Fatty acid composition of seed oils from sixAdansonia species with particular reference to cyclopropane and cyclopropene acids

The oil content of sixAdansonia species (Bombacaceae family) of Madagascar (Adansonia grandidieri, A. za, A. digitata, A. fony, A. madagascariensis andA. suarenzensis) and Africa (A. digitata) ranges from 8 to 46%. All the oils give a positive response to the Halphen test. Malvalic, sterculic and dihydrosterculic acids were detected using gas liquid chromatography-mass spectrometry (GLC-MS). Epoxy or hydroxy fatty acids were not found in these oils. Fatty acid composition was determined by GLC using glass capillary columns coated with BDS and Carbowax 20 M. Results obtained for cyclopropenic fatty acids (CPEFA) were compared to those given by glass capillary GLC after derivatization with silver nitrate in methanol, by hydrogen bromide titration and by proton magnetic resonance (PMR). Good agreement was observed for the results given by the various methods. Malvalic acid content ranges from 3 to 28%, sterculic acid from 1 to 8% and dihydrosterculic acid from 1.5 to 5.1%. Odd-numbered fatty acids (Pentadecanoic and hepatadecanoic) were also observed in minute amounts (0.1–1.1%). Among the normal fatty acids, we observed mainly palmitic (21–46%), oleic (15–40%) and linoleic (12–32%). The relationship between fatty acid composition andAdansonia species is discussed.     

Cyclopropenoid Fatty Acids of Sida grewioides and Hibiscus caesius (Malvaceae) Seed Oils

Evidence is provided that sterculic and malvalic acids occur together in seed oils of Sida grewioides and Hibiscus caesius. Sida grewioides oil contains 1.3% sterculic and 2.1 % malvalic acids; Hibiscus caesius oil contains 1.0 % sterculic and 5.7 % malvalic acids. The cyclopropenoid acids were characterised by gas liquid chromatography (GLC) of the silver nitrate-methanol treated methyl esters using Sterculia foetida esters as a reference standard. A third unusual component, identified as epoxy acid, also occurs in Sida grewioides oil as a trace constituent.     

HBr-Reactive acids ofMalva sylvestris seed oil

Malva sylvestris seed oil contained 5.6% sterculic, 11.0% malvalic, 1.6% vernolic, 15.6% lauric, 6.6% myristic, 26.6% palmitic, 5.6% palmitoleic, a trace of stearic, 23.0% oleic and 4.0% linoleic acids. The co-occurrence of malvalic and sterculic acids was established by gas liquid chromatography (GLC) of the silver nitrate-methanol treated esters usingSterculia foetida esters as the reference standard. Co-occurrence of epoxy acid (vernolic acid) was confirmed withVernonia anthelmintica as the lipid standard.     

Analysis of conjugated octadecatrienoic acids inmomordica balsamina seed oil by GLC and13C NMR Spectroscopy

Separation of conjugated octadecatrienoic acids by open tubular gas liquid chromatography (GLC) was performed using glass capillary columns coated with Carbowax 20 M and with OV-1. The equivalent chain length of geometrical isomers of the conjugated octadecatrienoic acids belonging to the two series C_18:3Δ^8.10.12 and C_18:3Δ^9.11.13 were determined. The application of these results to the study of theMomordica balsamina seed oil shows that this oil contains two conjugated octadecatrienoic fatty acids in appreciable amounts, punicic acid (50%) and α-eleostearic acid (13%). The isomerization of conjugated acids inM. balsamina seed oil was followed for one year. Quantitation of octadecatrienoic acids using GLC gave results similar to those obtained with¹³C NMR.     

Gas-liquid chromatographic analysis of cyclopropenoid fatty acids

A method is described for the analysis of cyclopropenoid fatty acids in oils. The method consists of reacting the methyl esters of the cyclopropenoid fatty acids with silver nitrate in methanol to form ether and ketone derivatives. The derivatives formed from the cyclopropenoid fatty acids are separated from the methyl esters of the normal fatty acids by gas-liquid chromatography on a 15% diethylene glycol succinate column. The method is applicable to oils containing from 0.01% to 100% of cyclopropenoid fatty acids. The derivatives of oils containing lew levels of cyclopropenoids are separated from the normal methyl esters by alumina chromatography prior to gas-liquid chromatography. Studies on the quantitative aspects of the derivative formation, alumina chromatography, and gas-liquid chromatography are reported. Analyses for total cyclopropenoid fatty acid content of cottonseed oil andSterculia foetida oil by the gas-liquid chromatographic and hydrobromic acid titration procedures showed good agreement. Replicate analyses of a sample ofSterculia foetida oil for malvalic and sterculic acid gave coefficients of variation of 6.04% and 1.17%, respectively.     

