Abstract
The main aim of this study was the characterization of coriander essential oil. The major volatile compounds in coriander seed essential oil were linalool, γ-terpinene, α-pinene, camphor, decanal geranyl acetate, limonene, geraniol, camphene, and D-limonene, while the major volatile compounds identified in coriander leaves essential oil were (E)-2-decenal, linalool, (E)-2-dodecenal, (E)-2-tetradecenal, 2-decen-1-ol, (E)-2-undecenal, dodecanal, (E)-2-tridecenal, (E)-2-hexadecenal, pentadecenal, and α-pinene. The essential oil from coriander seeds showed significant radical scavenging activity (66.48 ± 0.80%) at a concentration of 500 μg in comparison with essential oil of coriander leaves (56.73 ± 1.82%). Methanol extracts of both seed and leaves showed the significant radical scavenging activity (64.40 ± 0.81%) and (72.19 ± 0.64%) at 500 μg/mL, respectively, in comparison with the n-hexane extracts, which were (52.67 ± 2.05%) and (60.80 ± 1.01%), respectively, at a concentration of 500 μg/mL. Reducing power results showed that at a concentration from 100–500 μg, coriander seed essential oil gave the absorbance (0.734 ± 1.146), while coriander leaves essential oil gave the absorbance (0.815 ± 1.274). While in non-volatile extracts, the maximum value reached 0.796 ± 0.01 for methanol extract of coriander leaves and for seeds is 0.593 ± 0.04, while the maximum value for n-hexane extract of coriander seeds was 0.624 ± 0.01 and leaves was 0.734 ± 0.04 at a concentration of 500 μg/mL. Our study suggested that coriander seeds and leaves may be used as a potential source of food flavoring and antioxidants.
INTRODUCTION
Bioactive constituents with antioxidant activity are found in high concentrations in plants, in addition to fruits and vegetables that are recommended at the present to be an optimal source of such components. Dietary phytochemicals are considered as an effective tool to cure various human physiological disorders.Citation[1] Several epidemiological studies have indicated that high intake of natural products is associated with reduced risk of a number of chronic diseases, such as atherosclerosis and cancer.Citation[2] The benefits resulting from the use of natural products rich in bioactive substances has promoted the growing interest of food industries.Citation[3] An interest is growing for the search of natural antioxidants for the public perception that natural and dietary antioxidants are safer than synthetic analogues.Citation[4,Citation5]
From the safety point of view, one of the important sources for the search of natural antioxidants is herbs and spices. Among them, the coriander has much importance due to its versatile use as an herb as well as a spice. Coriander (Coriandrum sativum L.) is a culinary and medicinal plant from the Umbelliferae family. The genus Coriandrum includes the cultivated plant Coriandrum sativum and the wild species Coriandrum tordylium.
The coriander fresh leaves contain: moisture: 87.9 g/100 g; protein: 3.3 g/100 g; carbohydrates: 6.5 g/100 g; total ash: 1.7 g/100 g; calcium: 0.14 g/100 g; phosphorus: 0.06 g/100 g; iron: 0.01 g/100 g; vitamin B2: 60 mg/100 g; niacin: 0.8 mg/100 g; vitamin C: 135 mg/100 g; vitamin A: 10,460 I.U. (International unit)/100 g. Coriander seeds contain nearly 11 g of starch, 20 g of fat, 11 g of protein, and nearly 30 g of crude fiber per 100 g.Citation[6] Coriander seed oil is included among the 20 major essential oils in the world market.Citation[7] The oil is extensively used as a flavoring agent in all types of food products, including alcoholic beverages, tobacco, candy, pickles, meat sauce, and seasonings. The average use levels range from 0.1 to 100 ppm. Coriander oil is reported to possess antimicrobial properties against selected pathogenic and saprophytic microorganisms, indicating that it may be useful as a disinfectant.Citation[8] Coriander is also used in aromatherapy. The essential oil content of the dried fruits varies from very low (0.03%) to a maximum report of 2.7%. The predominant constituent of essential oil of coriander is linalool, which forms approximately two-thirds of the oil.Citation[9,Citation10] Coriander oil may have use as a free radical scavenger, preventing oxidative deterioration in foods. Coriander oil was shown to have greater activity against the radical generating activity of 1,1-diphenyl-2-picrylhydrazyl in several oils.Citation[11] The main aim of this study was the investigation of volatile and non volatile components present in seeds and leaves of coriander (Coriandrum sativum L.; Umbelliferae) as well as determination of their antioxidant activity.
