Fish meal-derived lecithin-rich fat emulsion and its application as a supplier of omega-3 polyunsaturated fatty acids to blood cells

Abstract

Prolonged intravenous infusion in man of commercial lipid emulsions with lecithins derived from either soya or egg yolk induces a depletion of essential omega-3 polyunsaturated fatty acids (n-3 PUFA) in the circulating blood cell membranes. Our experiment aims to replace the conventional lecithins with n-3 PUFA-rich lecithin derived from marine fish in order to study whether it could maintain the status of these crucial fatty acids of blood cells.Four grades of fish meal (FM) with crude fat and lecithin contents of respective 11-14 and 2-3 g/100g were used. Their total fatty acids determined by gas chromatographic technique comprised of 27-31% polyenes including 15-19% docosahexacnoic acid (DHA, C22:6 n-3). Lecithin with 25-30% purity was prepared from grade 1 FM after three consecutive organic solvent extractions: methanol/n-hexane/acetone. The obtained kecithin had choline upto 66-70% with DHA content of 20-23%. FM-derived lecithin-rich fat emulsions (FM-LRFE) as well as other two emulsions with lecithins derived from either egg yolk (EY-LRFE) or soya (SY-LRFE) were prepared by mechanical dispersion. All three emulsions had similar triglyceride to lecithin (TG-LE) ratio of 3:1 (w/w).The exchanges of fatty acid between blood cells and lecithin-rich fat emulsion were studied in vitro. Red blood cells (RBC) with 40% hematocrit were incubated for 1 h with either FM-LRFE, EY-LRFE or SY-LRFE at the lecithin concentrations of 100-300 mg/100 ml incubation mixture. Neither emulsion affected blood cell membrane cholesterol to phospholipids ratio. However, membranes’ n-3 PUFA was alternated after the incubations with SY-LRFE and EY-LRFE. Including with SY-LRFE, membrane linoleic acid (C18:2 n-6) accumulated whereas DHA dropped leading to a marked reduction of n-3/n-6 PUFA ratio (p<0.05). By contrast, FM-LRFE provided DHA to RBC and raised membrane n-3 PUFAs significantly (p<0.05).In conclusion, FM-LRFE not only prevents the loss of n-3 PUFA from blood cells but also acts as a good n-3 PUFA supplier. ACKNOWLEDGEMENT I wish to express my deep gratitude and sincere appreciation to my advisor, Assistant Professor Dr. Winai Dahlan for his excellent supervision, instruction, advice, guidance and encouragement throughout this thesis. I would like to express my gratefulness to my co-advisor, Assistant Professor Dr. Somkiat Pyatiratitivorakul for his useful suggestions and full encouragement. My sincere gratitude is also extended to Dr. Sumate Tantratian, Associate Prodessor Dr. Wichai Cherdchewasart and Assistant Professor Dr. Byaporn na Nagara for serving as thesis committee, for their valuable comments and also useful suggestions. My acknowledgement is also expressed to Fats and Oils Research Center (FORC), Faculty of Allied Health Science, Chulalongkorn University for their chemical and instruments supported throughout my two years of this thesis and I would like to thank the Departments of Clinical Chemistry and Clinical Microscopy, Faculty of Allied Health Sciences, Chulalongkorn University for the access to use some instruments that are necessary for my thesis. I am also grateful for the financial support of the National Science and Technology Development Agency and FORC during my study. Sincere thanks are also express to all the friends of the Biotechnology Programme and the member of the Faculty of Allied Health Sciences, Chulalongkorn University for their assistance and friendship. Lastly but most importantly, I am greatly indebted to my father, mother, my brother and everybody in my families for their unlimited love support and understanding.