Antioxidant activity, volatile compounds and fatty acid compositions of Cephalaria syriaca seeds obtained from different regions in Turkey

C. Kavaka and A. Baştürka,*

aVan Yüzüncü Yıl University, Faculty of Engineering, Department of Food Engineering, 65080Van, Turkey.

*Corresponding author: ayhanbasturk@gmail.com

 

SUMMARY

Crude oil yield, fatty acid composition, volatile compounds, antioxidant activity and some characteristics of Cephalaria syriaca seeds collected from different locations in Turkey were studied. Antioxidant capacity was determined by DDPH and ABTS tests and the results were in the range of 18.8-67.3% and 0.0-41.8 mmol Trolox eq g-1 DW, respectively; while total phenolic contents were between 4339-11907 mg GAE kg-1. The average α-tocopherol content was found to be in the range of 54-467 mg kg-1. Oil yield was between 11.2-24.0%. Oleic and linoleic acids were the predominant fatty acids. A total of 30 different volatile compounds were identified in the samples, mostly consisting of alcohols and aldehydes. The results of this study showed that Cephalaria syriaca seeds can be considered as alternative raw material in the production of edible oil, and can be used as a source of natural antioxidants and food additives.

 

RESUMEN

Actividad antioxidante, compuestos volátiles y composición en ácidos grasos de semillas de Cephalaria syriaca obtenidas de diferentes regiones de Turquía. Se estudió el rendimiento de aceite crudo, la composición en ácidos grasos, los compuestos volátiles, la actividad antioxidante y algunas características de las semillas de Cephalaria syriaca recolectadas en diferentes lugares de Turquía. La capacidad antioxidante se determinó mediante pruebas DDPH y ABTS y los resultados estuvieron en el rango de 18.8-67.3% y 0.0-41.8 mmol Trolox eq g-1 DW, respectivamente, mientras que el contenido fenólico total estuvo entre 4339-11907 mg GAE kg-1. El contenido promedio de α-tocoferol se encontró en el rango de 54-467 mg kg-1. El rendimiento del aceite estuvo entre 11,2-24,0%. Los ácidos oleico y linoleico fueron los ácidos grasos predominantes. Se identificaron un total de 30 compuestos volátiles diferentes en las muestras, principalmente alcoholes y aldehídos. Los resultados de este estudio mostraron que las semillas de Cephalaria syriaca pueden considerarse como materia prima alternativa en la producción de aceite comestible, y pueden usarse como fuente de antioxidantes naturales y aditivos alimentarios.

 

Submitted: 19 September 2019; Accepted: 31 October 2019; Published online: 14 October 2020

ORCID ID: Kavak C https://orcid.org/0000-0003-4542-7473, Baştürk A https://orcid.org/0000-0001-7701-9306

KEYWORDS: ABTS; Acetaldehyde; Cephalaria syriaca; DPPH; GC-MS; Hexanal; Phenolics

PALABRAS CLAVE: ABTS; Acetaldehído; Cephalaria syriaca; DPPH; Fenólicos; GC-MS; Hexanal

Citation/Cómo citar este artículo: Kavak C, Baştürk A. 2020. Antioxidant activity, volatile compounds and fatty acid compositions of Cephalaria syriaca seeds obtained from different regions in Turkey. Grasas Aceites 71 (4), e379. https://doi.org/10.3989/gya.0913192

Copyright: ©2020 CSIC. This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) License.


 

CONTENT

1. INTRODUCTIONTOP

The interest in different edible oils, including plant seeds with high nutrition value, industrial and pharmaceutical significance, has recently increased. Since oils obtained from different sources generally have different fat compositions, no oil source alone is considered sufficient for all purposes. This has brought about the demand for new oil sources. In line with the increasing demand and scientific studies on the nutritional properties of these oils, determining their quality properties and composition from non-conventional seeds has gained importance (Nehdi, 2011).

Cephalaria Schrad. ex Roem. and Schult. originates from the Greek word for head (kephale). Cephalaria species have flowers which are densely arranged on the floral receptacle in the form of a head. There are 94 endemic plant species which are members of the Cephalaria (Dipsacaceae) family and it has a wide distribution in regions of the Mediterranean, Balkan, Middle East and North Africa (Davis, 1970; Gokturk et al., 2003). Of these plant species which belong to the Cephalaria family, 29 show a wide distribution in Turkey (Gokturk and Sumbul, 2014). It has been reported that Cephalaria species have various biological properties including antibacterial, antifungal, antioxidant and cytotoxic activities (Kirmizigül et al., 1996; Mustafaeva et al., 2008; Pasi et al., 2009; Sarıkahya and Kırmızıgül, 2010). Therefore, it is used in medicine, agriculture and veterinary medicine (Kayce and Kirmizigül, 2010). Cephalaria syriaca L. (CS), pelemir in Turkish, is predominantly found in the southeastern region of Turkey as a weed in cereal fields. The oil of this plant seed is sometimes extracted and used in the baking industry to enhance the quality of bakery products (Yazicioğlu et al., 1978). There is no extensive study on the antioxidant activity, volatile compound or fatty acid composition of CS seeds, which are widely grown in Turkey.

The aim of this study was to determine and compare crude oil yield, fatty acid composition, volatile compounds, antioxidant activity and some characteristics of Cephalaria syriaca seeds collected from different altitudes and locations in Turkey.

2. MATERIALS AND METHODSTOP

2.1. Plant materials and chemicalsTOP

The CS seeds used in the study were collected from different locations, at different altitudes, longitudes and latitudes, as determined by a Global Positioning System (GPS), at their maturation stage from June to August, 2017, according to their maturation levels. Samples were collected from the provinces of Mardin, Van, Gaziantep, Bitlis, Erzincan, Diyarbakır, Ağrı, Şanlıurfa, Siirt, Muş and Batman, all located in Turkey (Figure 1). Three groups of samples, each consisting of fifteen plants, were collected per location. Seed samples were coded as CS1, CS2…, and CS11, according to the locations from where they were collected, as given in Table 1. Folin-Ciocalteu’s reagent, methanol, n-hexane, isooctane, potassium persulfate methanol, isooctane, potassium persulfate, α-, β-, γ- and δ-tocopherol standards were obtained from Merck (Darmstadt, Germany). 2,2-diphenyl-1picrylhydrazyl (DPPH), 2,2+-azinobis-3-ethylbenzothiazoline-6-sulfonic acid, 5-methyl 2 hexanone, trolox and standards of fatty acid methyl esters (37 FAME mix) were obtained from Sigma Chemical Co. (Sigma–Aldrich GmbH, Sternheim, Germany).

TABLE 1. Geographical information on location of Cephalaria syriaca samples collected
Cephalariasyriaca (location) Code Altitude, m Latitude Longitude
Mardin CS1 596 37°15′07.51″ 40°43′36.76″
Van CS2 1668 38°34′52.93″ 43°17′56.65″
Gaziantep CS3 980 37°02′41.84″ 37°17′08.84″
Bitlis CS4 1703 38°25′50.31″ 42°07′47.02″
Erzincan CS5 1376 39°42′26.63″ 39°29′10.32″
Diyarbakır CS6 718 37°53′31.99″ 40°09′20.50″
Ağrı CS7 1687 39°42′04.42″ 43°02′14.46″
şanlıurfa CS8 457 37°06′27.54″ 38°54′38.55″
Siirt CS9 711 37°56′07.09″ 41°53′58.22″
Muş CS10 1584 38°48′12.61″ 41°33′27.65″
Batman CS11 748 37°53′06.18″ 41°14′52.27″

Figure 1. Map of locations where the samples of CS (Cephalaria syriaca) seeds collected.

