines the in vitro antioxidant and antimicrobial properties of the essential oil and various extracts from the herbal parts of Origanum syriacum L var bevanii. Polar subfractions of methanol extracts from both deodorised and non-deodorised materials showed the highest DPPH (2,2-diphenyl-l-picrylhydrazyl) radical-scavenging activity, with IC50 values of 21.40 and 26.98 µg ml−1 respectively, whereas the IC50 of the essential oil was 134.00 µg ml−1. The antioxidant potential of the extracts appeared to be closely related to the presence of polar phenolics. However, the inhibitive effect on linoleic acid oxidation might be promoted by the presence of non-polar phenolics, as both hexane and dichloromethane extracts showed high antioxidant activities. The antimicrobial activity of the essential oil was superior to those of the other extracts. Nineteen compounds representing 962 g kg−1 of the essential oil were identified; carvacrol (669 g kg−1) was the main component. Overall, the results suggest that the essential oil and extracts from the herbal parts of O syriacum could be used as natural preservative ingredients in the food industry. Copyright © 2004 Society of Chemical Industry
    Journal of the Science of Food and Agriculture 08/2004; 84(11):1389 - 1396. · 1.44 Impact Factor
  • Article: In vitro antioxidant, antimicrobial, and antiviral activities of the essential oil and various extracts from herbal parts and callus cultures of Origanum acutidens.
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    ABSTRACT: The essential oil and various extracts obtained from Origanum acutidens and methanol extracts (MeOH) from callus cultures have been evaluated for their antioxidative, antimicrobial, and antiviral properties. The essential oil exhibited strong antimicrobial activity with a significant inhibitory effect against 27 (77%) of the 35 bacteria, 12 (67%) of the 18 fungi, and a yeast tested and moderate antioxidative capacity in DPPH and beta-carotene/linoleic acid assays. GC and GC-MS analyses of the oil resulted in the identification of 38 constituents, carvacrol being the main component. The MeOH extracts obtained from herbal parts showed better antioxidative effect than that of butylated hydroxytoluene (BHT), whereas callus cultures also exhibited interesting antioxidative patterns. Concerning antiviral activity, none of the extracts inhibited the reproduction of influenza A/Aichi virus in MDCK cells. The MeOH extracts from herbal parts inhibited the reproduction of HSV-1, and also callus cultures exerted slight antiherpetic effect.
    Journal of Agricultural and Food Chemistry 07/2004; 52(11):3309-12. · 2.82 Impact Factor
  • Article: The in vitro antioxidant and antimicrobial activities of the essential oil and methanol extracts of Achillea biebersteini Afan. (Asteraceae).
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    ABSTRACT: The essential oil and methanol extracts from A. biebersteinii Afan. (Asteraceae) were evaluated for their antimicrobial and antioxidant activities in vitro. The oil showed stronger antimicrobial activity than the extracts. Their antioxidant features were also evaluated using diphenyl-1-picrylhydrazyl (DPPH), inhibition of superoxide and hydroxyl radicals and inhibition of the lipid peroxidation assays. Particularly, polar subfraction of the methanol extract showed antioxidant activity. The GC-MS analysis of the oil has resulted in the identification of 23 components; piperitone, eucalyptol, camphor, chrysanthenone and borneol were the main components. Antimicrobial activity tests carried out with the fractions of the oil showed that the activity was mainly observed in those containing eucalyptol and camphor, in particular, followed by borneol and piperitone.
    Phytotherapy Research 07/2004; 18(6):451-6. · 2.09 Impact Factor
  • Article: In vitro antimicrobial and antioxidant activities of the essential oils and various extracts of Thymus eigii M. Zohary et P.H. Davis.
