Fatty Acid Composition of Some Cucurbitaceae Seed Oils

Abstract

Seed oils of nine species of Cucurbitaceae were analyzed by gas chromatography and other techniques. The oil of Ecballiz~m elaterium yielded 227, of punicic acid; Cucumis dipsaceus and Cucurbita jicijolia had the ordinary palmitic-oleic-linoleic composition; a variety of iVoinordica charantia had 5iYo of U-eleostearic acid. Occurrence of punicic acid as the major acid of Trichosanthes anguina was confirmed. KO evidence could be found for the existence of a n isomer of linoleic acid in Teuairia pedata oil. The fatty acid composition was determined quantitatively for the above oils and for those of Cucumis melo, Lagenaria siceraria, and L u . a cylindrica. The 4-bromophenacyl esters of a-eleostearic and punicic acids were prepared.Seed oils of the Cucurbitaceae family fall into two distinct groups, one having the ordinary palmitic-oleic-linoleic composition, the other having a considerable proportion of conjugated triene fatty acids in the glycerides. The first group includes the common cultivated cucurbits. The second or conjugated oil group consists of certain species of Cucurbita, ,Vomordica, Telfairia, and Trichosanthes.Nine species of the family were exanlined in the present work to ascertain or co~lfirnl the identity of the conjugated acids and to resolve certain anomalies in previous studies. Ecballium elaterium, Czlcumis dipsaceus, and Cz~curbita ficifolia had not been analyzed previously. The percentage co~nposition of each oil was determined by gas-liquid chromatography (GLC) of the methyl esters, in conjunction with ultraviolet absorption analysis. The conjugated acids, when present in substantial amount, were isolated and purified-by crystallization a t low temperatures. They were identified by orthodox chemical methods. KESULTS A N D DISCUSSIONPreliminary data are shown in Table I. The high refractive indices of the first three oils indicate conjugated unsaturation and this was confirmed by their ultraviolet spectra and by isolation of conjugated triene fatty acids (see Table 11). None of the oils had an absorption peak in the region of 233 mp; thus they contained no appreciable amount of conjugated diene acid.In the analysis of the methyl esters by GLC, neither myristic nor linolenic acid was observed, although these two acids had been reported in some species by earlier workers (11,15,16). The results suggest that seed oils of Cucurbitaceae contain little or no linolenic acid. No acids other than those shown in Table I1 were observed. The infrared spectra did not disclose any evidence of oxygenated acids and GLC analysis showed that C20 and C22 acids were absent.There was evidently some loss of conjugated triene ester on the GLC column during the analysis. Accordingly, the content of conjugated triene was determined by ultraviolet absorption analysis and the amount of each non-conjugated acid was calculated as a percentage of the remainder.

<b>Physicochemical and antimicrobial properties of <i>Trichosanthes anguina</i> and <i>Swietenia mahagoni seeds</i></b>

“…The fatty acids found were palmitic, stearic, oleic, linoleic and punicic for T. anguina and palmitic, stearic, arachidic, oleic, linoleic and linoleinic for S. mahogani seed oils. These results partially agree with the findings of other [8,10,29]. The differences in our results from them could be explained by variations in soil and climatic conditions.…”

“…The solvent extracts of T. anguina and S. mahagoni seeds yielded 31.0 and 49.0% oil, which are almost near to the reported values 29.1% [29] and 47.5% [6], respectively. The information on detailed characteristics of seed oils and nutritional compositions of seeds from same species are too scanty for meaningful comparisons.…”

“…As can be seen from o C for T. anguina seed oil reported elsewhere [29]. The specific gravity and refractive index of S. mahagoni seed oil are lower than those in the present sample of T. anguina.…”

“…The linoleic acid enriched in fatty acid profile (20.1% in T. anguina and 30.1% in S. mahagoni), may be the precursor of prostaglandins (known to occur in accessory genital gland, seminal plasma and lung tissue of human body) and play a vital role in human health [37]. Regarding the unsaturated fatty acids in T. anguina, punicic acid was the major one, its percentage being 45.1, which was higher than the value 42.80% detected by Chisholm and Hopkins [29] and was lower than the value 46.30% reported by Lakshminarayana et al [10] with the same seed oil. The punicic acid content in T. anguina was lower than the value 51.7% in Trichosanthes nervifolia, but higher than the value 41.8% of Trichosanthes bracteata seed oils reported by Lakshminarayana et al [38].…”

Comparison of Separation of Seed Oil Triglycerides Containing Isomeric Conjugated Octadecatrienoic Acid Moieties by Reversed-Phase HPLC

“…Triglycerides of Oil with (9Z,11E,13E)-octadeca-9,11,13-trienoic Acid Moieties From the series of plant sources with seed oils enriched with (9Z,11E,13E)-octadeca-9,11,13-trienoic or α-eleostearic acid [17], Momordica charantia was chosen as a source with high content of the acid simultaneously with other ordinary acids being suitable for increments calculation. The oil is known [19] to be built with linoleic, oleic, palmitic, stearic and α-eleostearic (α-El) acid.…”