Paresh C. Dutta

Cholesterol and phytosterol oxidation products : analysis, occurrence, and biological effects

Cholesterol Oxidation Products 1. Cholesterol Oxidation Mechanisms 2. Extraction and Purification of Cholesterol Oxidation Products 3. Determination of Cholesterol Oxidation Products by Gas Chromatography 4. Determination of Cholesterol Oxidation Products by High-Performance Liquid Chromatography 5. Determination of Cholesterol Oxidation Products by Thin-Layer Chromatography 6. Harmonization of Cholesterol Oxidation Product Analysis 7. Formation and Content of Cholesterol Oxidation Products in Egg and Egg Products 8. Formation and Content of Cholesterol Oxidation Products in Milk and Dairy Products 9. Formation and Content of Cholesterol Oxidation Products in Meat and Meat Products 10. Formation and Content of Cholesterol Oxidation Products in Seafood and Seafood Products 11. Formation and Content of Cholesterol Oxidation Products in Other Foods 12. Origin and Content of Cholesterol Oxidation Products in Biological Samples 13. Cholesterol Oxidation Products and Atherosclerosis 14. Cholesterol Oxidation Products: Other Biological Effects Phytosterol Oxidation Products 15. Formation and Content of Phytosterol Oxidation Products in Foods 16. Determination of Phytosterol Oxidation Products in Foods and Biological Samples 17. Biological Effects of Phytosterol Oxidation Products, Future Research Areas and Concluding Remarks

Oxidative stability and lipid composition of macadamia nuts grown in New Zealand

This study was undertaken to identify the parameters which might influence the stability and storage characteristics of some selected cultivars of macadamia nuts grown in New Zealand. Four cultivars of macadamia nuts (Macadamia tetraphylla) were harvested from the North Island of New Zealand during 1997. Total lipids, composition of fatty acids, tocopherols, sterols and stability of oils, were determined on the oil extracted from the fresh nuts. The total lipid content of the nuts ranged from 69 to 78%, while the stability of the oil measured by Rancimat test ranged from 3.6 to 19.8 h. Peroxide values of the fresh oil ranged from 0.56 to 3.61 meq O2/kg oil. The major fatty acids were oleic acid, palmitoleic acid and palmitic acid; oleic acid accounted for 40.6 to 59% of the total fatty acids. The polyunsaturated fatty acid (18:2+18:3) content was low, ranging from 3.0 to 4.7%. a-Tocopherol (0.8‐1.1 mg/g lipids) and d-tocopherol (3.5‐4.8 mg/g lipids) were the only two tocopherols identified in the extracted oil. The major sterols identified were sitosterol (901‐1354 mg/g lipids), 5-avenasterol (82‐207 mg/g lipids), campesterol (61‐112 mg/g lipids) and stigmasterol (8‐19 mg/g lipids). # 2000 Elsevier Science Ltd. All rights reserved.

Phytosterols as functional food components and nutraceuticals.

Series Introduction, F. ShahidiPrefaceContributorsOccurrence and Levels of Phytosterols in Foods, V. Piironen and A. LampiAnalysis of Phytosterols in Foods, A. Lampi, V. Piironen, and J. ToivoPlant Sterol Analysis in Relation to Functional Foods, G. Duchateau, H. Janssen, and A. LouterAnalysis of Phytosterols in Biological Samples, A. KuksisDoes Phytosterol Intake Affect the Development of Cancer?, L. Norm?n and S. AnderssonRole of Plant Sterols in Cholesterol Lowering, L. Norm?n, J. Frohlich, and E. TrautweinPlant Sterols in Functional Foods, R. MoreauSafety of Phytosterols and Phytosterol Esters as Functional Food Components, D. KritchevskyPotential Health Risks Associated with Large Intakes of Plant Sterols, W. Ratnayake and E. VavasourChemistry, Analysis, and Occurrence of Phytosterol Oxidation Products in Foods, P. DuttaBiological Effects and Safety Aspects of Phytosterol Oxides, L. Dean and L. BoydProspects of Increasing Nutritional Phytosterol Levels in Plants, T. Miettinen and H. GyllingIndex

Evaluation of GC and GC–MS methods for the analysis of cholesterol oxidation products

