Angiotensin II modification by decomposition products of linoleic acid-derived lipid hydroperoxide

Comparison of the preventive effects of Murraya exotica and Murraya paniculata on alcohol-induced gastric lesions by pharmacodynamics and metabolomics

ETHNOPHARMACOLOGICAL RELEVANCE

Multi-source phenomenon is very common for traditional Chinese medicine (TCM). Both Murraya exotica L. (ME) and Murraya paniculata (L.) Jack (MP) are used as the source plants of Murrayae Folium et Cacumen (MFC), a traditional Chinese medicine recorded in Chinese Pharmacopoeia for promoting qi and relieving pain, mainly for the treatment of stomach pain, rheumatism and arthralgia. However, up to now, there has been no comparative study of these two plants on their efficacies and mechanisms, thus, further research is needed to evaluate their similarity and difference in order to judge the reasonability for their common usage.

AIM OF THE STUDY

This study aims to compare the effects and potential mechanisms of ME and MP, the two source plants of MFC on gastric lesions in rats by pharmacodynamics and metabolomics.

MATERIALS AND METHODS

A rat model of gastric lesions induced by 70% aqueous ethanol and 150 mmol/L HCl was established and adopted to evaluate the gastric protective effects of ME and MP by analysis of the lesion index, histopathological changes (observed by H&E staining and TUNEL staining) and cytokine levels (IL-1β, IL-6, TNF-α, MTL, and GAS). The potential mechanisms were investigated by LC-MS metabolomic analysis of the rat plasma.

RESULTS

ME and MP showed the similar effects on improving the lesions of rat stomachs and reducing the cytokine levels related to inflammation and digestion of rats. The metabolomics results showed that the metabolism of rats with gastric lesions was abnormal mainly in lipid metabolism, energy metabolism, and amino acid metabolism. ME and MP demonstrated a similar metabolic modulation for gastric lesions by acting on the similar pathways and metabolites. Also, PLA2 pathway was proved as an important pathway for ME and MP modulation of glycerophospholipid metabolism in gastric lesions.

CONCLUSIONS

Our results proved that it is feasible and reasonable to use both of ME and MP as the source plants of MFC, at least for the treatment of gastric lesions, due to their similar pharmacodynamics and metabolic modulation ability. Moreover, the combination of pharmacodynamics and metabolomics is an efficient means for multi-source TCM study.

Regulation of arachidonic acid oxidation and metabolism by lipid electrophiles

Arachidonic acid (AA) is a precursor of enzymatic and non-enzymatic oxidized products such as prostaglandins, thromboxanes, leukotrienes, lipoxins, and isoprostanes. These products may exert signaling or damaging roles during physiological and pathological conditions, some of them being markers of oxidative stress linked to inflammation. Recent data support the concept that cyclooxygenases (COX), lipoxygenases (LOX), and cytochrome P450 (CYP450) followed by cytosolic and microsomal dehydrogenases can convert AA to lipid-derived electrophiles (LDE). Lipid-derived electrophiles are fatty acid derivatives bearing an electron-withdrawing group that can react with nucleophiles at proteins, DNA, and small antioxidant molecules exerting potent signaling properties. This review aims to describe the formation, sources, and electrophilic anti-inflammatory actions of key mammalian LDE.

Screening of Chemical Modifications in Human Skin Keratins by Mass Spectrometry-Based Proteomic Analysis via Noninvasive Sampling and On-Tape Digestion

Proteins are continuously exposed to diverse chemical stresses, and the resulting chemical modifications can provide significant information on biological events. Keratins are the main constituent of human skin and are the major target proteins of various chemical modifications. We have previously developed a mass spectrometry-based noninvasive proteomic methodology to screen oxidative modifications in human skin keratins. We have improved this methodology in terms of sample preparation time and amino acid sequence coverage using an on-tape digestion method. After sampling by tape stripping, skin proteins on the tape were subjected to reduction/alkylation, followed by trypsin digestion without a presolubilization step using detergents. To screen chemical modifications in keratins, target modifications and tryptic target peptides carrying the modification sites were determined from in vitro experiments with major reactive chemical species (4-hydroxy-2(E)-nonenal (HNE), 4-oxo-2(E)-nonenal, glucose, methylglyoxal, peroxynitrite, and hydrogen peroxide). The developed method was used to screen target modifications in controls and patients with a swollen red rash. Basal levels of lipid-derived modification, oxidation, nitration, and glycation in keratins were detected in controls. Principal component analysis based on the relative chemical modification resulted in a clear classification of both groups within a 95% confidence interval. Lipid-derived HNE modification increased most significantly in the patient group. This methodology can be easily applied to patients with other diseases, and the target modifications can be used as biomarkers of certain physiological conditions.

Enzymatic and non-enzymatic detoxification of 4-hydroxynonenal: Methodological aspects and biological consequences

4-Hydroxynonenal (HNE), an electrophilic end-product deriving from lipid peroxidation, undergoes a heterogeneous set of biotransformations including enzymatic and non-enzymatic reactions. The former mostly involve red-ox reactions on the HNE oxygenated functions (phase I metabolism) and GSH conjugations (phase II) while the latter are due to the HNE capacity to spontaneously condense with nucleophilic sites within endogenous molecules such as proteins, nucleic acids and phospholipids. The overall metabolic fate of HNE has recently attracted great interest not only because it clearly determines the HNE disposal, but especially because the generated metabolites and adducts are not inactive molecules (as initially believed) but show biological activities even more pronounced than those of the parent compound as exemplified by potent pro-inflammatory stimulus induced by GSH conjugates. Similarly, several studies revealed that the non-enzymatic reactions, initially considered as damaging processes randomly involving all endogenous nucleophilic reactants, are in fact quite selective in terms of both reactivity of the nucleophilic sites and stability of the generated adducts. Even though many formed adducts retain the expected toxic consequences, some adducts exhibit well-defined beneficial roles as documented by the protective effects of sublethal concentrations of HNE against toxic concentrations of HNE. Clearly, future investigations are required to gain a more detailed understanding of the metabolic fate of HNE as well as to identify novel targets involved in the biological activity of the HNE metabolites. These studies are and will be permitted by the continuous progress in the analytical methods for the identification and quantitation of novel HNE metabolites as well as for proteomic analyses able to offer a comprehensive picture of the HNE-induced adducted targets. On these grounds, the present review will focus on the major enzymatic and non-enzymatic HNE biotransformations discussing both the molecular mechanisms involved and the biological effects elicited. The review will also describe the most important analytical enhancements that have permitted the here discussed advancements in our understanding of the HNE metabolic fate and which will permit in a near future an even better knowledge of this enigmatic molecule.