MATERIALS AND METHODS
Procurement of Raw Materials and Chemicals
Fresh coriander (Coriandrum sativum L.) seeds and leaves were procured from Ayub Agricultural Research Institute, Faisalabad, Pakistan. Folin-Ciocalteu reagent, gallic acid, anhydrous sodium carbonate, 1,1-diphenyl-2-picrylhdrazyl, methanol, n-hexane, dichloromethane, potassium hexacyanoferrate, trichloroacetic acid, ferric chloride, phosphate buffer, and standard compounds of flavor were purchased from Sigma (St. Louis, MO, USA).
Proximate Analysis
The samples of both seeds and leaves of coriander were analyzed for the moisture, ash, crude fat, crude protein, and crude fiber according to methods No. 44-15A, 08-01, 30-25, 46-30, and 32-10, respectively, as given in the AACC.Citation[12] Carbohydrate contents of coriander seed and leaves were determined to be a nitrogen free extract (NFE) by the following formula:
Extraction of Volatile Compounds
The volatile compounds from seeds or leaves were extracted through hydrodistillation by using clavenger type apparatus.Citation[13] A weighed amount (100 g) of seeds or leaves was put in the flask of clevenger-type apparatus and 1 L of distilled water was added in the flask. The sample was heated continuously for 3 h at a temperature 120°C. Since the extraction rate of volatiles from coriander leaves was very low (0.1%), it was difficult to collect the essential oil directly from the receiving tube of the clevenger apparatus. Therefore, the distillate containing essential oil was collected from the receiving tube in a glass bottle and than it was run for 6 h continuously in liquid-liquid extractor using dichloromethane as the solvent in the receiving flask of the liquid-liquid extractor. After that, the solvent was evaporated via rotary evaporation and concentrated to 1 mL. The essential oils were stored in sealed bottles at freezing temperature until further analysis. The experiment was repeated thrice.
Extraction of Non-Volatile Compounds
The non-volatile compounds were extracted by a solvent extraction method.Citation[13] The weighed amount (250 g) of both samples (seeds and leaves) were taken in two different glass bottles and these bottles were filled with the solvent (n-hexane or methanol) until a layer formed above the samples. The samples were continuously shaken for 48 h in 3-h intervals. Then the samples were filtered by filter paper and the extract obtained was subjected to rotary evaporation for the removal of the solvent from the samples under vacuum. The distillation was stopped when the volume of extract remaining was ∼1 mL. Solvent was further removed under a purified N2 stream. The samples were kept under N2 in sealed vials in a freezer until use. The experiment was repeated three times.
Identification of Volatiles
Volatile compounds were identified using gas chromatography. Volatile compounds present in essential oils of seeds and leaves were identified by comparison with the gas chromatographic retention index. An Agilent model 6890 gas chromatograph equipped with a 30 m × 0.25 mm i.d. (df) (0.25 μm) bonded phase DB-1 fused silica capillary column (Agilent, Folsom, CA, USA) and a flame ionization detector was used to obtain the Kovats gas chromatographic retention index, which also was compared to published data. The oven temperature was programmed from 35 to 220°C at 3°C/min and held for 40 min. The linear helium carrier gas flow rate was 29 cm/s. The injector temperature and detector temperature were 200 and 250°C, respectively.
Determination of Total Phenolic Content (TPC)
Total phenolic compounds were estimated by the Folin-Ciocalteu method.Citation[14] From a known concentration of the sample solution, 125 μL of the sample was placed in a test tube, and 500 μL of distilled water was added to it. After that, 125 μL of Folin-Ciocalteu reagent was added to it and was left stand for 6 min. Then 1.25 mL of 7% sodium carbonate was added to it. A final volume of 3 mL was made by adding 1 mL of distilled water. The samples were given a stand time of 90 min for completion of the reaction. Absorbance of the samples in triplicate at 760 nm was measured by using a UV-vis spectrophotometer. Gallic acid was used as a standard along with the samples and its absorbance was measured at 725 nm. Gallic acid solution was prepared by taking 25 mg and dissolving it in 25 mL of distilled water. Concentrations of gallic acid ranging from 0 to 450 μg/mL were used and its standard curve was used for the calculation of the total phenolic contents in the samples.