 

2.2. Preparation of methanolic extractTOP

9.5 mL methanol were added to 5 g hexane-defatted ground Cephalaria seed, and the contents were homogenized with a homogenizer (Heidolph, SilentCrusher M, Schwabach, Germany) at 10.000 rpm for 15 s. The homogenized sample was agitated at room temperature for 2 h at 200 rpm in a circular shaker (Heidolph, unimax 1010, Kelheim, Germany). Then, the contents were centrifuged at 8000 × g for 10 min at 4 °C. Following centrifugation, the supernatant was separated from the residue, and the residue was subjected to the same treatment in duplicate. The supernatants obtained at the end of extraction were combined and completed to 25 mL with methanol.

2.3. Seed analysesTOP

2.3.1. Proximate analysis of seedsTOP

The recommended methods of the Association of Official Analytical Chemists AOAC, (2005) were adopted to determine the levels of moisture, ash, crude protein and crude oil. The moisture content was determined by drying the samples at 105 °C to constant weight. The ash content was determined in a laboratory furnace at 600 °C, and the temperature was increased gradually. Nitrogen content was determined by using the Kjeldhal method. Crude oil was obtained by the Soxhlet extraction method by exhaustively extracting 10 g of each sample in a Soxhlet apparatus using hexane as the extractant. Each measurement was performed in triplicate and the results were averaged.

2.3.2. Determination of total phenolic contentTOP

The phenolic content (TPC) of CS seed extracts was determined using the Folin-Ciocalteu reagent (Singleton and Rossi, 1965). Samples (0.4 mL, two replicates) were placed in test tubes; 2 mL of Folin-Ciocalteu’s reagent and 1.6 mL of sodium carbonate (7.5%) were added. The tubes were agitated and allowed to stand for 60 min. Absorption was measured at 765 nm in a UV-spectrophotometer (Agilent 8453, Agilent technologies, CA, USA). Gallic acid was used as a standard for the calibration curve (y = 0.0063x + 0.049). The total phenolic content was expressed as gallic acid equivalent (mg GAE/kg dry extract).

2.3.3. Antioxidant activity tests TOP

DPPH radical scavenging assay. The DPPH free radical removal activity of the CS seed extracts was determined by the Blois method (Blois, 1958). Prior to the procedure, the methanolic DPPH solution was prepared for analysis. 0.0065 g DPPH were weighed and completed to 250 mL with methanol (0.025 g/L methanol). For the analysis, 0.1 mL CS seed extract was prepared and a 3.9 mL DPPH solution was added and mixed using a vortex and kept for 60 minutes at room temperature in the dark. At the end of this period, the absorbance of the UV spectrophotometer was read at 515 nm. In the control sample, the spectrophotometer was reset with pure methanol using solvent instead of sample. At the end of the 60 min, the amount of DPPH inhibited in the reaction medium was determined using Equation 1.

I = DPPH inhibited by the sample, %

A1 = absorbance of the sample

A2 = absorbance of the control

ABTS assay. ABTS analysis was performed using the method proposed by Re et al., (1999). Measurements were carried out spectrophotometrically by observing the disappearance of the ABTS radical, a stable blue-green compound. The reaction between ABTS and potassium persulfate yields a blue-green ABTS∙+ chromophore. 7 mmol of ABTS (2,2+-azinobis-3-ethylbenzothiazoline-6-sulfonic acid) and 2.45 mmol potassium persulfate were reacted at room temperature in the dark for 12-16 h to yield the stock ABTS∙+ radical cation. The obtained ABTS∙+ radical cation was diluted with ethanol to give 0.70 ± 0.02 absorbance at 734 nm. Then, 20 μL of extract were mixed with 1980 μL ABTS∙+ radical cation for 6 minutes at room temperature in the dark and measured in the UV spectrophotometer at 734 nm. The results were calculated using the Trolox standard curve (y = 38.484x-2.602) and Equation 2, and were presented as mmol trolox eq/g dry weight.

A6: Absorbance at the 6th min

A1: Absorbance at the 1st min

2.3.4. Determination of volatile compounds TOP

The determination of volatile compounds was carried out by GC-MS according to Krist et al., (2006), with some modifications. Analyses were performed in 3 replicates. Before starting the analysis, 0.1 mL 5-methyl 2 hexanone was completed to 10 mL with pure water by the internal standard (IS) and prepared for analysis. 3 grams of ground seeds were placed in 30 mL vials, and 10 mL pre-boiled and cooled pure water were added and homogenized using a homogenizer (Heidolph Silent Crusher M, Schwabach, Germany) at 13000 rpm. Then, the solution was added to 10 μL internal standard and a magnetic stirrer was added. After the lids of the vials were sealed and conditioned for 5 min at 40 °C in the heating block by immersing them in an appropriate fiber (50/30μm-thick, DVB/CAR/PDMS as the absorbant), they were left to absorb the volatile components in the peak space for 40 minutes in a heated magnetic stirrer set to 40 °C and 140 rpm. At the end of this period, the fiber was held at the injection port of the gas chromatography device for 5 min to pass the fiber-holding volatile components to the GC-MS system column. A TRB-5MS (30 m length, 0.250 mm internal diameter, 0.25 μm film thickness) capillary column was used in the analyses. The operating conditions were set as follows: injection block temperature of 250 °C; detector temperature of 250 °C; carrier gas was He; flow rate at 1 mL/min; temperature of the MS source was 230 °C; MS quadrupole temperature of 150 °C; injection mode was splitless; electron energy of 70 eV; mass range of 15-210 atomic mass units. The oven temperature was held at 40 °C for 2 min, raised from 40 to 70 °C with 5 °C increments per min, held at 70 °C for 1 min, raised from 70 to 240 °C with 10 °C increment per min, and held at 240 °C for 30 min. Then, identifications of the components in the chromatogram were compared with the information in the Wiley and NIST libraries and the calculated retention indexes (RI). In addition, the mass spectra of the defined components and the mass spectra of the internal standard were used to calculate the amounts (μg/kg).

2.4. Analysis of seed oilsTOP

2.4.1. Extraction of oilsTOP

The oil samples required for planned analyses including fatty acid composition, peroxide value (PV), free fatty acid (FFA), tocopherol and color parameters were obtained by cold extraction. 130 mL n-hexane were added to ground CS (35 g) and kept in the circular shaker at 180 rpm for 2 h. The extracts were filtered and the hexane was evaporated at 40 ºC in a rotary evaporator. The seed oils were stored at + 4 ºC in the dark until use.

2.4.2. Determination of FFA and PVTOP

The methods recommended by AOCS, (1989b) were adopted to determine FFA contents (method Ca 5a-40/93) and PV (method Cd 8-53).

2.4.3. Fatty acid composition TOP

First, fatty acid methyl esters (FAMEs) were formed as described by Basturk et al., (2007). After formation of the methyl esters, 1 mL from the clear upper phase was injected into the injection port of the device, a QP 2010 Ultra Shimadzu GC-MS with MS detector combined with a FID detector. The column details and working conditions were as follows: DB-23 column (60 m x 0.25 mm, 0.25 μm); carrier gas was He at a total flow of 36.6 mL/min; the column flow was 0.66 mL/min; linear speed was 21.2 cm/sec at a split ratio of 50. The initial temperature was 80 ºC, which was increased at 10 ºC/min until the final temperature of 220 ºC; injection and detection temperatures were 250 ºC. The total analysis time was 34 min and the ion source temperature was 200 ºC. Fatty acid methyl esters were identified by chromatography with authentic standards (Sigma) and from the NIST 05 MS Library Database. Quantification of the fatty acid methyl ester profiles was made by considering the relative peak areas, expressed as the relative percentage of the individual area of each one as related to the total area of compounds in the chromatogram. FAMEs analyses were performed in 3 replicates.

