Cyclic fatty acids: natural sources, formation during heat treatment, synthesis and biological properties.

The effect of cyclopropene fatty acids, sterculic and malvalic, on the lipids of yeasts grown under nitrogen limiting, lipid accumulating, conditions was studied. The ratio of stearic to oleic acid showed a dose response effect, with an increase in stearic acid content as the dose of cyclopropene fatty acid increased, and a corresponding reduction in oleic acid. Linoleic and linolenic acids were not affected to the same extent. These effects are shown for the yeasts Candida sp. 107, Trichosporon cutaneum, and Rhodosporidium toruloides.

Modification of fatty acid composition of lipid accumulating yeasts with cyclopropene fatty acid desaturase inhibitors

The present study aims at characterization of Jatropha species occurring in India using nuclear and organelle specific primers for supporting interspecific gene transfer. DNA from 34 accessions comprising eight agronomically important species (Jatropha curcas, J. gossypifolia, J. glandulifera, J. integerrima, J. podagrica, J. multifida, J. villosa, J. villosa. var. ramnadensis, J. maheshwarii) and a natural hybrid, J. tanjorensis were subjected to molecular analysis using 200 RAPD, 100 ISSR and 50 organelle specific microsatellite primers from other angiosperms. The nuclear marker systems revealed high interspecific genetic variation (98.5% polymorphism) corroborating with the morphological differentiation of the species used in the study. Ten organelle specific microsatellite primers resulted in single, discrete bands of which three were functional disclosing polymorphism among Jatropha species. The PCR products obtained with organelle specific primers were subjected to sequence analysis. PCR products from two consensus chloroplast microsatellite primer pairs (ccmp6 and 10) revealed variable number of T and A residues in the intergenic regions of ORF 77–ORF 82 and rp12–rps19 regions, respectively in Jatropha. Artificial hybrids were produced between J. curcas and all Jatropha species used in the study with the exception of J. podagrica. Characterization of F1 hybrids using polymorphic primers specific to the respective parental species confirmed the hybridity of the interspecific hybrids. Characterization of both natural and artificially produced hybrids using chloroplast specific markers revealed maternal inheritance of the markers. While the RAPD and ISSR markers confirmed J. tanjorensis as a natural hybrid between J. gossypifolia and J. curcas, the ccmp primers (ccmp6 and 10) unequivocally established J. gossypifolia as the maternal parent. Evaluation of backcross interspecific derivatives of cross involving J. curcas and J. integerrima indicate scope for prebreeding and genetic enhancement of Jatropha curcas through interspecific hybridization.

Genetic analysis of Jatropha species and interspecific hybrids of Jatropha curcas using nuclear and organelle specific markers

Unwashed rat liver microsomes were used to study the inhibition of the Δ6 and Δ9 desaturases by cyclopropenoid fatty acids with the ring structure about the 9,10 or 6,7 carbon atoms. The 9,10 cyclopropenoid acid (sterculic acid) is shown to be an effective inhibitor of only Δ9 desaturase and then only in the presence of MgCl2 and coenzyme A (prepresence of MgCl2 and coenzyme A (presumably due to the formation of sterculoyl-CoA). Two 6,7 cyclopropenoid acids of different chain lengths showed no marked inhibition of either the Δ6 or Δ9 desaturase. By the use of [3H]-sterculic acid, it has been shown that under conditions of high inhibition of the Δ9 desaturase the inhibitor is not covalently attached to the enzyme at any point. This disproves older ideas on the mechanism of inhibition that assumed reaction between the cyclopropenoid ring and sulphydryl groups on the enzymes.

Studies on the inhibition of the desaturases by cyclopropenoid fatty acids

Fatty acid compositions of seed oils from three species of Bombacaceae, eleven from Malvaceae, and six from Sterculiaceae were determined. Each of the seed oils contains varying amounts of both malvalic and sterculic acids accompanied by one or both of the corresponding cyclopropane fatty acids. In addition, the seed oil of Pachira aquatic Aubl. (Bombacaceae) contains 12.8% alpha-hydroxysterculic acid.

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Cyclopropene fatty acids of selected seed oils from bombacaceae, malvaceae, and sterculiaceae.

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.

D. T. Hopkins

Papers

Gas-liquid chromatographic analysis of cyclopropenoid fatty acids