1,1-Diphenyl-2-Picrylhdrazyl (DPPH) Scavenging Activity
The antioxidant activity of volatile and non-volatile compounds was determined by the two methods. The free radical scavenging activity of coriander extracts (volatiles and non-volatile) was measured by a spectrophotometer at 517 nm.Citation[3] A methanol solution of DPPH was prepared immediately before the assay. Various concentrations of each coriander non-volatile extract sample (100–500 μg/mL) and the same concentrations of volatiles extracts (100–500 μg) were taken separately in different test tubes using triplicate and then 1 mL of DPPH solution was added in each test tube containing the extract. The reaction mixtures were shaken vigorously and allowed to stand for 30 min at room temperature in a dark place. The absorbance of the samples was measured by spectrophotometer at 517 nm. Butylated hydroxytoluene (BHT) was used as a standard antioxidant to validate the assay.
Ferric Reducing Antioxidant Power (FRAP)
Antioxidant activity was also determined by ferric reducing power using a spectrophotometer at 700 nm.Citation[15] One ml of each extract/fractions (100–500 μg/mL) was mixed with 2.5 ml of phosphate buffer (0.2 M, pH 6.6) and 2.5 ml of 1% potassium hexacyanoferrate. The mixture was incubated at 50°C for 20 min. Then 2.5 ml of 10% tricholroacetic acid was added to the mixture and centrifuged at 3000 rpm for 20 min. One ml of aliquot of the supernatant was mixed with 2.5 ml of distilled water and 0.5 ml of FeCl3 (0.1%) and absorbance was measured at 700 nm. An increase in absorbance was interpreted as increased ferric reducing activity.
Statistical Analysis
Data obtained was analyzed using the statistical package, Costat-2003 Cohort, version 6.1 (Cohort Software, Monterey, CA, USA). Data is presented as mean ± standard deviation.Citation[16]
RESULTS AND DISCUSSIONS
Proximate Analysis of Coriander Seeds and Leaves
The results regarding the proximate composition of coriander seeds and leaves are presented in . Moisture content in fresh leaves was found to be higher (86.71 ± 0.11%), while the seeds have a low moisture content (6.2 ± 0.10%). The present study also reveals that coriander seed have more protein (12.58 ± 0.77%) and crude fat (9.12 ± 0.09%) in comparison to leaves, which have crude protein of 4.05 ± 0.21% and crude fat of 0.95 ± 0.01%. Also, coriander leaves have less crude fiber (5.24 ± 0.23%) than coriander seed (37.14 ± 0.07%). Some previous studies showed that coriander leaves have a moisture content of 87.9% while seeds have a moisture content of 11.37%.Citation[7] Another study showed that seed has a moisture content of 6.65%.Citation[17] According to the results of other researchers, coriander seeds have crude protein and crude fat content of 11.75% and 9.8%, respectively.Citation[17] Some other scientists have found that the coriander leaves have crude protein content of 3.3% and crude fat content of 1.2%.Citation[6] In the literature, it was also found that the crude fiber in coriander seed was 28.43%.Citation[7]
Table 1 The chemical composition of coriander seeds and leaves
Volatile Compounds Extracted from Coriander Seed
The essential oil (volatile compounds) from coriander (Coriandrum sativum L.) seeds was extracted by a clevenger-type apparatus through hydrodistillation. The yield of coriander seed essential oil (CSEO) was 1.1 ± 0.1%. Yield of essential oil varies from 0.03–2.6%, depending on the species, growing region, and climatic conditions.Citation[7,Citation17] shows the major volatile compounds in coriander seed identified through gas chromatography. The major volatile compounds in coriander seed were linalool (55.59%), γ-terpinene (7.47%), α-pinene (7.14%), camphor (5.59%), decanal (4.69%), geranyl acetate (4.24%), limonene (3.10%), geraniol (2.23%), camphene (1.78%), and D-limonene (1.36%). Composition of coriander seed essential oil was found to be different at different places in the world. Gil et al.