Identification of Acylglycerols Containing Dihydroxy Fatty Acids in Castor Oil by Mass Spectrometry

Ricinoleate, a monohydroxy fatty acid, in castor oil has many industrial uses. Dihydroxy fatty acids can also be used in industry. The C₁₈ HPLC fractions of castor oil were analyzed by electrospray ionization mass spectrometry of lithium adducts to identify the acylglycerols containing dihydroxy fatty acids and the dihydroxy fatty acids. Four diacylglycerols identified were diOH18:1-diOH18:1, diOH18:2-OH18:1, diOH18:1-OH18:1 and diOH18:0-OH18:1. Eight triacylglycerols identified were diOH18:1-diOH18:1-diOH18:1, diOH18:1-diOH18:1-diOH18:0, diOH18:2-diOH18:1-OH18:1, diOH18:1-diOH18:1-OH18:1, diOH18:1-diOH18:0-OH18:1, diOH18:2-OH18:1-OH18:1, diOH18:1-OH18:1-OH18:1 and diOH18:0-OH18:1-OH18:1. The locations of fatty acids on the glycerol backbone were not determined. The structures of these three newly identified dihydroxy fatty acids were proposed as 11,12-dihydroxy-9-octadecenoic acid, 11,12-dihydroxy-9,13-octadecadienoic acid and 11,12-dihydroxyoctadecanoic acid. These individual acylglycerols were at the levels of about 0.5% or less in castor oil and can be isolated from castor oil or overproduced in a transgenic oil seed plant for future industrial uses.     

Ratios of Regioisomers of Triacylglycerols Containing Dihydroxy Fatty Acids in Castor Oil by Mass Spectrometry

The triacylglycerols (TAG) containing dihydroxy fatty acids have been recently identified by mass spectrometry in castor oil. These new dihydroxy fatty acids were proposed as 11,12-dihydroxy-9-octadecenoic acid (diOH18:1), 11,12-dihydroxy-9,13-octadecadienoic acid (diOH18:2) and 11,12-dihydroxyoctadecanoic acid (diOH18:0). The ratios of regioisomers of the TAG were estimated by fragment ions from the loss of fatty acids at the sn-2 position as α,β-unsaturated fatty acids by electro spray ionization-mass spectrometry of the lithium adducts (MS³). The content of regioisomeric diOH18:1-OH18:1-diOH18:1 (ABA, with two different fatty acids) was about 92% in the total of stereoisomeric diOH18:1-OH18:1-diOH18:1, OH18:1-diOH18:1-diOH18:1 and diOH18:1-diOH18:1-OH18:1 combined. The approximate contents of other regioisomers were as follows: diOH18:1-OH18:1-OH18:1 (92%), diOH18:1-diOH18:0-diOH18:1 (91%), diOH18:2-OH18:1-OH18:1 (80%) and diOH18:0-OH18:1-OH18:1 (96%). The ratios of regioisomers of TAG (ABC) containing three different fatty acids were estimated as about 7:1:2 (OH18:1:diOH18:1:diOH18:2) and about 7:2:1 (OH18:1:diOH18:0:diOH18:1). Ricinoleate (OH18:1) was predominately at the sn-2 position of TAG (both AAB and ABC) containing dihydroxy fatty acids and ricinoleate. Dihydroxy fatty acids were mainly at the sn-1,3 positions of TAG containing dihydroxy fatty acids and ricinoleate in castor oil. The ratios of the three regioisomers of TAG (ABC) containing three different fatty acids by mass spectrometry are first reported here.     

The Component Fatty Acids and Glycerides of Castor Oil

Gas-liquid chromatographic analysis of methyl esters of two samples of castor oil gave the following (as wt %): palmitate 1.2, 0.9; stearate 0.7, 1.2; arachidate 0.3, 0.2; hexadecenoate 0.2, 0.2; oleate 3.2, 3.3; linoleate 3.4, 3.7; linolenate 0.2, 0.2; ricinolE'ate 89.4, 89.0; and dihydroxystearate 1.4, 1.3. Oxidative cleavage of purified methyl ricinoleate indicated that the double bond was exclusively in the 9舑10 position. Castor oil glycerides were fractionated in a 100-tube CCD apparatus using 90% ethanol and commercial hexane as solvents. Analysis of pooled fractions showed (as mole %) triricinolein 68.2, diricinoleins 28.0, mono-ricinoleins 2.9 and nonricinoleins 0.9. These results coupled with lipase hydrolysis of the whole oil and of the fractions agree well with the distribution pattern proposed by Vander Wal.     