2.4.4. Determination of α-tocopherol TOP

The tocopherol content of the samples was determined on a HPLC device (Shimadzu, Kyoto, Japan) according to the AOCS Official Method (Ce 8-89) (AOCS, 2003). In CS samples, the oil samples obtained by cold extraction were diluted with n-hexane at a ratio of 1:10, then filtered through a 0.45 μm (MillipareMillex-LCR Hydrophilic PTFE) filter and injected into the device. The HPLC operating conditions were as follows: LiChrosorb Si60 column (250 × 4mm, ID) 5 μm, at a flow rate of 1 mL/min (isocratic flow); the mobile phase contained hexane: isopropyl alcohol (99:1); wavelength was 295 nm; column temperature was 25 °C. The compounds appearing in the chromatograms were identified as retention times and spectral data by comparison with standards of α-, β-, γ- and δ-tocopherols. Results were expressed in mg/kg oil. The measurements were taken in triplicate.

2.4.5. Color measurement TOP

The L*, a*, b* color values of the samples were determined by using a colorimeter (CR-400 Konica, Minolta, Tokyo, Japan). First, calibration of the device was carried out on a white plate and black hole provided by the manufacturer. For absolute measurements, approximately 20 mL of oil sample were placed on the measuring head and three readings were taken in different positions. The average values of L*, a*, and b* were given based on three subsequent readings.

2.5. Statistical analysisTOP

Statistical analyses were performed using SPSS software (version 20.0 for Windows, SPSS Inc., Chicago, Illinois). The collected data from the different dependent variables were analyzed statistically according to the analysis of variance with three replicates as a general test at each location. The differences between mean values were analyzed using Duncan’s multiple range tests at the 0.05 level of significance.

3. RESULTS AND DISCUSSIONTOP

3.1. Physicochemical properties of CS seedsTOP

A proximate composition of CS seeds is given in Table 2. The crude fat content was between 11.2-24.0%, depending on harvest location. CS1 showed the highest fat content, followed by CS11. Similar ratios were obtained in previous studies. The fat content of CS was previously reported to be between 24.9 and 25.8%, by Yazicioğlu et al., (1978), as 25.14% by Uslu, (2016), 30.3% by Bretagnolle et al., (2016), 19.32-25.15% by Rahimi et al., (2019) and between 19.08 and 23.99% by (Katar et al., 2012). The fat content obtained in the present study was generally consistent with the previously reported results. However, it changed within a relatively large range depending on the harvest location.

TABLE 2. Proximate composition of CS seeds
Sample Oil % Protein (%) Moisture% Ash%
CS1 23.99 ± 0.52f 20.00 ± 1.94de 10.85 ± 0.88de 6.26 ± 0.52abc
CS2 19.22 ± 0.27e 16.46 ± 0.35ab 13.75 ± 0.89f 5.64 ± 0.52ab
CS3 16.67 ± 0.59d 19.51 ± 1.15cde 9.82 ± 0.21bcd 6.65 ± 0.59bc
CS4 19.33 ± 0.49e 15.40 ± 0.37a 9.53 ± 0.54bc 5.59 ± 0.34ab
CS5 18.52 ± 0.42e 14.67 ± 1.00a 11.14 ± 0.25e 6.88 ± 0.58bc
CS6 15.03 ± 0.54cd 21.08 ± 0.83e 10.98 ± 0.31de 6.78 ± 0.91bc
CS7 13.29 ± 0.28bc 16.38 ± 0.31ab 8.97 ± 0.48b 6.97 ± 0.62bc
CS8 11.95 ± 2.01ab 18.61 ± 0.16cd 10.20 ± 0.16cde 7.58 ± 0.58c
CS9 11.18 ± 0.82a 17.61 ± 0.20bc 10.38 ± 0.31cde 7.25 ± 0.54c
CS10 19.85 ± 0.38e 20.48 ± 0.55de 7.62 ± 0.28a 5.05 ± 1.19a
CS11 22.47 ± 1.00f 21.22 ± 1.12e 10.62 ± 0.48cde 6.54 ± 0.25abc
*Small letters indicate significant differences within each column for the mean ± SD values calculated from three determinations by one-way ANOVA and Duncan’s test (P ≤ 0.05). Cephalaria syriaca L. samples according to location; CS1: Mardin, CS2: Van, CS3: Gaziantep, CS4: Bitlis, CS5: Erzincan, CS6: Diyarbakir, CS7: Agri, CS8: Sanliurfa, CS9: Siirt, CS10: Mus, CS11: Batman.

The moisture content of the seeds was found to be in the range of 7.6-13.8%. Uslu (2016) found the moisture content as 6.08%. CS2 showed the highest moisture content; while that of CS10 was the lowest. There was no significant difference among the group of samples of CS3, CS4 and CS7, which was lower in moisture content compared to CS1, CS5, CS6, CS8, CS9 and CS11group. The ash contents of the samples were determined to be in the range of 5.05-7.58% in the present study. These values were similar to the ash ratio of 5.34% as determined by Uslu (2016). The protein content detected in the CS samples was in the range of 14.7-21.2%. The highest protein yields were in CS11, CS6, CS10 and CS1 samples, in descending order. Protein contents were reported in previous studies as 15.54% by Uslu (2016) and 16.4-22.5% by Altıniğne and Saygın (1985), and were in agreement with this study. The proximate composition of seeds may vary depending on many factors including harvest time, local weather conditions, geographical location, etc.

3.2. Total phenolic content and antioxidant activity of CS seedsTOP

TPC and antioxidant activity of CS seeds are given in Table 3. The highest TPC were found in CS1, CS7, CS10 and CS11 samples, in descending order. The two groups that differed were CS1, CS2, CS4, CS5, CS7, CS8, CS10 and CS11, which were significantly different from CS3, CS6 and CS9 (P < 0.05). Sarikahya et al., (2015) determined the total amount of phenolic compounds as 57-3037 mg GAE/kg in the aerial parts of ten different Cephalaria species, except for C. syriaca. Of these species, C.tchihatchewii, C.aristata and C. speciosa were found to have the highest phenolic contents (3037, 2907 and 2658 mg GAE/kg, respectively). The CS seeds in the present study were found to be higher in TCP values.

TABLE 3. Total phenolic content and antioxidant activity of CS seeds
Sample Total Phenolic Content (mg GAE/kg dry seeds) DPPH (Inhibition %) ABTS (mMolTrol. eq./gDW)
CS1 11907 ± 2068c* 45.35± 4.17d 23.68 ± 1.33c
CS2 9805 ± 1335bc 20.95± 2.90a 38.24 ± 1.87e
CS3 6408 ± 565ab 20.60 ± 0.00a 23.34 ± 1.61c
CS4 10406 ± 1322c 18.80 ± 1.13a 28.89 ± 3.35d
CS5 8452 ± 1523bc 21.45 ± 1.20ab 32.27 ± 1.23d
CS6 4758 ± 1602a 20.75 ± 2.33a 9.84 ± 0.25b
CS7 11802 ± 1482c 67.25 ± 3.46e 41.77 ± 0.31e
CS8 9363 ± 1787bc 29.50 ± 0.28c 38.35 ± 1.26e
CS9 4339 ± 580a 26.00 ± 0.99bc 0.00 ± 0.00a
CS10 11046 ± 2596c 22.95 ± 0.21ab 25.08 ± 2.45c
CS11 10081 ± 329c 42.90 ± 0.14d 37.90 ± 1.28e
*Small letters indicate significant differences within each column for the mean ± SD values calculated from three determinations by one-way ANOVA and Duncan’s test (P ≤ 0.05). Cephalaria syriaca L. samples according to location; CS1: Mardin, CS2: Van, CS3: Gaziantep, CS4: Bitlis, CS5: Erzincan, CS6: Diyarbakir, CS7: Agri, CS8: Sanliurfa, CS9: Siirt, CS10: Mus, CS11: Batman.