Cyclopropenoic acids ofPavonia sepium seed oil

The seed oil ofPavonia sepium (Malvaceae) contains sterculic (7%) and malvalic (4%) acids. Countercurrent distribution in a hexane-acetonitrile system concentrated and resolved the homologus cyclopropenoid methyl esters. Reductive ozonolysis of selected countercurrent distribution fractions gave β-diketoesters, which were identified by gas chromatography-mass spectrometry as derivatives of sterculic and malvalic acids.Pavonia sepium is the first known species in the plant family Malvaceae whose seed oil contains more sterculic than malvalic acid. Presented at the AOCS-ISF World Congress, Chicago, October 1970. ARS, USDA.     

GC-MS characterization (Chemical lonization and electron impact modes) of the methyl esters and oxazoline derivatives of cyclopropenoid fatty acids 1

The CI-(CH₄) mass spectra of the methyl esters and the EI mass spectra of the oxazoline derivatives of three cyclopropenoid fatty acids (malvalic, sterculic and α- hydroxy-sterculic acid) from the seed oil ofPachira aquatica were found to be useful for structure elucidation of such compounds. Furthermore, some hitherto unknown minor fatty acids were identified and the nuclear magnetic resonance data of the oil and α-hydroxysterculic acid methyl ester are presented.     

Cyclopropenoid Fatty Acids of Sterculia Oils by Gas Liquid Chromatography

Silver nitrate treated methyl esters of the seed oils of Sterculia alata, Sterculia foetida, Sterculia guttata and Sterculia villosa were subjected to gas liquid chromatography and were found to contain sterculic and malvalic acids (4.0, 17.6; 55.7, 11.4; 5.8, 2.1 and 3.2, 2.5%, respectively), besides the conventional fatty acids. IR and NMR of the oils confirmed the cyclopropenoid moiety in these oils. Seed oil of Sterculia foetida was used as a standard reference.     

Improved gas chromatographic analysis of fatty and resin acid mixtures with special reference to tall oil

A gas liquid chromatography system for the analysis of complex mixtures of fatty and resin acids has been developed. On 30–40 m long, 0.3 mm ID glass capillary columns coated with 1,4-butanediol succinate (BDS) and attaining over 90,000 effective theoretical plates, all main fatty and resin acids in wood extractives and various tall oil products can be separated and quantitatively determined without need of any prefractionation of the acids. Also the levopimaric acid is well separated. Retention values, including their temperature dependence, on columns coated with BDS or SE-30 are given for 49 significant fatty and resin acids. Applications on wood extractives, sulfate soaps, and crude and distilled tall oil are presented and discussed.     

Cyclopropenoid fatty acids in abutilon ramosum seed oil

Seed oil of Abutilon ramosum was found to contain the following fatty acids (wt.%): malvalic (2.48%), sterculic (1.29%), myristic (1.0%), C₁₅:0 (1.78%), palmitic (19.1%), palmitoleic (0.51%), stearic (6.53%), oleic (23.72%), linoleic (42.55%) and linolenic (0.91%). The qualitative and quantitative analysis of the fatty acids were carried out by HBr-titration and the gas-liquid chromatography of the silver nitrate-methanol-treated esters using the fatty acid esters of the oil of sterculia foetida as reference standard.     

Cyclopropene fatty acids in some Malaysian edible seeds and nuts: I. Durian (Durio zibethinus,Murr.)

