In vitro Antioxidant and Chromatographic Quantification of Supercritical Fluid Extracts Obtained from Coriander (Coriandrum sativum L.).
Summary: In modern era, various plant sources like herbs and spices are in limelight owing to their health enhancing and disease preventing characteristics. Amongst herbs and spices, coriander (locally known as "dhanya") is known for its therapeutic properties in the Indo-Pak subcontinent. It is one of the widely cultivated herbs/spice and is native to North Africa, southern Europe and southwestern Asia. In the current research project, supercritical fluid extraction technique was employed to obtain extracts from coriander seeds and herb at different pressures i.e. 2000, 3000 and 4000 psi. In vitro antioxidant assays exhibited that maximum total phenolic and flavonoid contents (1773+-68 mg GAE/100 g and 1142+-41 mg CE/100 g) were exhibited by coriander leaves extract taken at 3000 psi.
Accordingly, the maximum DPPH scavenging activity, FRAP and [beta]-carotene antioxidant activity was also measured in coriander leaves extract i.e. 82+-3%, 109+-6 umol TE/g DW and 48+-1%, respectively. Coriander seeds also showed significant antioxidant activity followed by coriander stems. Gas chromatographic analyses of extracts exhibited maximum level of linalool in coriander seeds extract taken at 3000 psi (320+-3 mg/100 g) and HPLC analyses of coriander extracts showed that major phenolic compound present in coriander leaves is quercetin -3-o-rutinoside (448+-4 mg/100 g). It can be concluded that coriander leaves possess better antioxidant activity followed by coriander seeds and stems.
However, major active component of coriander seeds was linalool, whilst, coriander leaves possess more phenolic compounds as compared to seeds. The findings of the current study is useful for future researchers intended to develop novel food products along with exploring the therapeutic potential of coriander seeds and herbs.
Keywords: Coriander, supercritical fluid extraction, antioxidants, linalool, quercetin-3-o-rutinoside, GC/HPLC
Modern era has witnessed an increasing awareness regarding the health benefits of numerous bioactive components like phenolic acids, flavonoids, carotenoids, anthocyanins, minerals and vitamins. Plant based food sources possess rich phytochemistry and they exhibit high antioxidant activity. Amongst herbs, coriander (locally known as "dhanya") is known from years for its health enhancing characteristics all over the globe especially in Indo-Pak subcontinent. It is one of the widely cultivated herbs and native to Northern America, Southern Europe and South Western Asian region. Scientifically, coriander (Coriandrum sativum L.) belongs to the Umbelliferae (Apiaceae) family. The herb portion consist on leaves and stems, whilst, coriander seeds have also been used for numerous therapeutic purposes.
Promising health promoting characteristics and nutritional significance of coriander seeds are owing to the presence of several bioactive components like sterols, tocols, fatty acids and volatile constituents. Coriander leaves possess components like flavonoids, phenolic acids and essential oils. Though, the leaves are not well studied as the seeds of coriander .
Coriander seeds are rich source of essential/volatile oil. Generally, the extraction of essential oil from coriander seeds is carried out by hydro or steam distillation, but, in recent era another novel technique known as supercritical fluid extraction technique (SFE), is in limelight. SFE is an environment friendly technique and it gives extract with higher purity and better quality as compared to conventional techniques without any traces of residual solvent. Yield of essential oil is highly dependent on the origin of cultivar, geographic location and climatic conditions. Several meta-analyses have stated that the predominant constitutes of coriander essential oil were alcoholic monoterpenes, among them linalool was prominent . Although, the concentration of active components varied in different varieties of coriander from region to region i.e. Iranian, Algerian, Indian, Pakistani and Tunisian varieties [3, 4, 5].
Moreover, fresh coriander leaves and stem part possess polyphenols, phenolic acids, flavonoids and essential oil [6, 7]. The aroma of fresh coriander is entirely different from that of mature seed . The basal leaves exhibited more fatty acid contents as compared to upper one. The characterization of leaf fatty acid explored that the predominant fatty acids were polyunsaturated fatty acids. Accordingly, the most abundant polyunsaturated fatty acid was [alpha]-linolenic followed by linoleic, palmitic and heptadecenoic acids .