The DPPH analysis revealed that the samples showed inhibition (radical scavenging effect) between 18.8 and 67.3%. The highest radical scavenging effect was determined in CS7, followed by CS1 and CS11. Rahimi et al., (2019) studied the effect of different fertilizers on the antioxidant capacity of the Cephalaria syriaca plant and concluded that the antioxidant activity of the samples (DPPH) was between 47.10-60.16%. According to Kaur and Kapoor (2002), DPPH inhibition activity can be classified into three major groups as high (≥ 50%), moderate (20-50%) and low (≤ 20%). Therefore, CS4 was in the low activity group, CS7 was in the high one and the others were in the moderate activity group.

ABTS is often used to test the initial radical scavenging activity of antioxidant compounds or plant extracts. The ABTS+ that was obtained as a result of the oxidation of ABTS with potassium persulfate was presented as an excellent tool to determine the antioxidant activity of hydrogen donor antioxidants and chain-breaker antioxidants (Leong and Shui, 2002). The ABTS results (TEAC values) for the seeds, except for CS9, were found between 9.8 and 41.8 mmol Trolox eq/g DW values. The highest TEAC value was found in CS7; while the lowest was found in CS6. In the case of CS9, no antioxidant activity (TEAC) was detected.

3.3. Volatile compounds in CS seedsTOP

The volatile compounds of the CS seeds are given in Table 4; while the GC chromatograms of volatile compounds and detailed information are given in Figure 2. 30 different volatile compounds were detected in the CS seeds collected from the 11 different locations. These consisted of 10 aldehydes, 13 alcohols, 2 monoterpenes, 2 ketones, 1 hydrocarbon, and 1 ester in addition to 1 unidentified species. The total amount of aldehydes in the samples varied between 72.3 and 521.6 μg/kg. Total aldehyde values were ordered as CS8 > CS6 > CS1 > CS9 > CS7 > CS11 > CS4 > CS2 > CS3 > CS10 > CS5. The most dominant aldehydes were hexanal, 2-hexenal, butanal 3-methyl, benzaldehyde and acetaldehyde. Nonanal was not detected in CS1, CS2, CS3, CS4, CS10 or CS11 samples. The highest amount of detected aldehyde was hexanal (11.90-162.65 μg/kg). The second most dominant component in this group was acetaldehyde and was found in the range of 12.60-54.80 μg/kg. The acetaldehyde contents were not different among the samples of CS2, CS3, CS4, CS6, CS9, CS10 and CS11; whereas differences among other samples were significantly different (P < 0.05). Benzaldehyde was found in all samples and its content was significantly different (P < 0.05). Butanal 3-methyl was the other dominant aldehyde and was detected in the range of 6.6-82.4 μg/kg, significantly different among the samples (P < 0.05). As seen in Table 4, the total amount of alcohols was higher than aldehydes (81.00-1227.75 μg/kg). The most dominant compounds in the alcohol group were hexanol, myrtenol and 1-butanol 3-methyl, respectively. The highest value was found in CS8; whereas the lowest value was found in CS6. While the differences among the hexanol values in CS1, CS2, CS3, CS6, CS10 and CS11 samples were not significant, the mean values for other samples were significantly different (P < 0.05). Myrtenol was detected in all the samples and ranged from 2.6 to 126.3 μg/kg (P < 0.05). In monoterpenes, the α-thujene values varied in the range of 0.9-20.6 μg/kg and differed statistically in all samples except for CS1, CS2 and CS3 (P < 0.05). Another monoterpene, β-pinene, was found to be in the range of 1.10-44.55 μg/kg in all samples (P < 0.05). α-thujene and β-pinene were determined to be the highest in CS8 (20.60 and 44.55 μg/kg, respectively). Metantetranitro was detected in all samples between 10.80 and 34.85 μg/kg (P < 0.05). In general, the total amount of volatile compounds was at the highest level in CS8, collected from the Şanlıurfa province. According to the literature, there was no study on the volatile compounds of CS seeds. As one exception, Sarıkahya et al., (2013) investigated the volatile compounds of the essential oil from 10 endemic Cephalaria species, but did not include CS grown in Turkey- A total of 28 components were identified including geraniol, α-cedrene and p-cymene.

