Intact polar lipids

Since flow cytometry allows rapid,simultaneous and quantitative measurementsrelated to cell morphology andphysiologicy, the lipid-specificfluorescent dye, Nile Red, was employed forthe in vivo lipid quantification of Crypthecodinium cohnii, a heterotrophicmarine dinoflagellate rich inpolyunsaturated long chain fatty acids. Thefluorescence signal was linearly correlatedwith the neutral and polar lipid content asdetermined by gravimetric techniques. Asignificant correlation of NR signal wasalso observed between the polar to neutrallipid ratio and docohexaenoic acid percell. The results demonstrate a method forrapid lipid quantification that can be usedin the selection, isolation and culturecontrol of C. cohnii clones with highlipid and DHA content.

Glycerol dibiphytanyl glycerol tetraether-based intact polar lipids (IPL GDGTs) are used as biomarkers for living Archaea and are analyzed utilizing a variety of extraction and quantification techniques. Most IPL GDGT studies have used a modified Bligh–Dyer extraction method, but it has been suggested that Soxhlet extraction may be more efficient for environmental samples and biomass. We investigated the impact of three different extractions (Soxhlet, Bligh–Dyer and accelerated solvent extraction, ASE), two IPL quantification methods and two work up techniques (Na2SO4 and SiO2 column) on the amount and distribution of CL (core lipid)- and IPL-derived GDGTs and crenarchaeol-based IPLs in marine sediments from the Arabian Sea and Icelandic shelf, as well as a microbial mat from a Dutch beach. The different extraction procedures gave a similar yield of CL- and IPL-derived GDGTs. Direct analysis of crenarchaeol IPLs showed, however, that, while GDGTs with a monohexose head group were not affected by the extraction method, there was a large effect on IPL GDGTs containing dihexose or hexose, phosphohexose head groups. Quantification of IPL-derived GDGTs by way of either separation over a silica column or by subtraction of CL GDGTs in the total lipid extract before and after hydrolysis gave similar results, but the ‘subtraction-method’ had a relatively large quantification error. However, the silica column, as well as drying over a Na2SO4 column, resulted in a loss of the hexose, phosphohexose IPLs by up to 80%. Based on the results, a modified Bligh–Dyer extraction with as little further treatment as possible is recommended to allow measurement of the full range of IPL GDGTs in sediments.

Antioxidative activities of native soy lecithin and mixtures of quercetin and lecithin (1:1, w/w) in the protection of triolein models stored under accelerated oxidative conditions for 15 days in the dark at 60 °C were studied. The progress of oxidation was followed by recording the ultraviolet absorptivity and measuring the formation of oxidative products (peroxide value (PV)). The antiradical action of different models against DPPH radicals was screened during Shaal oven test. The factors influencing the oxidative stability of different triolein models were also discussed. Inverse relationships were noted between PVs and oxidative stabilities at termination of the storage. Absorptivity at 232 and 270 nm in models containing lecithin increased gradually with the increase in time, due to the formation of conjugated dienes and polyenes. In general, oxidative stabilities of quercetin–lecithin-enriched models were better than in models containing lecithin or quercetin alone, most likely as a consequence of synergism between polar lipids and quercetin. Moreover, increases in concentration of quercetin–lecithin mixture resulted in an increase in its antioxidative activity. These results may be useful for improving the antioxidative activity and health impact of commercial lecithin in different food applications.

Semecarpus anacardium (family Anacardiaceae) has many applications in the Ayurvedic and Siddha systems of medicine in India. Detailed knowledge on the composition of S. anacardium oil, in consideration of potential utilization, is of major importance. In this investigation, column chromatography, gas chromatography, thin layer chromatography and liquid chromatography techniques were performed to analyze lipid classes, fatty acids and fat-soluble bioactives of S. anacardium crude seed oil. The amount of neutral lipids in the crude seed oil was the highest, followed by glycolipids and phospholipids, respectively. Linoleic followed by palmitic and oleic were the major fatty acids. The ratio of unsaturated fatty acids to saturated fatty acids was higher in neutral lipid classes than in the polar lipids. The main sterol compounds were β-sitosterol, campesterol and stigmasterol. δ-Tocopherol followed by β-tocopherol were the main tocopherols. When S. anacardium seed oil and extra virgin olive oil were compared for their radical scavenging activity toward 1,1-diphenyl-2-picrylhydrazyl radical and galvinoxyl radical (by electron spin resonance spectrometry), S. anacardium seed oil exhibited a stronger RSA.

