Effects of fatty acids on lysis of Streptococcus faecalis.

Palmitic, stearic, oleic, and linoleic acids at concentrations of 200 nmol/ml all inhibited autolysin activity 80% or more in whole cells or cell-free extracts. This concentration of the saturated fatty acids palmitic acid and stearic acid had little or no effect on the growth of whole cells or protoplasts. However, the unsaturated fatty acids oleic acid and linoleic acid induced lysis in both situations. This lytic effect is apparently not related to any uncoupling activity or inhibition of energy catabolism by unsaturated fatty acids. It is concluded that unsaturated fatty acids induce cell and protoplast lysis by acting as more potent membrane destabilizers than saturated fatty acids.     

Effect of ethanol and fatty acids on malolactic activity ofLeuconostoc oenos

Medium-chain fatty acids (C₆ to C₁₂), produced by yeast metabolism during alcoholic fermentation, are known to be inhibitory to lactic acid bacteria. The purpose of this work was to clarify the effect of both ethanol and decanoic and dodecanoic acids on the growth and malolactic activity of aLeuconostoc oenos strain isolated from Portuguese red wine. Ethanol in concentrations up to 12% had no significant effect on malolactic activity but strongly inhibited cell growth. The fatty acids decanoic acid, in concentrations up to 12.5 mg l^–1, and, dodecanoic acid up to 2.5 mg l^–1 seemed to act as growth factors stimulating also malolactic activity; at higher concentrations they exerted an inhibitory effect. We found clear pH dependence between pH 3.0 and pH 6.0, between decanoic acid concentration and its effect on malolactic activity, indicating that the undissociated molecule is the active form. At pH 3.0 the results can be explained by considering that fatty acids enter the cell as protonated molecules and dissociate in the cytoplasm due to the higher internal pH, leading to increased intracellular hydrogenous concentration. This may be the basis of two different effects that contribute to the observed inhibition: decrease in the intracellular pH and dissipation of the transmembrane proton gradient, thus inhibiting intracellular enzymes and ApH-dependent transport systems.     

Antimicrobial activity of fatty acids from fruits of Peucedanum cervaria and P. alsaticum

Plants of the genus Peucedanum have been used in traditional medicine for a long time to treat different diseases including infectious diseases. The hexane fruits extracts of Peucedanum cervaria and P. alsaticum were examined for antimicrobial activity and analyzed for their fatty acid content. Fatty acid composition of oils were analyzed by GC/FID in methyl ester form. Minimal inhibitory concentrations (MICs) of fatty acid fractions against twelve reference bacterial and yeast strains were performed by the twofold serial microdilution broth method. Fourteen fatty acids were identified. Oleic and linoleic acids were found to be dominant. The extracts from both plants examined exhibited inhibitory effects against Gram‐positive strains tested with different MIC values (0.25–2 mg/ml); however, extract from P. alsaticum possessed stronger antibacterial properties and a broader spectrum. The growth of Gram‐negative bacteria and Candida spp. strains was not inhibited even at the highest extract concentration used (MIC>4 mg/ml). Standard fatty acids exhibited inhibitory effects towards all bacterial and yeast strains used in this study; however, the majority of bacteria were more sensitive to linoleic than to oleic acid. These results revealed, for the first time, that hexane extracts obtained from fruits of P. alsaticum and P. cervaria possess moderate in vitro antibacterial activity against Gram‐positive bacteria including staphylococci. Linoleic and oleic acids appear to be the compounds responsible for this effect, and a synergistic antimicrobial effect between these two fatty acids was indicated.     

The Occurrence of Renin Inhibitor in Rice: Isolation,Identification, and Structure-Function Relationship

We found renin inhibitory activity in rice. The physico-chemical data on the isolated inhibitors were identical to those of oleic acid and linoleic acid. Oleic acid and linoleic acid competitively inhibited renin activity, with K_i values of 15.8 and 19.8 μM respectively. Other unsaturated free fatty acids also inhibited renin activity, but saturated fatty acids had no effect on it.     

First Report about Mineral Content,Fatty Acids Composition and Biological Activities of Four Wild Edible Mushrooms

The goal of this research was a comprehensive analysis of four wild edible mushroom species, Cantharellus cinereus, Clavariadelphus pistillaris, Clitocybe nebularis and Hygrocybe punicea, which have not been analyzed so far. Extracts of different polarities have been prepared and evaluated for their antioxidant activities by DPPH, ABTS, FRAP, TRP and CUPRAC methods. For all extracts, total phenolic content was determined. Based on the analysis, it was shown that solvent type had a significant effect on the antioxidant capacities of mushroom extracts, so water extracts showed the highest activity. Furthermore, the analysis includes determination of mineral composition, fatty acid profiles and antimicrobial activity. Unsaturated fatty acids, which are very important for human health, are dominant in the studied mushroom species. Linoleic and oleic acid consist of over 50 % of the total fatty acid composition. Seventeen biologically important and toxic elements have been analyzed by ICP‐OES and ICP‐MS and results showed that the element concentrations were species‐dependent. Also, it has been found that analyzed mushrooms did not show any antimicrobial activity. Chemometric analysis was used to understand the connection between the extracts of different polarities.     

