γ-linolenic acid content and fatty acid composition of boraginaceae seed oils

Nurgun Erdemoglua

Senay Kusmenoglua

Mecit Vuralb

a Gazi University, Faculty ofPharmacy, Department ofPharmacognosy,Ankara, Turkey

b Gazi University, Faculty ofScience and Art,Department of Biology,Ankara, Turkey

ª-Linolenic acid content and fatty acid compositionof Boraginaceae seed oils

Eleven species of the Boraginaceae family collected in Turkey were analyzed withrespect to the amount of g-linolenic acid as well as fatty acid composition. g-Linolenicacid was found in all species, except for Heliotropium lasiocarpum Fisch. & Mey. andHeliotropium dolosum De Not. Seed oil content ranged from 1.5% in H. lasiocarpum to22.0% in Anchusa leptophylla ssp. leptophylla. The content of g-linolenic acid rangedfrom 1.7% of total fatty acids in Paracaryum racemosum (Schreber) Britten var. race-mosum to 13.7% in A. leptophylla Roemer & Shultes ssp. leptophylla. According todata from our study, A. leptophylla ssp. leptophylla (13.7%), Anchusa azurea Millervar. azurea (11.9%) and Echium plantagineum L. (12.2%) might be considered as newsources of g-linolenic acid.

Keywords: Boraginaceae, fatty acids, gas chromatography, g-linolenic acid, seed oil.

1 Introduction

The plant family Boraginaceae Juss. is known as the mostcommon source of g-linolenic acid (GLA, C18:3n-6). Sev-eral families besides the Boraginaceae such as Scrophu-lariceae, Saxifragaceae, Onagraceae, Aceraceae, Ranun-culaceae and Primulaceae contain GLA [1]. GLA is alsofound in marine algae [2], mosses [3], fungi and microor-ganisms [4].

GLA is a metabolite of linoleic acid (LA, C18:2n-6) evolv-ing from hepatic bioconversion of LA. Activation of theliver D6-desaturase enzyme increases the transformationof linoleic acid to long-chain polyunsaturated fatty acidssuch as GLA. D6-desaturation is usually the rate-limitingstep for the production of the essential long-chain polyun-saturated fatty acids. Thus, preparations of GLA aremainly used to treat hereditary or acquired D6-desaturaseenzyme deficiency in humans, primarily in elderly peopleand in people under conditions of stress, diabetes oralcoholism [1, 5]. The common plant sources of commer-cial GLA are borage (Borago officinalis L., 23%) [6], eve-ning primrose (Oenothera biennis L., 9.6%) [7] and blackcurrant (Ribes nigrum L., 15–20%) [8].

Several studies have reported on the fatty acid composi-tion of seed oil from different species of the Boraginaceaefamily [4, 9–14]. The fatty acid compositions of the Bora-ginaceae seed oils are highly variable depending on geno-type and environmental factors such as soil type and

temperature [1]. The amounts of GLA, LA and a-linolenicacid (ALA, C18:3n-3), stearidonic acid (SA, C18:4n-3) anderucic acid (C22:1n-9) are of chemotaxonomic signifi-cance for the Boraginaceae [12, 15].

The Boraginaceae family is widely distributed in Turkeyand consists of approximately 32 native genera and 301species [16, 17]. However, until now these species havenot been evaluated with respect to GLA content. This isthe first study on the GLA content and fatty acid composi-tion of the seed oils from several Boraginaceae speciesgrowing in Turkey.

2 Material and methods

2.1 Plant materials

Mature plant seeds were collected from different regions ofTurkey in the natural habitats of the plants. The plants wereidentified by M. Vural, Ph.D. All specimens were kept in theHerbarium of Gazi University (GAZI). Tab. 1 shows the col-lection sites and times for each kind of plant.

2.2 Sample preparation

Three samples of each species were used for analysis.The seeds of the plants were dried while protected fromlight. After weighing, seeds were ground with anhydroussodium sulfate and extracted for 4 h with petroleum ether(bp 40–60 7C) in a Soxhlet apparatus. Then, the solventwas evaporated under vacuum at 40 7C. Residual solventwas removed from the oily residues by a stream of nitro-gen, and the residues were stored at 4 7C.