TABLE 4. Volatile compounds (μg/kg) identified in Cephalaria syriaca seeds
Compounds RI CS1 CS2 CS3 CS4 CS5 CS6 CS7 CS8 CS9 CS10 CS11
Aldehydes
Acetaldehyde 622 54.80 ± 6.12d 26.20 ± 1.84b 24.95 ± 2.01b 25.60 ± 2.56b 13.70 ± 0.74a 22.80 ± 2.15b 12.60 ± 1.84a 46.80 ± 3.90c 21.95 ± 2.28b 28.70 ± 2.80b 22.55 ± 2.32b
Propanal, 2-methyl 638 8.65 ± 1.22e 7.30 ± 0.49de 6.00 ± 1.03cd 4.40 ± 0.61bc 4.65 ± 0.75c 11.00 ± 1.54f 4.85 ± 0.30c 12.65 ± 1.30f 4.00 ± 0.33bc 2.00 ± 0.14a 2.60 ± 0.24ab
Butanal, 3-methyl 670 25.85 ± 3.83cd 22.95 ± 2.53cd 18.95 ± 2.22bc 24.90 ± 2.81cd 6.60 ± 0.62a 21.80 ± 2.81bc 38.75 ± 0.72e 82.40 ± 9.57f 31.35 ± 3.21de 13.40 ± 1.63ab 25.25 ± 1.97cd
Butanal, 2-methyl 674 7.20 ± 1.10bc 6.05 ± 0.21b 6.60 ± 0.45bc 9.75 ± 1.07c 7.50 ± 0.37bc 7.90 ± 0.41bc 13.90 ± 1.02d 35.30 ± 3.44f 9.65 ± 0.83c 3.00 ± 0.59a 20.35 ± 2.05e
Pentanal 695 2.75 ± 0.83a 6.55 ± 0.68c 6.95 ± 0.88c 6.70 ± 0.57c 4.45 ± 0.51b 6.00 ± 0.48bc 4.45 ± 0.62b 16.70 ± 1.20d 2.85 ± 0.27a --- 2.25 ± 0.18a
2-Butenal, 2-methyl 732 2.00 ± 0.18a 2.05 ± 0.20a 1.65 ± 0.34a 1.25 ± 0.24a 2.20 ± 0.23a --- 1.60 ± 0.37a 10.50 ± 1.17b 1.60 ± 0.16a 1.20 ± 0.17a ---
Hexanal 790 25.20 ± 2.97ab 33.35 ± 2.36bc 29.10 ± 2.55bc 42.10 ± 4.82c 29.15 ± 2.97bc 69.25 ± 5.84d 23.25 ± 2.57ab 162.65 ± 16.39e 32.25 ± 3.22bc 24.10 ± 2.08ab 11.90 ± 0.23a
2-Hexenal 841 1.00 ± 0.11a --- --- 1.45 ± 0.31a --- 3.40 ± 0.44a 18.20 ± 0.69a 107.40 ± 77.46b 22.95 ± 2.39a 0.70 ± 0.03a 5.05 ± 0.48a
Benzaldehyde 948 22.90 ± 2.26d 8.20 ± 0.82b 5.50 ± 0.48ab 6.00 ± 0.99ab 2.65 ± 0.38a 6.00 ± 0.59ab 16.10 ± 0.88c 38.40 ± 3.89f 18.00 ± 1.51c 5.60 ± 0.65ab 31.45 ± 1.80e
Nonanal 1090 --- --- --- --- 1.35 ± 0.27a 4.65 ± 0.51b 1.80 ± 0.25a 8.75 ± 1.00c 1.00 ± 0.04a --- ---
Sum   150.35 ± 3.00f 112.65 ± 2.25c 99.70 ± 1.61b 122.15 ± 2.91d 72.25 ± 1.85a 152.80 ± 2.64f 135.50 ± 3.24e 521.55 ± 9.89g 145.60 ± 2.29f 78.70 ± 2.32a 121.40 ± 2.38d
Alcohols
Ethanol 626 7.00 ± 1.17cd 8.55 ± 0.72de 12.35 ± 0.78f 4.35 ± 0.57b 5.70 ± 0.71bc 10.45 ± 1.06ef 5.80 ± 0.45bc 17.25 ± 1.88g 6.15 ± 0.95bc 5.90 ± 0.55bc 2.00 ± 0.14a
Silanediol, dimethyl- 690 5.10 ± 0.96bc 2.85 ± 0.66a 6.95 ± 0.99d 7.25 ± 0.65d 9.05 ± 0.93e 3.80 ± 0.45ab 3.20 ± 0.11a 6.20 ± 1.00cd 3.80 ± 0.65ab 4.10 ± 0.44ab 3.00 ± 0.20a
1-Butanol, 3-Metil 724 9.65 ± 1.19ab 6.20 ± 1.03a 3.25 ± 0.68a 10.90 ± 1.70ab 6.60 ± 0.99a 15.55 ± 1.48b 32.35 ± 3.61c 80.95 ± 7.78e 47.65 ± 3.97d 6.70 ± 0.91a 40.75 ± 4.09d
1-Butanol, 2-methyl 727 4.60 ± 0.81ab 2.50 ± 0.44a 2.45 ± 0.52a 4.65 ± 0.52ab 2.20 ± 0.27a 7.05 ± 0.66b 13.30 ± 2.93c 35.70 ± 3.48d 14.00 ± 1.50c 1.20 ± 0.14a 7.55 ± 0.82b
1-Pentanol 756 5.65 ± 0.59ab 4.80 ± 0.58ab 5.45 ± 0.54ab 5.10 ± 0.52ab 14.60 ± 0.72c 5.85 ± 0.55b 3.30 ± 0.31ab 30.00 ± 3.39d 5.25 ± 0.51ab 6.00 ± 1.22b 2.85 ± 0.27a
1-Pentanol, 4-methyl 827 4.65 ± 0.59b 2.15 ± 0.16a 4.95 ± 0.96b 1.85 ± 0.40a --- 1.90 ± 0.40a 2.40 ± 0.38a 12.90 ± 0.57c 4.70 ± 0.72b 1.50 ± 0.27a 4.15 ± 0.42b
1-Pentanol, 3-methyl 834 13.50 ± 1.95cd 4.05 ± 0.45a 3.00 ± 0.27a 9.65 ± 1.63bc 2.30 ± 0.30a 4.50 ± 0.52a 15.15 ± 1.51d 45.65 ± 4.53e 16.50 ± 1.60d 6.00 ± 0.58ab 10.50 ± 0.91c
2-Hexen-1-ol, (E) 855 1.50 ± 0.01a 1.50 ± 0.16a --- --- 0.60 ± 0.03a 2.75 ± 0.86a 15.50 ± 1.50b 82.85 ± 7.45d 27.20 ± 2.60c 0.60 ± 0.03a 7.25 ± 0.74a
Hexanol 857 75.80 ± 10.86a 44.30 ± 3.37a 56.70 ± 5.77a 86.64 ± 7.10ab 168.90 ± 19.23c 35.90 ± 3.45a 90.95 ± 10.54ab 684.20 ± 64.83d 138.20 ± 13.48bc 44.70 ± 4.36a 59.20 ± 6.60a
1-Octen-3-ol 968 3.20 ± 0.41a 4.35 ± 0.99a --- 4.40 ± 0.40a 1.95 ± 0.24a 3.30 ± 0.58a 90.35 ± 9.66c 72.00 ± 6.79b 7.15 ± 1.06a 1.70 ± 0.18a 4.55 ± 0.34a
Benzenemethanol 1022 4.10 ± 0.76ab --- --- --- --- 1.70 ± 0.23a 8.05 ± 0.76bc 16.35 ± 1.78d 10.45 ± 1.10c --- 8.65 ± 3.45c
Isopinocarveol 1124 0.40 ± 0.08a --- --- --- --- --- 11.35 ± 1.00c 17.40 ± 1.17d 4.95 ± 0.65b --- 1.95 ± 0.16a
Myrtenol 1182 57.15 ± 6.65de 23.95 ± 2.67bc 15.35 ± 1.67ab 14.80 ± 1.88ab 6.15 ± 0.86a 30.70 ± 3.38c 46.10 ± 4.70d 126.30 ± 12.02f 65.50 ± 7.21e 2.60 ± 0.47a 57.20 ± 5.81de
Sum   192.30 ± 4.72e 105.20 ± 1.74b 110.45 ± 2.57b 149.59 ± 2.67d 218.05 ± 3.76f 123.45 ± 3.90c 337.80 ± 5.26g 1227.75 ± 9.23i 351.50 ± 5.81h 81.00 ± 1.41a 209.60 ± 2.81f
Monoterpenes
α-Thujene 921 --- --- --- 10.55 ± 1.92b 0.90 ± 0.13a 9.21 ± 2.26b 17.70 ± 1.47c 20.60 ± 1.48c 3.60 ± 0.31a 2.70 ± 0.47a 1.80 ± 0.20a
β-Pinene 962 1.20 ± 0.27a 4.35 ± 0.62ab 1.10 ± 0.13a 17.10 ± 1.41e 4.05 ± 0.34ab 8.85 ± 0.75cd 25.60 ± 2.90f 44.55 ± 3.34g 9.95 ± 1.22d 1.30 ± 0.13a 5.85 ± 0.47bc
Sum   1.20 ± 0.14a 4.35 ± 0.42ab 1.10 ± 0.14a 27.65 ± 1.99f 4.95 ± 0.30bc 18.06 ± 1.30e 43.30 ± 1.29g 65.15 ± 3.20h 13.55 ± 1.90d 4.00 ± 0.17ab 7.65 ± 0.44c
Ketones
2-propane 630 5.30 ± 0.41b 8.60 ± 0.64de 10.35 ± 1.74ef 13.00 ± 1.46g 5.95 ± 0.68bc 12.60 ± 1.64fg 7.20 ± 0.85bcd 10.50 ± 0.86ef 2.50 ± 0.49a 8.20 ± 1.13cde 5.90 ± 0.48bc
Acetone 881 1.50 ± 0.17bc 1.20 ± 0.15ab 1.90 ± 0.33c 0.90 ± 0.16ab 2.55 ± 0.37d 1.50 ± 0.23bc 1.20 ± 0.18ab 7.75 ± 0.66e 1.20 ± 0.10ab 1.00 ± 0.03ab 0.60 ± 0.04a
Sum   6.80 ± 0.54b 9.80 ± 0.55cd 12.25 ± 1.88de 13.90 ± 1.64e 8.50 ± 1.03bc 14.10 ± 2.22e 8.40 ± 0.66bc 18.25 ± 1.80f 3.70 ± 0.13a 9.20 ± 0.20bc 6.50 ± 0.16b
Hidrokarbon
Hexane 647 19.35 ± 2.26ab 75.60 ± 5.37e 32.35 ± 3.99c 40.90 ± 3.24d 26.90 ± 3.93bc 15.00 ± 1.53a 27.60 ± 2.69c 46.65 ± 4.17d 12.80 ± 1.24a 25.00 ± 2.25bc ---
Ester
Acetic acid, ethyl ester 655 3.95 ± 0.98bcd 3.60 ± 0.44b 3.80 ± 0.30bc 8.05 ± 1.12f 5.60 ± 0.83de 6.10 ± 0.59e 5.30 ± 0.61cde 11.80 ± 1.15g 4.10 ± 0.38bcd 2.50 ± 0.27ab 1.20 ± 0.13a
Other
Methane, tetranitro 617 18.30 ± 1.48b 19.25 ± 2.21b 34.85 ± 3.46e 24.90 ± 2.70cd 25.50 ± 2.66cd 20.85 ± 1.80bc 22.30 ± 0.72bc 28.95 ± 1.61d 10.80 ± 1.56a 13.55 ± 1.51a 13.25 ± 1.29a
*Small letters indicate significant differences in the same row for the mean± SD values calculated from three determinations by one-way CS4: Bitlis, CS5: Erzincan, CS6: Diyarbakir, CS7: Agri, CS8: Sanliurfa, CS9: Siirt, CS10: Mus, CS11: Batman. Major consitutents are ANOVA and Duncan’s test (P ≤ 0.05). Cephalaria syriaca L. samples according to location; CS1: Mardin, CS2: Van, CS3: Gaziantep, given in bold font.

