**2. Materials and Methods**

#### *2.1. Preparation of the S. maxima Extracts*

100 g of dried *S. maxima* (cultivated in Korea Institute of Ocean Science and Technology, Jeju Center, Korea) was pretreated with 70% ethanol (*w*/*w*) at a ratio of 1:10 (*w*/*w*) for 8 h using an ultrasonicator (AUG-R3-900, ASIA ULTRASONIC, Gyeonggi-do, Korea) installed with a temperature controller at 40 kHz with 800 W of input power and constant room temperature. Then, the pretreated *S. maxima* was further extracted by a reflux condenser (TL-6Point, Misung Scientific Co., Yangjoo, Korea) at 65 ◦C for 4 h. For the conventional ethanol extraction, 100 g of dried *S. maxima* were extracted with 1 L of 70% ethanol (*w*/*w*) at 80 ◦C for 12 h by a reflux condensing extractor. Then, the extracts from each experiment were concentrated using a rotary vacuum evaporator (N-N series, EYELA, Rikakikai Co., Tokyo, Japan) and freeze-dried with a freeze-dyer (PVTFA 10AT, ILSIN, Suwon, Korea) before the use. The extract from each process was expressed as an ultrasonic extract (UE) from the ultrasonic pretreated process at room temperature and ethanol extract (EE) from conventional hot ethanol extraction process at 80 ◦C, respectively.
