(599at) Mechanistic Studies of Differential Cytotoxicities of Rhamnolipids Between in Vitro and in Vivo

Rhamnolipids have been evidenced safe in animal tests while present sensitive cytotoxicity on mammalian cells in vitro., As found in this study, for each of the three cell lines, both mono-rhamnolipid and di-rhamnolipid elicited cytotoxicity when the surface tension of medium decreased under 41 mN/m. And the presence of FBS in medium could lower the efficacy of rhamnolipid on reducing surface tension via binding to FBS and thus attenuated the cytotoxicity. The correlation of cytotoxicity with surface tension similarly occurred on two anionic surfactants (SDS and SDBS) which was of quite different molecular structures from rhamnolipids. Hence, the surface activity rather than its specific molecular structure should cause the rhamnolipid cytotoxicity. Moreover, rhamnolipids was lowly dissolved in simulated gastric juice, which could help to explain its largely attenuated cytotoxicity in vivo. This mechanistic illustration of the high biosafety of rhamnolipids in vivo could offer a valuable guidance for the applications.