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, γ‐terpinene, p‐cymene, α‐terpinene and α‐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. Copyright © 2009 Society of Chemical Industry     

Carotenoid pigment composition, polyphenol content, and antioxidant activities of extracts from orange-colored Chinese cabbage

We investigated the carotenoid pigment composition in orange-colored Chinese cabbage (OC) (Brassica rapa; cultivar (cv), Orange queen) and (normal) Chinese cabbage (NC) (B. rapa; cv, Yūki), and evaluated the antioxidant activities of their carotenoid and phenolic extracts. Although the major carotenoid pigments in NC are lutein and β-carotene, OC contained 7Z, 9Z, 7’Z, 9’Z tetra-cis-lycopene (prolycopene) and phytoene as the major carotenoid pigments along with β-carotene. The total carotenoid content of extracts from OC was two-fold higher than the extracts from NC. The 2,2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical-scavenging activity of carotenoid extracts from OC [169 ± 2 μmol Trolox equivalent/100 g dry weight. (DW) (average ± SD)] was significantly higher than the carotenoid extracts from NC (132 ± 7 μmol Trolox equivalent/100 g DW) (P < 0.001). Moreover, the total phenols of methanolic extracts from OC (387 ± 11 mg/100 g DW) was significantly higher than the methanolic extracts from NC (263 ± 2 mg/100 g DW) (P < 0.001), and the superoxide anion radical-scavenging (SOD-like) activities of methanolic extracts from OC (70 ± 2%) were also higher than the methanolic extracts from NC (61 ± 2%) (P < 0.001). These results suggest that OC contains large amounts of carotenoid and phenolic compounds with radical-scavenging activity in comparison to NC.     

Salt effect on phenolics and antioxidant activities of Tunisian and Canadian sweet marjoram (Origanum majorana L.) shoots

BACKGROUND: Two varieties of Origanum majorana (Canadian and Tunisian) were evaluated for their phenolic, flavonoid and tannin contents, individual phenolic compounds and antioxidant activities under NaCl constraint. RESULTS: The results showed a significant variability in phenolic composition and antioxidant behavior between the two varieties under salt stress. The phenolic composition of methanolic extracts was determined by reversed‐phase high‐performance liquid chromatography. Amentoflavone was the predominant flavonoid compound; in addition, trans‐2‐hydrocinnamic acid became the major phenolic acid with salt treatment of the Tunisian variety. In the control, Canadian variety extract was characterized by high levels of gallic acid and amentoflavone. However, under 75 mmol L^?1 NaCl, gallic acid content doubled, whereas amentoflavone content was maintained in the Canadian variety. Stimulation of phenolic acid biosynthesis was observed in these two varieties under salt treatment despite the fact that shoots of the Tunisian variety showed higher antioxidant activities compared to those from the Canadian variety. Tunisian O. majorana might have developed tolerance to salinity and avoided tissue damage by activating enzymes involved in the galactosylation of quercetin into quercetin‐3‐galactoside and quercetin‐3‐rhamnoside. CONCLUSION: Our results confirmed the tolerance of Tunisian O. majorana plants. Copyright © 2012 Society of Chemical Industry     

调味香料马玉兰挥发油化学成分的研究

采用水蒸气蒸馏法提取了调味香料马玉兰的挥发油,并利用气相色谱/质谱(GC/MS)联用技术和保留指数比较法分析了该挥发油的化学成分。从马玉兰挥发油中鉴定了40种化合物,占挥发油总量的95.06%。我国马玉兰挥发油的主要成分为4-萜品醇(33.00%)、氧化石竹烯(11.91%)、对伞花烃(6.84%)、α-松油醇(6.66%)和斯巴醇(6.00%)。     

Factors influencing antioxidant activities and total phenolic content of guava leaf extract

The aim of this study is to investigate the influence of certain factors on the yield, antioxidant activity (AA) and total phenolic content (TPC) of guava leaf extract. The effects of pretreatment of leaf sample prior to extract, extraction method, and the leaf age were investigated. Folin-Ciocalteau was used to determine the TPC. Trolox equivalent antioxidant capacity (TEAC) and equilibrium concentration (EC) were used for evaluation of AA. Results indicated that ultrasonication is the most suitable method for guava leaf extraction as it yielded the extract with the significantly highest TPC and AA. Blanching followed by ice water cooling (BCD) was suggested for the pretreatment process of guava leaves. The study of leaf maturity demonstrated that the highest activity was from the young leaves. Hot water was the best solvent to extract the active principles. The extract of BCD pretreated young leaves, extracted by hot water exhibited the highest TPC and AA with the TEAC and EC values of 24.30 ± 0.50 and 20.41 ± 0.67 mM/mg, respectively. These values are 1.88 and 8.72 times higher than the synthetic antioxidant butylated hydroxy toluene (BHT) and 1.75 and 1.21 times higher than vitamin E, respectively. It was concluded that pretreatment and drying process, method of extraction and leaf maturity played important roles on the bioactive compounds and their antioxidant power of guava leaf extract.     

