*4.1. Materials*

African monkey kidney cell line (Vero) was purchased from the Korean cell line bank (KCLB, Seoul, Korea). Media for the cell line maintenance (Roswell Park Memorial Institute-1640; RPMI-1640) and serum (fetal bovine serum; FBS) including antibiotics (penicillin, streptomycin) were purchased from Gibco-BRL (Grand Island, NY, USA). 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), 1-diphenyl-2-picrylhydrazyl (DPPH), 2,2-azobis(2-amidinopropane) hydrochloride (AAPH), 5,5-dimethyl-1-pyrolin N-oxide (DMPO), and α-(4-Pyridyl-1-oxide)-N-tert-butylnitrone (POBN) were purchased from Sigma (St. Louis, MO, USA). H2O2 and FeSO4.7H2O used were purchased from Fluka Co. (Buchs, Switzerland). Furthermore, dimethyl sulfoxide (DMSO), 2,7-dichlorofluorescein diacetate (DCF-DA), and 2,2-azino-bis(3-ethylbenzthiazoline)-6-sulfonic acid (ABTS) were obtained from Sigma-Aldrich (St. Louis, MO, USA).

## *4.2. Collection of Seaweed and Extraction*

*P. boryana* samples were collected from the shores of Fulhadhoo Island (4.8849 ◦N, 72.9350 ◦E), the Maldives in January of 2018. Samples were immediately washed with running water to remove epiphytes and sand. Samples were then lyophilized and ground into powder. A sample portion (50 g) was added to 500 mL of distilled water. Optimal pH value was obtained via the addition of 1M of HCL. Celluclast assisted extraction was carried out in a period of 24 h under shaking kinetics with optimal conditions (pH 4.5, 50 ◦C). Following the extraction, the enzyme was inactivated via heating the mixture in 100 ◦C for 10 min. The filtrate was obtained and pH was brought back to neutral value. The sample was identified as enzymatic extract of *P. boryana* (PBE).