The lipidic extract of the seaweed Gracilariopsis longissima (Rhodophyta, Gracilariales): a potential resource for biotechnological purposes?

In recent years seaweeds increasingly attracted interest in the search for new drugs and have been shown to be a primary source of bioactive natural products including antibiotics. In the present investigation the antimicrobial activity of Gracilariopsis longissima lipidic extract was assayed and its chemical characterization was carried out by means of advanced analytical techniques such as gas-chromatography and multinuclear and multidimensional NMR spectroscopy. G. longissima lipidic extract showed an antibacterial activity against several Vibrio species. These results are interesting considering both the resistance against antibiotics developed by vibrios and the need to control fish and shellfish diseases due to vibriosis. Analysis of fatty acid methyl esters performed by gas-chromatography showed that palmitic acid methyl ester (16:0) was the predominant saturated fatty acid (42%), while, among monounsaturated fatty acids, oleic acid methyl ester (18:1) prevailed (8.5%). Because the palmitic acid represents the main component of fatty acids we hypothesized its involvement in the antibacterial activity observed. However, a pure sample of palmitic acid did not show an antibacterial activity. The fatty acid profile of G. longissima revealed also an interesting composition in polyunsaturated fatty acids and in particular the ratio of ω-3 to ω-6 fatty acids was >1 thus suggesting that this macroalga may be used as a natural source of ω3. Moreover, the (1)H NMR spectrum in CDCl(3) of algal lipid fraction shows the characteristic signals of saturated and unsaturated fatty acids as well as other metabolites. Interestingly, in the lipid extract the presence of polyhydroxybutyrate, a linear biodegradable and biocompatible polyester, was clearly identified by NMR spectroscopy. In conclusion, the lipidic extract of G. longissima on account of its antimicrobial activity, nutritional value and content in biodegradable and biocompatible polyester represents an interesting potential biotechnological resource.     

Involvement of autolysin in cellular lysis of Bacillus subtilis induced by short- and medium-chain fatty acids.

The addition of saturated C6, C8, C10, and C12 fatty acids appeared to lyse actively growing cells of Bacillus subtilis 168, as judged by a decrease in the optical density of the culture. Of these fatty acids, dodecanoic acid was the most effective, with 50% lysis occurring in about 30 min at a concentration of 0.5 mM. These conditions also decreased the amount of peptidoglycan estimated by the incorporated radioactivity of N-acetyl-D-[1-14C]glucosamine. At concentrations above 1 mM, however, bacterial lysis was not extensive. Dodecanoic acid did not affect autolysis of the cell wall. The lytic action of dodecanoic acid was greatly diminished in cells in which protein synthesis was inhibited and in an autolytic enzyme-deficient mutant. The results suggest that fatty acid-induced lysis of B. subtilis 168 is due to the induction of autolysis by an autolytic enzyme rather than massive solubilization of the cell membrane by the detergent-like action of the fatty acids.     

The lethal effect of carrot on Listeria species

When shredded or sliced carrots were inoculated with Listeria monocytogenes the number of viable listerias decreased rapidly. On carrot slices stored at 8°C there was a decrease after 3 d followed by an increase, after 7 d, to numbers similar to those present initially. The numbers of spoilage micro-organisms increased throughout storage at 8°C. Carrots macerated in a Stomacher Lab Blender also showed an antilisterial activity which resulted in a decrease in number of viable bacteria and in sublethal damage. The effect was shown by five carrot cultivars and acted on nine strains of L. monocytogenes and single strains of L. innocua, L. ivanovii, L. seeligeri, L. welshimeri . This antilisterial effect was heat-labile, was inactivated after a few hours at 4°C or at 30°C and was active over the pH range 5.8 to 7.0. Maceration of carrots in an Atomix blender for 1 min or in liquid nitrogen destroyed the antilisterial activity.     