Correspondence: Nurgun Erdemoglu, Gazi University, Facultyof Pharmacy, Department of Pharmacognosy, 06330 Ankara,Turkey. Phone: 190-312-505-3195371, Fax: 190-312-2235018;e-mail: [email protected]

160 DOI 10.1002/ejlt.200300910 Eur. J. Lipid Sci. Technol. 106 (2004) 160–164

2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.ejlst.de

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Eur. J. Lipid Sci. Technol. 106 (2004) 160–164 Fatty acid composition of Boraginaceae 161

Tab. 1. The collected plant materials, collection sites and date of collection.

Plants Locality Date of Collection

Anchusa azurea Miller var. azurea Ankara-Ayas Road July 1998Anchusa x thirkeana Gusul. Nevsehir, Urgup August 1998Anchusa leptophylla Roemer & Shultes ssp. leptophylla Bursa, Uludag, Kirazli plateau September 1998Echium italicum L. Ankara, Batikent July 1998Echium plantagineum L. Istanbul, Atakoy October 1998Heliotropium lasiocarpum Fisch. & Mey. Ankara-Ayas Road July 1998Heliotropium dolosum De Not. Ankara, Cankaya June 1998Moltkia aurea Boiss. Ankara, Dikmen July 1998Onosma halophilum Boiss. & Heldr. Aksaray, Golyazi August 1998Paracaryum lithospermifolium (Lam.) Grande ssp. cariense (Boiss.)

R. Mill var. carienseKonya, Akdag August 1998

Paracaryum racemosum (Schreber) Britten var. racemosum Nevsehir, Zelve July 1998

2.3 Gas chromatography of fatty acid esters

Fatty acid composition was determined by gas chroma-tography after esterification to methyl esters according toMorrison and Smith [18]. Heptadecanoic acid (C17:0) wasused as an internal standard. The fatty acid methyl esterswere dissolved in dichloromethane and separated byusing a cross-linked methyl silicone capillary column(Ultra-1) 50 m 6 0.2 mm i.d. (0.33 mm film thickness) in aHewlett Packard (Palo Alto, CA, USA) 5890 gas chroma-tograph. The column temperature was 250 7C. The injec-tion port temperature was 250 7C and a split ratio of 50:1was used. The initial oven temperature was 180 7C. Thetemperature was increased at a rate of 2 7C/min to250 7C and then held at 250 7C for 10 min. The samplesize was 0.2 mL and injections were done in triplicate.The temperature of the flame ionization detector was250 7C. Helium was used as the carrier gas at a flow rateof 0.9 mL/min. Peaks were identified by comparison withknown standards.

2.4 Statistical analysis of data

Data obtained from three independent analyses of mate-rials were expressed as means (6 SD). Statistical differ-ences between means were calculated by the Tukey testfor multiple comparisons. P ,0.05 was considered assignificant.

3 Results and discussion

Seed oil content and fatty acid composition of eleven Bor-aginaceae plant seeds belonging to six different generawere analyzed by gas chromatography. Results of thepresent study are given in Tab. 2 and 3 for seed oil content

and fatty acid composition, respectively. There were sig-nificant differences in fatty acid profiles between speciesof the different genera (Tukey p ,0.05) (Tab. 2 and 3). Sig-nificant differences were also observed in unsaturatedfatty acid composition between species within the samegenus, except for oleic acid in the genus Anchusa, SA inthe genus Echium, and eicosenoic acid (gondoic acid,C20:1n-9) in the genera Echium and Paracaryum (Tab. 2).In addition, there were significant differences in saturatedfatty acid composition between species in the samegenus, except for four fatty acids; palmitic acid in thegenus Anchusa, capric and palmitic acids in the genusEchium, and stearic acid in the genus Heliotropium(Tab. 3).