Abstract Various methods are used to analyse cholesterol oxidation products (COP) due to the unavailability of a standard method. In order to select a suitable method for the enrichment of COP, three methods of saponification (A–C), and transesterification (D) of tallow with three levels (5, 10 and 20 μg) of spiked COP, were evaluated. Further enrichment of COP was done by solid phase extraction, quantified by GC, and confirmed by GC–MS. The in-house method A, and method D showed,the best results among the four methods evaluated. The recoveries at all levels of spiked COP were generally higher than 60% in method A. The recoveries of all spiked COP at 5 μg level were consistently lower in method D compared with method A. From the results of this study it can be concluded that method A may be more suitable for the analysis of very low levels of COP in foods.

A single step solid-phase extraction method for complete separation of sterol oxidation products in food lipids.

One of the crucial steps in determination of sterol oxidation products (SOPs) in foods is their enrichment and purifications by various preparative methods for further analysis by GC and GC-MS. Among the preparative methods, SPE of various adsorbents and solvent systems, are being used most widely. At present, no single step SPE method is suitable to completely separate the SOPs. In this study, a SPE (1g silica) method, suitable for both transesterified and cold saponified oil samples, was developed to separate completely SOPs from other lipid components. This method resulted in high recovery from rapeseed oil of added 5beta,6beta-epoxycholestan-3beta-ol (94-96%), cholest-5-en-3beta-ol-7-one(94%), cholestane-3beta,5alpha,6beta-triol (88-91%), cholest-5-en-3beta,7alpha-diol and 5alpha,6alpha-epoxycholestan-3beta-ol (88-90%). The method has a high sample capacity of up to 1g transesterified or cold-saponified oil sample. The method was tested and applied to different vegetable oils and to monitor the effects of refining processes on POPs in hazelnut oil.

Wax esters of different compositions produced via engineering of leaf chloroplast metabolism in Nicotiana benthamiana

In a future bio-based economy, renewable sources for lipid compounds at attractive cost are needed for applications where today petrochemical derivatives are dominating. Wax esters and fatty alcohols provide diverse industrial uses, such as in lubricant and surfactant production. In this study, chloroplast metabolism was engineered to divert intermediates from de novo fatty acid biosynthesis to wax ester synthesis. To accomplish this, chloroplast targeted fatty acyl reductases (FAR) and wax ester synthases (WS) were transiently expressed in Nicotiana benthamiana leaves. Wax esters of different qualities and quantities were produced providing insights to the properties and interaction of the individual enzymes used. In particular, a phytyl ester synthase was found to be a premium candidate for medium chain wax ester synthesis. Catalytic activities of FAR and WS were also expressed as a fusion protein and determined functionally equivalent to the expression of individual enzymes for wax ester synthesis in chloroplasts.

Protective effect of Actiniopteris radiata (Sw.) Link. against CCl4 induced oxidative stress in albino rats

ETHNOPHARMACOLOGICAL RELEVANCE Actiniopteris radiata is a herb with great medicinal value and is evaluated for hepatoprotective activity. To investigate the protective effect of ethanolic extract of Actiniopteris radiata (EEAR) on CCl₄ induced oxidative stress in male Wistar albino rats. MATERIALS AND METHODS EEAR were administered for 8 consecutive weeks to rats. Group I - control; Group II - toxin control (30% CCl₄); Group III and Group IV received EEAR (250 and 500 mg/kg respectively). Antioxidant status in liver were estimated by determining the activities of the antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx); as well as by determining the levels of lipid peroxidation (LPO) and reduced glutathione (GSH). In addition, isoenzyme pattern and mRNA expression of the antioxidants were studied. Partial characterization of EEAR was performed by Liquid chromatography-mass spectrometry (LC-MS). RESULTS CCl₄ induced oxidative stress as evidenced from increase in LPO along with reduction of SOD, CAT, GPx and GSH. Treatment with EEAR (250 and 500 mg/kg) mitigated the CCl₄ induced oxidative stress. An analysis of the isozyme pattern of these antioxidant enzymes revealed variations in SOD2, CAT, GPx2 and GPx3 in CCl₄ treated rats, which were normalized after EEAR treatment. Furthermore, expression of genes for the antioxidant enzymes, were down-regulated by CCl₄ treatment, which were reversed by EEAR. The results of partial characterization of EEAR by LC-MS revealed the presence of rutin and other 7 unknown phenolic derivatives. CONCLUSIONS These findings suggest the protective effect of EEAR against CCl₄ induced oxidative stress might be attributed to the presence of flavonoids and phenolic compounds.