The effect of temperature, water activity and sorbic acid on ketone rancidity produced by Penicillium crustosum Thom in coconut and palm kernel oils

In a model system medium-chain fatty acids (MCFA) C₆–C₁₂ in coconut and palm kernel oil are converted to methyl ketones, one carbon atom less than the parent fatty acids, by two strains of Penicillium crustosum Thom. Conversion rates of up to 32% were seen for decanoic acid at 25°C. The optimum temperature for ketone production was 25°C in liquid suspension culture. Coconut oil contains 3.23 mmol/g MCFAs compared with 2.34 mmol/g for palm kernel oil. Coconut oil is more prone to fungal spoilage (growth and ketone production) than palm kernel oil. The main end product of fermentation was 2-undecanone reflecting the high concentration of dodecanoic acid in the substrates. Ketonic rancidity is fungal engendered. The reaction can be controlled by reducing the temperature (4°C), reducing the water activity (0.91) or by addition of sorbic acid (20 mmol/l).     

Biochemical composition of Tunisian Nigella sativa L. at different growth stages and assessment of the phytotoxic potential of its organic fractions

The present study was conducted to study some biochemical characteristics of Tunisian Nigella sativa at different developmental stages of plant growth (vegetative, flowering and fruiting stages) and to screen the chemical constituents and the phytotoxic activity of their organic extracts on lettuce (Lactuca sativa L.). The GC–MS analysis of petroleum ether fractions revealed that N. sativa seeds were rich in linoleic acid (58% of total fatty acids), oleic acid (22% of total fatty acids) and palmitic acid (12% of total fatty acids). The fatty acid composition of aerial parts showed an increase in the level of saturated fatty acids accompanied by a concomitant decrease of polyunsaturated fatty acids levels during the developmental stage. The phytochemical investigation showed that among the organic extracts, the methanolic extract from aerial parts harvested at the fruiting stage contained the highest amounts of phenolic and flavonoid compounds. The phytotoxic study revealed that N. sativa negatively affected the growth of lettuce plants. This effect was largely dependent on the developmental stage at which material was collected and the nature of extracting solvent. The methanolic extract of aerial parts harvested at the vegetative stage was the most active on seedling growth of lettuce.     

Fatty acid synthesis is a target for antibacterial activity of unsaturated fatty acids

Long-chain unsaturated fatty acids, such as linoleic acid, show antibacterial activity and are the key ingredients of antimicrobial food additives and some antibacterial herbs. However, the precise mechanism for this antimicrobial activity remains unclear. We found that linoleic acid inhibited bacterial enoyl-acyl carrier protein reductase (FabI), an essential component of bacterial fatty acid synthesis, which has served as a promising target for antibacterial drugs. Additional unsaturated fatty acids including palmitoleic acid, oleic acid, linolenic acid, and arachidonic acid also exhibited the inhibition of FabI. However, neither the saturated form (stearic acid) nor the methyl ester of linoleic acid inhibited FabI. These FabI-inhibitory activities of various fatty acids and their derivatives very well correlated with the inhibition of fatty acid biosynthesis using [(14)C] acetate incorporation assay, and importantly, also correlated with antibacterial activity. Furthermore, the supplementation with exogenous fatty acids reversed the antibacterial effect of linoleic acid, which showing that it target fatty acid synthesis. Our data demonstrate for the first time that the antibacterial action of unsaturated fatty acids is mediated by the inhibition of fatty acid synthesis.     

Uptake and incorporation of saturated and unsaturated fatty acids into macrophage lipids and their effect upon macrophage adhesion and phagocytosis.

Murine thioglycollate-elicited peritoneal macrophages were cultured in the presence of a variety of fatty acids added as complexes with bovine serum albumin. All fatty acids tested were taken up readily by the cells and both neutral and phospholipid fractions were enriched with the fatty acid provided in the medium. This generated a range of cells enriched in saturated, monounsaturated or polyunsaturated fatty acids, including n-3 acids of fish oil origin. Saturated fatty acid enrichment enhanced macrophage adhesion to both tissue culture plastic and bacterial plastic compared with enrichment with polyunsaturated fatty acids. Macrophages enriched with the saturated fatty acids myristate or palmitate showed decreases of 28% and 21% respectively in their ability to phagocytose unopsonized zymosan particles. Those enriched with polyunsaturated fatty acids showed 25-55% enhancement of phagocytic capacity. The greatest rate of uptake was with arachidonate-enriched cells. Phagocytic rate was highly correlated with the saturated/unsaturated fatty acid ratio, percentage of polyunsaturated fatty acid and index of unsaturation, except for macrophages enriched with fish-oil-derived fatty acids; they showed lower phagocytic activity than expected on the basis of their degree of unsaturation. These results suggest that membrane fluidity is important in determining macrophage adhesion and phagocytic activity. However, in the case of phagocytosis, this effect may be partially overcome if the cells are enriched with fish-oil-derived fatty acids. Thus it may be possible to modulate the activity of cells of the immune system, and so an immune response, by dietary lipid manipulation.     

