José Luis Guil-Guerrero

Fatty acids and carotenoids from Stinging Nettle (Urtica dioica L.)

Several parts (leaves at different maturity stages, stems, roots and seeds) of an edible wild vegetable, Stinging Nettle (Urtica dioica L.) were analysed for fatty acids by GLC and carotenoids by reversed-phase HPLC and gradient elution. α-linolenic acid was the pre-dominant fatty acid in leaves, while seeds were richer in linoleic acid. Nine carotenoids were identified in the leaves. For all leaf maturity levels, lutein, lutein isomers, β-carotene and β-carotene isomers were the major carotenoids. Neoxanthin, violaxanthin and lycopene were also important contributors in specific leaf maturity stages.

Evaluation of the antioxidant activity of three microalgal species for use as dietary supplements and in the preservation of foods

The antioxidant activity of the microalgal ethanolic extracts of Porphyridium cruentum, Phaeodactylum tricornutum and Chlorella vulgaris was determined by means of the β-carotene-linoleate model system. The results show that the activity of C. vulgaris extract was higher than those obtained for the other microalgal extracts tested and for the synthetics BHA (butylated hydroxyanisole), and BHT (butylated hydroxytoluene). In addition, the major constituents present in the ethanolic extracts of the three microalgae species were analyzed by means of GC and GC-mass spectrometry. The results showed that the tested microalgae may be an important source of natural antioxidants, as an alternative to higher plants or the production by chemical synthesis.

γ-Linolenic acid purification from seed oil sources by argentated silica gel chromatography column

Abstract The polyunsaturated fatty acid γ-linolenic acid (GLA,18:3ω6), which has several pharmaceutical properties, has been purified from the seed oil of three plant species, Anchusa azurea, Scrophularia sciophila and Echium fastuosum. The process consists of four main steps, (i) simultaneous extraction and saponification of the seeds; (ii) urea fractionation method; (iii) urea-concentrate methylation; (iv) argentated silica gel column chromatography of the urea-concentrate methylated. Argentated silica gel chromatography yields high purity GLA in the process in A. azurea and S. sciophila, with yields in the combined process of 73 and 64%, respectively. With E. fastuosum, the recovery for the combined process was 60%, with a final purity 86%, due to the presence of the α-linolenic acid (ALA, 18:3ω3), which elutes with GLA in the chromatography column. The suitability of a process without urea concentration is also compared and discussed.

Nutritional composition ofSonchus species (S asperL,S oleraceusL andS tenerrimusL)

Analyses of the nutritional composition of tender leaves of three species of Sonchus (S. asper L, S oleraceus L and S tenerrimus L) from different locations in the south east of Spain were carried out. The proximate composition, as well as the content of mineral elements (Na, K, Ca, Mg, P, Fe, Cu, Zn and Mn), fatty acids, vitamin C, carotenoids and oxalic acid were determined. The results, which referred to fresh weight, emphasised the low proportion of available carbohydrates. Vitamin C contents were high, and ranged from 457 mg kg−1 (S tenerrimus) to 779 mg kg−1 (S oleraceus). Carotenoids were found in a high proportion (158 mg kg−1) in S oleraceus. Mineral element contents were similar to other green leafy vegetables. Fibre was present in amount above 30 g kg−1 in the three species. Essential fatty acids of the ω3 series were highest in S oleraceus (44·97%). It is believed that these species of Sonchus could be used for nutritional purposes, due to the high concentrations of nutrients that they contain.

γ-Linolenic Acid Enrichment from Borago officinalis and Echium fastuosum Seed Oils and Fatty Acids by Low Temperature Crystallization

Solvent winterization of seed oil and free fatty acids (FFAs) was employed to obtain gamma-linolenic acid (GLA; 18:3omega6) concentrates from seed oils of two Boraginaceae species, Echium fastuosum and Borago officinalis. Different solutions of seed oils and FFAs from these two oils at 10%, 20% and 40% (w/w) were crystallized at 4 degrees C, -24 degrees C and -70 degrees C, respectively, using hexane, acetone, diethyl ether, isobutanol and ethanol as solvents. Best results were obtained for B. officinalis FFAs in hexane, reaching a maximum GLA concentration of 58.8% in the liquid fraction (LF). In E. fastuosum, the highest GLA concentration (39.9%) was also achieved with FFAs in hexane.