Generally, solvent extraction is practiced to extract polyphenols and essential oils from plant matrix such as herbs and spices . Nowadays, sophisticated and novel techniques are in vogue to extract active moieties from different parts of coriander. Amongst, Supercritical Fluid Extraction (SFE) is known as green extraction technology. In this system, instead of organic solvents, carbon dioxide is used in supercritical state to isolate nutraceutics from powdered raw material. Improvement in extraction efficiency and reduction in off flavor development are the major attributes of this technology .
Considering aforementioned facts, the present research project was designed to isolate bioactive components of coriander leaves, seeds and stems using a green and novel technology i.e. supercritical fluid extraction technique, followed by antioxidant analyses and chromatographic quantification of major bioactive components of extracts.
Purchase of chemicals/reagents and raw materials
Coriander herbs and seeds of Pakistani variety were purchased from local market. The analytical and high performance liquid chromatographic grade reagents and chemicals were procured form international suppliers i.e. Merck and Sigma Aldrich. Afterwards, the herb portion i.e. coriander leaves and stems, were separated and washed to remove impurities along with adhered dirt. Coriander seeds were also cleaned to remove impurities. Then, the raw materials were dried in dehydrator at 40AdegC followed by grinding to obtain fine powder. The powders were stored in airtight plastic bags for further analyses.
Supercritical Fluid Extraction
Decoction of coriander seeds, leaves and stems (Table 1) was carried out by employing supercritical fluid extractor using carbon dioxide as solvent (SFT-150), at three different pressures and constant temperature of 40AdegC for optimal mass transfer . Alongside, HPLC grade ethanol was also employed as co-solvent at a flow rate of about 0.5 mL/min, to enhance the extraction rate of polar commodities.
Table 1. Treatments for supercritical fluid extraction
Raw Material###Treatment###Pressure (psi)
Phytochemical screening tests
Phytochemical screening tests of resultant supercritical extracts were carried out to validate the effect of different extraction conditions.
Total phenolic content (TPC)
Total phenolics content (TPC) of coriander seeds, leaves and stem extracts were calculated by employing Folin-Ciocalteu method . The principle of this method includes the formation of phophotungstic blue by the reduction of phosphotungstic acid resulting in the increased number of phenolic groups and ultimately raise the absorbance.
Purposely, 50 uL supercritical extract (50 mg/mL) was separately added in a test tube already having 250 uL of Folin-Ciocalteu's reagent (diluted 1:10 with de-ionized water). Afterwards, sodium carbonate solution (Na2CO3) of 20% was further added in the same test tube in quantity of about 750 uL. Then distill water was added to make the volume up to 5 mL. A stay period of two hours was given to the prepared solution in dark place for color development and then absorbance was taken using UV/visible light Spectrophotometer (CECIL CE7200) at 765 nm. A control was also run along with samples for comparison purposes. TPC were estimated from the linear equation of a standard curve prepared with gallic acid. TPC was calculated as mg gallic acid equivalent per 100 g (mg gallic acid/100 g).
Total phenolic compounds was measured by following formula:
C is the total phenolic contents
c is the gallic acid concentration (mg/mL)
V is the volume of extract used (mL)
M is the weight of coriander extract (g)
Total Flavonoids Content (TFC)
TFC was ascertained on the basis of flavonoid-aluminium complex developed . Catechin was utilized as a standard to estimate the total flavonoids in coriander extracts. For the purpose, coriander extract (50 mg/mL) of 1 mL was added in a flask and then distill water was added to make the volume up to 5 mL trailed by the incorporation of sodium nitrite (5% w/v) in quantity of 0.3 mL. After a stay time of 5 min, AlCl3 of 10% concentration was added in amount of 0.6 mL and 2 mL of 1 M sodium hydroxide was added. Afterwards, 2.1 mL distill water was mixed with solution. Then, UV/visible spectrophotometer was employed to measure the absorbance at 510 nm.
In vitro antioxidant assays
To assess the free radical scavenging efficiency of different extracts, antioxidant capacity was measured by performing following assays.
Free radical scavenging ability (DPPH assay)
DPPH (2,2-diphenyl-1-picrylhydrazyl) is a purple colored free radical, which causes the synthesis of hydrazine (a yellow shaded compound) by interacting with hydrogen atoms of antioxidants. Protocol of Wangensteen et al.  was used to find out DPPH scavenging activity of coriander extracts with some modifications. Coriander extract (50 mg/mL) of 0.025 mL was dissolved 10 mL methanol. Afterwards, 3 mL of DPPH solution was mixed with respective solvent and 77 uL of sample extract was added. Samples were placed in dark place for a period of 15 min and then UV/visible spectrophotometer was employed to take absorbance at 517 nm.
