Browsing by Author "Gunawardane, M."

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Antioxidant and Nutritional Properties of Domestic and Commercial Coconut Milk Preparations
(International Journal of Food Science, 2020) Karunasiri, A.N.; Gunawardane, M.; Senanayake, C.M.; Jayathilaka, N.; Senevirathne, K.N.
The aqueous extract of scraped coconut kernel is known as coconut milk. Coconut milk preparations are also commercially available in the form of desiccated powders or liquids. While these various coconut milk preparations are heavily used in cooking in the Asian countries as a major source of dietary fat, limited studies have been conducted on their chemical and nutritional composition. In this study, we have determined the chemical composition and nutritional effects of both domestic preparations of coconut milk and the commercially available counterparts. The results indicate that the phenolic compounds of all coconut milk preparations provide protection against oxidative damage on lipids and inhibit oxidative damage of both proteins and DNA. The lipid profiles are not significantly affected by the consumption of the three coconut milk preparations despite their different fat contents.
Effect of coconut milk on intestinal barrier function and management of oxidative stress
(Faculty of Graduate Studies, University of Kelaniya Sri Lanka, 2022) Ambanpola, N.; Anjali, N. V. P.; Manilgama, T.; Gunawardane, M.; Seneviratne, K. N.; Jayathilaka, N.
Coconut milk (CM) is a major source of dietary fat in a Sri Lankan meal. It is rich in saturated, medium-chain fatty acids (MCFA) and various polyphenols. Some of the ingested fats and polyphenols are not absorbed in the small intestine and reach the colon. This study assessed the formation of metabolic products from CM and the influence of CM on intestinal barrier function. Twelve-week-old female Wistar rats were housed at 25 ± 1°C with a 12 h light and dark cycle. Rats were randomly assigned to two experimental groups (12 rats/ group). Ad libitum access to water and a diet containing 4.2 % total fat; from that 3% fat by means of soybean oil (SOD) control or CM (CMD) was provided for four weeks. Six rats from each group fasted for 10–12 h and were treated with ethanol (20%, 6 g/kg body weight) by oral gavage (SODM and CMDE groups were obtained). Blood (1 mL) was then drawn from the tail vein. Plasma antioxidant capacity, lipid peroxidation, and protein carbonyl content were determined by 2,2-diphenyl-1-picryl-hydrazy (DPPH) assay, ferric reducing antioxidant power (FRAP) assay, protein carbonyl assay, and thiobarbituric acid reactive substances (TBARS) assay according to previously reported methods. At the end of the feeding experiments, animals were subjected to barbiturate euthanasia and a transverse abdominal incision was made. The cecal wash samples with phosphate-buffered saline (pH 7.4) were stored at -80 °C. Liver and brain samples were also harvested. All experimental procedures were approved by the Ethics Review Committee, University of Kelaniya. Short-chain fatty acids (SCFAs) in the cecal wash, plasma, liver, and brain samples were quantified by Gas chromatography. SCFA levels were determined by the standard curves of each SCFA. Shapiro-Wilk normality test (P<0.05) and t-test was used for the statistical comparison. Acetate, propionate, and butyrate concentrations were 802.9±0.4 μg/mL, 156.3±2.1 μg/mL, 20.5±0.4 μg/mL and 802.8±0.4 μg/mL, 153.5±1.7 μg/mL, 19.9±0. μg/mL in CMD and SOD cecal wash samples respectively. Acetate, propionate, and butyrate concentrations were 236.2±0.1 μg/mL, 16.2±0.2 μg/mL, 1.3±0.0 μg/mL and 226.3±1.4 μg/mL, 14.4±0.2 μg/mL, 1.2±0.0 μg/mL in CMD and SOD plasma samples respectively. There was a significant (P<0.05) difference between plasma acetate and propionate levels in CMD compared to SOD. SCFAs were not detected in liver and brain samples. Saccharolytic microbes ferment oligo- and polysaccharides and produce SCFAs. Following their production SCFAs are rapidly absorbed by colonic cells and those not metabolized by colonic cells pass into the liver. Thus, only a small amount of the SCFAs reach systemic circulation and other tissues. Alcohol causes oxidative stress by releasing reactive oxygen species (ROS) during alcohol metabolism. Polyphenols serve as exogenous antioxidants, and they scavenge free radicals to control ROS. According to the four assays, there were no significant differences in the antioxidant capacity between the four groups suggesting no antioxidant effect of coconut milk over soy oil control. Thus, CM has a significant (P<0.05) impact on SCFAs passing through the intestinal barrier but no effect on the management of oxidative stress than soy oil.
