B R I E F C O M M U N I C a T I O

DOI 10.1007/s10600-019-02675-x Chemistry of Natural Compounds, Vol. 55, No. 2, March, 2019

B R I E F C O M M U N I C A T I O N S

FATTY ACID COMPOSITION OF DIFFERENT Quercus SPECIES

Mahmut Kaplan,1 Kagan Kokten,2* Aydin Sukru Bengu,3 Yusuf Murat Kardes,1 Aydin Das,4 and Akife Dalda Sekerci5

Quercus is among the largest woody species (500 species) including trees and shrubs (Fagaceae) [1]. They are used in several industries such as human nutrition, wild and culture animal nutrition, dye, tannin, and oil and fuel production [2]. Quercus species can adapt to different climate and environmental conditions easily and are sometimes used in erosion control practice [2]. These species are quite common in North America, Europe, and East Asia. The acorn chemical composition [3], oil [4], and fatty acids [5] greatly vary with the species and ecological conditions of the growing regions. The present study was conducted to characterize seven different acorn (Quercus sp.) species with regard to fatty acid composition. In this study, the fatty acid composition of acorns of seven different Quercus species was analyzed, and the results are shown in Table 1. The fatty acid composition of the studied acorns used as animal feed showed different concentrations of saturated and unsaturated fatty acids. The main components in the seed oils of these species are oleic (18:1), linoleic (18:2), and palmitic acids (16:0). The palmitic acid in the acorns of these species of Quercus ranged from 17.18 to 21.45% (Table 1). From the data presented it can be seen that the highest palmitic acid was found in Quercus coccifera, while the lowest percentage was found in Quercus libani. The palmitic acid of acorn obtained in our work agreed with that reported by some researchers [4, 6–9] but was higher than that reported by authors [10–14]. The palmitic acid was higher in three species (Q. cerris, Q. vulcanica, and Q. coccifera) as compared to the other species. Stearic acid (18:0) was detected to be between 2.80 and 3.08% in other species except for Q. marcolepis, Q. vulcanica, and Q. coccifera. The highest stearic acid was detected in Q. infectoria, and the lowest, in Q. libani. The stearic acid values we found were lower than those in [6] by 3–6% and in [13] by 3.14–3.41%, but higher than those in [8] by 1.1–1.2%, in [11] by 1.20–2.70%, and in [14] by 0.74–1.57%, and similar to those of [4] 1–5%, of [10], 1.60–4.15%, of [7], 2.5–3.1% , of [4], 1.5–4.5%, and of [11] 1.60–4.47%. Oleic acid was found in high quantities in all species. It ranged from 47.47 to 56.75% in all species. The oleic acid of acorn of Quercus species obtained in our work agreed with that reported by [2, 4, 6, 14] but was lower than that reported by [7, 9–13]. Linoleic acid, an unsaturated fatty acid, was the predominant component of acorn oils of all the studied Quercus species. Linoleic acid ranged from 23.02 to 28.20%. The highest linoleic acid was found in Q. cerris, while the lowest percentages of linoleic acid were found in Q. macrolepis. The linoleic acid of acorn of Quercus species obtained in our work agreed with that reported by [2, 4, 6] but was higher than that reported by [7, 9–14]. Linolenic acid was found to be 1.96% only in the Q. libani. While the values we obtained for linolenic acid were in agreement with the values of many scientists [2, 4, 6, 8, 11], some investigators found low values [7, 10, 12–14]. This is why it is thought that the species used in the research are different.

1) Department of Field Crops, Faculty of Seyrani Agriculture, Erciyes University, Kayseri, Turkey; 2) Department of Field Crops, Faculty of Agriculture, Bingol University, Bingol, Turkey, e-mail: [email protected]; 3) Department of Medical Services and Techniques, Vocational School of Health Services, Bingol University, Bingol, Turkey; 4) Department of Animal Science, Faculty of Veterinary Medicine, Harran University, Sanliurfa, Turkey; 5) Department of Horticulture, Faculty of Agriculture, Erciyes University, Kayseri, Turkey. Published in Khimiya Prirodnykh Soedinenii, No. 2, March–April, 2019, pp. 268–269. Original article submitted October 25, 2017.

Fatty acid Q. infectoria Q. petraea Q. libani Q. cerris Q. macrolepis Q. vulcanica Q. coccifera

16:0 18.29 18.37 17.18 20.32 19.74 20.88 21.45 17:0 – – – – – – 0.74 17:1 – – – – – – 0.52 18:0 3.08 3.07 2.80 3.02 – – – 18:1 54.20 54.17 50.75 47.47 56.75 51.75 53.54 18:2 23.61 23.79 26.74 28.20 23.02 26.57 23.15 18:3 – – 1.96 – – – – 20:1 0.41 0.29 0.31 0.50 0.49 0.48 0.31 22:0 0.41 0.31 0.26 0.49 – 0.32 0.29 ΣSFA 21.78 21.75 20.24 23.83 19.74 21.20 22.48 ΣUSFA 78.22 78.25 79.76 76.17 80.26 78.80 77.52

The total unsaturated fatty acid (TUSFA) of studied Quercus species was between 76.17% and 80.26% (Table 1). From the table it can be seen that the highest TUSFA was found in Q. macrolepis, while the lowest percentage was found in Q. cerris. The total saturated fatty acid (TSFA) of the studied Quercus species was between 19.74 and 23.83%. Q. cerris has the highest level of TSFA (23.83%), as are Q. coccifera (22.48%), Q. infectoria (21.78%), and Q. petraea (21.75%). The lowest percentages of TSFA were found in Q. marcolepis. Changes in fatty acid levels were observed in different Quercus spp. taxa [2, 9, 12–14]. Differences in fatty acid were detected in different Quercus spp. genotypes [4, 6]. Plant Samples. In this study, seven different acorn species (Quercus petraea, Quercus libani, Quercus infectoria, Quercus cerris, Quercus macrolepis, Quercus vulcanica, Quercus coccifera) collected from Kahramanmaras, Bingol, and Isparta Provinces of Turkey were used as the plant material. The samples were collected in 2016. The samples were dried at 70°C for 48 h in three replications. The dried samples were then ground to pass 1 mm sieve and made ready for chemical analyses. Oil Extraction and Preparation of Fatty Acid Methyl Esters (FAME). Impurities were removed from the acorns, and the cleaned acorns were ground into powder using a ball mill. The acorn sample was homogenized in 10 mL of hexane–isopropanol (3:2) at 10.000 rpm for 30 sec and centrifuged at 5000 rpm for 10 min [15]. The upper part was taken and put into test tubes by filtration. Capillary GLC. Fatty acids in the lipid extracts were converted into methyl esters by means of 2% sulfuric acid (v/v) in methanol [16]. The fatty acid methyl esters were extracted with n-hexane. Then the methyl esters were separated and quantified by gas chromatography-mass spectrometry (GC-MS) and flame ionization detection (FID) coupled to a software computing recorder. Chromatography was performed with a capillary column (GC-MS instrument (USA) of Agilent brand 7890A/5970 C and SGE an Analytical BPX90 100 m × 0.25 mm × 0.25 μm column (Australia) was used with nitrogen as carrier gas (flow rate 1 mL/min). The temperatures of the column, detector, and injector valve were 120–250°C, 230°C, and 250°C, respectively. All samples were given to the device using autosampler. Identification of the individual method was performed by frequent comparison with authentic standard mixtures that were analyzed under the same conditions.

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