Antioxidant and cytotoxic activities of sulfated polysaccharides from five different edible seaweeds

In recent times, there has been a growing interest in the exploration of antioxidants and global trend toward the usage of seaweeds in the food industries. The low molecular weight up to 14 kDa sulfated polysaccharides of seaweeds (Portieria hornemannii,Spyridia hypnoides,Asparagopsis taxiformis, Centroceras clavulatumandPadina pavonica) were evaluated for in vitro antioxidant activities and cytotoxic assay using HeLa cell line and also characterized by FTIR. The high yield (7.74% alga dry wt.) of sulfated polysaccharide was observed inP. hornemanniifollowed byS. hypnoides(0.69%), C. clavulaum(0.55%) andA. taxiformis(0.17%). In the brown seaweedP. pavonica,the sulfated polysaccharide yield was 2.07%. High amount of sulfate was recorded in the polysaccharide ofA. taxiformisfollowed byC. clavulaum, P. pavonica, S. hypnoidesandP. hornemanniias indicative for bioactivity. The FTIR spectroscopic analysis supports the sulfated polysaccharides ofS. hypnoides, C. clavulatumandA. taxiformisare similar to agar polymer whereas the spectral characteristics ofP. hornemanniihave similarities to carrageenan. The higher DPPH activity and reducing power were recorded in the polysaccharide of brown seaweedP. pavonicathan the red seaweeds as follows: DPPH activities:S. hypnoides > A. taxiformis > C. clavulatum > P. hornimanii; Reducing power:A. taxiformis > P. hornimanii > S. hypnoides > C. clavulatum.The polysaccharide fractions contain up to 14 kDa from red seaweedsP. hornemanniiandS. hypnoidesfollowed by brown seaweedP. pavonicaexhibit cytotoxic activity in HeLa cancer cell line (and are similar to structural properties of carrageenan extracted fromP. hornemannii). The low molecular weight agar like polymer ofS. hypnoidesand alginate like brown seaweedP. pavonicashowing better in vitro antioxidant activities that are capable of exhibiting cytotoxicity against HeLa cell line can be taken up further in-depth investigation for nutraceutical study.