Norsyahida Mohd Fauzi

A comparison of five lipid extraction solvent systems for lipidomic studies of human LDL

Lipidome profile of fluids and tissues is a growing field as the role of lipids as signaling molecules is increasingly understood, relying on an effective and representative extraction of the lipids present. A number of solvent systems suitable for lipid extraction are commonly in use, though no comprehensive investigation of their effectiveness across multiple lipid classes has been carried out. To address this, human LDL from normolipidemic volunteers was used to evaluate five different solvent extraction protocols [Folch, Bligh and Dyer, acidified Bligh and Dyer, methanol (MeOH)-tert-butyl methyl ether (TBME), and hexane-isopropanol] and the extracted lipids were analyzed by LC-MS in a high-resolution instrument equipped with polarity switching. Overall, more than 350 different lipid species from 19 lipid subclasses were identified. Solvent composition had a small effect on the extraction of predominant lipid classes (triacylglycerides, cholesterol esters, and phosphatidylcholines). In contrast, extraction of less abundant lipids (phosphatidylinositols, lyso-lipids, ceramides, and cholesterol sulfates) was greatly influenced by the solvent system used. Overall, the Folch method was most effective for the extraction of a broad range of lipid classes in LDL, although the hexane-isopropanol method was best for apolar lipids and the MeOH-TBME method was suitable for lactosyl ceramides.

An inter-laboratory validation of methods of lipid peroxidation measurement in UVA-treated human plasma samples

Abstract Lipid peroxidation products like malondialdehyde, 4-hydroxynonenal and F2-isoprostanes are widely used as markers of oxidative stress in vitro and in vivo. This study reports the results of a multi-laboratory validation study by COST Action B35 to assess inter-laboratory and intra-laboratory variation in the measurement of lipid peroxidation. Human plasma samples were exposed to UVA irradiation at different doses (0, 15 J, 20 J), encoded and shipped to 15 laboratories, where analyses of malondialdehyde, 4-hydroxynonenal and isoprostanes were conducted. The results demonstrate a low within-day-variation and a good correlation of results observed on two different days. However, high coefficients of variation were observed between the laboratories. Malondialdehyde determined by HPLC was found to be the most sensitive and reproducible lipid peroxidation product in plasma upon UVA treatment. It is concluded that measurement of malondialdehyde by HPLC has good analytical validity for inter-laboratory studies on lipid peroxidation in human EDTA-plasma samples, although it is acknowledged that this may not translate to biological validity.

Synthesis of unsymmetrical monocarbonyl curcumin analogues with potent inhibition on prostaglandin E2 production in LPS-induced murine and human macrophages cell lines.

The syntheses and bioactivities of symmetrical curcumin and its analogues have been the subject of interest by many medicinal chemists and pharmacologists over the years. To improve our understanding, we have synthesized a series of unsymmetrical monocarbonyl curcumin analogues and evaluated their effects on prostaglandin E2 production in lipopolysaccharide-induced RAW264.7 and U937 cells. Initially, compounds 8b and 8c exhibited strong inhibition on the production of PGE2 in both LPS-stimulated RAW264.7 (8b, IC50=12.01μM and 8c, IC50=4.86μM) and U937 (8b, IC50=3.44μM and 8c, IC50=1.65μM) cells. Placing vanillin at position Ar2 further improved the potency when both compounds 15a and 15b significantly lowered the PGE2 secretion level (RAW264.7: 15a, IC50=0.78μM and 15b, IC50=1.9μM while U937: 15a, IC50=0.95μM and 15b, IC50=0.92μM). Further experiment showed that compounds 8b, 8c, 15a and 15b did not target the activity of downstream inflammatory COX-2 mediator. Finally, docking simulation on protein targets COX-2, IKK-β, ERK, JNK2, p38α and p38β were performed using the conformation of 15a determined by single-crystal XRD.

Effects of chalcone derivatives on players of the immune system.

The immune system is the defense mechanism in living organisms that protects against the invasion of foreign materials, microorganisms, and pathogens. It involves multiple organs and tissues in human body, such as lymph nodes, spleen, and mucosa-associated lymphoid tissues. However, the execution of immune activities depends on a number of specific cell types, such as B cells, T cells, macrophages, and granulocytes, which provide various immune responses against pathogens. In addition to normal physiological functions, abnormal proliferation, migration, and differentiation of these cells (in response to various chemical stimuli produced by invading pathogens) have been associated with several pathological disorders. The unwanted conditions related to these cells have made them prominent targets in the development of new therapeutic interventions against various pathological implications, such as atherosclerosis and autoimmune diseases. Chalcone derivatives exhibit a broad spectrum of pharmacological activities, such as immunomodulation, as well as anti-inflammatory, anticancer, antiviral, and antimicrobial properties. Many studies have been conducted to determine their inhibitory or stimulatory activities in immune cells, and the findings are of significance to provide a new direction for subsequent research. This review highlights the effects of chalcone derivatives in different types of immune cells.

Analysis of oxidized and chlorinated lipids by mass spectrometry and relevance to signalling

Oxidized and chlorinated phospholipids are generated under inflammatory conditions and are increasingly understood to play important roles in diseases involving oxidative stress. MS is a sensitive and informative technique for monitoring phospholipid oxidation that can provide structural information and simultaneously detect a wide variety of oxidation products, including chain-shortened and -chlorinated phospholipids. MSn technologies involve fragmentation of the compounds to yield diagnostic fragment ions and thus assist in identification. Advanced methods such as neutral loss and precursor ion scanning can facilitate the analysis of specific oxidation products in complex biological samples. This is essential for determining the contributions of different phospholipid oxidation products in disease. While many pro-inflammatory signalling effects of oxPLs (oxidized phospholipids) have been reported, it has more recently become clear that they can also have anti-inflammatory effects in conditions such as infection and endotoxaemia. In contrast with free radical-generated oxPLs, the signalling effects of chlorinated lipids are much less well understood, but they appear to demonstrate mainly pro-inflammatory effects. Specific analysis of oxidized and chlorinated lipids and the determination of their molecular effects are crucial to understanding their role in disease pathology.