Figure 2. GC chromatograms of fatty acid esters obtained from Cephalaria syriaca seed oils. Cephalaria syriaca L. samples according to locations; CS1: Mardin, CS2: Van, CS3: Gaziantep, CS4: Bitlis, CS5: Erzincan, CS6: Diyarbakir, CS7: Agri, CS8: Sanliurfa, CS9: Siirt, CS10: Mus, CS11: Batman

 

3.4. Fatty acid composition of CS seed oilsTOP

The fatty acid composition of CS seed oils is given in Table 5. Chromatograms and detailed information are given in Figure 3. The most abundant fatty acid in the CS seed oil was oleic acid (C18:1) followed by linoleic (C18:2), myristic (C14:0) and palmitic (C16:0) acids. Oleic acid varied between 28.10 and 33.22% and linoleic acid was in the range of 26.84–31.70% with no statistically significant difference. Yazicioğlu et al., (1978) reported that the oleic acid of oil from CS seeds collected from Kayseri and Diyarbakır (Turkey) was 25.5 and 20.6%; while linoleic acid was 36.3 and 37.6%, respectively. The amounts of oleic acid found in the present study were higher; whereas linoleic acid was lower than these findings. Bretagnolle et al., (2016) reported that oleic and linoleic acids were 19.3 and 42.9%, respectively.

TABLE 5. Fatty acid composition (%) of the Cephalaria syriaca seed oils
Fatty acids CS1 CS2 CS3 CS4 CS5 CS6 CS7 CS8 CS9 CS10 CS11
Lauric (C12) 2.40 ± 0.23ab 2.40 ± 0.3ab 2.60 ± 0.30b 2.40 ± 0.17ab 1.90 ± 0.14a 2.32 ± 0.23ab 2.50 ± 0.18b 2.30 ± 0.23ab 2.60 ± 0.21b 2.46 ± 0.28ab 2.70 ± 0.20b
Miristic (C14) 16.20 ± 2.15a 14.80 ± 2.26a 17.10 ± 0.30a 15.20 ± 2.72a 14.80 ± 1.17a 16.38 ± 2.19a 14.60 ± 2.33a 14.70 ± 2.12a 17.30 ± 2.12a 16.44 ± 2.31a 16.30 ± 2.36a
Palmitic (C16) 12.00 ± 1.54a 11.40 ± 2.06a 11.60 ± 2.14a 11.70 ± 1.17a 12.30 ± 0.56a 11.83 ± 2.49a 11.20 ± 1.19a 11.20 ± 2.88a 12.20 ± 1.84a 11.32 ± 2.57a 11.60 ± 3.25a
Palmitoleic (C16:1) 1.90 ± 0.06c 2.30 ± 0.3d 0.50 ± 0.04a 0.80 ± 0.07ab 0.80 ± 0.05ab 0.89 ± 0.1b 2.70 ± 0.27e 0.60 ± 0.08ab 0.70 ± 0.08ab 0.58 ± 0.07ab 0.70 ± 0.08ab
Stearic (C18) 4.00 ± 0.56abc 4.90 ± 0.33abc 5.10 ± 0.27bc 4.80 ± 0.41abc 5.20 ± 0.71c 3.91 ± 0.41ab 4.50 ± 0.38abc 4.20 ± 0.27abc 3.80 ± 0.57a 4.55 ± 0.92abc 4.30 ± 0.49abc
Oleic (C18:1) 32.70 ± 2.79a 28.10 ± 2.76a 32.20 ± 2.67a 29.10 ± 2.29a 31.10 ± 2.12a 33.22 ± 2.69a 29.20 ± 2.81a 31.00 ± 2.26a 30.70 ± 2.97a 30.97 ± 2.96a 32.80 ± 2.70a
Linoleic (C18:2) 27.00 ± 2.25a 31.20 ± 2.29a 27.00 ± 2.39a 31.70 ± 2.19a 29.50 ± 2.23a 26.84 ± 2.43a 27.20 ± 2.16a 31.70 ± 2.40a 28.50 ± 2.79a 30.30 ± 2.55a 26.90 ± 2.47a
Linolenic (C18:3) 0.50 ± 0.02ab 0.30 ± 0.01a 0.30 ± 0.03a 0.40 ± 0.04a 0.40 ± 0.04a 0.78 ± 0.01cd 1.00 ± 0.13de 1.20 ± 0.21e 1.00 ± 0.01de 0.33 ± 0.06a 0.70 ± 0.27bc
Arachidic (C20) 0.90 ± 0.03a 1.10 ± 0.30a 1.00 ± 0.13a 1.10 ± 0.13a 1.10 ± 0.24a 1.02 ± 0.13a 0.90 ± 0.08a 0.80 ± 0.10a 0.90 ± 0.11a 0.95 ± 0.13a 1.10 ± 0.26a
cis11eicosenoik (C20:1) 0.50 ± 0.04a 0.60 ± 0.07a 0.60 ± 0.06a 0.60 ± 0.01a 0.60 ± 0.08a 0.56 ± 0.07a 0.60 ± 0.06a 0.60 ± 0.08a 0.50 ± 0.06a 0.62 ± 0.08a 0.60 ± 0.07a
Others 1.90 ± 0.25ab 2.90 ± 0.27b 2.00 ± 0.25ab 2.20 ± 0.16ab 2.30 ± 0.21ab 2.25 ± 0.30ab 5.60 ± 1.70c 1.70 ± 0.16ab 1.80 ± 0.25ab 1.48 ± 0.33a 2.30 ± 0.30ab
ΣSFA 35.50 ± 4.05a 34.60 ± 0.52a 37.40 ± 2.54a 35.20 ± 2.25a 35.30 ± 1.40a 35.46 ± 0.21a 33.70 ± 1.79a 33.20 ± 4.86a 36.80 ± 3.49a 35.72 ± 1.34a 36.00 ± 5.06a
ΣMUFA 35.10 ± 2.89a 31.00 ± 3.13a 33.30 ± 2.69a 30.50 ± 2.21a 32.50 ± 1.98a 34.67 ± 2.66a 32.50 ± 2.60a 32.20 ± 2.43a 31.90 ± 3.11a 32.17 ± 2.94a 34.10 ± 2.86a
ΣPUFA 27.50 ± 2.26a 31.50 ± 2.31a 27.30 ± 2.36a 32.10 ± 2.23a 29.90 ± 2.19a 27.62 ± 2.42a 28.20 ± 2.29a 32.90 ± 2.19a 29.50 ± 2.77a 30.63 ± 2.60a 27.60 ± 2.21a
ΣUFA 62.60 ± 4.32a 62.50 ± 3.42a 60.60 ± 3.56a 62.60 ± 2.27a 62.40 ± 4.21a 62.29 ± 2.74a 60.70 ± 2.26a 65.10 ± 3.15a 61.40 ± 2.1a 62.80 ± 1.85a 61.70 ± 4.12a
UFA/SFA 1.8 1.8 1.6 1.8 1.8 1.8 1.8 2.0 1.7 1.8 1.7
*Small letters indicate significant differences in the same row for the mean ± SD values calculated from three determinations by one-way ANOVA and Duncan’s test (P ≤ 0.05). Cephalaria syriaca L. samples according to location; CS1: Mardin, CS2: Van, CS3: Gaziantep, CS4: Bitlis, CS5: Erzincan, CS6: Diyarbakir, CS7: Agri, CS8: Sanliurfa, CS9: Siirt, CS10: Mus, CS11: Batman.