Essential oil composition,antimicrobial and antioxidant activities of Satureja cuneifolia Ten.

Satureja cuneifolia Ten. is a well-known aromatic plant which is frequently used as a spice and herbal tea in Anatolia. S. cuneifolia oil was analyzed by gas chromatography/mass spectrometry (GC/MS). The major components of S. cuneifolia oil were carvacrol (44.99%) and p-cymene (21.61%). The essential oil of S. cuneifolia exhibited antimicrobial activity against all of the tested foodborne and spoilage bacteria. The minimum inhibitory concentration (MIC) values for test bacteria which were sensitive to the essential oil of S. cuneifolia were in the range of 600–1400 μg/ml. Antioxidant activities of the essential oil and the methanolic extract from S. cuneifolia were evaluated by using DPPH radical scavenging, β-carotene–linoleic acid bleaching and metal chelating activity assays. In addition, the amounts of total phenol components in the plant methanolic extract (222.5 ± 0.5 μg/mg) and the oil (185.5 ± 0.5 μg/mg) were determined.     

In vitro antioxidant activities of the methanol extracts of four Helichrysum species from Turkey

This study was designed to examine the in vitro antioxidant activities of the methanol extracts of four Helichrysum species (Helichrysum noeanum Boiss., H. chionophilum Boiss. & Bal., H. plicatum DC. subsp. plicatum, H. arenarium (L.) Moench. subsp. aucheri (Boiss.) Davis & Kuphicha). The extracts were screened for their possible antioxidant activitiy by two complementary test systems, namely DPPH free radical-scavenging and β-carotene/linoleic acid systems. In the first case, non-polar subfractions of the methanol extracts of Helichrysum species studied did not show any antioxidant activity, while the most active one was H. chionophilum (IC₅₀ =40.5 μg/ml) among the polar subfractions. In the β-carotene/linoleic acid test system, inhibition rates of the oxidation of linoleic acid of H. noeanum and H. arenarium were very close to each other. The inhibition rate of the synthetic antioxidant BHT was determined to be 96%. Since the polar extracts of Helichrysum species dealt with here exhibited interesting antioxidant activities when compared to BHT, we believe that it would be useful to take the results into consideration as an alternative for food processing industries.     

Influence of winemaking techniques on the resveratrol content, total phenolic content and antioxidant potential of red wines

In this paper, the influence of winemaking techniques and cultivars on the resveratrol content, total phenolic content and antioxidant potential of red wines was studied. Wines were made from the cultivars Merlot, Cabernet Sauvignon, Pinot Noir and Prokupac. Applied winemaking technologies included thermovinification and separation of must from pomace. The analysis of trans- and cis-resveratrol in wines was performed by HPLC, while the total phenolic content and antioxidant potential was determined by spectrophotometric methods. The total resveratrol content in analysed samples ranged from 0.35 to 4.85 mg/l; Merlot wines had the highest average resveratrol content, while the lowest was found for native cultivar Prokupac. Although the resveratrol content depended on grape variety, correlation between the winemaking technology applied and the resveratrol level in wines was not observed. The total phenolic content (TPC) varied from 544.4 to 1410.4 mg/l expressed as gallic acid equivalents, and the antioxidant potential, assayed by DPPH in terms of SC₅₀ (mean scavenging concentration), ranged from 0.58 to 2.91 μl/ml. Obtained results showed that thermovinificated wine samples had higher amount of phenolic compounds. Significant negative correlation was observed (p < 0.05) between the total phenolic content and SC₅₀, but there was no significant correlation (p > 0.05) between the resveratrol content and SC₅₀ or TPC. This study could contribute to the establishment of optimal conditions for producing red wines which contain more beneficial phenolic compounds.     

Antioxidant activity of sage (Salvia officinalis and S fruticosa) and oregano (Origanum onites and O indercedens) extracts related to their phenolic compound content

In this study the antioxidant activity of methanolic extracts of oregano and sage samples was tested. Samples of oregano belonged to Origanum onites and O indercedens species, whilst samples of sage belonged to Salvia officinalis and S fruticosa species. Two methods were used to evaluate the antioxidant activity of sage and oregano extracts: the crocin test and the Rancimat test. The methanolic extracts were also analysed by HPLC for the qualitative/quantitative determination of phenolic compounds. The total phenolic compound content of oregano samples showed no significant differences between the two species, but rosmarinic acid was present in higher amount in O indercedens. Carvacrol content sharply differentiated flowers from leaves. Samples of O indercedens had a higher antioxidant activity evaluated by the crocin test, whereas no differences were evidenced by the Rancimat test. For sage samples, carnosic acid and methyl carnosate showed a significant difference between the two species, with S fruticosa samples having a higher content than S officinalis samples. Samples of S fruticosa also had a higher antioxidant activity evaluated by the crocin test. The antioxidant activities of sage samples were, on average, higher than those of oregano samples. Some samples of sage had a very high antioxidant activity, with induction times more than 10‐fold higher than that of lard used as the reference sample. © 2002 Society of Chemical Industry     

