Ferroptosis is a non-apoptotic form of cell death induced by small molecules in specific tumour types, and in engineered cells overexpressing oncogenic RAS. Yet, its relevance in non-transformed cells and tissues is unexplored and remains enigmatic. Here, we provide direct genetic evidence that the knockout of glutathione peroxidase 4 (Gpx4) causes cell death in a pathologically relevant form of ferroptosis. Using inducible Gpx4(-/-) mice, we elucidate an essential role for the glutathione/Gpx4 axis in preventing lipid-oxidation-induced acute renal failure and associated death. We furthermore systematically evaluated a library of small molecules for possible ferroptosis inhibitors, leading to the discovery of a potent spiroquinoxalinamine derivative called Liproxstatin-1, which is able to suppress ferroptosis in cells, in Gpx4(-/-) mice, and in a pre-clinical model of ischaemia/reperfusion-induced hepatic damage. In sum, we demonstrate that ferroptosis is a pervasive and dynamic form of cell death, which, when impeded, promises substantial cytoprotection.

Inactivation of the ferroptosis regulator Gpx4 triggers acute renal failure in mice

The natural antimicrobial compound carvacrol shows a high preference for hydrophobic phases. The partition coefficients of carvacrol in both octanol-water and liposome-buffer phases were determined (3.64 and 3.26, respectively). Addition of carvacrol to a liposomal suspension resulted in an expansion of the liposomal membrane. Maximum expansion was observed after the addition of 0.50 μmol of carvacrol/mg of l-α-phosphatidylethanolamine. Cymene, a biological precursor of carvacrol which lacks a hydroxyl group, was found to have a higher preference for liposomal membranes, thereby causing more expansion. The effect of cymene on the membrane potential was less pronounced than the effect of carvacrol. The pH gradient and ATP pools were not affected by cymene. Measurement of the antimicrobial activities of compounds similar to carvacrol (e.g., thymol, cymene, menthol, and carvacrol methyl ester) showed that the hydroxyl group of this compound and the presence of a system of delocalized electrons are important for the antimicrobial activity of carvacrol. Based on this study, we hypothesize that carvacrol destabilizes the cytoplasmic membrane and, in addition, acts as a proton exchanger, thereby reducing the pH gradient across the cytoplasmic membrane. The resulting collapse of the proton motive force and depletion of the ATP pool eventually lead to cell death.

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The phenolic hydroxyl group of carvacrol is essential for action against the food-borne pathogen Bacillus cereus

Comparison of effects of dietary saturated, monounsaturated, and polyunsaturated fatty acids on plasma lipids and lipoproteins in man.

https://pure.rug.nl/ws/files/3297346/1994JBiolChemSikkema.pdf

Interactions of cyclic hydrocarbons with biological membranes.

In the present paper, we report the antimicrobial efficacy of three monoterpenes [linalyl acetate, (+)menthol, and thymol] against the gram-positive bacterium Staphylococcus aureus and the gram-negative bacterium Escherichia coli. For a better understanding of their mechanisms of action, the capability of these three monoterpenes to damage biomembranes was evaluated by monitoring the release, following exposure to the compounds under study, of the water-soluble fluorescent marker carboxyfluorescein from unilamellar vesicles with different lipidic compositions (phosphatidylcholine, phosphatidylcholine/phosphatidylserine [9:1], phosphatidylcholine/stearylamine [9:1], and phosphatidylglycerol/cardiolipin [9:1]). Furthermore, the interaction of the terpenes tested with dimyristoylphosphatidylcholine multilamellar vesicles as model membranes was monitored by means of differential scanning calorimetry. Finally, the results were related to the relative lipophilicity and water solubility of the compounds examined. Taken together, our findings lead us to speculate that the antimicrobial effect of (+)menthol, thymol, and linalyl acetate may result, at least partially, from a perturbation of the lipid fraction of microorganism plasma membrane, resulting in alterations of membrane permeability and in leakage of intracellular materials. Besides being related to physicochemical characteristics of the drugs (such as lipophilicity and water solubility), this effect seems to be dependent on lipid composition and net surface charge of microbial membranes. Furthermore, the drugs might cross the cell membranes, penetrating into the interior of the cell and interacting with intracellular sites critical for antibacterial activity.

