Comparative analysis of sugar and mineral content of Sargassum spp. collected from different coasts of Sri Lanka

Sargassum is one of the major and commercially viable macro-algae found in the coastal zone of Sri Lanka. Sargassum wightii and Sargassum crassifolium were identified as the two major Sargassum species, along with substantial amounts of S. polycystum. An approximately 144t dry weight of these three main Sargassum species has been roughly estimated. During this study, a comprehensive survey of the polysaccharide content and their composition was undertaken. Out of the 21 different Sargassum samples collected from the different coastal zones of Sri Lanka, the alginate content varied from 16 to 33% on the dry weight basis, whereas, the fucoidan content varied from 1 to 6%. The comparison of sugar composition showed glucose as the major sugar representing 26.2–33.5% of the total sugar content. Fucose represented 8.2–13.0% of the total sugar content. The mannuronic acid (M) to guluronic acid (G) ratio varied from 0.7 to 1.8 amongst the samples analyzed. This study also compared the mineral composition, namely the K, Na, Ca, Mg, Fe, Mn, Zn, Cu, Ni, Co, Cr, Se, Pd, As, and Cd contents. The results indicate Sargassum as a rich source of mineral and trace elements. The total macro-mineral content (Na + K + Ca + Mg) of Sargassum species was 134.92 ± 65.47 mg g⁻¹. The total micro-elements content (Se + Fe + Zn + Mn + Cu + Cr + Ni) was 1.95 ± 1.75 mg g⁻¹.