Sequential ultrasonic/microwave assisted extraction of fucoidan from Nizamudinia zanardinii and evaluation of its biological activities

In the current study, the combination of ultrasound and microwave methods (UM) has been used for the extraction of fucoidan from Nizamuddinia zanardinii and the effect of this method on the chemical and monosaccharide composition, molecular weight, cytotoxic (against human cervical cancer cell (HeLa) and hepatocellular carcinoma cell (HepG2)), and immunomodulatory activities of the recovered fucoidan have also been investigated. The fucoidan yield under UM method was 5.53%. The extracted fucoidan chemically included 45.87% carbohydrate, 10.17% protein, 27.16% sulphate, and 1.1% uronic acid. The fucose (35.65%), mannose (28.94%), galactose (26.35%), xylose (7.74%), and glucose (1.33%) were the main monosaccharides of the extracted fucoidan. The average molecular weight of fucoidan was 748 kDa. The results also demonstrated that the extracted fucoidan had 62.41-78.08% and 62.45-70.29 % cytotoxic activity for HeLa and HepG2 cells, respectively. The nitric oxide (NO) production of RAW264.7 cells was increased with increasing the concentration of fucoidan and maximum NO production was found to be 37.79 µmol at 50 μg/mL.