Synthesis and Physical Properties of Symmetrical and Non-symmetrical Triacylglycerols Containing Two Palmitic Fatty Acids

A series of symmetrical (ABA) and non-symmetrical (AAB) triacylglycerol (TAG) isomers containing “A,” palmitic (P; 16:0) acid, and “B,” either oleic (O; 9c-18:1), elaidic (E; 9t-18:1), linoleic (L; 9c,12c-18:2) or linolenic (Ln; 9c,12c,15c-18:3) fatty acids were synthesized by esterification of the thermodynamically more-stable 1,3-di- or 1(3)-monoacylglycerols [1,3-DAG or 1(3)-MAG], respectively. 1,3-dipalmitoylglycerol (1,3P-DAG) was esterified with O, L or Ln acid to prepare the symmetrical TAG isomers POP, PLP and PLnP, while the O- E-, L- and Ln-1(3)MAG precursors, synthesized or obtained commercially, were esterified with P acid to prepare the non-symmetrical TAG isomers OPP, EPP, LPP and LnPP, respectively. The drop point(s), solid fat content and melting point values of the synthesized TAG were determined. The 1,3-dipalmitoylglycerol (1,3P-DAG) and 1(3)P-MAG precursors were prepared, in multi-gram quantities, by partial glycerolysis (glycerol/p-toluenesulfonic acid) of tripalmitin. After fractionation by silica gel chromatography, the 1(3)P-MAG and 1,3P-DAG isomers (ca. 80% of total MAG or DAG) were purified (>98%) by crystallization from acetone [silver ion-HPLC was utilized to determine the structural purities of the DAG (or MAG) precursors, and the synthesized TAG]. Esterification of the appropriate, thermodynamically more-stable MAG or DAG precursors was found to be a very versatile method for synthesis (in 80–90% yields) of multi-gram (3–5 g) quantities of symmetrical and non-symmetrical TAG isomers, in chemical and structural purities of >96 and 97–99%, respectively. The 1- and 3- positions on the glycerol backbone of the MAG, DAG and TAG molecules are assumed to be equivalent. Mention of trade names or commercial products in this (publication) is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the US Department of Agriculture.     

Distribution of Triacylglycerols and Fatty Acids in Soybean Oil with Thermal Oxidation and Methylene Blue Photosensitization

Profiles of triacylglycerols (TAG) and fatty acids were compared in soybean oil thermally oxidized at 180 °C for 60 min or methylene blue photosensitized for 10 h. Headspace oxygen in thermally oxidized and photosensitized soybean oil decreased significantly (p < 0.05) as oxidation time increased. Relative contents of linoleic and linolenic acids decreased and those of oleic acid increased during oxidation. In both thermal and photosensitized oxidation, TAG with lower than 44 equivalent carbon number including dilinoleoyllinolenoylglycerol (LLLn, 40), trilinolein (LLL, 42), oleoyllinoleoyllinolenoylglycerol (OLLn, 42), dilinoleoyloleoylglycerol (LLO, 44), and dilinoleoylpalmitoylglycerol (PLL, 44) significantly decreased, while those with dioleoyllinoleoylglycerol (OOL, 46) increased significantly in relative peak areas (p < 0.05). Photosensitized oxidation decreased TAG containing linoleic and linolenic acids significantly faster than thermal oxidation in soybean oil (p < 0.05), which may be due to the singlet oxygen reaction. Photosensitized soybean oils can be differentiated from thermally oxidized samples using the distributions of TAG by principal component analysis.     

Clickable Lipids: Azido and Alkynyl Fatty Acids and Triacylglycerols

Hydroxy fatty acids (FAs), which were isolated from glycolipids that can be prepared fermentatively from fats and oils, have been synthetically modified to contain azide and alkyne functional groups. These particular functional groups were chosen because they can participate in a copper-catalyzed reaction that combines them to form a 1,4-triazole, known as a “click” reaction, which has been widely used in a variety of fields but remains underutilized in FA chemistry. Depending on the starting hydroxy FA, these groups can be close to the carboxy unit (using 3-hydroxydecanoate) and hence the polar glycerol group, or distant from it (using 17-hydroxyoctadecanoate). These structural alternatives will impart different properties to the triacylglycerols that are subsequently prepared from the modified FA. Finally, the click reaction was used to conjugate triacylglycerols to each other and to other molecules such as a glycolipid or a protected amine.     