Modification of Fatty Acid,Essential Oil and Phenolic Contents of Salt‐Treated Sweet Marjoram (Origanum majorana L.) According to Developmental Stage

Abstract: Variation in the composition of Origanum majorana L. essential oil (EO) and fatty acids were studied under salt treatment. Plant material has been harvested at 2 phenological stages: early vegetative stage (EVS) and late vegetative stage (LVS) or prefloral. Our results showed that the application of 75 mM NaCl increased total lipid contents in marjoram shoots and caused great qualitative changes in the fatty acids profiles. NaCl treatment reduced and stimulated the EO yields, respectively, at EVS and LVS and induced quantitative changes in the chemical EO composition in shoots. Phenolic contents were higher during the LVS than EVS in the absence and the presence of salt. Under control conditions, RP‐HPLC analysis of the methanolic extract of marjoram dried shoots showed a predominance of flavonoid during the EVS whereas phenolic acids predominated during the LVS. However, under 75 mM NaCl, we noted a predominance of flavonoid at LVS and constant levels of phenolic and flavonoid classes at the EVS. For control treatment and at both EVS and LVS, the main components identified were respectively rosmarinic acid gallic as phenolic acids and amentoflavone as flavonoid. In the presence of salt and at the EVS, we observed a significant increase in trans‐2 hydrocinnamic, gallic acid and quercetin‐3‐galactoside contents. However, for the LVS, salt induced a stimulation of gallic acid, apigenin, and amentoflavone. Our results showed that LVS had the highest contents of bioactive compounds, and could be considered as the best stage for harvesting marjoram plants. Practical Application: In this study, the fatty acid composition, essential oil, and phenolic content of Origanum majorana were investigated. This is important for potential application of marjoram as functional food at the late vegetative stage. The richness of O. majorana in volatile and phenolic active compounds known for their antioxidant, antimicrobial, and insecticidal activities could support the utilization of this plant in a large field of application including cosmetic, pharmaceutical, agro alimentary, and biological defense.     

Antioxidant capacity and total phenolic content of selected plants from Turkey

A total of 28 different plants from different regions of Çanakkale, Turkey, were investigated for their antioxidant capacity and total phenol contents to find new potential sources of natural antioxidants. The antioxidant capacity of methanolic extracts prepared from various parts of plants was evaluated by both trolox equivalent antioxidant capacity (TEAC) and 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) assays, while the total phenolics were determined using the Folin‐Ciocalteu method. The TEAC values of plant extracts ranged in a large scale from 1472.36 to 17.61 μmol of trolox equivalents per g dry weight (dw), and EC₅₀ values (concentration at which 50% radical scavenging occurred) varied from 0.174 to 42.475 mg dw of plant, while the total phenol content of plant extracts ranged between 117.20 and 1.27 mg of gallic acid equivalents per g dw. There was a positive linear correlation between the TEAC and total phenols of plant materials (r = 0.916). The extracts of Hypericum perforatum, Arbutus andrachne and Paliurus spina‐christii showed higher antioxidant activities (both TEAC and DPPH assays). However, there was no clear relationship between TEAC and EC₅₀ values (r = 0.477) of plant extracts.     

Relationship between the antioxidant properties and the phenolic and flavonoid content in traditional balsamic vinegar

The antioxidant properties of traditional balsamic vinegar as regards its phenolic and flavonoid content comparing it to selected vinegars and red wines have been investigated. The polyphenols were separated from interfering compounds utilizing C18 columns. The polyphenolic content was determined utilizing both Folin–Ciocalteu and peroxidase assays. The antioxidant capacity was quantified using both ABTS and FRAP assays. The results show that traditional balsamic vinegar has lower antioxidant activity and phenolic and flavonoid content than Nero d’Avola but higher than the other tested products. The antioxidant capacity of wines and vinegars is highly correlated with their phenolic content, measured by peroxidase assay and it is also highly correlated with their flavonoid content while in traditional balsamic vinegar and balsamic vinegar this correlation diminishes. The study describes a simple and fast method of separating from other compounds and of measuring polyphenols in the analysis of red wines and vinegars with complex composition such as traditional balsamic vinegar.     