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    ABSTRACT: This study was designed to examine the in vitro antimicrobial and antioxidant activities of the essential oil and various extracts obtained from aerial parts of Thymus eigii. The essential oil was particularly found to possess stronger antimicrobial activity, whereas other nonpolar extracts and subfractions showed moderate activity and polar extracts remained almost inactive. GC-MS analysis of the oil resulted in the identification of 39 compounds, representing 93.7% of the oil; thymol (30.6%), carvacrol (26.1%), and p-cymene (13.0%) were the main components. The samples were also subjected to a screening for their possible antioxidant activity by using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and beta-carotene-linoleic acid assays. In the former case, the polar subfraction of the methanol extract was found to be superior to all extracts tested, only 16.8 microg/mL of which provided 50% inhibition, whereas all extracts, particularly the polar ones, seem to inhibit the oxidation of linoleic acid in the latter case. These data were further supported by total phenolics analysis, indicating that the antioxidative potential of the extracts was closely related to their phenolic constituents.
    Journal of Agricultural and Food Chemistry 04/2004; 52(5):1132-7. · 2.82 Impact Factor
  • Article: Antimicrobial activity of essential oil and methanol extracts of Achillea sintenisii Hub. Mor. (Asteraceae).
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    ABSTRACT: The essential oil, obtained by Clevenger distillation, and water-soluble and water-insoluble parts of the methanol extracts of Achillea sintenisii Hub. Mor. were individually assayed for their antimicrobial activities against 12 bacteria and two yeasts, Candida albicans and C. krusei. No activity was exhibited by the water-soluble subfraction, whereas both the water-insoluble subfraction of the methanol extracts and the essential oil were found to be active against some test microorganisms studied. Since the essential oil possessed stronger activity than the other extracts tested, it was further fractionated and the fractions were evaluated for their antimicrobial activity, followed by GC-MS analysis, resulting in the identification of 32 compounds which constituted 90.2% of the total oil. The GC-MS analysis of the oil and its fractions revealed that the main components of the oil, e.g. camphor and eucalyptol, possessed appreciable activity against C. albicans and Clostridium perfringens. The fi ndings presented here also suggest that the other constituents of the oil, e.g. borneol and piperitone can also be taken into account for the activity observed.
    Phytotherapy Research 12/2003; 17(9):1005-10. · 2.09 Impact Factor
  • Article: Antioxidant and antimicrobial activity of the essential oil and methanol extracts of Achillea millefolium subsp. millefolium Afan. (Asteraceae).
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    ABSTRACT: 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.
    Journal of Ethnopharmacology 09/2003; 87(2-3):215-20. · 3.01 Impact Factor
  • Article: Antimicrobial and antioxidant activity of the essential oil and methanol extracts of Thymus pectinatus Fisch. et Mey. Var. pectinatus (Lamiaceae).
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    ABSTRACT: The essential oil, obtained by using a Clevenger distillation apparatus, and water-soluble (polar) and water-insoluble (nonpolar) subfractions of the methanol extract of Thymus pectinatus Fisch. et Mey. var. pectinatus were assayed for their antimicrobial and antioxidant properties. No (or slight) antimicrobial activity was observed when the subfractions were tested, whereas the essential oil showed strong antimicrobial activity against all microorganisms tested. Antioxidant activities of the polar subfraction and the essential oil were evaluated using 2,2-diphenyl-1-picrylhydrazyl, hydroxyl radical, superoxide radical scavenging, and lipid peroxidation assays. The essential oil, in particular, and the polar subfraction of the methanol extract showed antioxidant activity. The essential oil was analyzed by GC/MS, and 24 compounds, representing 99.6% of the essential oil, were identified: thymol, gamma-terpinene, p-cymene, carvacrol, and borneol were the main components. An antimicrobial activity test carried out with fractions of the essential oil showed that the activity was mainly observed in those fractions containing thymol, in particular, and carvacrol. The activity was, therefore, attributed to the presence of these compounds. Other constituents of the essential oil, such as borneol, gamma-terpinene, and p-cymene, could be also taken into account for their possible synergistic or antagonistic effects. On the other hand, thymol and carvacrol were individually found to possess weaker antioxidant activity than the crude oil itself, indicating that other constituents of the essential oil may contribute to the antioxidant activity observed. In conclusion, the results presented here show that T. pectinatus essential oil could be considered as a natural antimicrobial and antioxidant source.