Identification of Minor Acylglycerols Less Polar than Triricinolein in Castor Oil by Mass Spectrometry

Acylglycerols in castor oil less polar than triricinolein were identified by electrospray ionization–mass spectrometry using the lithium adducts of the acylglycerols in the HPLC fractions of castor oil. Thirty four new molecular species of acylglycerols containing hydroxy fatty acids in castor oil were identified by MS. The chain lengths of fatty acid substituents were C16, C18, C20, C22 and C23. The numbers of double bonds of the fatty acids were from zero to three. The numbers of hydroxyl groups on the fatty acid chains were from zero to three as previously reported. The structure of fatty acid, OH18:2, was proposed as 12-hydroxy-9,13-octadecadienoic acid. An unusual odd-numbered long-chain fatty acid, 23:0 (tricosanoic acid), was identified. Some new estolides and tetraacylglycerols, were identified as (12-ricinoleoylricinoleoyl)-ricinoleoyl-linoleoyl-glycerol (RRRL), (12-ricinoleoylricinoleoyl)-ricinoleoyl-oleoyl-glycerol (RRRO), (12-ricinoleoylricinoleoyl)-ricinoleoyl-palmitoyl-glycerol (RRRP), (12-ricinoleoylricinoleoyl)-ricinoleoyl-stearoyl-glycerol (RRRS) and (12-ricinoleoylricinoleoyl)-ricinoleoyl-linolenoyl-glycerol (RRRLn). The normal fatty acid (non-hydroxylated) of these tetraacylglycerols were directly attached to the glycerol backbone. The biosynthetic pathway of castor oil is proposed.     

Chromatography of Lipids Containing Cyclopentenyl Fatty Acids

Abstract

Tropical plants of the family Flacourtiaceae produce seeds whose lipid constituents are rich in cyclopentenyl fatty acids (1). The major naturally occurring acids of this type are hydnocarpic (11-(2-cyclo-penten-1-yl)-undecanoic), chaulmoogric (13-(2-cyclopenten-1-yl)-tridecanoic), and gorlic (13-(2-cyclopenten-1-yl)-6-tridecenoic) acids.     

Trifunctional Acids Derived from Dehydrated Hardened Castor Oil

Dehydration and splitting of hydrogenated castor oil produces a mixture of fatty acids containing about 80% of the iso-oleic acids having the double bond in 11 and 12 positions in approximately equal proportions (as demonstrated by periodate/permanganate scission) and largely in the trans configuration. This technical iso-oleic acid reacts as expected with maleic anhydride to produce a mixture of isomeric iso-oleyl succinic anhydrides. When the oleate is reacted as the methyl ester the crude product can be distilled to produce methyl iso-oleyl succinic anhydride (M. O. S. A.) free from polymeric material. The yields of product under different conditions of time, temperature and ratio of maleic anhydride to fatty esters have been studied.     

Quantification of Nonanal and Oleic Acid Formed During the Ozonolysis of Vegetable Oil Free Fatty Acids or Fatty Acid Methyl Esters

The ozonolysis of unsaturated lipids is a process that has been used to generate aldehydes, acids, alcohols, and other biobased chemical intermediates. Reported here is a method that can be used to measure the formation of nonanal and oleic acid during the ozonolysis of unsaturated vegetable oil fatty acids or their methyl esters to indicate the extent of the ozonolysis reaction. Derivatization was performed using boron trifluoride in methanol solution to transform nonanal and oleic acid into nonanal dimethyl acetal and oleic acid methyl ester, respectively. Undecanal and 10‐heptadecenoic acid were used as internal standards and separation was performed using gas chromatography coupled with a flame ionization detector. The method was validated by performing a standard addition procedure in which nonanal or oleic acid standards were spiked into samples collected during the ozonolysis of oleic acid or canola oil fatty acid methyl ester (FAME). Linear regression results indicated that the measured nonanal and oleic acid are in good agreement with the actual amounts of nonanal and oleic acid added to the sample with at least 98 % recovery. The application of the method was demonstrated by the successful measurement of nonanal and oleic acid formed throughout the ozonolysis process for high oleic canola oil FAME.     