A set of 20 Mollicutes strains representing different lines of descent, including the type species of the genus Mycoplasma, Mycoplasma mycoides, Acholeplasma laidlawii and a strain of Mesoplasma, were subjected to polar lipid and fatty acid analyses in order to evaluate their suitability for classification purposes within members of this group. Complex polar lipid and fatty acid profiles were detected for each examined strain. All strains contained the polar lipids phosphocholine-6′-α-glucopyranosyl-(1′-3)-1, 2-diacyl-glycerol (MfGL-I), 1-O-alkyl/alkenyl-2-O-acyl-glycero-3-phosphocholine (MfEL), sphingomyelin (SphM), 1-O-alkyl/alkenyl-glycero-3-phosphocholine (lysoMfEL), the unknown aminophospholipid APL1 and the cholesterol Chol2. A total of 19 strains revealed the presence of phosphatidylethanolamine (PE) and/or phosphatidylglycerol (PG), and the presence of diphosphatidylglycerol (DPG) was detected in 13 strains. The unknown aminolipid AL1 was found in the extracts of 17 strains. Unbranched saturated and unsaturated compounds predominated in the fatty acid profiles. Major fatty acids were usually C16:0, C18:0, C18:1 ω9c and ‘Summed feature 5’ (C18:2 ω6, 9c/C18:0 anteiso). Our results demonstrated that members of the M. mycoides cluster showed rather homogenous polar lipid and fatty acid profiles. In contrast, each of the other strains was characterized by a unique polar lipid profile and significant quantitative differences in the presence of certain fatty acids. These results indicate that analyses of both polar lipid and fatty acid profiles could be a useful tool for classification of mycoplasmas.

Since flow cytometry allows rapid,simultaneous and quantitative measurementsrelated to cell morphology andphysiologicy, the lipid-specificfluorescent dye, Nile Red, was employed forthe in vivo lipid quantification of Crypthecodinium cohnii, a heterotrophicmarine dinoflagellate rich inpolyunsaturated long chain fatty acids. Thefluorescence signal was linearly correlatedwith the neutral and polar lipid content asdetermined by gravimetric techniques. Asignificant correlation of NR signal wasalso observed between the polar to neutrallipid ratio and docohexaenoic acid percell. The results demonstrate a method forrapid lipid quantification that can be usedin the selection, isolation and culturecontrol of C. cohnii clones with highlipid and DHA content.

Archaeal and bacterial glycerol dialkyl glycerol tetraether lipids (GDGTs) are used in various proxies, such as TEX86 and the BIT index. In living organism, they contain polar head groups (intact polar lipids – IPLs). IPL GDGTs have also been detected in ancient marine sediments and it is unclear whether or not they are fossil entities or are part of living cells. In order to determine the extent of degradation of IPL GDGTs over geological timescales, we analyzed turbidite deposits, which had been partly reoxidized for several kyr after deposition on the Madeira Abyssal Plain. Analysis of core lipid (CL) and IPL-derived GDGTs showed a reduction in concentration by two orders of magnitude upon post-depositional oxidation, while IPL GDGTs with a mono- or dihexose head group decreased by 2–3 orders of magnitude. The BIT index for CL- and IPL-derived GDGTs increased substantially upon oxidation from 0.1 to up to 0.5. Together with changing MBT/CBT values, this indicates preferential preservation of soil-derived branched GDGTs over marine isoprenoid GDGTs, combined with in situ production of branched GDGTs in the sediment. The TEX86 value for IPL-derived GDGTs decreased by 0.07 upon oxidation, while that of CL GDGTs showed no significant change. Isolation of IPLs revealed that the TEX86 value for monohexose GDGTs was 0.55, while the that for dihexose GDGTs was substantially higher, 0.70. Thus, the decrease in TEX86 for IPL-derived GDGTs was in agreement with the dominance of monohexose GDGTs in the oxidized turbidite, probably caused by a combination of in situ production as well as selective preservation of terrestrial isoprenoid GDGTs. Due to the low amount of IPL GDGTs vs. CL GDGTs, the impact of IPL degradation on CL-based TEX86 paleotemperature estimates was negligible.

Seeds and pulp of cactus pear (Opuntia ficus-indica L.) were compared in terms of fatty acids, lipid classes, sterols, fat-soluble vitamins and β-carotene. Total lipids (TL) in lyophilised seeds and pulp were 98.8 (dry weight) and 8.70 g/kg, respectively. High amounts of neutral lipids were found (87.0% of TL) in seed oil, while glycolipids and phospholipids occurred at high levels in pulp oil (52.9% of TL). In both oils, linoleic acid was the dominating fatty acid, followed by palmitic and oleic acids, respectively. Trienes, γ- and α-linolenic acids, were estimated in higher amounts in pulp oil, while α-linolenic acid was only detected at low levels in seed oil. Neutral lipids were characterised by higher unsaturation ratios, while saturates were higher levels in polar lipids. The sterol marker, β-sitosterol, accounted for 72% and 49% of the total sterol content in seed and pulp oils, respectively. Vitamin E level was higher in the pulp oil than in the seed oil, whereas γ-tocopherol was the predominant component in seed oil and δ-tocopherol was the main constituent in pulp oil. β-Carotene was also higher in pulp oil than in seed oil. Oils under investigation resembled each other in the level of vitamin K1 (0.05% of TL). Information provided by the present work is of importance for further chemical investigation of cactus pear oil and industrial utilisation of the fruit as a raw material of oils and functional foods.