[9] studied the chemical composition of coriander and they found that the linalool (the main component in CSEO) was 72.3% in Argentinean and 77.7% in European, while α-pinene was 5.9% and 4.4%, γ-terpinene 4.7% and 5.6%, camphor 4.6% and 2.4%, limonene 2.0% and 0.9%, in Argentinean and European coriander, respectively. Smallfield et al.Citation[18] found that linalool, α-pinene, γ-terpinene, camphor, and limonene were 65.8, 6.8, 6.1, 5.1, and 2.7%, respectively, in CSEO. MisharinaCitation[19] found that linalool is 68.00% in Russian CSEO. Our results are inconsistent with Smallfield et al.Citation[18] and Gil et al.,[9] who found that linalool was the main compound in the coriander seed essential oil. Studies also showed that the composition of CSEO is also effected by duration and condition of storage.Citation[19] In our research, it was observed that the amount of linalool was 55.59%, which is lower than the previous studies of Smallfield et al.,Citation[18] Misharina,Citation[19] and Gil et al.[9] This might be due to the environmental conditions and locations. So, considering ecological implications and applications in agriculture, knowledge of the chemical composition related to site degradation may allow the production of crops with specific quality and with their “personal bodyguards” via chemical signals that protect them in a very environmentally friendly manner.
Table 2 The main volatile compounds identified from coriander seed essential oil using gas chromatography
Volatile Compounds Extracted from Coriander Leaves
The yield of essential oil extracted from coriander leaves through hydrodistillation and liquid-liquid extraction was 0.1 ± 0.01%. shows the main volatile compounds obtained by hydrodistillation followed by solvent extraction and analyzed by gas chromatographic analysis. The major volatile compounds identified in coriander leaves essential oil (CLEO) were (E)-2-decenal (32.23%), linalool (13.97%), (E)-2-dodecenal (7.51%), (E)-2-tetradecenal (6.56%), 2-decen-1-ol (5.45%), (E)-2-undecenal (4.31%), dodecanal (4.07%), (E)-2-tridecenal (3.00%), (E)-2-hexadecenal (2.94%), pentadecenal (2.47%), and α-pinene (1.9%). Detailed analysis of coriander herb essential oil showed the presence of major components, which were reported by Potter and FagersonCitation[20] and by Mookherjee et al.Citation[21] They found that the (E)-2-decenal, dodecenal, (E)-2-tridecenal, and dodecanal were the major compounds. However, linalool was also present in our oil, since no effort was made to separate fruits, which contain internal oil canals rich in linalool.Citation[22] 7-Dodecenal was also found in a very low concentration in our study in comparison with previous results by MacLeod and Islam,Citation[23] who found that 7-dodecenal was the main component in CLEO.
Table 3 Compounds identified from coriander leaves essential oil via gas chromatography
Extraction of Non-Volatiles Components
Non-volatiles, from both seeds and leaves, of coriander were extracted through solvent-extraction using methanol and n-hexane solvents. In the case of methanol as a solvent, the yields of non-volatiles from seeds and leaves of coriander were 5.43 ± 0.35 and 9.38 ± 0.39%, respectively, while in case of n-hexane, the yields of non-volatiles from both seeds and leaves of coriander were 0.9 ± 0.20 and 1.6 ± 0.17%, respectively. It was found that the extraction of non-volatiles is more with methanol because methanol is a polar solvent. Methanol dissolved more contents than n-hexane.
Estimation of Total Phenolic Contents
Total phenolic content of the n-hexane and methanol extracts of coriander seed and leaf samples were measured by using Folin's reagent. Although, it overestimates the total phenolics due to interfering compounds, such as ascorbic acid, it is so far the only single and widely used method for estimating total phenols.
