Augustine Soon Hock Ong

Effect of dietary palm oil and its fractions on rat plasma and high density lipoprotein lipids.

Male Sprague Dawley rats were fed semipurified diets containing 20% fat for 15 weeks. The dietary fats were corn oil, soybean oil, palm oil, palm olein and palm stearin. No differences in the body and organ weights of rats fed the various diets were evident. Plasma cholesterol levels of rats fed soybean oil were significantly lower than those of rats fed corn oil, palm oil, palm olein or palm stearin. Significant differences between the plasma cholesterol content of rats fed corn oil and rats fed the three palm oils were not evident. HDL cholesterol was raised in rats fed the three palm oil diets compared to the rats fed either corn oil or soybean oil. The cholesterol-phospholipid molar ratio of rat platelets was not influenced by the dietary fat type. The formation of 6-keto-PGF1α was significantly enhanced in palm oil-fed rats compared to all other dietary treatments. Fatty acid compositional changes in the plasma cholesterol esters and plasma triglycerides were diet regulated with significant differences between rats fed the polyunsaturated corn and soybean oil compared to the three palm oils.

Fatty acid synthesis in the oil palm (Elaeis guineensis): incorporation of acetate by tissue slices of the developing fruit

Oil palm (E. guineensis) fruits at three stages of development were studied. At week 12–13 after anthesis, the endosperm had started accumulating oil and tissue slices incorporated [1-14C] acetate into fatty acids which resembled those found in the mature endosperm. The mesocarp contained very little oil and incorporated acetate into polar lipids. At week 16–17, the mesocarp started to accumulate oil; this was reflected in the [14C] lipid products from acetate incubation. At or just prior to this stage, an increase in the endogenous linoleic and linolenic acid content and the increase in fruit size indicated cellular growth in the mesocarp tissue. At week 20–21 the fruit was ripe, and both endosperm and mesocarp tissues were filled with storage oil. [14C] Fatty acids synthesized from acetate by mesocarp slices at this stage were the same as the endogenous storage fatty acids in bothE. guineensis andE. oleifera. A very weak fatty acid synthesizing activity was seen in the mature endosperm, but the products had no relationship to the storage lipid.

Changes in fatty acid composition of the lipid classes in developing oil palm mesocarp.

During fruit development of oil palm (Elaeis guineensis) oil deposition in the mesocarp startedca12–13 weeks after flowering (WAF) and continued until the fruit ripened at 20 WAF. Over the next 1–2 weeks oil continued to be deposited but the fruit became loose and readily detached from the bunch. The lipids extracted at this stage contained over 50 % free fatty acids andca6%, polar lipids. The major fatty acids in the storage triacylglycerols were 16:0,18:1 and 18:2. The fatty acid composition of the neutral lipid classes and polar lipids during oil deposition were similar except that the latter also contained a high proportion of 18:3. Longer chain acids (20:3 and 22:0) were detected in certain lipid classes at 8 and 12 WAF.

Lipid metabolism in oil palm (Elaeis guineensis and Elaeis oleifera) protoplasts

Abstract Protoplasts were enzymatically prepared from the mesocarp of two species of oil palm (Elaeis guineensis Jacq. and E. oleifera HBK and Cortes) 16–20 weeks after anthesis and from rapidly multiplying embryogenic cultures of E. guineensis. The protoplasts were purified by density gradient centrifugation in 20% (w/v) sucrose. Radioactive incorporation studies showed that the protoplasts metabolized [1-14C]acetate to lipids, water-soluble compounds and 14CO2. The [14C]fatty acids obtained consisted mainly of C16: 0, C18: 0 and C18: 1. C16: 1, a very minor fatty acid in palm oil, was also labelled and accounted for 8–39% of total fatty acids synthesized by the mesocarp and embryogenic culture protoplasts. The ratio of labelled C18: 0 to C18: 1 was found to vary with the age of the fruit from which the protoplasts were prepared. Thin layer chromatography (TLC) of the labelled lipids showed the presence of all neutral acylglycerol classes. However the distribution of radiolabel in the various classes differed from those previously reported for oil palm mesocarp [K.C. Oo et al. Lipids, 20 (1985) 205] and embryoid tissue slices [E. Turnham and D.H. Northcote, Phytochem., 23 (1984) 35]. Ozonolysis showed that all the labelled C18: 1 acid was vaccenic acid.

Stearic acids at sn -1, 3 positions of TAG are more efficient at limiting fat deposition than palmitic and oleic acids in C57BL/6 mice

In the present study, we investigated the effect of long-acyl chain SFA, namely palmitic acid (16:0) and stearic acid (18:0), at sn-1, 3 positions of TAG on obesity. Throughout the 15 weeks of the experimental period, C57BL/6 mice were fed diets fortified with cocoa butter, sal stearin (SAL), palm mid fraction (PMF) and high-oleic sunflower oil (HOS). The sn-1, 3 positions were varied by 16:0, 18:0 and 18:1, whilst the sn-2 position was preserved with 18:1. The HOS-enriched diet was found to lead to the highest fat deposition. This was in accordance with our previous postulation. Upon normalisation of total fat deposited with food intake to obtain the fat:feed ratio, interestingly, mice fed the SAL-enriched diet exhibited significantly lower visceral fat/feed and total fat/feed compared with those fed the PMF-enriched diet, despite their similarity in SFA-unsaturated fatty acid-SFA profile. That long-chain SFA at sn-1, 3 positions concomitantly with an unsaturated FA at the sn-2 position exert an obesity-reducing effect was further validated. The present study is the first of its kind to demonstrate that SFA of different chain lengths at sn-1, 3 positions exert profound effects on fat accretion.

