Determination of the active transport of fucoidan derived from Okinawa Mozuku across the human intestinal Caco-2 cells as assessed by size-exclusion chromatography

Introduction: In order to clarify the mechanism of fucoidan transport, we developed the chromatographic determination method. Method: A size-exclusion chromatography (SEC) method for the determination of Okinawa-fucoidan using Develosil 300 Diol-5 (60 x 8.0 mm I.D., 30 nm pore-diameter) with the eluent containing 1% nonionic detergent is developed. Determination range (UV at 210 nm) is from 0 to 100 ng of fucoidan with the linear calibration line inserting to zero. Results: A transport activity of fucoidan is demonstrated by using Caco-2 cells (model of gut transport system); i.e., the initial transport velocity 12 nmol/h/mg of protein (25-fold slower rate as compared to a bacterial L-alanine active-transport activity 300 nmol/h/mg of protein) is found to occur. Since this fucoidan transport is inhibited by 10 mM sodium azide (respiration inhibitor) and 0.05 mM FCCP (uncoupler), this transport by Caco-2 cells is found to be an active one requiring energy-source. On the other hand, colchicine (inhibitor of phagocytosis/pinocytosis) and mannitol (putative competitive-inhibitor of tight-junction transport) cannot inhibit the fucoidan transport at all. Conclusion: We firstly report that the active transport occurs for such a high molecular-weight sulphated-polyfucose of fucoidan in vitro using Caco-2 cells. (C) 2015 Elsevier B.V. All rights reserved.