The results regarding the total phenolic contents are presented in . It was found that the methanol extract of coriander leaves is rich in total phenolic contents, which contain 30.25 ± 3.42 mg/g, while the n-hexane extract of coriander leaves contain 18.67 ± 1.50 mg/g. On the other hand, in the methanol extract of coriander seeds, 29.21 ± 2.87 mg/g phenolic content was found, while total phenolic content in the n-hexane extract of seed was 11.45 ± 1.18 mg/g. Previous studies showed that antioxidant activity is directly related to total phenolic contents. It means the sample having the higher total phenolic content will show the higher antioxidant activity.Citation[24] A significant correlation existed between antioxidant activity and total phenolics, measured by HPLC analysis in some selected herbs, showing that phenolic compounds were the dominant antioxidant components.Citation[25]
Table 4 Total phenolic contents in different extracts of coriander
Determination of Antioxidant Activity (AOA) from Coriander Extracts
Antioxidant activity of all volatile and non-volatile extracts of coriander seeds and leaves was measured by using two methods, DPPH free radical scavenging activity assay and FRAP, because in the literature we found that it is generally a recognized practice to use two different methods for the investigation of antioxidant activities of samples.Citation[26]
DPPH Free Radical Scavenging Activity
The radical scavenging activities (percentage of quenched radicals) were determined for the volatile extracts of both coriander seeds and leaves.
AOA of Volatile Extracts
Many aromatic plants and spices, especially coriander seed and leaves essential oils, have been known to support various biological activities, such as antimicrobial, antifungal, and antioxidant properties.Citation[27] shows the results of radical scavenging activities of essential oils extracted from coriander seeds and leaves. Both samples exhibit dose-response activity. It means that the antioxidant activity increases with an increase in dose/concentration. Six different concentrations of 100, 150, 200, 250, 300, and 500 μg were used to determine the radical scavenging activities. The essential oil from coriander seeds showed significant radical scavenging activity (66.48 ± 0.80%) at a concentration of 500 μg in comparison with essential of coriander leaves (56.73 ± 1.82%). Coriander seed essential oil was shown to have greater antioxidant activity against radical generating activity of 1,1-diphenyl-2-picrylhydrazyl in several oils. The order of effectiveness among various oil in inhibiting free radicals was coriander > black cumin > cottonseed > peanut > linseed > olive.Citation[11] Our results agreed with the results reported by Wangensteen et al.,Citation[27] who found that scavenging activity of CSEO is higher than CLEO. The antioxidant activity of coriander seed essential oil might be due to the presence of linalool in high concentrations as compared to the leaves' essential oil. There have been many reports on the antioxidant activities of essential oils from various plants, including capers,Citation[26] carnation,Citation[28] clove, and other spices. It is difficult to pinpoint the compounds giving antioxidant activities to the samples because these oils contained numerous compounds. However, some compounds, such as linalool, α-pinene, limonene, and camphene, identified in the present study have been reported to possess strong antioxidant activity.Citation[29] BurdockCitation[30] investigated the linalool for its safety and described the biological effects and toxicity of linalool. Coriander oil has been approved for use in food by the Food and Drug Administration (FDA), Federal Emergency Management Agency, USA (FEMA), and the Council of Europe. The FDA has approved coriander essential oil as being generally recognized as safe with no limitation cited for it's use as a flavoring agent and adjuvant.Citation[31]
Table 5 DPPH scavenging activity of methanol extracts, n-hexane extracts, and essential oil of coriander leaves and seeds at different concentrations
Antioxidant Activities of Non-Volatile Extracts
