Production of levan from Bacillus subtilis var. natto and apoptotic effect on SH-SY5Y neuroblastoma cells

Levan is a high-valued polysaccharide of fructose produced by several microbial species. These polysaccharides have been described as effective therapeutic agents in some human disease conditions, such as cancer, heart diseases and diabetes. The objective of this study was to examine the effect of levan (β-(2 → 6)-fructan) produced through sucrose fermentation by B. subtilis var. natto on the proliferation rate, cytotoxicity, and apoptosis of human neuroblastoma SH-SY5Y cells. It was obtained 41.44 g/L of levan in 18 h by biotechnological fermentation and SH-SY5Y cells were exposed to 1000 μg/mL of levan. The treatment with 1000 μg/mL of levan induced apoptosis in SH-SY5Y cancer cells by the significant increase in Annexin V/7-AAD and caspase 3/7 activation, but did not decrease proliferation or triggered a cytotoxic effect. 1000 μg/mL levan treatment is a promising therapeutic strategy for SH-SY5Y neuroblastoma cells. •B. subtilis var. natto produced 41.44 g/L levan yield.•NMR spectroscopy analysis exposed that the EPS was a levan type EPS as a β-(2 → 6)-linked fructan.•The molecular weight of B. subtilis levan was predominant about 8.807 g/mol.•Levan exhibited in vitro apoptotic activity against neuroblastoma cells line SH-SY5Y through caspase 3/7 pathway.