Synthesis and Evaluation of Surface and Biological Properties of Some Lactic Acid-Based Anionic Surfactants

In the present study, 11 lactic acid-based anionic surfactants were synthesized and evaluated for their surface and biological activities. The synthesis involved the esterification of lactic acid with a range of fatty alcohols differing in chain length as well as in branching and unsaturation. The resultant ester was sulfonated by treatment with chlorosulfonic acid followed by salt formation with aqueous NaOH solution. The surface properties of all the synthesized surfactants were determined using surface tensiometry. Synthesized surfactants showed low critical micelle concentration (CMC) values and a decreasing trend with an increase in the alkyl chain length. Alkyl branching also led to a mild change in CMC values when compared with linear counterparts having the same number of carbon atoms, though such decreases or increases were observed to be dependent on the position and number of the branching. Some of the synthesized surfactants exhibited good antimicrobial and anti-cancer activities against the tested microbial strains and cell lines.