Ratios of Regioisomers of Minor Acylglycerols Less Polar than Triricinolein in Castor Oil Estimated by Mass Spectrometry

We have recently reported the identification of forty new minor molecular species of acylglycerols containing hydroxy fatty acids less polar than triricinolein by electrospray ionization mass spectrometry of the lithium adducts. The ratios of regioisomers of triacylglycerols (ABC and AAB types) and tetraacylglycerols (AAAB type) identified were estimated by the relative abundances of the fragment ions from the neutral losses of fatty acids as α,β-unsaturated fatty acids at the sn-2 position. The order of the contents of regioisomers of triacylglycerols with the fatty acids at the sn-2 position are: nonhydroxy fatty acids > monohydroxy fatty acids > dihydroxy fatty acids > trihydroxy fatty acids. For tetraacylglycerols (AAAB type) such as ricinoleoylricinoleoyl–ricinoleoyl–oleoyl–glycerol (RRRO), ricinoleoylricinoleoyl chain was predominately at the sn-2 position, while ricinoleate was not detected at the sn-2 position.     

Analysis of Triacylglycerols and Free Fatty Acids in Algae Using Ultra-Performance Liquid Chromatography Mass Spectrometry

To assess the suitability of microalgal strains for biodiesel production the lipid content and composition, especially individual triacylglycerols (TAG) and free fatty acids (FFA) must be determined. In this study, the compositions and concentrations of TAG and FFA were analysed in four halophytic algal species, Dunaliella salina, D. tertiolecta, D. bardawil, and D. granulata. These species were selected as part of a larger screen to identify species suitable for biofuel feedstocks. An accelerated solvent extraction instrument was used for lipids and fatty acid extraction using a dichloromethane–hexane solvent system. Ultra-performance liquid chromatography coupled with mass spectrometry (MS) detection was optimized and applied to the quantitative analysis of TAG and FFA in the different algal extracts. Individual TAG were characterized structurally using direct electrospray ionization (ESI) MS and MS/MS techniques. Cationic adducts (NH₄ ⁺) of TAG were detected and quantified in the positive ESI MS and MS/MS modes, while the negative ESI mode was used for FFA analysis. Over 20 TAG were identified and quantified in the four Dunaliella strains. Analysis of FFA compositions demonstrated that the most abundant FFA in these four algal species were palmitic, linolenic, linoleic, and oleic acids.     

Content and Fatty Acid Composition of Neutral Acylglycerols in Euonymus Fruits

The content and fatty acid (FA) composition of FA neutral acylglycerols (NAG), a mixture of 1,2,3-triacyl-sn-glycerols (TAG) and 3-acetyl-1,2-diacyl-sn-glycerols (acDAG), were determined in the seeds and arils of fruits of 14 Euonymus L. species. On the average, the seeds exceeded the arils in the absolute and relative dry matter content 2.9- and 1.9-fold, respectively, and separate plant species greatly differed in NAG composition. The proportions of TAG in the NAG of seeds and arils were 4–5 and ~98 %, respectively. The degree of FA unsaturation in aril NAG was higher than in the seed NAG, and in acDAG—higher, than in TAG. In the NAG, 14 major FA molecular species (excluding minor FA) were found, and linoleic, oleic, palmitic, and linolenic acids were predominant. NAG of separate taxonomic units of the genus Euonymus L. differed from each other in the concentration of major FA as well as other FA. So, by using statistical analysis, it was definitely established that the species from the subgenus Euonymus were characterized by an increased content of linoleic acid, while those from the subgenus Kalonymus, by the predominance of oleic acid. Meanwhile, the species of the section Euonymus were marked by an enhanced concentration of a number of hexa- and octadecenoic FA positional isomers.     

Vernolic and Cyclopropenoic Fatty Acids in Piper nigrum Seed Oil

The seed oil of Piper nigrum has the following fatty acid composition: capric (4.1%), lauric (2.5%), myristic (3.1%), palmitic (27.2%), stearic (7.3%), oleic (29.9%), linoleie (7.7%), vernolie (7.7%), malvalie (6.3%), and sterculic (4.2%) acids.     

Wax and Fatty Acids from Rice Bran Oil Sludges

Sludges obtained as tank settlings from solvent-extracted rice bran oil have been shown to be rich sources of wax and fatty acids. The wax content is variable, being about 18% in one sample and about 39% in a second sample of sludge. The wax was bleached to light colour. The crude wax shows good compatibility with other types of waxes. The oil fraction of sludges is high in free fatty acids (over 70%), about three fourth of which could be vacuum-distilled directly to yield light-coloured fatty acids.     