Novel Conjugates of 1,3-Diacylglycerol and Lipoic Acid: Synthesis, DPPH Assay, and RP-LC-MS-APCI Analysis

1,3-Diacylglycerol is known to reduce body weight and fat deposits in humans. α-Lipoic acid is a potent antioxidant and effective against many pathological conditions, including obesity and related metabolic syndromes. The present work is based on the hypothesis that the hybrid molecules of 1,3-diacylglycerol and lipoic acid possess synergistic and/or additive effects compared with the parent compounds against obesity, overweight, and related metabolic syndromes. Laboratory scale synthesis of 1,3-dioleoyl-2-lipoyl-sn-glycerol (yield 80%) and 1,3-dioleoyl-2-dihydrolipoyl-sn-glycerol (yield 70%) was performed for the first time and supported by NMR and MS data. Free radical scavenging capacity of the conjugates was assayed using DPPH test. A remarkably high in vitro free radical scavenging capacity was demonstrated for the 1,3-dioleoyl-2-dihydrolipoyl-sn-glycerol (EC50 value 0.21). RP-HPLC-MS-APCI analysis showed satisfactory separation between the conjugates (R~1). Protonated molecular ion of the conjugates at m/z 809 and m/z at 811, respectively, and their characteristic fragment ions were abundant.

Eggs of Baltic salmon displaying M74, yolk sac mortality syndrome have elevated levels of cholesterol oxides and the fatty acid 22:6 n-3

Abstract In this study, level of cholesterol oxidation products (COPs), fatty acids and carotenoids were compared between healthy and M74 yolk sac mortality syndrome-affected eggs in two Swedish stocks of Baltic salmon ( Salmo salar ). In addition were eggs from one stock of Atlantic salmon, originating from a Swedish west coast river analysed. This syndrome is believed to be the result of a combined environmental load of anthropogenic substances like chloroorganic pollutants and their metabolites. The syndrome is so far only found in Baltic salmon spending their post-smolt period in the Baltic Sea. COPs were significantly higher ( p =0.0289) in Baltic salmon eggs suffering from M74 than in healthy eggs, while no difference was found between healthy Baltic salmon eggs and those from the Atlantic stock ( p >0.05). The absolute level of COPs varied between rivers and year classes, while the level of cholesterol was relatively stable. However, the level of COPs was always higher in the M74-affected eggs compared to their healthy counterparts. The content of the fatty acid 22:6 n-3 (DHA; docosahexaenoic acid) was higher and astaxanthin lower in M74-affected eggs ( p =0.0056; p =0.0078, respectively) compared to healthy ones of the same stock and year class.

Cholesterol and lipid oxidation in raw and pan-fried minced beef stored under aerobic packaging.

BACKGROUND The type of packaging atmosphere has been reported as a technological factor that consistently affects the quality of lipid fraction in meat. Oxidation of cholesterol and lipids was evaluated before and after pan frying in commercial refrigerated minced beef stored under aerobic atmosphere for 1 and 8 days. RESULTS In raw beef, cholesterol and lipid oxidation developed at a slow rate. Cholesterol oxidation products (COPs) did not significantly vary (approximately 8 microg COPs g(-1) of fat) over 8 days, while in the same period thiobarbituric acid reactive substances (TBARS) less than doubled (from 0.7 to 1.2 malondialdehyde equivalents kg(-1) of muscle). Pan frying did not influence the oxidative degree in the fresh product but consistently catalyzed cholesterol oxidation in stored beef. A significant increase was assessed in beef at the end of storage: from 8.6 to 30.0 microg COPs g(-1) of fat in raw and cooked beef, respectively. CONCLUSION Aerobic packaging did not appear as a pro-oxidant factor in fresh minced beef with a good oxidative quality during a short period of refrigerated storage.