Alongside, black samples were also run which contains the same quantity of solvent and DPPH solution without extract. The free radical-scavenging activity of each coriander decoction was presented as percent decline in the level of DPPH owing to extract.
Reduction of absorbance (%) = [(AB - AA) / AB] x 100
AB = Absorbance of blank sample at t = 0 minute
AA = Absorbance of tested extract solution at t = 15 minutes
[beta]-carotene bleaching assay
Antioxidant activity of the coriander extracts was estimated by employing assay based on coupled oxidation of [beta]-carotene and linoleic acid . For the purpose, [beta]-carotene in quantity of 2 mg was mixed with chloroform (20 mL), linoleic acid (40 mg) and Tween 20 (400 mg). Then, chloroform was removed using rotary evaporator and 0.10 mL sample (50 mg/mL) was added in 3 mL of prepared emulsion. Afterwards, the solution was place in water bath for a period of 2 hours. ss-carotene oxidation was estimated at 470 nm on spectrophotometer.
Ferric reducing antioxidant power assay (FRAP)
The FRAP assay was carried out following the method of Kaiser et al., . Purposely, 0.5 mL coriander extract was taken in a test tube and then 1.25 mL of 0.2 M phosphate buffer was added along with 1.25 mL of 1% potassium ferricyanide. Afterwards, 1.25 mL of TCA was added of 10% concentration with the addition of ferric chloride (0.1%). Then the solution was incubated at room temperature for a period of about ten minutes and spectrophotometric absorbance was measured at 700 nm wavelength.
Selection of best treatments
On the basis of in vitro phytochemical and antioxidant analyses one best treatment was selected from each coriander component i.e. coriander leaves, seeds and stems, for conducting chromatographic analyses.
Quantification of linalool in the selected treatments was carried out by gas chromatography using the protocol described by Alves-Silva et al. . The supercritical extracts were subjected to GC analysis using a Gas Chromatograph (Model: 14-A, Shimadzu, Japan) with a capillary column of HP-5 MS (5% phenylmethylsiloxane, length = 30m, inner diameter = 0.25mm and film thickness = 0.25um) using FID detector. The temperatures of detector and injector were set at 300 and 250AdegC, respectively. The oven temperature was kept at 40AdegC for 5 min; raised to 200AdegC at 3.0AdegC/min and held for 1 min; raised to 280AdegC at 15AdegC/min and held for 10 min. Carrier gas used in this experiment was helium set at 1 mL/min flow rate. A standard of linalool was also run at the same condition for comparison purpose.
HPLC quantification of phenolic compounds
HPLC quantification of phenolic acids and flavonoids were performed as per the guidelines of Sultana and Anwar . For sample preparation, 5 mL of plant extract was solvated with 6 mL of H2O and 12 mL of methanol. Afterwards, the mixture was shaken for 5 min following addition of 10 mL of 6 M HCL. It was given stay for 2 hr in water bath at 60AdegC. Afterwards, the sample was filtered using 0.2 mm nylon filter and filtrate was injected in the HPLC system (PerkinElmer, Series 200, USA) fitted with column Shim-Pack CLC-ODS (C-18), 25 cm x 4.6 mm, 5 um and detected via UV-Vis detector. The mobile phase was gradient solvent system; A (water:acetic acid; 94:6 pH = 2.27) and B (100% acetonitrile) consisted of acetonitrile + water, 10:90 (v/v) at a flow rate of 1 mL/min. The absorbance was recorded at 280 nm for quercitin, gallic acid, p-coumeric acid, vanillic acid, trans-4-hydroxy 3 methoxy-cinnamic acid, 4 hydroxy 3 methoxy benzoic acid and sinipic acid by comparing with standard peaks.
Whilst, HPLC specification were somewhat different for kaempferol like acetonitrile:dicholoromethane:methanol-60:20:20 mobile phase at 1 mL/min flow rate and 248 nm as detection absorbance. Quantification of all compounds was done using calibration curves of appropriate standards.