The aril and seeds of the fruit Durian (Durio zibethinus, Murr.) were examined for their protein content and fatty acid composition by gas liquid chromatography (GLC). The values (area percentage) for fatty acids as methyl esters were: aril=14∶0 (0.91%); 16∶0 (34.13%); 16∶1 (7.10%); 18∶0 (1.21%); 18∶1 (42.14%); 18∶2 (7.85%) and 18∶3 plus 20∶0 (5.69%), Seeds=14∶0 (0.12%); 16∶0 (12.20%); 16∶1 (1.15%); 18∶0 (1.42%); 18∶1 (8.42%); 18∶2 (6.50%); dihydrosterculic acid (2.52%); 18∶3 plus 20∶0 (11.30%); malvalic acid (15.72%); sterculic acid (38.53%) and 22∶0 (1.21%). The germ oil contained the highest amount of sterculic acid. The cooking temperatures employed reduced the malvalic and sterculic acid contents in seeds only by ca. 22% and 19%, respectively.     

Cyclopropenoid fatty acids in seed oils ofSida acuta andSida rhombifolia (malvaceae)

Seed oils ofSida acuta andSida rhombifolia were found to contain sterculic (11.0, 10.8%) and malvalic (1.7, 2.0%) acids respectively, in addition to the normal fatty acids. Co-occurrence of these acids was established by gas liquid chromatography of the silver nitrate-methanol-treated methyl esters usingSterculia foetida esters as a reference standard. This gas liquid chromatography technique of quantitation was found most suitable to estimate these acids in low level cyclopropenoid acid-containing seed oils.     

Operating variables in the analysis of tall oil acids by capillary gas chromatography

Factors influencing the analysis of fatty and resin acid methyl esters by capillary gas chromatography have been investigated. Methods to calculate equivalent chain length (ECL) values and their limitations are first discussed. Retention data, expressed as equivalent chain lengths (ECL) were determined on SE-30, SP-2100 and Carbowax 20M columns. The medium length (20–30-m) polysiloxane columns, SE-30 and SP-2100, provided overall better resolution and shorter retention times than the more polar Carbowax 20M column of similar length. The temperature dependence of ECL values was investigated for all three columns in the range 180–210 C. Retention times and ECL values were more temperature-dependent for the Carbowax 20M than for the other two stationary phases. The effects of split ratio and method of injection on the precision and accuracy of the analysis were also examined. Using optimal conditions of analysis established in this paper, the difference between measured and actual weights of an internal standard added to two tall oil samples was determined to be less than 3%.     

Hydrazine reduction in the gas liquid chromatographic analysis of the methyl esters of cyclopropenoic fatty acids

Hydrazine was used to hydrogenate the double bond of cyclopropenoic fatty acids (CPEFA) without cleaving the cyclic system. Using gas liquid chromatography (GLC), quantitation studies showed that it was possible to accurately determine CPEFA at concentrations as low as 0.1%. Studies with kapok seed oil methyl esters illustrated the potential application of such a technique to selectively hydrogenate the CPEFA to cyclopropanoic fatty acids (CPAFA), rendering them stable on the column, with a minimum effect on the degree of unsaturation of the remaining double bonds. Hydrazine reduction was found to be a simple and accurate method of measuring CPEFA in seed oils. Decomposition of pure methyl sterculate (methyl 9,10-methylene-9-octadecenoate) on GLC columns of various polarities also was examined.     

Separation of petroselinic (cis-6 18:1) and oleic (cis-9 18:1) acids by gas-liquid chromatography of their isopropyl esters

Petroselinic (cis-6 18:1) and oleic (cis-9 18:1) acids that occur together in Umbelliferae seeds can be resolved by gasliquid chromatography (GLC) of their methyl or isopropyl esters on a 50 m × 0.25 mm fused-silica capillary column coated with a 100% cyanopropyl polysiloxane stationary phase (CP Sil 88). The use of isopropyl esters instead of methyl esters increases the difference between equivalent chainlengths from 0.06 carbon unit up to 0.08. This is sufficient to obtain an almost base-line resolution between the two components.cis-Vaccenic acid is completely separated from oleic acid in both derivative forms. GLC of fatty acid isopropyl esters on an appropriate capillary column thus appears to be the simplest means to simultaneously and accurately quantitate petroselinic, oleic andcis-vaccenic acids.     

