en Biotechnology Biotechnology پژوهشي Orginal research papers Seaweeds have been introduced as an important sources of food and pharmaceutical active agents since last century. In this study, the chemical composition and functional characteristics of (common names) <em>Nizamuddinia zanardinii</em> and <em>Iyengaria stellata,</em> were investigated. The total carbohydrate and ash contents were the two most abundant components in these seaweeds but their crude lipid and fiber contents were low. The protein content was higher in <em>I. stellata</em> followed over <em>N. zanardinii</em>. Atomic absorption spectrophotometry of the ashes showed that <em>I. stellata</em> contained higher amounts of both macrominerals (Ca, Mg) and trace elements (Fe, Zn) than <em>N. zanardinii</em>. Results of antioxidant properties showed that total phenolic (3.37 mg 100g^-1), total antioxidant (27.08 mg g^-1) and reducing power (22.76%) were higher in <em>N. zanardinii</em> than <em>I. stellata</em>, while DPPH free radical scavenging (7.16%) was higher in <em>I. stellata</em>. The results suggest that both the seaweeds could be used as a potential source of nutrient and antioxidant compounds in food and pharmaceutical industries. Brown seaweeds, Chemical composition, Antioxidant activity, Mineral composition 85 98 http://jifro.ir/browse.php?a_code=A-10-2336-1&slc_lang=en&sid=1 E. Mohammadi esmat.mohammadi69@gmail.com 100319475328460032499 100319475328460032499 Yes Gorgan University of Agricultural Sciences and Natural Resources B. Shabanpour baharh.shabanpour@gmail.com 100319475328460032500 100319475328460032500 No Gorgan University of Agricultural Sciences and Natural Resources M. Kordjazi kordjazi.moazameh@gmail.com 100319475328460032501 100319475328460032501 No Gorgan University of Agricultural Sciences and Natural Resources