Fatty and Resinic Acids Extraction from Crude Tall Oil

Abstract

The separation of fatty and resinic acidic fractions from crude tall-oil soap solutions with n-heptane by the technique of dissociation extraction is discussed. The theory of the overall process is supported by a systematic study developed to cover the high selectivity demonstrated in the differential solubility and the aptness between fatty and diterpenic acids to both liquids phases. To study the main factors affecting those liquid-liquid extraction systems and the amphiphilic behavior of such molecules involved, sodium salts aqueous solutions of crude tall oil and synthetic mixtures as molecular acidic models were used.     

Practical Syntheses of Triacylglycerol Regioisomers Containing Long-chain Polyunsaturated Fatty Acids

Docosahexaenoic acid (DHA, 22:6n-3) is known to protect against a range of degenerative disease conditions and aid in the development of eye and brain function in infants. In dietary lipids DHA is found primarily in the triacylglycerol (TAG) form. However, the effects of the positional distribution of DHA in TAG on lipid functional properties such as bioactivity and oxidative stability are not clearly understood. Studies on this subject for the most part are limited by a lack of regioisomerically pure TAG model compounds containing DHA or similar long-chain (LC)-polyunsaturated fatty acids (PUFA). This paper reports on the development of a practical procedure, based on chemical and enzymatic reactions, for the syntheses of regioisomerically enriched, symmetrical and unsymmetrical TAG isomers containing two palmitic acid and one of linoleic acid, linolenic acid, or DHA. 1,3-Selective acylation of glycerol with vinyl esters of fatty acids catalyzed by Candida antarctica lipase and direct coupling with fatty acids in the presence of the coupling agents 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 4-dimethylaminopyridine furnished 1,3-dihexadecanoyl-2-docosahexaenoyl glycerol and its unsymmetrical isomer 1,2-dihexadecanoyl-3-docosahexaenoyl glycerol in 99 and 60% yield, respectively. Critical to the success of the unsymmetrical TAG synthesis is the demonstration that PUFA-containing glycerol acetonides can readily survive appropriately tailored acid-catalyzed conditions. In this way, sufficient quantities of highly regioisomerically enriched PUFA-containing unsymmetrical monoacylglycerols (MAG) and TAG have now become routinely accessible. The methods are amenable to scale-up and could be adopted for regioenriched synthesis of a wide range of TAG.     

Lipid Classes,Fatty Acids and Triglycerides in Papaya Seed Oil

Seed oil from papaya, cultivated in Vietnam, which accounted for 28% of the whole dried seeds and 54% of the endosperm was characterized by composition of lipid classes, fatty acids and triglycerides. Eleven triglyceride groups differing in unsaturation are determined by argentation thin-layer chromatography and densitometry. The fatty acid and triglyceride compositions of papaya seed oil are close to those of olive oil and characterize it as a good natural raw material.     

尿素包合法分离橡胶籽油中的多价不饱和脂肪酸

用尿素包合法从橡胶籽油混合脂肪酸中分离多价不饱和脂肪酸 ,用正交设计实验法对分离工艺进行研究 ,其最佳分离条件是 :原料配比为m(混合脂肪酸 )∶m(尿素 )∶m(乙醇 ) =1 0 0∶1 5∶1 8,回流时间 12 0min。经一次尿素包合法分离即可得到多价不饱和脂肪酸质量分数大于90 %的产品 ,实验收率大于 35 %     

Seed Lipids of Sesamum indicum,L. and Related Wild Species in Sudan I: Fatty Acids and Triacylglycerols

The fatty acid composition and triacylglycerol profile of seeds of three wild species of sesame viz, Sesamum alatum, Thonn., S. radiatum, Schum & Thonn. and S. angustifolium, (Oliv) Engl. were determined by capillary gas chromatography and high performance liquid chromatography, respectively. Results were compared with those obtained for different pure line and mixed genotypes of S. indicum, Linn., the overall world wide cultivated sesame. Oleic and linoleic acids are the major fatty acids in all samples. The wild species have slightly different saturated acid composition compared to S. indicum. S. alatum contained more palmitic acid (P) while S. radiatum and S. angustifolium contained more stearic acid. S. alatum also contained higher amounts of oleic acid (O) and lower amounts of linoleic acid (L). The major triacylglycerols were: LLO (20–25%), LLL (10–20%), LOO (15–19%), PLL (8–11%) and PLO (6–10%). S. alatum was also different from the other three species in having higher percentages of PLO (10.1%) and OOO (8.7%) compared to 6.3–8.1% of PLO and 3.4–4.9% of OOO in the other three species.