Characterization of cyclopropenoid acids in selected seed oils

Evidence is provided that sterculic and malvalic acids occur together in seed oils ofSterculia foetida, Hibiscus syriacus, andLavatera trimestris. Sterculia foetida oil contains 54.5% sterculic and 6.7% malvalic acids;Hibiscus syriacus oil contains 16.3% malvalic and 3.4% sterculic; andLavatera trimestris oil contains 7.7% malvalic and 0.6% sterculic acids.Hibiscus syriacus oil also contains 1.5% dihydrosterculic acid. The cyclopropenoid acids were characterized by hydrogenation in conjunction with gas-liquid chromatography and by oxidation to β-dioxo acids with subsequent cleavage with peracetic acid. Acetolysis of epoxides in the presence of cyclopropenes was effected by room temperature treatment with acetic acid-10% sulfuric acid (5∶2). This is a laboratory of the Northern Utilization Research and Development Division, Agricultural Research Service, U. S. Department of Agriculture.     

Preparation of malvalic and sterculic acid methyl esters from Bombax munguba and Sterculia foetida seed oils

A method has been developed for the preparation of highly pure malvalic (cis-8,9-methyleneheptadec-8-enoic) and sterculic (cis-9,10-methyleneoctadec-9-enoic) acid methyl esters starting from Bombax munguba and Sterculia foetida seed oils. The methyl esters of these oils were prepared by sodium methylate-catalyzed transmethylation followed by cooling (6°C) the hexane solution of crude methyl esters and separation of insoluble fatty acid methyl esters by centrifugation in the case of B. munguba and by column chromatography in the case of S. foetida. Subsequently, the saturated straight-chain fatty acid methyl esters were almost quantitatively removed by urea adduct formation. Finally, methyl malvalate and methyl sterculate were separated from the remaining unsaturated fatty acid methyl esters, in particular methyl oleate and methyl linoleate, by preparative high-performance liquid chromatography on C₁₈ reversed-phase using acetonitrile isocratically. Methyl malvalate and methyl sterculate were obtained with purities of 95–97 and 95–98%, respectively.     

Cyclic fatty acid monomer formation in frying fats. I. Determination and structural study

The formation of monomeric cyclic fatty acids was studied in a model system in which partially hydrogenated soybean oil (PHSO) was heated intermittently for 80 hr of simulated deep fat frying. Oil samples (fresh and heated) and their methyl esters were fractionated according to their molecular size using gel permeation chromatography (GPC). Oils and GPC fractions were analyzed for cyclic monomers by the following steps: (i) preparation of fatty acid methyl esters (FAME); (ii) microhydrogenation of FAME; (iii) urea fractionation of hydrogenated FAME; (iv) analysis by capillary gas liquid chromatography (GLC), and (v) structural characterization of cyclic monomer peaks by mass spectrometry (GC-MS). Under simulated frying conditions the concentration of cyclic monomers increased from 736 ppm (0.07%) in fresh oil to 1803 ppm (0.18%) in heated oil. GC-MS with capillary columns allowed the identification of several C₁₈ α-disubstituted cyclohexane and cyclopentane isomers as hydrogenated methyl esters. Other noncyclic and contaminant compounds eluting within the expected GLC retention range of cyclic monomers also were identified in all the samples and GPC fractions.     

Gas-liquid chromatographic analysis of cyclopropene fatty acids

A gas-liquid chromatographic method is described for the quantitative estimation of cyclopropene fatty acids as their methyl mercaptan derivatives. This method estimates individual cyclopropene acids as well as normal and cyclopropane acids. Nine seed oils were analyzed for their cyclopropene fatty acid content. Evidence was obtained for the presence of a cyclopropene fatty acid of shorter chain length than malvalic inAlthaea rosea cav and one with a higher chain length than sterculic inBombacopsis glabra seed oil. This method is less accurate for cottonseed oil than for the other oils tested because of the appearance of some unsymmetrical peaks of unknown origin. The mercaptan derivatives of the cyclopropene acids may be isolated by silver ion thin-layer chromatography. Small amounts of cyclopropane fatty acids were found in a number of the oils analyzed for cyclopropene fatty acids. Presented at the AOCS meeting, Chicago, October 1964.     

Measurement of lipase activity in single grains of oat (Avena sativa L.)

Seed oil ofSterculia colorata is found to contain the following acids (wt %): sterculic (4.9%), malvalic (3.2%), myristic (0.3%), palmitic (29.4%), stearic (1.7%), oleic (56.6%), and linoleic (3.9%). The co-occurrence of malvalic and sterculic acids was established by gas liquid chromatography of the silver nitrate methanol-treated esters usingS. foetida esters as reference standard.