Figure 3. GC-MS chromatograms of volatile compounds of Cephalaria syriaca seeds.
1: Methane, tetranitro-; 2: Acetaldehyde; 3: Ethanol; 4: 2 propane; 5: Propanal, 2-methyl-; 6: Butanal, 2-methyl-; 7: Acetic acid, ethyl ester; 8: Butanal, 3-methyl-; 9: Butanal, 2-methyl-; 10: Silanediol, dimethyl-; 11: Pentanal; 12: 1-Butanol, 3-Methyl-; 13: 1-Butanol, 2-methyl-; 14: 2-Butenal, 2-methyl-; 15: 1-Pentanol; 16: Hexanal; 17: 1-Pentanol, 4-methyl-; 18: 1-Pentanol, 3-methyl-; 19: 2-Hexenal; 20: 2-Hexen-1-ol; 21: Hexanol; 22: Acetone; 23: alpha.-Thujene; 24: Benzaldehyde; 25: .beta.-Pinene; 26: 1-Octen-3-ol; 27: Benzenemethanol; 28: Nonanal; 29: Isopinocarveol; 30: Myrtenol. Cephalaria syriaca L. samples according to locations; CS1: Mardin, CS2: Van, CS3: Gaziantep, CS4: Bitlis, CS5: Erzincan, CS6: Diyarbakir, CS7: Agri, CS8: Sanliurfa, CS9: Siirt, CS10: Mus, CS11: Batman.

1: Methane, tetranitro-; 2: Acetaldehyde; 3: Ethanol; 4: 2 propane; 5: Propanal, 2-methyl-; 6: Butanal, 2-methyl-; 7: Acetic acid, ethyl ester; 8: Butanal, 3-methyl-; 9: Butanal, 2-methyl-; 10: Silanediol, dimethyl-; 11: Pentanal; 12: 1-Butanol, 3-Methyl-; 13: 1-Butanol, 2-methyl-; 14: 2-Butenal, 2-methyl-; 15: 1-Pentanol; 16: Hexanal; 17: 1-Pentanol, 4-methyl-; 18: 1-Pentanol, 3-methyl-; 19: 2-Hexenal; 20: 2-Hexen-1-ol; 21: Hexanol; 22: Acetone; 23: alpha.-Thujene; 24: Benzaldehyde; 25: beta.-Pinene; 26: 1-Octen-3-ol; 27: Benzenemethanol; 28: Nonanal; 29: Isopinocarveol; 30: Myrtenol. Cephalaria syriaca L. samples according to locations; CS1: Mardin, CS2: Van, CS3: Gaziantep, CS4: Bitlis, CS5: Erzincan, CS6: Diyarbakir, CS7: Agri, CS8: Sanliurfa, CS9: Siirt, CS10: Mus, CS11: Batman.

 

The highest myristic acid content was found in the CS9 sample with 17.30%; whereas the lowest value was found in CS7 at 14.60%, with no statistical difference (Table 5). Yazicioğlu et al., (1978) determined that myristic acid was in the range of 18.4 and 20.5%. In our study, palmitic acid varied between 11.20 and 12.30%, which was not statistically different. Palmitic acid was reported to be 8.8-10.0% by Yazicioğlu et al., (1978) and 9.5% by Bretagnolle et al., (2016) in previous studies. We found that stearic acid (C18: 0) was in the range of 3.80-5.20%. Stearic acid was reported to be in the range of 1.9-2.0% by Yazicioğlu et al., (1978), and 2.5% by Bretagnolle et al., (2016). The difference between the samples in terms of linolenic acid was statistically significant (P < 0.05). The highest linolenic acid content (1.20%) was found in CS8; while the lowest value (0.30%) was determined in CS2 and CS3. Sarikahya et al., (2015) studied the fatty acid composition of the aerial parts of 10 different Cephalaria species, not including CS. In all the species studied, oleic acid was in the range of 10.28–31.65%; while linoleic acid was in the range of 17.81-37.67%; palmitic acid in the range of 10.54-23.81%; lauric acid in the range of 0.44-2.15%; myristic acid in the range of 2.54-12.79%; stearic acid in the range of 2.35-4.61%; and linolenic acid in the range of 6.29-36.65%. Sarikahya et al., (2015) studied the aerial parts, which usually include leaves, flowers, branches, etc. However, in this study, the fatty acid composition of the seeds was studied, which is the main reason why the results are different from those previously reported. On the other hand, the differences in fatty acid profiles of CS seed oils may be due to factors including species, location, collection time and extraction technique.

The Total saturated fatty acids (ΣSFA) of the oil samples ranged between 33.2 and 37.4%; while total monounsaturated fatty acids (ΣMUFA) varied between 30.5 and 35.1% and total polyunsaturated fatty acids (ΣPUFA) were in the range of 27.30–32.90%. Bretagnolle et al., (2016) determined ΣSFA, ΣMUFA and ΣPUFA to be 35.3, 21.1 and 43.3%, respectively. The American Heart Association and the National Academy of Sciences (First National Academy of Medicine) have recently given dietary recommendations, focusing not only on the amount of fatty acids, but also on the dietary fatty acid types, and often recommend replacing them for MUFA and PUFAs (Krauss et al., 2000). The present study showed that CS species had approximately equal ratios of SFA, MUFA and PUFA. On the other hand, the total content of unsaturated fatty acids was found to be higher than saturated fatty acids, which is generally desirable as a high consumption of saturated fatty acids is shown to be associated with hearth and coronary diseases (Chowdhury et al., 2014). These fatty acids play key roles in human health and growth. It has also been reported that they have positive effects on the prevention and treatment of diseases such as heart and joint diseases, immune system diseases and cancer (Cabre et al., 2012; Gerber, 2012). All of the samples examined can be considered as potentially good for health as the ratio of UFA/SFA in all CS seed oils was greater than 1, and some were close to 2 (Kostić et al., 2017).

