Study of Antioxidative Properties of Some Mono Amino‐Acid‐Type and Dipeptide‐Type Surfactants

Abstract

Surfactants of tryptophan, tyrosine, and histidine were successfully synthesized. They were then modified to obtain dipeptide‐type surfactants with better solubility in both polar and nonpolar solvents, giving more emphasis to the development of water‐soluble amino‐acid‐type surfactants. All developed materials were designed to have functionality as antioxidants (AOX). The investigation of free radical scavenging capacity at pre‐micellar concentrations revealed greater Trolox equivalent (TE, relative scavenging capacity to Trolox) results for Trp‐type surfactants followed by Tyr‐type and His‐type. As expected, the synthesized surfactants exhibited comparable AOX properties to their parent amino acids. The AOX behavior of these surfactants was also checked in micellar concentrations, and the trend was found to be analogous: Trp‐type > Tyr‐type > His‐type surfactants. However, all of them were acting as better AOX in the micellar state than in the monomeric state. Investigating the synergistic effect found no interaction between the “amino acid–surfactant” pairs or the “surfactant–surfactant” pairs with varying ratios. They showed total AOX activity with respect to that of each material. This work opens up the door to the application of some new oil and water‐soluble amino‐acid‐type surfactants having auspicious AOX activity.