Seed oil content ranged from 1.5% in H. lasiocarpum to22.0% in A. leptophylla ssp. leptophylla. The amount ofGLA in seed oils ranged from 1.7% in P. racemosum var.racemosum to 13.7% in A. leptophylla ssp. leptophylla.The amount of GLA in total seed weight ranged from0.1% in P. racemosum var. racemosum to 3.1% in A. lep-tophylla ssp. leptophylla. The amount of GLA in the oil andthe seeds as well as oil content were highest in A. lepto-phylla ssp. leptophylla. GLA was not detected in only twoHeliotropium species, H. lasiocarpum and H. dolosum.The amount of GLA in A. leptophylla ssp. leptophylla, M.aurea and P. racemosum var. racemosum was found to bestatistically significant (p ,0.05). In the literature, it wasreported that high amounts (over 20%) of GLA have rarelybeen found in the seed oil from plants [4, 9]. In Ucciani’sstudy, the amount of GLA was found to be higher than20% in five Boraginaceae plants [4]. Recently, Guil-Guer-rero et al. reported that Macaronesian Echium specieswere a major source of GLA [9]. In the same study, GLAwas found to make up over 20% of the seed oil from 11out of 19 Echium species. Echium callythyrsum consti-


162 N. Erdemoglu et al. Eur. J. Lipid Sci. Technol. 106 (2004) 160–164

Tab. 2. Oil content and unsaturated fatty acid composition of Boraginaceae species. Data are expressed as a mean 6 SD.Mean values within the same column sharing a common letter are not significantly different (p .0.05). *Statistically signifi-cant (p ,0.05).

Plants Oil[% seedweight]

GLA[% seed]

GLA[% oil]

C16:1n-7 C18:1n-9 C18:2n-6 C18:3n-3 C18:4n-3 C20:1n-9 C22:1n-9 C24:1n-9

[% of total fatty acids]

A. azureavar. azurea

8.6 1.0 11.960.15c tr 23.160.37d 42.360.34* nd nd 3.660.24cd 4.560.41a 0.360.06a

A. x thirkeana 5.2 0.3 4.660.33a tr 22.360.96d 14.860.66bc 4.660.33a tr 2.360.10* 1.360.04* trA. leptophylla

ssp. leptophylla 22.0 3.1 13.760.16* tr 21.361.07d 26.460.26* 15.860.20* 4.260.23* 3.160.24c 2.360.18* trE. italicum 7.6 0.5 6.760.05b tr 10.660.07a 11.060.11a 41.261.05* 11.960.19b 0.460.41ab tr ndE. plantagineum 11.1 1.4 12.260.21c tr 17.060.04c 16.060.16c 29.260.28* 12.360.16b 0.560.13ab tr trH. lasiocarpum 1.5 nd nd tr 16.360.51c 61.561.32* nd nd nd tr ndH. dolosum 1.9 nd nd 0.560.07 11.860.31ab 47.360.96* 1.860.25* nd nd tr trM. aurea 5.3 0.4 7.460.07* tr 12.960.09b 14.260.68bc 32.360.35* 4.860.12* 0.760.11b tr ndO. halophilum 7.1 0.5 6.460.19b tr 30.161.35e 22.460.55* 11.760.50* 2.660.34a tr tr ndP. lithospemifo-

lium ssp.cariense var.cariense 6.2 0.3 4.860.14a tr 29.260.85e 13.760.47b 9.460.26* 2.960.11a 3.960.19d 6.160.06* nd

P. racemosumvar. racemosum 7.7 0.1 1.760.15* tr 25.760.97* 9.860.73a 4.560.27a 0.460.12* 3.860.32d 4.860.37a 0.360.05a

nd – not detected; tr – trace, ,0.3%.

Tab. 3. Saturated fatty acid composition of Boraginaceae species. Data are expressed as a mean 6 SD. Mean valueswithin the same column sharing a common letter are not significantly different (p .0.05); *Statistically significant (p,0.05).