Roselle is cardioprotective in diet-induced obesity rat model with myocardial infarction

Aims: Obesity increase the risks of hypertension and myocardial infarction (MI) mediated by oxidative stress. This study was undertaken to investigate the actions of roselle aqueous extract (R) on cardiotoxicity in obese (OB) rats and thereon OB rats subjected to MI. Main methods: Male Sprague‐Dawley rats were fed with either normal diet or high‐fat diet for 8 weeks. Firstly, OB rats were divided into (1) OB and (2) OB + R (100 mg/kg, p.o, 28 days). Then, OB rats were subjected to MI (ISO, 85 mg/kg, s.c, 2 days) and divided into three groups: (1) OB + MI, (2) OB + MI + R and (3) OB + MI + enalapril for another 4 weeks. Key findings: Roselle ameliorated OB and OB + MIs cardiac systolic dysfunction and reduced cardiac hypertrophy and fibrosis. The increased oxidative markers and decreased antioxidant enzymes in OB and OB + MI groups were all attenuated by roselle. Significance: These observations indicate the protective effect of roselle on cardiac dysfunction in OB and OB + MI rats, which suggest its potential to be developed as a nutraceutical product for obese and obese patients with MI in the future.

Effects of synthetic chalcone derivatives on oxidised palmitoyl arachidonoyl phosphorylcholine-induced proinflammatory chemokines production

Oxidised 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphorylcholine (OxPAPC) induces the production of proinflammatory chemokines has been widely studied for its role in vascular inflammation. There is increasing evidence on the role of chalcones as potential anti-inflammatory agents but less is known about its effects on OxPAPC-induced chemokines production and the involvement of unfolded protein response (UPR) signalling, particularly through XBP1 pathway. The present study sought to investigate the inhibitory potential of synthetic chalcone derivatives on the release of interleukin-8 (IL-8) and monocyte chemoattractant protein-1 (MCP-1), induced by OxPAPC through XBP1 signalling pathway on differentiated U-937 macrophages. The effects of synthetic chalcone derivatives on the chemokines productions were investigated using enzyme-linked immunosorbent assays, while the inhibitions of XBP1 signalling were detected using western immunoblot. Results show that all the three tested synthetic chalcone derivatives inhibited OxPAPC-induced chemokines production in a concentration-dependent manner. Compound 1.5 exhibited the strongest inhibition of IL-8 and MCP-1 at 61.4 ± 4.23% and 63.8 ± 2.16%, respectively. Compound 1.5 also achieved the lowest IC50 values for both IL-8 (18.33 ± 1.59 μM) and MCP-1 (13.05 ± 1.37 μM) inhibitions. For XBP1 protein expression, both compound 1.4 and 1.5 exhibited significant concentration-dependent suppression of the protein expressions. The results suggest that synthetic chalcone derivatives may serve as potential alternatives for future development of anti-inflammatory agents, particularly in vascular inflammation.

Hibiscus sabdariffa (Roselle) Polyphenol-rich Extract Averts Cardiac Functional and Structural Abnormalities in Type 1 Diabetic Rats

Diabetes mellitus is often associated with cardiac functional and structural alteration, an initial event leading to cardiovascular complications. Roselle (Hibiscus sabdariffa) has been widely proven as an antioxidant and recently has incited research interest for its potential in treating cardiovascular disease. Therefore, this study aimed to determine the cardioprotective effects of H. sabdariffa (roselle) polyphenol-rich extract (HPE) in type-1-induced diabetic rats. Twenty-four male Sprague-Dawley rats were randomized into 4 groups (n = 6/group): nondiabetic, diabetic alone (DM), diabetic supplemented with HPE (DM+HPE), and diabetic supplemented with metformin. Type-1 diabetes was induced with streptozotocin (55 mg/kg intraperitoneally). Rats were forced-fed with HPE (100 mg/kg) and metformin (150 mg/kg) daily for 8 weeks. Results showed that HPE supplementation improved hyperglycemia and dyslipidemia significantly (p < 0.05) in the DM+HPE compared with the DM group. HPE supplementation attenuated cardiac oxidative damage in the DM group, indicated by low malondialdehyde and advanced oxidation protein product. As for the antioxidant status, HPE significantly (p < 0.05) increased glutathione level, as well as catalase and superoxide dismutase 1 and 2 activities. These findings correlate with cardiac function, whereby left ventricle developed pressure in DM+HPE (79.13 ± 3.08 mm Hg) was higher significantly compared with DM (45.84 ± 1.65 mm Hg). Coronary flow of DM+HPE (17.43 ± 0.62 mL/min) was also greater compared with DM (13.02 ± 0.6 mL/min), showing that HPE supplementation improved cardiac contractility and relaxation rate significantly (p < 0.05). Histological analysis showed a marked decrease in cardiomyocyte hypertrophy and fibrosis in DM+HPE compared with the DM group. Ultrastructural changes and impairment of mitochondria induced by diabetes were minimized by HPE supplementation. Collectively, these findings suggest that HPE is a potential cardioprotective agent in a diabetic setting through its hypoglycemic, anti-hyperlipidemia, and antioxidant properties.