Statistical analysis was employed on the obtained data using Statistix 8 analytical software, to assess the level of significance . Furthermore, the obtained data was represented as mean +- standard deviation.
Results and Discussion
The results of the tested attributes are conferred herein:
Phytochemical screening tests
In vitro phytochemical screening tests were carried out to estimate the total phenolic content and total flavonoids as well as antioxidant perspectives of coriander components. The statistical analyses (F value) of the findings showed that for all the three components i.e. seeds, leaves and stems, the different treatment conditions imparted significant effect on the five selected parameters i.e. total phenolic contents, total flavonoids, DPPH, FRAP and [beta]-carotene.
Total phenolic content (TPC)
It was noticed (Table 2) that in coriander seeds, the highest content of total phenolics was measured in 2000 psi (TS1) as 1256+-56, 928+-36 and 472+-22 mg GAE/100 g, respectively. However, coriander leaves exhibited relatively higher level of total phenolics as compared to seeds and stems.
The maximum TPC was measured in TL2 (3000 psi) trailed by TL3 (4000 psi) and TL1 (2000 psi) as 1773+-68, 1298+-59 and 775+-22 mg GAE/100 g. The same trend was noticed in the case of coriander stems i.e. TSt2 (857+-29), TSt3 supercritical extract taken at 3000 psi (TS2) followed by the extract taken at 4000 (TS3) and (613+-24) and TSt1 (405+-20).
Overall, it was established that coriander leaves possess maximum total phenolic contents followed by coriander seeds whilst, coriander stems exhibited minimum level.
Table-2: Effect of extracting conditions on the TPC and TFC of SFE extracts.
components###(mg GAE/100g)###(mg CE/100g)
Current results of total phenolic content are in consensus with the outcomes of study conducted by Zekovic et al. , it was revealed that level of polyphenols isolated from coriander seeds by using subcritical water at 60 bars pressure and temperature of 100AdegC, were about 998 mg/100 g DW. However, another group of scientists reported less polyphenolic content in methanolic decoction of coriander seeds obtained via soxhlet extraction method, it was expounded that the coriander extract of Syrian variety had the maximum total phenolic content followed by Tunisian and Egyptian as 1.09+-0.06, 1.00+-0.02 and 0.94+-0.05 (mg GAE/ g, dry weight), respectively . Certainly, total phenolic contents in the methanolic extract of Tunisian coriander was reported to be 1.04 mg GAE/g DW . Although, the total phenolic content in the Canadian variety was found to be very much different which was about 15.16 mg GAE/g DW, whilst, it was 12.10 mg GAE/g DW for the Tunisian variety .
In previous decade one of researcher groups, Bajpai et al.  explicated the total phenolic content of coriander seeds and coriander leaves as 20.30+-0.73 and 6.80+-0.05 mg GAE/g DW, correspondingly. Latter, in an investigation, it was illustrated that maximum total phenolic content was found in coriander leaves blanched at 100AdegC with water for the period of 1 min i.e. 126.0+-9.1 mmol GAE/kg DM, compared to the unheated control sample (49.2+-3.4 mmol GAE/kg DM). In case of coriander fruits, maximum total phenolic contents was measured at the same conditions as 55.4+-0.9 mmol GAE/kg DM . Previously, it was noticed that methanolic and hexane extract of coriander leaves possessed more phenolic content as compared to coriander seeds extracts i.e. 30.25+-3.42 and 18.67+-1.50 mg/g, respectively, in coriander leaves and 29.21+-2.87 and 11.45+-1.18 mg/g, correspondingly, in coriander seeds .
Overall, it can be conferred that coriander leaves possess higher total phenolic content as compared to coriander seeds.
Total flavonoid content (TFC)
Total flavonoids also followed the same trend as total phenolic contents. In coriander seeds, leaves and stems, maximum total flavonoids were identified in extracts taken at 3000 psi (T S2 , T L2 and T St2 ) i.e. 624+-29, 1142+-41 and 44+-2 mg CE/100 g, respectively. Moreover, supercritical extracts taken at 4000 psi exhibited flavonoids for all the three components i.e. seeds (448+-20 mg CE/100 g), leaves (1078+-42 mg CE/100 g) and stems (38+-1 mg CE/100 g).