Mechanisms of Antibacterial Action of Three Monoterpenes

Separation of polar lipids by two-dimensional thin layer chromatography providing resolution of all the lipid classes commonly encountered in animal cells and a sensitive, rapid, reproducible procedure for determination of phospholipids by phosphorus analysis of spots are described. Values obtained for brain and mitochondrial inner membrane phospholipids are presented.

Two dimensional thin layer chromatographic separation of polar lipids and determination of phospholipids by phosphorus analysis of spots

Curvilinear regression course of human brain lipid composition changes with age.

Three spectrophotometric procedures for determination of chromatographically separated glycosphingolipids (cerebroside, sulfatide, ganglioside) are described and compared. Hydrolysis to release long chain base followed by reaction of the amino group with trinitrobenezene sulfonic acid (TNBS) and measurement at 340 mμ was shown to give values in good agreement with those obtained by reaction of the carbohydrate moiety with α-naphthol or anthrone and measurement at 550 and 625 mμ respectively. The TNBS method is also applicable to ceramide.

Spectrophotometric determination of molar amounts of glycosphingolipids and ceramide by hydrolysis and reaction with trinitrobenzenesulfonic acid.

Variations in lipid composition of human brain during development and in the sphingolipidoses: use of two-dimensional thin-layer chromatography

THE MOLAR amount of gangliosides in human brain first rises and then declines steadily with age (ROUSER and YAMAMOTO, 1968). This report presents the fatty acid distribution in gangliosides from human brains at different ages. Lipids were extracted and the gangliosides were separated from other lipids by Sephadex column chromatography as previously described (SLAKOTOS and ROUSER, 1965; ROUSER, SIMON and KRITCHEVSKY, 1969). The fatty acid composition of the ganglioside fraction from Sephadex chromatography was determined directly and after thin layer chromatographic purification. For TLC, the sample was applied as a row of spots, the chromatogram was developed with ch1oroform:methanol: water (65: 25: 4, by vol . ) , and gangliosides (which did not migrate from the point of application) were scraped from the plate. After drying under vacuum over KOH pellets in a desiccator flushed with NZ, the methyl esters were prepared by adding 1.5-2 ml of boron trifluoride in methanol (14 g/100 ml), flushing the tube with N1, capping the tube tightly and heating at 110°C for 90 min. After cooling, 1-5-2 ml of water were added and the esters were extracted into hexane by using three 2-ml portions. Gas chromatography was performed with a Loenco Model 15B apparatus equipped with a hydrogen flame detector. Columns of SE-30 (2.5-3 % w/w) on 100/120 mesh Gas Chrom Q (obtained from Applied Science Laboratories, State College, Penn.) were packed into 6 ft x & in. stainless steel tubes. After columns were conditioned, analyses were performed at 180-200°C for 14-18 carbon acids and at 210-223°C for 18-26 carbon acids. Molar percentages were determined by measurements of peak areas (obtained by multiplication of peak height by peak width at one-half peak height) of sample and standard fatty acids.

Akira Yamamoto

Papers

Two dimensional thin layer chromatographic separation of polar lipids and determination of phospholipids by phosphorus analysis of spots

Curvilinear regression course of human brain lipid composition changes with age.

Spectrophotometric determination of molar amounts of glycosphingolipids and ceramide by hydrolysis and reaction with trinitrobenzenesulfonic acid.

Variations in lipid composition of human brain during development and in the sphingolipidoses: use of two-dimensional thin-layer chromatography

The fatty acid composition of total gangliosides in normal human whole brain at different ages.