It is well known that free radicals play an important role in auto-oxidation of unsaturated lipids in food stuffs. For example, oxidation of muscle cholesterol may be initiated by free polyunsaturated fatty acids.Citation[28] Non-volatiles from both seeds and leaves of coriander were extracted through solvent-extraction using methanol and n-hexane as solvents. Different concentrations of extracts were made by dissolving the dry extracts in methanol. showed the antioxidant activities of methanol and n-hexane extracts of coriander various concentrations. The concentrations used were 100, 150, 200, 250, 300, and 500 μg/mL. Methanol extracts of both seed and leaves showed the significant radical scavenging activity (64.40 ± 0.81%) and (72.19 ± 0.64%) at 500 μg/mL, respectively, in comparison with the n-hexane extracts that were (52.67 ± 2.05%) and (60.80 ± 1.01%), respectively, at a concentration of 500 μg/mL. But antioxidant activity of methanol extract of coriander leaves was slightly less than the synthetic antioxidant BHT (83.69 ± 0.71%). Generally, the antioxidant activities of non-volatile extracts (methanol and n-hexane) of coriander leaves were significantly higher than the non-volatile extracts of coriander seed. This might be due to the presence of high phenolic contents.Citation[32] From the etheric extract of coriander cultivated in Brazil, β-carotene has been identified as the principle antioxidant component. No significant difference was found in its antioxidant activity when compared with other carotenoids, but it was inferior to BHT.Citation[32] In our present study, we found that the antioxidant activities of methanol extracts might be due to polyphenols and carotenoids.Citation[27]
Ferric Reducing Antioxidant Power (FRAP)
FRAP assay measures the ability of the extract to donate electron to ferric. The higher the FRAP value, the higher will be the antioxidant activity.Citation[33]
FRAP of Volatile Extracts
The antioxidant activity of volatiles extracts of coriander seeds and leaves were also measured by using FRAP.[15] The results of FRAP were found to be consistent with the results of DPPH free radical scavenging activity assay. shows the absorbance at different concentrations of coriander seed and leaves volatiles. The same concentrations were used as were used in the DPPH method. From a concentration of 100–500 μg, coriander seed essential oil gave the absorbance of 0.734 ± 0.031 ± 146 ± 0.01, while coriander leaves essential oil gave the absorbance of 0.815 ± 0.04 ± 1.274 ± 0.01. But coriander volatile extracts showed less absorbance as compared to BHT (1.234 ± 0.06 − 1.929 ± 0.02), a commercial antioxidant.
Table 6 Ferric reducing antioxidant power of essential oils and non-volatile extracts of coriander seeds and leaves
FRAP of Non-Volatile Extracts
The reducing ability of methanol and n-hexane extracts was also determined by using the FRAP method at the same concentration as for extracts in the DPPH method. There was a clear increase in the values by increasing the concentration (). The same as in the case of DPPH, the methanol extracts exhibited higher values than the n-hexane extracts confirming the fact that methanol is a better solvent than hexane. All the samples showed a significant effect on reducing the ferric ion. The maximum value reached was at 0.796 ± 0.01 for methanol extract of coriander leaves and for seeds it was 0.593 ± 0.04; while the maximum value for n-hexane extract of coriander seeds was 0.624 ± 0.01 and for leaves it was 0.734 ± 0.04. No sample could reach the synthetic antioxidant BHT for which the maximum value was 1.929 ± 0.02. On the other hand, leaves' extracts of both solvent methanol and n-hexane shows for reducing power as compared to non-volatile extract of seeds. From the antioxidant activities of non-volatile extracts of coriander seeds and leaves by using two methods, we found that methanol extract of coriander leaves showed significant antioxidant activity than non-volatile extract of coriander. But in the case of essential oils, it was found that the essential oil of coriander seed has more antioxidant activity than essential oil of coriander leaves.
CONCLUSION
From this study, it was clear that both seeds and leaves from coriander showed concentration-dependent inhibitory activity towards radical scavenging properties and reducing power activities. However, in the case of essential oils, the results are more potent from seeds than in leaves from coriander, while in the case of non-volatile extracts, the results are more potent in leaves as compared to seeds and it seems that the compounds of medium polarity are most potent, even if their total antioxidant contribution in the plant is small. A correlation was also observed between total phenolic contents and antioxidant effects, thus, a screening of phenolic content in coriander extracts will probably indicate the presence of compounds with antioxidant activity. Our results suggested that the inclusion of both seeds and leaves from coriander in the cuisine will increase the content of antioxidants and, thus, probably prevent oxidative deterioration of food. It seems that several different compounds mediate antioxidant activity. However, it is uncertain if the quantity of spices in the diet is enough to have an influence on the antioxidant defense of the body. Therefore, coriander seeds and leaves are recommended to be used as a potential source of food flavoring and antioxidants.
ACKNOWLEDGMENTS
The authors are extremely thankful to the Higher Education Commission, Islamabad, Pakistan for funding the project.