However, lowest flavonoids were present in the extracts taken at 2000 psi in seeds, leaves and stems i.e. 329+-14 mg CE/100 g (T S1 ), 818+-32 mg CE/100 g (T L1 ) and 32+-1 mg CE/100 g (T St1 ), correspondingly (Table 2).
Previously, in a scientific study the methanolic extracts of coriander green part has been investigated for total flavonoid contents along with phenolic contents, outcomes showed that TFC was 5259.52+-69.91 mg/kg and TPC was 1013.95+-11.24 mg/kg . Furthermore, total flavonoids were estimated in the methanolic extracts of coriander seeds ranging from 2.03-2.51 mg CE/g DW. It was noticed that the total flavonoids and total tannins were maximum in methanolic extract of Syrian variety . In a research, it was demonstrated that coriander seeds extracts contain total flavonoids of 12.6 quercetin equivalent/g coriander .
In vitro antioxidant assays
Among the extracts taken from coriander leaves TL2 exhibited maximum value for DPPH (82+-3%) followed by TL3 (75+-3%) and TL1 (62+-2%). Similar trend was depicted by the treatments of coriander seed i.e. TS2 exhibited higher free radical scavenging activity (64+-3%) as compared to TS3 and TS1 as 58+-2 and 46+-2%, respectively. The coriander stems showed minimum DPPH activity as compared to other two components the maximum DPPH activity was showed by TSt2 (46+-2%) trailed by TSt3 (29+-1%) and TSt1 (18+-1%) (Table-3).
Table-3: Effect of extracting conditions on the DPPH, FRAP and [beta]-carotene antioxidant assays of SFE extracts
components###(%)###(umol TE/g DW)###(%)
Ferric reducing antioxidant power of coriander seeds (Table 3) was maximum in TS2 (51+-2 umol TE/g DW) followed by TS3 (44+-2 umol TE/g DW) and TS1 (38+-1 umol TE/g DW). Similarly, TL2 extract of coriander leaves showed maximum FRAP assay as 109+-6 umol TE/g DW trailed by TL3 and TL1 i.e. 98+-5 and 79+-3 umol TE/g DW, respectively. Coriander stems showed ferric reducing antioxidant power comparable to coriander seeds and maximum was demonstrated by TSt2 (39+-2 umol TE/g DW) followed by TSt3 (37+-2 umol TE/g DW) and TSt1 (17+-1 umol TE/g DW).
Furthermore, among the treatments of coriander seeds, leaves and stems, TS2, TL2 and TSt2 demonstrated highest [beta]-carotene antioxidant activity as 16+-0.5, 48+-1 and 16+-1%, respectively, followed by TS3 (14+-0.7%), TL3 (42+-2%) and TSt3 (11+-1%), however, minimum activity was observed in TS1 (12+-0.4%), TL1 (35+-2%) and TSt1 (8+-1%), correspondingly (Table 3).
Previously, the ferric reducing antioxidant power (FRAP) of coriander leaves and seeds was estimated by Bajpai et al. , it was noticed that coriander leaves possess better FRAP value in terms of IC50 (4+-0.05 mg/mL) as compared to coriander seeds (12+-0.2 mg/mL IC50 value). Likewise, the maximum ferric reducing antioxidant power (109+-14 and 51+-2 mmol TE/kg DM) was observed in coriander leaves followed by coriander seeds . Moreover, the ferric reducing power of coriander extracts showed that Tunisian variety exhibited lower capacity as compared to Canadian variety i.e. EC50 = 780 and 700 ug/mL, respectively .
Regarding [beta]-carotene antioxidant activity the present results are in accordance with the suggestions of Bajpai and colleagues , they observed that coriander aerial parts exhibited better [beta]-carotene bleaching antioxidant activity as compared to coriander seeds i.e. 25.4+-1.1 and 18.1+-0.8%, correspondingly. Moreover, the antioxidant activity of about 69.83% was also noticed in the aqueous extract of coriander .