Reversible inhibition of bacterial bioluminescence by long-chain fatty acids

Long-chain unsaturated fatty acids, as well as certain saturated fatty acids such as lauric acid, are inhibitors of the in vivo luminescence of wild-type strains of four species of luminous bacteria (Beneckea harveyi, Photobacterium phosphoerum, P. fischeri, andP. leiognathi) as well as the myristic acid-stimulated luminescence in the aldehyde dim mutant M17 ofB. harveyi. Based on studies with the system in vivo, the principal site of action of all the fatty acids appears to be the reductase activity that converts myristic acid to myristyl aldehyde. This was confirmed by in vitro studies: Reductase activity in crude cell-free extracts is strongly inhibited by oleic acid.     

The lethal effect of carrot on Listeria species

When shredded or sliced carrots were inoculated with Listeria monocytogenes the number of viable listerias decreased rapidly. On carrot slices stored at 8 degrees C there was a decrease after 3d followed by an increase, after 7d, to numbers similar to those present initially. The numbers of spoilage micro-organisms increased throughout storage at 8 degrees C. Carrots macerated in a Stomacher Lab Blender also showed an antilisterial activity which resulted in a decrease in number of viable bacteria and in sublethal damage. The effect was shown by five carrot cultivars and acted on nine strains of L. monocytogenes and single strains of L. innocua, L. ivanovii, L. seeligeri, L. melshimeri. This antilisterial effect was heat-labile, was inactivated after a few hours at 4 degrees C or at 30 degrees C and was active over the pH range 5.8 to 7.0. Maceration of carrots in an Atomix blender for 1 min or in liquid nitrogen destroyed the antilisterial activity.     

Free fatty acids and sterols in the benthic spawn of aquatic molluscs, and their associated antimicrobial properties

The free lipid content of extracts from the spawn of 17 molluscs were analysed by gas chromatography/mass spectrometry. These extracts encompass the encapsulated embryos and extraembryonic structures from benthic gelatinous egg masses and leathery egg capsules covering five taxonomic groups. Palmitic and stearic acids were the dominant saturated fatty acids and oleic acid was the principal unsaturated acid found in the spawn. Cholesterol was the dominant sterol and the only sterol found in the spawn from every species. Extracts from gelatinous egg masses were found to contain proportionally more fatty acids compared to leathery egg capsules. No unsaturated fatty acids were found in any of the leathery egg capsules, including five neogastropods and one littorinimorph. Unsaturated fatty acids were present in all of the gelatinous egg masses, including two other littorinimorphs. This is the first study to demonstrate that unsaturated fatty acids possess significant bacteriolytic activity against four aquatic pathogens. Encapsulated Anaspidea egg masses contain relatively high concentrations of these unsaturated fatty acids and a lipid mixture modeled on these extracts was strongly bacteriolytic at concentrations down to 0.0001 mg/ml. By comparison, lipid mixtures modeled on extracts from the spawn of four other molluscan taxa with higher proportions of saturated fatty acid and cholesterol, were only partially active against some of the bacteria at 0.1 mg/ml. Thus, unsaturated fatty acids could explain the antimicrobial activity previously reported in lipid extracts of some, but not most, molluscan spawn. MDS ordination and ANOSIM revealed significant taxonomic differences in the composition of free lipids from molluscan spawn, suggesting that lipid analyses may be useful in future systematic studies of the Mollusca.     

Influence of ethanol on fatty acid composition of phospholipids in cultured neurons

Animals chronically exposed to ethanol show changes in neural membrane lipids which may underlie the development of tolerance and physical dependence. The object of this study was to investigate changes in the fatty acid composition of neuronal phospholipids cultured in the presence of ethanol (55 or 110 mM) for periods up to 7 days. Decreases were observed in the percentage of individual and total saturated fatty acids, while the double bond index: total saturated fatty acid ratio, increased. These changes do not support the hypothesis that neural membrane lipid composition changes to counteract the fluidizing action of ethanol.     