Critical considerations for fast and accurate regiospecific analysis of triacylglycerols using quantitative 13C NMR

Quantitative 13C NMR (qCNMR) has been used as an appealing methodology for regiospecific analysis of triacylglycerols in edible oils and fats. It has advantages of shorter analysis time, precision and accuracy over laborious conventional Grignard or enzymatic hydrolysis method. Previous reported studies have recommended diversified NMR acquisition and processing parameters for the same quantification work. Different quantitative data were obtained by using a distinct sets of NMR parameters. To overcome this problem, we conducted a systematic investigation to examine the role of each acquisition and processing parameters to obtain high accuracy and repeatability data. Principal acquisition parameters, for instance pulse flip angle, repetition delay and temperature were investigated to correlate the targeted accuracies and practical experimental conditions. New data on spin-lattice relaxation times (T1) for carbonyl carbons in a variety of oils and fats had been obtained and analyzed comprehensively. With this set of acquisition parameters and free induction decay (FID) data processing method, error of less than 2.0 mol% were obtained with high repeatability and versatility for the analysis of oils and fats from diverse sources, including the reaction intermediates by chemical interesterification, lipids content extracted from biological samples and those natural occurring oils without their regiospecific data reported up-to-date. Instead of the semi-quantitative approach in previous reports on fish oil, we used narrower spectral width targeting sn-position in triacylglycerols to obtain full quantitative data in a shorter analysis time. The present selection of data acquisition and processing parameters led to a blueprint for a generic approach to performing a routinely practiced qCNMR regiospecific analysis.

Interesterified Palm Olein (IEPalm) and Interesterified Stearic Acid-Rich Fat Blend (IEStear) Have No Adverse Effects on Insulin Resistance: A Randomized Control Trial

Chemically-interesterified (CIE) fats are trans-fat free and are increasingly being used as an alternative to hydrogenated oils for food manufacturing industries to optimize their products’ characteristics and nutrient compositions. The metabolic effects of CIE fats on insulin activity, lipids, and adiposity in humans are not well established. We investigated the effects of CIE fats rich in palmitic (C16:0, IEPalm) and stearic (C18:0, IEStear) acids on insulin resistance, serum lipids, apolipoprotein concentrations, and adiposity, using C16:0-rich natural palm olein (NatPO) as the control. We designed a parallel, double-blind clinical trial. Three test fats were used to prepare daily snacks for consumption with a standard background diet over a period of 8 weeks by three groups of a total of 85 healthy, overweight adult volunteers. We measured the outcome variables at weeks 0, 6, and at the endpoint of 8. After 8 weeks, there was no significant difference in surrogate biomarkers of insulin resistance in any of the IE fat diets (IEPalm and IEStear) compared to the NatPO diet. The change in serum triacylglycerol concentrations was significantly lower with the IEStear diet, and the changes in serum leptin and body fat percentages were significantly lower in the NatPO-diet compared to the IEPalm diet. We conclude that diets containing C16:0 and C18:0-rich CIE fats do not affect markers of insulin resistance compared to a natural C16:0-rich fat (NatPO) diet. Higher amounts of saturated fatty acids (SFAs) and longer chain SFAs situated at the sn-1,3 position of the triacylglycerol (TAG) backbones resulted in less weight gain and lower changes in body fat percentage and leptin concentration to those observed in NatPO and IEStear.

Effects of Palm Olein-Olive Oil Blends on Fat Deposition in Diet-Induced Obese Mice

Current knowledge on the partial replacement of palm olein with olive oil on fat deposition is inadequate, thus leading to our interest to unveil the effects of palm olein on fat deposition by using mouse model. Our findings revealed that the normalized subcutaneous adipose tissues weight, liver weight and body weight gain of mice fed with either palm olein or the blends were remarkably lower than the mice fed with olive oil. The weight of subcutaneous adipose tissues of mice fed with palm olein and blend (PO:OO=50:50) were significantly lower than the mice fed with olive oil. In addition, body weight of the mice in palm olein group were significantly lower than those fed with olive oil group. The results implied that the mice fed with palm olein and palm olein-olive oil blends are less fattening than those fed with olive oil.

Lipid Biosynthesis in Oil Palm Protoplasts

Protoplasts offer several advantages for metabolic studies. They provide a homogenous single-celled system and ensure the even distribution of precursors into the cell. The reaction products can be isolated more quickly and at higher purity. One of the main attractions of employing protoplasts for studying lipid metabolism is their ease of lysis. Organelles can be separated with minimal injury. The study of lipid metabolism in mesocarp and embryoid protoplasts of the oil palm is described.