PlantsC6:0 C8:0 C10:0 C14:0 C16:0 C18:0 C22:0

[% of the total fatty acids]

A. azurea var. azurea tr 0.360.03a 1.260.18abc tr 7.860.28bcd 2.460.16bcd 0.360.02*A. x thirkeana tr 2.460.06* 18.661.65g 1.060.07 8.960.13de 3.160.23e trA. leptophylla ssp. leptophylla tr 0.460.03a 0.760.05a tr 8.660.15cd 2.360.15bc trE. italicum 1.360.16* 1.060.19b 3.660.60bcd tr 7.660.54bc 1.960.01ab trE. plantagineum tr 0.360.02a 0.960.06ab tr 6.960.08b 2.960.06de ndH. lasiocarpum 1.860.05a 1.660.07c 5.660.33de nd 5.060.15a 2.560.06cde trH. dolosum 0.660.04* 2.860.15* 13.060.44f tr 8.460.02cd 2.560.11bcd ndM. aurea 1.960.06a 1.860.06c 6.760.23e tr 7.660.10bc 2.160.04abc 0.860.06*O. halophilum nd 0.560.07a 3.760.13cd tr 10.161.09e 6.960.47* 0.560.03*P. lithospemifolium ssp. cariense

var. cariense tr 1.060.15b 12.160.76f 1.660.24 7.260.20b 2.060.16abc trP. racemosum var. racemosum 7.460.13* 5.160.11* 19.662.34g tr 4.360.34a 1.660.17a nd

nd – not detected; tr – trace, ,0.3%.

tuted the richest source of GLA (26.3%) in all investigatedsamples [9]. In our study, we investigated E. plantagineumamong these Echium species with regard to GLA amountand overall fatty acid content. While Guil-Guerrero et al.reported that GLA amounted to 9.2% in E. plantagineum[9], it was determined as reaching 12.2% in our study. Inanother study on the occurrence of GLA in the other

Macaronesian Echium species as well as several ende-mic Boraginaceae species, the highest GLA amount(27.4%) was found in E. gentianoides. The content ofGLA in Heliotropium erosum was determinated as quitelow (1.5%), but we did not detect GLA in two other Helio-tropium species [11]. Despite the fact that the fatty acidprofiles described for the above-mentioned Boragina-


Eur. J. Lipid Sci. Technol. 106 (2004) 160–164 Fatty acid composition of Boraginaceae 163

ceae plants are similar to the profiles of our study, theamounts of GLA given in the present study are lowerthan the amounts presented in those studies.

Velasco and Goffman evaluated 36 species of the Bora-ginaceae family for oil content and fatty acid composi-tion [12]. They found that all species of Boraginaceaecontained GLA, with the lowest GLA content (0.7%)given in Cerinthe major and the highest (24.4%) given inBorago officinalis. The amount of GLA was reported as10.2% in A. azurea var. azurea. In our study, the amountof GLA in A. azurea var. azurea was 11.9%. In addition,Velasco and Goffman revealed that the maximum levelsof GLA were found in the tribe Boraginae. We also foundthe highest amounts of GLA in A. leptophylla ssp. lepto-phylla which belongs to the tribe Boraginae. It was men-tioned [12] that the subfamily Heliotropioideae was char-acterized by low amounts of ALA, GLA, SDA and long-chain monosaturated fatty acids. Our findings were inagreement with Velasco and Goffman’s results: GLAwas not detected in two Heliotropium species, the low-est amount of ALA was found in H. dolosum (1.8%) andALA was even undetectable in other Heliotropium spe-cies. In addition, SA was also not found in two Heliotro-pium species.