    Journal of Agricultural and Food Chemistry 02/2003; 51(1):63-7. · 2.82 Impact Factor
  • Article: Compositions and the in vitro antimicrobial activities of the essential oils of Achillea setacea and Achillea teretifolia (Compositae).
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    ABSTRACT: 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.
    Journal of Ethnopharmacology 12/2002; 83(1-2):117-21. · 3.01 Impact Factor
  • Article: Screening of the antioxidative and antimicrobial properties of the essential oils of Pimpinella anisetum and Pimpinella flabellifolia from Turkey
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    ABSTRACT: The aerial parts of two endemic Pimpinella [Pimpinella anisetum Boiss. & Ball. and Pimpinella flabellifolia (Boiss.) Benth. ex Drude] were hydro-distilled to produce oils in the yields of 2.07% (v/w) and 2.61% (v/w), respectively. The oils were analysed by GC and GC/MS. Twenty-one and nineteen components were identified, representing 99.5% and 99.7% of the oils, respectively. The main compounds of P. anisetum were (E)-anethole (82.8%) and methyl chavicol (14.5%), whereas limonene (47.0%), (E)-anethole (37.9%) and α-pinene (6.0%) were the major constituents of P. flabellifolia. The oils were screened for their possible antioxidant activities by two complementary test systems, namely DPPH free radical-scavenging and β-carotene/linoleic acid systems. In the first case, P. anisetum oil exerted greater antioxidant activity than that of P. flabellifolia oil with an IC50 value of 5.62 ± 1.34 μg/ml. In the β-carotene/linoleic acid test system, the oil of P. anisetum was superior to P. flabellifolia with 70.5% ± 2.86 inhibition rate. Essential oils of the plants studied here were also screened for their antimicrobial activities against six bacteria and two fungi. The oils showed moderate antimicrobial activity against all microorganisms tested.
    Food Chemistry.
  • Article: The in vitro antioxidative properties of the essential oils and methanol extracts of Satureja spicigera (K. Koch.) Boiss. and Satureja cuneifolia ten
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    ABSTRACT: This study was designed to examine the in vitro antioxidant activities of the essential oil and methanol extracts of Satureja spicigera and S. cuneifolia from Turkish flora. GC and GC/MS analysis of the essential oils resulted in the identification of 40 and 29 compounds, representing the 99.4% and 99.5% of the oils, respectively. Major constituents of the oils were carvacrol (42.5% and 67.1%), γ-terpinene (21.5% and 15.2%) and p-cymene (20.9% and 6.7%), respectively. Methanol extracts were also obtained from the aerial parts of the plants. The samples were subjected to a screening for their possible antioxidant activities by using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and β-carotene–linoleic acid assays. In general, samples obtained from S. cuneifolia exerted greater antioxidant activities than did those obtained from S. spicigera. In the DPPH test system, free radical-scavenging activity of S. spicigera oil was determined to be 127 ± 1.63 μg/ml, whereas IC50 value of S. cuneifolia was 89.1 ± 2.29 μg/ml. In the β-carotene–linoleic acid test system, antioxidant activities of the oil were 81.7 ± 1.14% and 93.7 ± 1.83%, respectively. Antioxidant activities of the synthetic antioxidant, BHT, ascorbic acid, curcumin and α-tocopherol were also determined in parallel experiments.
    Food Chemistry.
  • Article: Antimicrobial and antioxidative activity of the essential oil and various extracts of Cyclotrichium origanifolium (Labill.) Manden. & Scheng.
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    ABSTRACT: This study was designed to examine the in vitro antimicrobial and antioxidant activity of the essential oil and various extracts prepared by using solvents of varying polarity from Cyclotrichium origanifolium (Labill.) Manden. & Scheng. The essential oil was particularly found to possess stronger antimicrobial activity while other non-polar extracts and subfractions showed moderate activity and polar extracts remained almost inactive. GC and GC/MS analysis of the oil resulted in the identification of 26 compounds, representing 99.6% of the oil; pulegone (49.8%), menthone (32.5%) and limonene (6.0%) were the main components. The samples were also subjected to a screening for their possible antioxidant activity by using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and β-carotene-linoleic acid assays. In the first case, the free radical scavenging activity of polar subfraction of deodorized methanol extract (DeMW) was superior to all other extracts. Especially polar extracts exhibited strongest activity than the non-polar extracts. In the case of linoleic acid system, oxidation of linoleic acid was effectively inhibited by non-polar (chloroformic) subfraction methanol extract (MC), where the oil was less effective. MC extract exhibits 79.2% inhibition that is close to synthetic antioxidant reagent BHT when compared to the other extracts tested.