REFERENCES
- Imran , A. , Butt , M.S. and Sharif , M.K. In Press . Phytochemical density of some promising commercial tea brands . International Journal of Food Properties ,
- Ajmal , M. , Butt , M.S. , Sharif , M.K. , Nasir , M. and Nadeem , M.T. 2006 . Preparation of fiber and mineral enriched pan bread by using defatted rice bran. Internaitonal Journal of Food Properties . 9 : 623 – 636 .
- El-Ghorab , A. , Shaaban , H.A. , El-Massry , K.F. and Shibamoto , T. 2008 . Chemical composition of volatile extract and biological activities of volatile and less-volatile extracts if juniper berry(Juniperus drupacea L.) fruit . Journal of Agricultural and. Food Chemistry , 56 : 5021 – 5025 .
- Nadeem , M. , Anjum , F.M. , Hussian , S. , Khan , M.I. , Khan , M.R. and Shahzad , S. 2010 . Chemical characteristics and antioxidant activity of seeds of different sunflower hybrids . Life Sciences International Journal , 4 ( 1 ) : 1349 – 1355 .
- Dorman , D. , Dastmalchi , K. , Oinonen , P. , Darwis , Y. , Laakso , I. and Hiltunen , R. 2008 . Chemical composition and in vitro antioxidant activity of lemon balm extract. Lebensmittl-Wissenschaft und-Technologie . 41 : 391 – 400 .
- Peter , K.V. 2004 . Handbook of Herbs and Spices , Vol. 2 , 158 – 174 . Woodhead Publishing Ltd : Abnigton Hall, England .
- Diederichsen , A. Coriander . 1996 . “ Promoting the conservation and use of underutilized and neglected crops. 3 ” . In Spices , Edited by: Purseglove , J.W. , Brown , E.G. , Green , C.L. and Robbins , S.R.J. Vol. 2 , 736 – 788 . New York : Longman .
- Elgayyar , M. , Draughon , F.A. , Golden , D.A. and Mount , J.R. 2001 . Antimicrobial activity of essential oils from plants against selected pathogenic and saprophytic microorganisms . Journal of Food Protection , 64 : 1019 – 1024 .
- Gil , A. , De La Fuente , E.B. , Lenardis , A.E. , Lopez Pereira , M. , Suarez , S.A. and Bandoni , A. 2002 . Coriander essential oil composition from two genotypes grown in different environmental conditions . Journal of Agricultural and Food Chemistry , 50 : 2870 – 2877 .
- Grosso , C. , Gerraro , V. , Figueiredo , A.C. , Barroso , J.G. , Coelho , J.A. and Palavara , A.M. 2002 . Supercritical carbon dioxide extraction of volatile oil from Italian coriander seeds . Food Chemistry , 111 : 197 – 203 .
- Ramadan , M.F. and Moersel , J.T. 2006 . Screening of the antiradical action of vegetable oils . Journal of Food Comp and Analysis , 19 : 838 – 842 .
- AACC . 2000 . Approved methods of American Association of Cereal Chemists , Am. Assoc. Cereal Chem., Inc.: St. Paul, Minnesota .
- El-Ghorab , A. , Fadel , H. , Marx , F. and El-sawy , A. 1999 . Effect of extraction techniques on the chemical composition and antioxidant activity of Eucalptus camaldulensis Var. brevirostris leaves oil . Zeitschrift für Lebensmittal-Untersuchung und - Forschung A , 208 : 212 – 216 .
- Sun , T. , Xu , Z. , Wu , C.T. , Janes , M. , Prinyawiwatkul , W. and No , H.K. 2006 . Antioxidant activities of different colored sweet bell pepper (Capsicum annum L.) . Journal of Food Science , 72 : 98 – 102 .
- Hinneburg , I. , Dorman , H.J.D. and Hiltunen , R. 2006 . Antioxidant activities of extracts from selected culinary herbs and spices . Food Chemistry , 97 : 122 – 129 .
- Steel , R.D. , Torrie , J.H. and Dicky , D.A. 1997 . Principles and Procedures of Statistics. A Biometrical Approach , 3rd , 204 – 227 . Singapore : McGraw Hill Book International Co .