Effect of fatty acids and monoglycerides on permeability of lipid bilayer

The effect of fatty acids and monoglycerides on barrier properties of liposomal membranes prepared from egg phosphatidylcholine was investigated. The incorporation of these lipids as liposomal membrane components induced the alteration of the permeability to less permeable liposomally entrapped drugs, sulfanilic acid and procainamide ethobromide (PAEB). Monoolein caused greatly increased permeability of both drugs and unsaturated fatty acids markedly enhanced the release rate of PAEB, while saturated fatty acids caused a small increase in the release rate.Electron spin resonance (ESR) investigation with 5-nitroxide stearic acid showed that fatty acids disordered the hydrophobic region of the lipid bilayer and the disordering effect of unsaturated fatty acids was greater than that of saturated ones. It was demonstrated that the incorporated fatty acids and monoglycerides interacted with the polar region of the membranes by ESR study with cholestane label and ¹H-NMR study. These results indicated that the increase in the membrane permeability caused by fatty acids and monoglycerides associated with the disorder in the membranes' interior and the interaction of the incorporated lipid with the polar head group of phospholipid.     

Identification of the components of the essential oil from Trollius europaeus flowers

The essential oil of Trollius europaeus flowers obtained by hydrodistillation was analyzed by gas chromatography coupled with mass spectrometry (GC–MS). The compounds giving fragrance of essential oils commonly used in perfumery 3,7-dimethyl-1,6-octadien-3-ol, nonanal, 3-methyl-2-pent-2-enyl-cyclopent-2-enone and oxacycloheptadec-8-en-2-one, rare in the Plant Kingdom, were tentatively identified. In the analyzed essential oil, the saturated fatty acids hexadecanoic acid (7.54 %), tetradecanoic acid (4.24 %), dodecanoic acid (3.10 %) and unsaturated fatty acids 9,12,15-octadecatrienoic acid (3.47 %), hydrocarbons, namely eicosane (20.03 %), hexadecane (8.63 %) and 1,2-benzenedicarboxylic acid (2.39 %), were also found.     

In vitro treatment of HepG2 cells with saturated fatty acids reproduces mitochondrial dysfunction found in nonalcoholic steatohepatitis

Activity of the oxidative phosphorylation system (OXPHOS) is decreased in humans and mice with nonalcoholic steatohepatitis. Nitro-oxidative stress seems to be involved in its pathogenesis. The aim of this study was to determine whether fatty acids are implicated in the pathogenesis of this mitochondrial defect. In HepG2 cells, we analyzed the effect of saturated (palmitic and stearic acids) and monounsaturated (oleic acid) fatty acids on: OXPHOS activity; levels of protein expression of OXPHOS complexes and their subunits; gene expression and half-life of OXPHOS complexes; nitro-oxidative stress; and NADPH oxidase gene expression and activity. We also studied the effects of inhibiting or silencing NADPH oxidase on the palmitic-acid-induced nitro-oxidative stress and subsequent OXPHOS inhibition. Exposure of cultured HepG2 cells to saturated fatty acids resulted in a significant decrease in the OXPHOS activity. This effect was prevented in the presence of a mimic of manganese superoxide dismutase. Palmitic acid reduced the amount of both fully-assembled OXPHOS complexes and of complex subunits. This reduction was due mainly to an accelerated degradation of these subunits, which was associated with a 3-tyrosine nitration of mitochondrial proteins. Pretreatment of cells with uric acid, an antiperoxynitrite agent, prevented protein degradation induced by palmitic acid. A reduced gene expression also contributed to decrease mitochondrial DNA (mtDNA)-encoded subunits. Saturated fatty acids induced oxidative stress and caused mtDNA oxidative damage. This effect was prevented by inhibiting NADPH oxidase. These acids activated NADPH oxidase gene expression and increased NADPH oxidase activity. Silencing this oxidase abrogated totally the inhibitory effect of palmitic acid on OXPHOS complex activity. We conclude that saturated fatty acids caused nitro-oxidative stress, reduced OXPHOS complex half-life and activity, and decreased gene expression of mtDNA-encoded subunits. These effects were mediated by activation of NADPH oxidase. That is, these acids reproduced mitochondrial dysfunction found in humans and animals with nonalcoholic steatohepatitis.KEY WORDS: Mitochondrial respiratory chain, Nonalcoholic steatohepatitis, NADPH oxidase, Oxidative phosphorylation, Proteomic, Nitro-oxidative stress, OXPHOS     

Oleic acid: an efficient inhibitor of glucosyltransferase

Among the extracts from 420 kinds of herbs, Prunus salicina, showing the highest glucosyltransferase inhibition activity, was purified and designated GTI-0163. Structural determination of GTI-0163 revealed it to be an oleic acid-based unsaturated fatty acid. GTI-0163 was an uncompetitive inhibitor of GTase. Among the unsaturated fatty acids, oleic acid showed a significantly higher GTase inhibitory activity than the saturated fatty acids or the ester form of oleic acid. These results strongly suggested that both the number of double bonds and the existence of free carboxyl groups of fatty acids play an important role in GTase inhibitory activity.