Study of the Antioxidative Properties of Several Amino Acid‐Type Surfactants and their Synergistic Effect in Mixed Micelle

Abstract

Cysteine and methionine, two sulfur‐containing amino acids (AA), were introduced in their surfactant forms as potential antioxidants. The antioxidative (AOX) properties of lauroyl methionine (C12‐Met) and lauroyl cysteine (C12‐Cys) was investigated by means of the oxygen radical absorbance capacity assay. Both the surfactants exhibited excellent AOX behavior at the premicellar state and micellar medium. The AOX behavior was found to be comparable for both the surfactants at their premicellar states. However, in micellar medium, C12‐Met showed better AOX property than C12‐Cys. The AOX power of the surfactants was compared with other previously developed AA‐type surfactants. The order of the AOX power was found to be: C12‐tryptophan > C12‐tyrosine ≈ C12‐methionine ≈ C12‐cysteine > C12‐histidine at the premicellar state and C12‐tryptophan > C12‐tyrosine > C12‐methionine > C12‐cysteine > C12‐histidine at the micellar state. C12‐Cys displayed lower AOX property in micellar medium due to its dimer formation tendency. Based on the HPLC and UPLC‐Q‐TOF‐MS analysis, the dimer formation of C12‐Cys was found to be accelerated due to the micellar environment and results into negative synergistic effect on other aromatic AA‐type surfactants. However, the presence of C12‐His in the micellar solution of C12‐Cys resulted no synergistic effect due to stronger H‐bonding between the surfactants and resulting less dimer formation.

Novel aminoacylases from Streptomyces griseus DSM 40236 and their recombinant production in Streptomyces lividans

“…The reactions with the remaining proteinogenic amino acids did not result in product formation. Lauroyl‐methionine is a biosurfactant with antioxidative properties and might thus be an interesting additive in cosmetic formulations [50]. The acceptance of further fatty acids is likely and can be investigated in future experiments.…”