Novel Cross-linking Compounds Formed through the Reaction of Nα-Acetyltryptophan with Hexanal

We separated three A^a-acetyitryptophan (Ac-Trp) derivatives formed through the reaction of Ac-Trp with hexanal, which is a major secondary product of lipid peroxidation. They were identified as 1-[N1-(Nα-acetyltryptophano)]-1-(Nα-acetyltryptophan-2-yl)hexane (Trp-HL-1), l,l-bis[N1-(Nα-acetyltryptophano)]hexane (Trp-HL-2) and 1,1 -bis(Nα-acetyltryptophan-2-yl)hexane (Trp-HL-3). Hexanal became a cross-linker between two Ac-Trp molecules on the formation of these compounds. Since Trp-HL-1 contained a newly formed asymmetric carbon atom, its diastereomers, Trp-HL-la and Trp-HL-lb, were separated and characterized by ORD.