    Journal of Food Engineering.
  • Article: Antioxidative activity of the essential oils of Thymus sipyleus subsp. sipyleus var. sipyleus and Thymus sipyleus subsp. sipyleus var. rosulans
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    ABSTRACT: The aim of present study was to compare the antioxidant potential of two Thymus species on the basis of the chemical compositions of oils obtained by hydrodistillation. In the case of Thymus sipyleus subsp. sipyleus var. sipyleus, 71 compounds were identified representing the 92.5% of the total oil. The major constituents of the oil were described as borneol (11.2%), α-muurolol (9.2%), β-caryophyllene (7.6%), geranial (7.3%) and neral (5.4%). On the other hand, 47 compounds were identified representing 98.7% of the oil of Thymus sipyleus subsp. sipyleus var. rosulans. This oil is characterised by the high monoterpene fraction (94.0%) and especially by the presence of the phenolic carvacrol (58.1%), thymol (20.5%) and their precursors p-cymene (4.1%) and γ-terpinene (4.4%). The oils were also subjected to screening for their possible antioxidant activity by using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and β-carotene/linoleic acid assays. In the first case, the free radical scavenging activity of the essential oil of T. sipyleus subsp. sipyleus var. rosulans was superior to var. sipyleus oil (IC50=220 ± 0.5 and 2670 ± 0.5 μg/ml, respectively). In the case of linoleic acid system, oxidation of linoleic acid was effectively inhibited by T. sipyleus subsp. sipyleus var. rosulans (92.0%), while the var. sipyleus oil had no activity. In the latter case, the linoleic acid inhibition rate of var. rosulans oil is close to the synthetic antioxidant BHT (96.0%).
    Journal of Food Engineering.
  • Article: The in vitro antimicrobial and antioxidant activities of the essential oils and methanol extracts of endemic Thymus spathulifolius
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    ABSTRACT: The present study was conducted to evaluate the in vitro antimicrobial and antioxidant properties of essential oil and methanol extracts from a unique and endemic plant, Thymus spathulifolius (Hausskn. and Velen.). The antimicrobial test results showed that the essential oil of T. spathulifolius strongly inhibited the growth of test microorganisms studied, except for 4 fungi species while polar and non-polar subfractions of the methanol extract had moderate antibacterial, but not antifungal and anticandidal activity. The antioxidative potential of the samples was evaluated using two separate methods, inhibition of free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) and β-carotene–linoleic acid systems. The polar subfraction of the methanol extract was able to reduce the stable free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) with an IC50 of 16.15 ± 0.5 μg/ml, which was lower than that of synthetic antioxidant, BHT, (19.8 ± 0.5 μg/ml). Inhibition values of linoleic acid oxidation were calculated as 92% and 89% for the oil and the polar subfraction, respectively. Gallic acid equivalent total phenolic constituent of the polar subfraction was 141.00 ± 0.90 μg/mg (14.1%, w/w). The chemical composition of a hydrodistilled essential oil of T. spathulifolius was analyzed by a GC and GC/MS system. A total of 28 constituents representing 99.2% of the oil were identified; thymol (36.5%), carvacrol (29.8%), p-cymene (10.0%) and γ-terpinene (6.3%) were the main components comprising 82.6% of the oil. Results presented here may suggest that the essential oil and extracts of T. spathulifolius possess antimicrobial and antioxidant properties, and therefore, they can be used as a natural preservative ingredient in food and/or pharmaceutical industry.
    Food Control.
  • Article: Antimicrobial and antioxidative activities of the essential oils and methanol extracts of Salvia cryptantha (Montbret et Aucher ex Benth.) and Salvia multicaulis (Vahl)
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    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 Chemistry.