3.5. Peroxide value, free fatty acids and α-tocopherol contents of CS seed oilsTOP

The PV of CS seed oils were found between 2.46 and 5.39 meqO2/kg (Table 6). These values were less than 10 meqO2/kg (as proposed by the CODEX-STAN 210–1999, Turkish Codex Standards). There was no significant difference among CS1, CS3, CS4, CS6, CS7, CS9, CS10, and CS11. The only samples that were significantly different from that group were CS2, CS5, and CS8 (P < 0.05).

TABLE 6. Peroxide value, free fatty acid and α-tocopherol content of Cephalaria syriaca seed oils
Sample PV (meqO2/kg) FFA free fatty acid (oleic acid %) α-tocopherol (mg/kg)
CS1 2.64 ± 0.04ab 0.28 ± 0.04a 368 ± 15.13d
CS2 3.97 ± 0.13bc 0.28 ± 0.01a 70 ± 2.33ab
CS3 3.93 ± 1.50abc 0.28 ± 0.00a 395 ± 18.53d
CS4 3.86 ± 0.02abc 0.27 ± 0.08a 464 ± 15.77f
CS5 5.39 ± 0.67d 2.38 ± 0.27e 332 ± 10.75c
CS6 3.82 ± 0.11ab 0.27 ± 0.06a 467 ± 12.3f
CS7 3.43 ± 0.70ab 0.70 ± 0.01cd 54 ± 1.98a
CS8 5.30 ± 0.59cd 0.83 ± 0.13d 85 ± 3.04b
CS9 2.80 ± 0.02ab 0.56 ± 0.16bc 458 ± 12.59ef
CS10 2.46 ± 0.70a 0.28 ± 0.07a 382 ± 11.53d
CS11 3.91 ± 0.01abc 0.42 ± 0.08ab 433 ± 12.88e
*Small letters indicate significant differences within each column for the mean ± SD values calculated from three determinations by one-way ANOVA and Duncan’s test (P ≤ 0.05). Cephalaria syriaca L. samples according to location; CS1: Mardin, CS2: Van, CS3: Gaziantep, CS4: Bitlis, CS5: Erzincan, CS6: Diyarbakir, CS7: Agri, CS8: Sanliurfa, CS9: Siirt, CS10: Mus, CS11: Batman.

According to O’Brien, (2004), PV is one of the most commonly used parameters to characterize oil quality. PV in the range of 1 to 5 meqO2/kg is classified as the indication of a low level of oxidation; while PV between 5 and 10 meqO2/kg is classified as moderate oxidation and PV in the range of 10-20 meqO2/kg is classified as having a high level of oxidation. In this study, all the samples, except for CS5 and CS8, can be considered to not exceed the level of low oxidation as those samples were high in UFA compared to other samples.

FFA were found in the range of 0.27-0.83 (as % oleic acid) except for CS5. In the case of CS5, this value was determined to be 2.38. In the literature, there was no study investigating the FFA or PV of CS seed oil. CS seed oils were found to contain α-tocopherol between 54 and 467 mg/kg; whereas other tocopherol analogs were not found (Table 6). The highest α-tocopherol was detected in CS6 (467 mg/kg); whereas the lowest was found in CS7 (54 mg/kg). The range of α-tocopherols in our study is much higher than that in the refined oils of corn (3.11-4.46 mg/kg), soybean (1.19-1.42 mg/kg), sunflower (9.52-11.4 mg/kg) and canola (3.82-4.95 mg/kg) (Castelo-Branco et al., 2016). Compared with other common vegetable oils, CS seed oil can be considered a good source of α-tocopherol. The differences in the contents of α-tocopherol in the CS seed oils under study may be due to differences in cultivar, variety and origin of the investigated CS seeds. According to the literature, there was no study investigating the α-tocopherol content of CS seed oil.

3.6. Color parameters of CS seed oilsTOP

The color characteristics of foods are important and greatly affect consumer preference (Faustman and Cassens, 1990). The L*, a* and b* color parameters of the seed oil samples are given in Table 7. L* values significantly varied between 18.63 and 24.87 (P < 0.05). The highest L* value (maximum brightness) was found in CS5 seed oil; whereas the lowest was in CS7. a* values were found between -1.01 and 2.37 (P < 0.05). CS8 had the highest redness; whereas CS2 had the lowest. In addition, CS1, CS2, and CS5 samples were on the green side of the scale. Differences between b* values were significant (P < 0.05). As indicated in Table 7, the b* values of the samples were in the range of 4.73-13.32. The highest b* value was in CS2; while the lowest was detected in CS7. Differences between these parameters were associated with location, soil and climatic conditions, probably due to geographic locations from where the plants were collected.

TABLE 7. Color values of Cephalaria syriaca seed oils
Sample L* a* b*
CS1 23.73 ± 0.14d -0.94 ± 0.10a 10.15 ± 0.10de
CS2 23.83 ± 0.49de -1.01 ± 0.20a 13.32 ± 0.74f
CS3 24.80 ± 0.28e 0.02 ± 0.13b 10.22 ± 0.02de
CS4 24.23 ± 0.71de 0.88 ± 0.23c 9.39 ± 0.07d
CS5 24.87 ± 0.12e -0.81 ± 0.01a 10.60 ± 0.04e
CS6 20.23 ± 0.04c 1.69 ± 0.08d 7.99 ± 0.21c
CS7 18.63 ± 1.03a 1.81 ± 0.02d 4.73 ± 0.33a
CS8 20.13 ± 0.21c 2.37 ± 0.40e 8.16 ± 0.74c
CS9 18.79 ± 0.21ab 2.04 ± 0.35de 5.94 ± 0.27b
CS10 24.00 ± 0.39de 0.60 ± 0.02c 10.06 ± 0.19de
CS11 19.75 ± 0.03bc 1.71 ± 0.48d 6.44 ± 0.54b
*Small letters indicate significant differences within each column for the mean ± SD values calculated from three determinations by one-way ANOVA and Duncan’s test (P ≤ 0.05). Cephalaria syriaca samples according to location; CS1: Mardin, CS2: Van, CS3: Gaziantep, CS4: Bitlis, CS5: Erzincan, CS6: Diyarbakir, CS7: Agri, CS8: Sanliurfa, CS9: Siirt, CS10: Mus, CS11: Batman.

4. CONCLUSIONSTOP

The results obtained in this study revealed that CS seeds were high in oil content, varying in the range of 11.2-24.0%, which seems to be a significant source of oleic and linoleic acids. Extraction yield of the oil samples varied according to location, and CS1 and CS11 samples in particular are significantly different form all the other samples. It was determined that the PV and FFA levels of the oil samples were within the limits given in the standards. CS11, CS6, CS10 and CS1 were found to have the highest protein contents (21% on average). It was seen that the highest levels of TPC and antioxidant capacity among the CS seeds were found in the samples CS1, CS7, and CS11. A total of 30 different volatile compounds were identified in the samples, dominated by alcohols and aldehydes. CS seed oils were found to contain α-tocopherol between 54 and 467 mg/kg; whereas other tocopherol analogs were not found. The results of this study showed that CS seeds can be considered as an alternative raw material for the production of edible oil. In addition, the oil can be used as a natural antioxidant and food additive for pharmacology and the food industry because of its relatively high antioxidant capacity. Further studies are needed to isolate and characterize the active compounds that are responsible from its promising antioxidant activity.

 

ACKNOWLEDGMENTSTOP

This research was supported by the Scientific Research Fund of Van Yüzüncü Yil University [grant numbers FYL-2017-5788].

 

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