In the case of DPPH scavenging assay it was observed that the ethanolic extracts of seeds and leaves exhibited a concentration dependent activity as depicted by IC50 values of 510+-12 and 389+-5 ug/mL, correspondingly. On the other hand, it was noticed that the lipophilic extracts and coriander oil fraction i.e. diethyl ether extract of leaves and dichloromethane seed extract) has not shown any activity in this assay owing to inability of donating hydrogen. Coriander seeds essential oil exhibited weak DPPH scavenging activity, while, during TBARS antioxidant assay, coriander oil showed high antioxidant potential . Recently, Msaada et al,  carried out the DPPH scavenging assay Tunisian, Syrian and Egyptian varieties of coriander and it was shown that maximum activity was exhibited by Tunisian (IC50 = 27.00+-6.57 ug/mL) followed by Egyptian (IC50 = 32.00+-2.87 ug/mL) and Syrian (IC50 = 36.00+-3.22 ug/mL) varieties.
Nonetheless, the ferric reducing antioxidant power (FRAP) of coriander leaves and seeds was estimated by Bajpai et al., , it was noticed that coriander leaves possess better FRAP value in terms of IC50 (4.1+-0.05 mg/mL) as compared to coriander seeds (12.8+-0.21 mg/mL). Likewise, the maximum ferric reducing antioxidant power in terms of mmol TE/kg DM was observed in coriander leaves and seeds i.e. 109.6+-14.1 and 51.2+-2.6 mmol TE/kg DM, respectively . Moreover, the ferric reducing power of coriander extracts showed that Tunisian variety exhibited lower capacity as compared to Canadian variety i.e. EC50 = 780 and 700 ug/mL . Regarding [beta]-carotene antioxidant activity, the present results are in accordance with the suggestions of Bajpai and colleagues (2005), they observed that coriander aerial parts exhibits better [beta]-carotene bleaching antioxidant capacity as compared to coriander seeds i.e. 25.4+-1.1 and 18.1+-0.8%, correspondingly.
Moreover, the antioxidant activity of about 69.83% was also noticed in the aqueous extract of coriander .
Chromatographic Quantification of Bioactive Ingredients
On the basis of phtytochemical and antioxidant outcomes supercritical extracts taken at 3000 psi were selected for chromatographic quantification of linalool and polyphenolic components. Means for the effect of treatments on linalool showed that maximum quantity was obtained in coriander seeds (TS2 = 320+-3 mg/100 g DW) trailed by coriander leaves (TL2 = 7+-0.08 mg/100 g DW), while, in coriander stems linalool was not detected in gas chromatographic analyses (Table 4).
Table-4: Quantification of active ingredients by GC and HPLC.
###Coriander###Linalool Quercetin-3-o-rutinoside Quercetin-3-o-glucuronide###Quercetin-3-o-glucoside###Kaempferol-3-o-rutinoside
Nevertheless, along with linalool coriander also possess various phenolic acids majorly quercetin derivatives and among them quercetin-3-o-rutinoside was majorly exists in coriander leaves. Maximum quercetin-3-o-rutinoside was noticed in selected treatment of coriander leaves (TL2) as 448+-4 mg/100g DW followed by coriander stem treatment TSt2 (76+-0.7 mg/100 g DW) and coriander seeds treatment TS2 (4+-0.07 mg/100 g DW). Likewise, quercetin-3-o-glucuronide, quercetin-3-o-glucoside and karmpferol-3-o-rutinoside were copious in TL2 treatment of coriander leaves (105+-1, 38+-0.4 and 30+-0.3 mg/100 g DW, respectively) followed by TSt2 treatment of coriander stems (18+-0.1, 7+-0.08 and 3+-0.04 mg/100g DW, respectively) and coriander seeds treatment TS2 as 8+-0.1, 5+-0.04 and 2+-0.01 mg/100 g DW, correspondingly.
The results of present study are in agreement with the outcomes of Pavlic et al. , it was noticed that the level of linalool in supercritical extracts of coriander seeds was ranged from 136.80 to 598.51 mg/100 g CS at 100 bars and 300 bars pressure, respectively. It was observed in that increasing the pressure enhances the recovery of linalool from the coriander samples. It was also expounded in the research investigation that amount of linalool extracted from coriander seeds, by employing subcritical water extraction technique, was about 172.01 to 346.65 mg/100 g CS, variations were owing to different conditions applied. Recently, in another scientific study, level of linalool obtained by subcritical water extraction at 60 bars pressure and 100AdegC was observed to about 65.56 mg/100 g DW. It was narrated in the study that different extraction conditions affected linalool content significantly.
