Water soluble polysaccharides from Spirulina platensis exhibited cyto/DNA protection and suppress the growth of gastric cancer cells via modulation of galectin-3

Polysaccharides from natural sources play a significant role in the management of different cancer types including gastric cancer. In this study, we reported the effect of spirulina polysaccharide (Sp) on galectin-3 modulatory activity on gastric cancer cells. The polysaccharide was isolated from the spirulina biomass, characterized, and the in silico, in vitro studies are carried out to assess the bioactivities. The isolated Sp possessed average molecular weight of 1457 kDa, and galactose (42%) as major sugar along with Rhamnose, Arabinose, Xylose, and Mannose. Further, characterization of Sp by FT-IR and NMR spectrum indicated the presence of (β1-4D) galactose sugar with galactoarabinorhamnoglycan backbone. Among the monosaccharides, galactose showed highest binding affinity with galectin-3 protein as evidenced by the in silico interaction study. The obtained Sp, inhibited the proliferation of AGS gastric cancer cells by 48 % without affecting normal NIH/3T3 cells as opposed to doxorubicin, a known anticancer drug. Also, Sp exhibited galectin-3 mediated haemagglutination inhibition with MIC of 9.37 μg/mL compared to galactose 6.25 μg/mL, sugar specific to galectin-3. The Sp treatment significantly (p<0.05) lowered the expression of galectin-3 by 32 % compared to untreated control cells. In addition, Sp exhibited the potent cytoprotection in RBCs, Buccal cells, and DNA exposed to oxidants. Thus, the findings suggest that the polysaccharide from spirulina offer a promising therapeutic strategy in the management of gastric cancer in addition to its currently known nutritional and pharmaceutical applications.