Total phenolic content,antiradical, antioxidant and antimicrobial activities of Rhododendron honeys

Fifty Rhododendron honey samples obtained from Black Sea Region of Turkey were screened for total phenolic content by the modified Folin–Ciocalteu method, for potential antioxidant activity using phosphomolybdenum assay and by the 1,1-diphenyl-2-picryl hydrazyl (DPPH) method for antiradical activity. The antimicrobial activity was studied by the agar diffusion method, using eleven bacteria and two yeasts.     

Essential oils of Origanum vulgare L. subsp. glandulosum (Desf.) Ietswaart from Tunisia: chemical composition and antioxidant activity

BACKGROUND: Characterisation of the essential oils from O. glandulosum collected in three locations of Tunisia, chemical composition and the evaluation of their antioxidant activities were carried out. RESULTS: The essential oils from Origanum vulgare L. subsp. glandulosum (Desf.) Ietswaart collected from three localities of north Tunisia—Krib, Bargou and Nefza—were obtained in yields of 2.5, 3.0 and 4.6% (v/w), respectively. The essential oils were analysed by GC and GC/MS and assayed for their total phenolics content, by the Folin–Ciocalteu method, and antioxidant effectiveness, using the 2,2‐diphenyl‐1‐picrylhydrazil (DPPH) radical scavenging assay. The main components of these essential oils, from Nefza, Bargou and Krib, were p‐cymene (36%, 40% and 46%), thymol (32%, 39% and 18%), γ‐terpinene (24%, 12% and 16%) and carvacrol (2%, 2% and 15%), respectively). The ability to scavenge the DPPH radicals, expressed by IC₅₀, ranged from 59 to 80 mg L^?1. The total phenolic content, expressed in gallic acid equivalent (GAE) g kg^?1 dry weight, varied from 9.37 to 17.70 g kg^?1 dw. CONCLUSIONS: A correlation was identified between the total phenolic content of the essential oils and DPPH radical scavenger capacity. The occurrence of a p‐cymene chemotype of O. glandulosum in the northern region of Tunisia is demonstrated. Copyright © 2010 Society of Chemical Industry     

Chemical composition and insecticidal properties of Origanum glandulosum (Desf.) essential oil from Algeria

BACKGROUND: To find natural compounds with insecticidal properties which could be an alternative to synthetic insecticides, oregano essential oil was tested against the insect Rhizopertha dominica devastating stored cereals. RESULTS: Oregano oils were isolated by steam distillation, analysed by gas chromatography and gas chromatography–mass spectrometry and investigated for their insecticidal activities against Rhizopertha dominica. Contact and fumigant toxicities of global oil and three of its fractions recovered respectively after 2 h and after 0–2.5, 2.5–5 and 5–10 min of extraction were tested using the filter paper method. Eighteen components, representing 92.6% of the oil, were identified. The major components were thymol (38.8%), carvacrol (32.9%), p‐cymene (7.9%) and γ‐terpinene (5.1%). Toxicity tests showed that insect mortality increases with the concentration used (0.39%, 0.78%, 1.56%, 3.12% and 6.24%V). For all concentrations, the contact effect of global oil and fraction F₂ was better than the fumigant effect. Whereas fractions F₁ and F₃ were more toxic by fumigation for concentrations lower or equal to 1.56%, their contact effect was more significant for concentrations higher than 1.56%. CONCLUSION: These results suggest that oregano oil has important insecticidal properties and may be useful as a natural grain protectant against Rhizopertha dominica to replace synthetic insecticides. Copyright © 2008 Society of Chemical Industry     

Effect of thermal treatment on phenolic composition and antioxidant activities of two celery cultivars

Various thermal processing treatments (blanching 3 min, boiling 10 min or steaming 10 min) of Shengjie celery (Apium graveolens L.) and Tropica celery (Cryptotaenia japonica Hassk.) were studied for the effects on the levels of caffeic, p-coumaric, ferulic acid, apigenin, luteolin, kaempferol and total phenolics (TPC) as well as on the antioxidant capacity by the DPPH (1, 1-diphenyl-2-picrylhydrazyl) and ABTS⁺ [2,2′-azinobis(3-ethylbenzthiazoline-6-sulfonate)] methods. Significant (p < 0.05) losses were found in boiled celery in TPC, 41.2%; DPPH, 40.6% and ABTS⁺, 35.2% on average. Blanching gave less extensive reductions in TPC, 37.8%; DPPH, 21.0% and ABTS⁺, 27.7% on average. Steaming had the most modest effect. The two cultivars exhibited different responses. Steaming did not cause losses in TPC and DPPH in Tropica celery. A significant positive correlation between antioxidant capacity (DPPH and ABTS+) values and the contents of flavonols or total phenolics acids was observed in this study.