Nutritional composition of Sonchus species (S asper L, S oleraceus L and S tenerrimus L)

Analyses of the nutritional composition of tender leaves of three species of Sonchus (S. asper L, S. oleraceus L and S. tenerrimus L) from different locations in the south east of Spain were carried out. The proximate composition, as well as the content of mineral elements (Na, K, Ca, Mg, P, Fe, Cu, Zn and Mn), fatty acids, vitamin C, carotenoids and oxalic acid were determined. The results, which referred to fresh weight, emphasised the low proportion of available carbohydrates. Vitamin C contents were high, and ranged from 457 mg kg -1 (S tenerrimus) to 779 mg kg -1 (S oleraceus). Carotenoids were found in a high proportion (158 mg kg -1 ) in S oleraceus. Mineral element contents were similar to other green leafy vegetables. Fibre was present in amount above 30 g kg -1 in the three species. Essential fatty acids of the ω13 series were highest in S oleraceus (44.97%). It is believed that these species of Sonchus could be used for nutritional purposes, due to the high concentrations of nutrients that they contain.

Gamma-linolenic acid from fourteen boraginaceae species

Abstract The seed oil of 14 Boraginaceae species was surveyed in a search for new sources of γ-linolenic acid (GLA, 18:3ω6). GLA content on total fatty acids ranges from the absence in Cordia and Halgania species to 23.9% in Lithospermum latifolium . The percentage of GLA on total seed weight reaches 3.9% in L. latifolium and Pulmonaria officinalis . The relatively high GLA percentage for Echium russicum suggest a distant taxonomic relationship when compared to other continental Echium .

Fatty acid profiles and cholesterol content of seven insect species assessed by several extraction systems

Species from Diptera (Hermetia illucens and Lucilia sericata), Coleoptera (Tenebrio molitor and Zophoba morio) and Orthoptera (Locusta migratoria, Acheta domestica and Anacridium aegyptium) were analyzed for fatty acid profiles and cholesterol content. The following solvent systems were tested for extraction: direct methylation (CH3OH/CH3COCl/hexane); n-hexane; acetone; ethanol/water; hexane/ethanol; and direct saponification (KOH and ethanol). Direct methylation was performed as control of extraction yields and to evaluate the possible use of these fats as biodiesel. Insect lipids were extracted by ethanol in a similar extent as did other tested organic solvents, while direct methylation of the biomass provided the highest yields. L. sericata and Z. morio contained high percentages of monounsaturated fatty acids; A. aegyptium and L. migratoria were two polyunsaturated fatty acid-enriched species, while H. illucens and Z. morio showed high proportions of medium-chain fatty acids. All extracted fats might be used in the alimentary industry, as evidenced by their low cholesterol content, as well as for biodiesel obtainment, as suggested by computed saponification, iodine and cetane values. Samples of H. illucens and L. migratoria showed exceptional cetane numbers (64.8 and 60.7, respectively), and all tested species except A. aegyptium exhibited an exceptional fatty acid profile for biodiesel production.

Hexane reduces peroxidation of fatty acids during storage

The free fatty acids eicosapentaenoic acid (C20:5ω3, EPA) and docosahexaenoic acid (C22:6ω3), obtained from the microalgae Phaeodactylum tricornutum, and the EPA methyl ester were compared with regard to their extent of peroxidation using different storage conditions. Several series were stored according to selected variables: hexane addition versus no addition, 4 °C versus 25 °C, and antioxidant addition (octyl gallate) versus no antioxidant addition, always in the dark. Previously, the EPA and methyl EPA structures were confirmed by NMR spectra to discard the formation of conjugated dienes after the downstream process. The results showed that the stability was higher for methyl EPA than for the free fatty acid, and that peroxidation can be retarded by low temperature storage and mainly by hexane addition. The peroxidation process was evaluated by the peroxide value (spectrophotometric method by iodine absorption), although the conjugated diene absorbance and the loss in percentage of the fatty acid have been tested as good indicators of the peroxidation process. A simple kinetic model that explains the peroxidation process during the initiation and propagation steps is given.

Gamma-linolenic acid from Cape Verdian Boraginaceae

The distribution of gamma-linolenic acid (GLA) was studied in the seed oil of six Cape Verdian Boraginaceae. The GLA ranges from trace levels in the three Heliotropum surveyed to 22.2% on saponifiable oil in Echium stenosiphon. All Echium species had GLA percentages in their seed oil around 20%. Echium seeds yield saponifiable oil from 15.8% (E. stenosiphon) to 17.3% (E. hypertropicum).