Recently, it was proved that level of linalool in supercritical extract of coriander was 717 mg/g in the sample obtained at 100 bars of pressure at 55AdegC of temperature . Previously, linalool level of about 596.1, 532.0 and 502.1 mg/g of extract was obtained at 100 bar pressure and 40AdegC temperature at different particle sizes .
Regarding the phenolic compounds the current data is in accordance with the previous findings of Barros et al. , it was explicated that the polyphenol profile of coriander green portion is majorly consist of quercetin-3-O-rutinoside (rutin), quercetin-3-O-glucuronide, dimethoxycinnamoyl hexoside, quercetin-3-O-glucoside and kaempferol-3-O-rutinoside present about 3296.16, 1237.13, 406.39, 405.36 and 320.86 mg/kg, respectively. Among other flavonoids p-coumaroylquinic acid, 3-O-caffeoylquinic acid, ferulic acid glucoside and caffeoylquinic acid were identified in the quantity of 303.83, 173.51, 122.29 and 7.92 mg/kg, correspondingly. It was also elucidated that the quercetin derivatives were the main bioactive commodities identified in the green part of coriander obtained from the Portugal .
Afterwards, it was narrated that coriander leaves possess more quercetin glucuronide as compared to fruits/seeds i.e. 0.29+-0.01 g/kg DM, in leaves and 0.17+-0.02 g/kg DM, in fruits/seeds. However, the rutin was only detected in coriander leaves as 0.20+-0.03 g/kg DM .
Previously, mostly conventional extraction techniques like solvent extraction, soxhlet extraction and hydrodistillation technique, were employed for the extraction of bioactive components from coriander leaves and seeds. However, supercritical fluid extraction has emerged as an efficient and novel alternative of all these conventional techniques owing to more precise recovery of antioxidants and being environment friendly. The outcomes of this research investigation also indorse the antioxidant potential of supercritical fluids extracts of coriander leaves, seeds and stems, taken at different extracting conditions.
It can be inferred from the above discussion that the antioxidant potential of different coriander portions i.e. leaves, seeds and stems, significantly varied from each other. Coriander leaves exhibited relatively higher antioxidant characteristics as compared to coriander seeds and stems. It can also be suggested that all the treatments exhibited an elevation in the antioxidant characteristics when pressure of supercritical fluid extractor was increased from 2000 to 3000 psi, while, a declining tendency was observed when pressure was further increased up to 4000 psi keeping the temperature constant. The possible reason for this behavior is may be at lower pressure conditions the less bioactive components were extracted from food matrix, whilst, at higher pressure degradation of bioactive components may occurred. Furthermore, coriander leaves possess more phenolic compounds as compared to coriander seeds.
However, the level of linalool was significantly higher in coriander seeds/fruits as compared to coriander leaves or stems. The present findings would be obliging for researchers to design novel therapeutic products by employing environment friendly and efficient techniques like SFE.
GAE: Gallic acid equivalent; CE: Catechin equivalent; TPC: Total phenolic content; TFC; Total flavonoid content; DPPH: 2,2-diphenyl-1-picrylhydrazyl; FRAP; Ferric reducing antioxidant power; TE: Trolox equivalent; DW: Dry weight; DM: Dry matter; PSI: Pound per square inch; SFE: Supercritical fluid extraction; HPLC: High pressure liquid chromatography; TCA: Trichloroacetic acid; GC: Gas chromatography; FID: Flame ionization detector; HCL: Hydrochloric acid.
The study will be helpful to researchers in understanding the antioxidant status of supercritical fluid extracts of coriander seeds and herb. It will also be useful in designing various novel functional foods based on coriander seeds and herb to ameliorate lifestyle related disorders. In the present study optimization of supercritical process is carried out, so, it would lowered the efforts of future explorers to obtain maximum recovery of bioactive components from coriander, economically. This investigation has opened new horizons for the researchers intended to work in the field of nutraceuticals and functional foods.
We would like to thank Higher Education Commission (HEC) of Pakistan for financial support and technical staff of National Institute of Food Science and Technology, University of Agriculture, Faisalabad, Pakistan, for their skillful assistance in operating hi-tech equipment like SFE, GC and HPLC.
Conflict of interest
Authors has shown no conflict of interest regarding this publication.
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|Publication:||Journal of the Chemical Society of Pakistan|
|Date:||Aug 31, 2018|
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