The amounts of other polyunsaturated fatty acids (PUFA:LA, ALA, SA) varied in each plant, as shown in Tab. 2.Amounts of LA ranged from 9.8% in P. racemosum var.racemosum to 61.5% in H. lasiocarpum which constitutesthe highest amount of a fatty acid so far found in seed oil.In addition, of all PUFA, the amount of LA was found to bethe highest. ALA ranged from 1.8% in H. dolosum to41.2% in E. italicum., and was not detected in the seedoil from H. lasiocarpum and A. azurea var. azurea. WhileALA levels were not significantly different in A. x thirkeanaand P. racemosum var. racemosum, ALA levels in otherspecies were determined as statistically significant(p ,0.05). SA ranged from 0.4% in P. racemosum var.racemosum to 12.3% in E. plantagineum. SA was notdetected in the seed oil from two Heliotropium speciesas well as in A. azurea var. azurea. Besides, the levels ofSA were found to be significantly different in A. leptophyllassp. leptophylla, M. aurea and P. racemosum var. racemo-sum (p ,0.05). No significant difference was observed forSA levels in two Echium species. Also, the highestamount of SA was found in Echium species (11.9% for E.italicum, 12.3% for E. plantagineum). The amounts of LAand ALA determined in our study were different fromthose in the above mentioned studies [9, 12]. The amountof LA was in good agreement with results from a Heliotro-pium species reported in Guil-Guerrero’s study (60.9% inH. erosum [11]). In our study, the amount of LA in H. lasio-carpum was 61.5%, but it was lower in another Heliotro-

pium species, H. dolosum (47.3%). With respect to theamount of SA, we obtained results similar to thosereported in other studies [9, 11]. While Guil-Guerrero etal. reported that the amount of SA was found as 12.9%in E. plantagineum [9], it was determined as 12.3% in thepresent study. In another study of the same researchers,SA in H. erosum was calculated to be of quite low amount(0.3%) [11], however, we could not detect SA in two Helio-tropium species. In Velasco and Goffman’s study, SA con-centration was determined to vary in a certain rangeamong the investigated species, similar to our results[12].

With respect to monounsaturated fatty acids (MUFA: pal-mitoleic, oleic, eicosenoic, erucic and tetracosenoicacids) we obtained values similar to those reported forother species of the Boraginaceae family [9, 11]. Theamount of oleic acid was found to be higher than otherMUFA (Tab. 2). Oleic acid (C18:1n-9) ranged from 10.6%in E. italicum to 30.1% in O. halophilum. Oleic acid con-tent was found to be significant only in P. racemosum var.racemosum (p ,0.05). Palmitoleic acid (C16:1n-7) wasfound in trace amounts in almost all seed oils except inH. dolosum (0.5%). Eicosenoic acid ranged from 0.4% inE. italicum to 3.9% in Paracaryum lithospermifolium ssp.cariense var. cariense. In the Boraginaceae species inves-tigated, the content of eicosenoic acid was consideredstatistically significant only in A. x thirkeana (p ,0.05).We did not determine eicosenoic acid contents in bothHeliotropium species. Erucic acid was found in only twogenera, Anchusa and Paracaryum, in amounts similar tovalues for other Boraginaceae [9]. Tetracosenoic acid(nervonic acid, C24:1n-9) was determined to be of lowamount (0.3%) in two different Boraginaceae species, A.azurea var. azurea and P. racemosum var. racemosum.

As shown in Tab. 3, saturated fatty acids (C6:0, C8:0,C10:0, C14:0, C16:0, C18:0, C22:0) were abundant in P.racemosum var. racemosum and A. x thirkeana. The totalamount of saturated fatty acids and capric acid contentwere found to be 38% and 19.6%, respectively, in P. race-mosum var. racemosum, and 34% and 18.6%, respec-tively, in A. x thirkeana. Results for saturated fatty acidsagree with values mentioned by other researchers [9, 11].

There were a few studies on essential fatty acids of var-ious species growing in Turkey [19, 20]. To the best of ourknowledge, the present study was the first one to evalu-ate the amounts of GLA and other fatty acids in severalBoraginaceae plants growing in Turkey. GLA was foundto different amounts in all species investigated except forthe two Heliotropium species. According to our findings,A. leptophylla ssp. leptophylla (13.7%), A. azurea var.azurea (11.9%), and E. plantagineum (12.2%) may beconsidered as new sources of GLA.


164 N. Erdemoglu et al. Eur. J. Lipid Sci. Technol. 106 (2004) 160–164

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[Received: October 14, 2003; accepted: January 8, 2004]


γ-linolenic acid content and fatty acid composition of boraginaceae seed oils

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