  • Article: Chemical composition and antioxidant activity of the essential oil of Clinopodium vulgare L.
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    ABSTRACT: This study was designed to examine the chemical composition and in vitro antioxidant activity of the essential oil of Clinopodium vulgare. GC–MS analysis of the oil resulted in the identification of 40 compounds, representing 99.4% of the oil; thymol (38.9%), γ-terpinene (29.6%) and p-cymene (9.1%) were the main components. The samples were subjected to a screening for their possible antioxidant activity by using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and β-carotene-linoleic acid assays. In the first case, IC50 value of the C. vulgare essential oil was determined as 63.0 ± 2.71 μg/ml. IC50 value of thymol and γ-terpinene, the major compounds of the oil, was determined as 161 ± 1.3 μg/ml and 122 ± 2.5 μg/ml, respectively, whereas p-cymene did not show antioxidant activity. In β-carotene-linoleic acid system, C. vulgare essential oil exhibited 52.3 ± 1.19% inhibition against linoleic acid oxidation. In both systems, antioxidant capacities of BHT, curcumine and ascorbic acid were also determined in parallel experiments.
    Food Chemistry. 103(3):766-770.
  • Article: Antioxidant activity of the essential oil and various extracts of Nepeta flavida Hub.-Mor. from Turkey
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    ABSTRACT: This study was designed to examine the chemical composition and in vitro antioxidant activity of the essential oil and various extracts (hexane, dichloromethane and methanol sub-fractions) of Nepeta flavida. GC and GC–MS analyses of the essential oil resulted in the identification of 68 compounds, representing 96.4% of the oil; 1,8-cineole (38.9%) and linalool (25.1%) were the main components, comprising 64.0% of the total oil. The samples were subjected to a screening for their possible antioxidant activities by using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and β-carotene-linoleic acid assays. In the first case, the IC50 value of the N. flavida essential oil was determined to be 42.8 ± 2.19 μg/ml. Among the extracts, the strongest activity was exhibited by the polar sub-fraction of the methanol extract with an IC50 value of 63.2 ± 1.75 μg/ml. In the β-carotene-linoleic acid system, N. flavida essential oil exhibited 86.3% ± 1.69 inhibition against linoleic acid oxidation. Among the extracts prepared with various solvents, a correlation was observed between the polarity and antioxidant activity. The extracts exhibited the same activity pattern in this system the most active one is the polar sub-fraction, 79.7% ± 0.89. On the other hand, 1,8-cineole, a major compound of the essential oil, exhibited marked antioxidant activity in both systems, whereas the other compound, linalool, did not show any activity. The amount of total phenolics was highest in the polar and non-polar sub-fractions. Particularly, a positive correlation was observed between the total phenolic content and the antioxidant activity of the extracts. As estimated from the results, amounts of phenolic compounds were less in hexane and dichloromethane extracts than in the others. In conclusion, antioxidant potentials of polar and non-polar methanol sub-fractions could be attributed to their high phenolic contents. In both systems, antioxidant capacities of BHT, ascorbic acid, curcumin and α-tocopherol were also determined in parallel experiments.
    Food Chemistry.
  • Article: Composition of the essential oils of Tanacetum argyrophyllum (C. Koch) Tvzel. var. argyrophyllum and Tanacetum parthenium (L.) Schultz Bip. (Asteraceae) from Turkey
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    ABSTRACT: The aerial parts of Tanacetum argyrophyllum (C. Koch) Tvzel. var. argyrophyllum and T. parthenium (L.) Schultz Bip. were hydro-distilled to produce the oils in the yields of 0.78% (v/w) and 0.43% (v/w), respectively. The oils were analysed by GC and GC/MS. Twenty-two and twenty-three components were identified representing 94.2% and 90.1% of the oils, respectively. The main compounds of T. argyrophyllum were cis-thujone (69.9%), trans-thujone (5.6%) and 1,8-cineole (3.2%), whereas camphor (56.9%), camphene (12.7%) and p-cymene (5.2%) were the major constituents of T. parthenium.
    Biochemical Systematics and Ecology.