Metagenomic analysis of the effect of coconut milk on the colon microbiota
(Faculty of Graduate Studies, University of Kelaniya Sri Lanka, 2022) Ambanpola, N.; Anjali, N. V. P.; Manilgama, T.; Gunawardane, M.; Seneviratne, K. N.; Jayathilaka, N.
The main source of fat in the diet affects the gut microbiome composition. Coconut milk (CM) has a high percentage of medium chain fatty acids (MCFA). A portion of MCFA reaches the colon and is fermented by the microbiota. This study was conducted with Wistar rats to study the effect of CM on colonic microbial diversity. Twelve-week-old female Wistar rats were randomly assigned to two experimental groups (12 rats/group). Ad libitum access to water and food was provided throughout the study. The control group was fed with a WHO-recommended diet containing 4.2 % total fat; of that 3% fat from soybean oil (SOD). The other group was fed a diet in which the fat component was replaced with CM (CMD). After 28 days, six rats from each group were fasted for 10–12 h and treated with ethanol (20%, 6 g/kg body weight) by oral gavage (SODE and CMDE). Mean ± standard deviation (SD) feed Intakes were 900.50±4.93 g, 899.50±9.31 g, 818.00±6.57 g, 820.00±6.57 g and body weight gains were 52.83±1.83 g, 52.33±1.75 g, 45.50±2.43 g, 47.33±2.34 g in CMD, CMDE, SOD and SODE groups respectively. Feed conversion rates were approximately equal in the four groups (average 0.0580±0.002). At the end of the feeding experiments, animals were subjected to barbiturate euthanasia and a transverse abdominal incision was made. The cecal wash samples with phosphate-buffered saline (pH 7.4) were stored at -80 °C. All experimental procedures were approved by the Ethics Review Committee, University of Kelaniya. Microbial DNA was isolated from cecal wash samples using DNeasy blood and tissue kit (Qiagen). The 16S rRNA gene libraries were prepared and sequenced according to the protocols recommended by Ion Torrent (Ion GeneStudio S5 prime system, Thermo Fisher Scientific). Trimmed sequences were clustered into operational taxonomic units (OTUs) with a hierarchical cutoff of 97.0% similarity using Ion Reporter v5.16. Taxonomic annotation was conducted against Curated MicroSEQ 16S Reference Library v2013.1 and Curated Greengenes v13.5 databases. Alpha-diversity and beta-diversity analyzes were performed using the QIIME2 platform. Bacteroidetes and Firmicutes phyla represent 90% of the cecal bacterial community across dietary groups. Other microbial phyla in the cecal wash samples were Actinobacteria, Proteobacteria, and Tenericutes. The cecal microbiota of CMD-fed rats was characterized by a significant increase (P<0.05) in the relative abundance of Desulfovibrionaceae, Eubacteriaceae, Erysipelotrichaceae, Lachnospiraceae Porphyromonadaceae, Ruminococcaceae bacterial families, and a decreased relative abundance of Bacteroidaceae, Clostridiaceae and Lactobacillaceae compared to the control diet. Studies have shown that alcohol promotes both dysbiosis and bacterial overgrowth. According to the two factor ANOVA, there was a significant difference (P<0.05) in colonic-microbiota between the four groups. Family level rarefaction plots were varied CMD>CMDE>SOD>SODE and CMD>SODE>CMDE>SOD according to Chao1 index and Simpson’s indexes respectively. Principle component analysis revealed four distinct clusters, suggesting that both diet and alcohol-induced oxidative stress affected gut microbiota. The elevated bacterial families have an impact on microbial-mediated saccharolytic functions, lipophilic functions, vitamin synthesis, and protection against intestinal infections. Thus, the intestinal microbiota in Wistar rats varies significantly with dietary fat source and oxidative stress conditions.