Bioactivities of sophorolipid with different structures against human esophageal cancer cells

Sophorolipids (SLs) obtained from yeast broth are mixtures of many sophorolipid molecules with different structures, and have attracted more attention since they were found to have good antimicrobial, anticancer, anti-inflammatory, and anti-HIV activities. We investigated the effects of sophorolipid molecules with different structures on human esophageal cancer cells in the present work.

Ten sophorolipid (SL) molecules were separated and purified from the sophorolipids mixture using preparative HPLC, and their structures were identified by MS analyses. The effects of sophorolipid molecules with different structures on two human esophageal cancer cell lines, KYSE 109 and KYSE 450, were investigated by MTT assay.

The structures of the 10 sophorolipid molecules differ in acetylation degree of sophorose, unsaturation degree of hydroxyl fatty acid, and lactonization or ring opening. The results demonstrated that the inhibition of diacetylated lactonic sophorolipid on two esophageal cancer cells (total inhibition at 30 μg/mL concentration) was stronger than that of monoacetylated lactonic sophorolipid (totally inhibition at 60 μg/mL concentration). Difference of unsaturation degree of hydroxyl fatty acid in SL molecules also had obvious influence on their cytotoxicity to esophageal cancer cells. The sophorolipid with one double bond in fatty acid part had the strongest cytotoxic effect on two esophageal cancer cells (total inhibition at 30 μg/mL concentration). Acidic sophorolipid showed hardly any anticancer activity against esophageal cancer cells.

In this study, the relationship of anticancer activities of natural sophorolipid molecules and the differences in their structures was revealed, which probably further reveals the mechanism of SL bioactivities and will be helpful in the modification of SL structures to obtain more novel SLs with excellent bioactivities.