Effects of Far Infrared Radiation Drying on Antioxidant and Anticoagulant Activities of Ecklonia cava Extracts

Abstract

Ecklonia cava is popular in Korea as a marine functional materials. Freeze drying (FD) is generally used for drying before extraction of bioactive compounds from E. cava. But, FD resulted in low productivity due to long drying time and the relatively high operating cost. On the other hand, far infrared radiation drying (FIRD) was known to be significant advantages such as higher drying rate, energy saving, and functional improvement. Hence, the objectives of this study were to evaluate the effectiveness of FIRD, the bioactive compound composition, and antioxidant and anticoagulant activities of water and enzymatic (Celluclast, Protamex) extracts from FIR-dried E. cava as compared to those extracts from FD-dried one. In this drying processing, FIRD was more effective than FD in the drying time, the extract yield, and the polyphenolic content in the extracts. Most FIRD extracts except for a dry condition at 80°C had lower IC50 values than FD extracts. Among them, Celluclast extract from E. cava dried by FIRD at 40°C (FIRD40-CE) was separated by HPLC and then radical scavenging activities of the separated compounds were directly evaluated by on-line coupled 2,2-azino-bis(3-ethylbenzthiazoline)-6-sulfonic acid (ABTS+) radical scavenging detection (RSD) system. The lower trace shows the peaks on ABTS+-RSD system which indicated the presence of antioxidant activity. In all the tested samples for anticoagulant activity of the extracts, Celluclast extracts from E. cava dried by FD (FD-CE) and FIRD40-CE were selected and a crude polysaccharide fraction with the molecular weights above 30 kDa was obtained. The crude polysaccharide fraction of FD-CE and FIRD40-CE showed the activated partial thromboplastin time activity. These results suggest that FIRD process would be more effective in releasing bioactive compounds from seaweed such as E. cava at an industrial scale.