International Postgraduate Research Conference (IPRC)
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Item Antioxidant Effect of Coconut Milk on Oxidative Damage in Commensal Lactobacilli in the Gastrointestinal Tract(International Postgraduate Research Conference 2019, Faculty of Graduate Studies, University of Kelaniya, Sri Lanka, 2019) Karunasiri, A.N.; Gunawardena, M.; Seneviratne, K.; Jayathilaka, N.Coconut milk (CM) is the aqueous extract of coconut endosperm which is rich in polyphenols. Coconut milk is commonly used in culinary applications in South Asia. In this study, protective effect of phenolic antioxidants (PA) extracted from CM was tested in lactobacilli which are the prominent probiotic forms in the human gut. These commensals help to maintain the immune and metabolic homeostasis. The intestinal environment can be altered by many factors that generate reactive oxygen species (ROS) resulting in oxidative stress. Enteric bacteria have been reported to mediate redox homeostasis through the regulation of ROS production. However, oxidative damage to the gut microbiota has been suggested to contribute to several diseases including intestinal and neurodegenerative disorders. Here, the activity of phenolic antioxidants extracted from CM on oxidative damage in Lactobacillus acedophillus, L. plantarum, L. lactis, L. casei and L. fermentum under aerobic conditions were evaluated based on the amount of products of macromolecular damage. The total polyphenol content of aqueous extract of CM was 8.21±0.13 mg/L as determined by the Folin Ciocalteu method. Bacterial cultures at optical density of 0.5 at 620 nm were incubated at 37°C under aerobic conditions to induce the oxidative damage. The cells were cultured overnight with a concentration series of PA (0, 0.4, 0.5, 0.6, 0.7, 0.8 and 0.9 mg/mL) to assess the protective effect on oxidative damage. The concentration of PA was kept below the concentration that affect cell viability as determined by 2,3,5-triphenyltetrazolium chloride assay at 620 nm. Lipid peroxide levels (μg/mL) and protein carbonyl levels (nmol/mL) were detected with thiobarbituric acid and 2,4-DNPH respectively. Growth under aerobic conditions affected the cell viability and induced significant (P<0.05) damage to proteins and lipids in the lactobacilli under investigation. Treatment with increasing concentrations of PA from CM showed a corresponding increase in the cell viability and a corresponding decrease in the amount of lipid peroxides and protein carbonyls under aerobic conditions. Therefore, PA from CM protect gut microbiota from oxidative damages in lipid and proteins without affecting their viability.Item Nutritional Effect of Consumption of Domestic and Commercially Available Coconut Milk Preparations in Wistar Rats.(In: Proceedings of the International Postgraduate Research Conference 2017 (IPRC – 2017), Faculty of Graduate Studies, University of Kelaniya, Sri Lanka., 2017) Senanayake, C.M.; Seneviratne, K.N.; Jayathilaka, N.; Ekanayaka, S.The use of both domestic coconut milk (CM) preparations and commerciallyavailable CM preparations in cooking has become popular. The present study involves evaluating In vivo effect of domestic CM prepared by blending (BCM), commercially available powdered CM (PCM) and liquid CM (LCM) on serum lipid profiles and serum antioxidant capacity using Wistar rats. Seven weeks old male Wistar rats were randomly assigned into treatment groups. Control group was fed with a semisynthetic diet recommended by WHO. Second, third and fourth groups were fed with semi synthetic diet which contains 12 mL BCM, PCM or LCM per kg of feed respectively. Blood was drawn on day before feeding experimental diets (Day 0), 30 days, 90 days, 120 days and 150 days after feeding experimental diets. Serum total cholesterol (TC), high density lipoprotein (HDL) and triglycerides (TG) were analyzed using a test kit. Low density lipoprotein (LDL) was determined using Friedewald equation. Antioxidant activity of serum was determined by ABTS assay and DPPH radical scavenging assay. TC levels of all groups were significantly (p<0.05) increased after 150 days of feeding compared to their day 0 levels. TC levels (mg/dL) of rats fed with BCM (80±4), PCM (80±5) and LCM (81±3) were similar to control group (77±7). However, rats fed with LCM showed a statistically significant (p<0.05) increase in TC compared to control group. Although, TG levels of CM diet groups indicated significant (p<0.05) increase on day 150 compared to their day 0 levels, these levels were similar to that of control group. Both HDL and LDL levels of CM diet groups remained same compared to control group at day 150. All CM diet groups showed a significantly (p<0.05) increased activity on day 150 compared to their day 0 levels.CM fat contains nearly 90 % saturated fat. However, majority of the saturated fat in CM fatis composed of short and medium chain fatty acids, which are beneficial to health. As such, adding CM to diet did not affect average levels of serum TC, LDL and TG of Wistar rats suggesting that none of the CM preparations under investigation contribute to detrimental changes in lipid profiles. All CM preparations, on the other hand, appear to increase serum antioxidant activity which may contribute in retarding oxidative damage to biomolecules. Financial assistance from National Research Council (12-012) and University Research Grant (RP/03/02/06/05/2015) areacknowledged.Item Determination of Nutrient composition of domestic and commercially available coconut milk preparations(Faculty of Graduate Studies, University of Kelaniya, 2015) Nadeeshani, D.L.W.R.; Seneviratne, K.N.; Jayathilaka, N.This study evaluated the nutrient composition of coconut milk (CM) prepared by blending (pressing) the grated coconut (Cocos nucifera L.) kernel and commercially available powdered or liquid CM. Nine randomly selected coconuts from ordinary tall coconut trees, three each from three regions in Kurunegala district were analyzed using standard methods. First extract (FE) of CM was prepared by blending a mixture of water and grated coconut kernel 1:1 (w:w) in a household blender. The strained pulp was used similarly, to prepare the Second Extract (SE). Commercial CM was prepared according to instructions on the packages. The results are given in Table 1.