- Khan , A.L. , Javid , H. , Rehman , N. , Khan , F. , Hussain , S.T. and Shinwari , Z.K. 2009 . Proximate and nutrient investigations of selected medicinal plants species of Pakistan . Pakistan Journal of Nutrition , 8 : 620 – 624 .
- Smallfield , B. , John , W. , Nigel , B.P. and Kenneth , G.D. 2001 . Coriander spice oil: Effects of fruit crushing and distillation time on yield and composition . Journal of Agricultural and. Food Chemistry , 49 : 118 – 123 .
- Misharina , T.A. 2001 . Effect of conditions and duration of storage on composition of essential oil from coriander seeds . Prikladnaia Biokhimiia i Mikrobiologiia , 37 : 726 – 732 .
- Potter , T. and Fagerson , I. 1990 . Composition of coriander leaf volatiles . Journal of Agricultural and Food Chemistry , 38 : 2054 – 2056 .
- Mookherjee , B.D. , Wilson , R.A. , Trenkle , R.W. , Zampino , M.J. and Sands , K.N. 1989 . “ New dimensions in flavor research: Herbs and spices ” . In Flavor Chemistry: Trends and Developments , 176 – 187 . Washington , DC : ACS Symposium Series 338; American Chemical Society .
- Purseglove , J.W. , Brown , E.G. , Green , C.L. and Robbins , S.R.L. 1981 . Coriander in Tropical Agriculture Series: Spices Edited by: Wrigley , G. 736 – 788 . Longman, Harlow , , U.K
- MacLeod , A. and Islam , R. 1976 . Volatile flavour components of coriander leaves . Journal of the Science of Food and Agriculture , 27 : 721 – 724 .
- Kahkonen , M.P. , Hopia , A.I. , Vuorela , H.J. , Rauha , J.P. , Pihlaja , K. and Kujala , T.S. 1999 . Antioxidant activity of plant extracts containing phenolic compounds . Journal of Agricultural and. Food Chemistry , 47 : 3954 – 3962 .
- Wojdyło , A. , Oszmian , J. and Czemerys , R. 2007 . Antioxidant activity and phenolic compounds in 32 selected herbs . Food Chemistry , 105 : 940 – 949 .
- El-Ghorab , A.H. , Shibamoto , T. and Ozcan , M.M. 2007 . Chemical composition and antioxidant activities of buds and leaves of Capers (Capparis ovata Desf. Var. canescens) cultivated in Turkey . Journal of Essential Oil Research , 19 : 72 – 77 .
- Wangensteen , H. , Samuelsen , A.B. and Malterud , K.E. 2004 . Antioxidant activity in extracts from coriander . Food Chemistry , 88 : 293 – 297 .
- El-Ghorab , A. , Mahghoub , M.H. and Bekheta , M. 2006 . Effect of some bio-regulators on the chemical composition of essential oil and its antioxidant activity of Egyptian carnation (Dianthus caryophyllus L.) . Journal of Essential Oil Bearing Plants , 9 : 214 – 222 .
- Shibamoto , T. and Wei , A. 2007 . Antioxidant activities and volatile constituents of various essential oils . Journal of Agricultural and. Food Chemistry , 55 : 1737 – 1742 .
- Burdock , G.A. 2002 . “ Coriander oil ” . In Fenaroli's Handbook of Flavor Ingredients , 4th , 344 – 345 . Boca Raton , FL : CRC Press .
- Hall , R.L. and Oser , B.L. 1965 . Recent progress in the consideration of flavoring ingredients under the food additives amendment III. GRAS substances. Coriander oil–Coriandrum sativum L . Food Technology , 19 : 269
- Guerra , N. , Melo , E. and Filho , J. 2005 . Characterization of antioxidant compounds in etheric coriander extract (Coriandrum sativum L.) . Journal of Food Composition and Analysis , 18 : 193 – 199 .
- Yan , L. , Teng , L. and Jhi , T. 2006 . Antioxidant properties of guava fruit: Comparison with some local fruits . Sunway Academic Journal , 3 : 9 – 20 .