N1-Acetylspermidine-d 6 (hydrochloride) is the deuterium labeled N1-Acetylspermidine hydrochloride. N1-Acetylspermidine hydrochloride is an acetyl derivative of polyamine. N1-acetylspermine is the substrate for the polyamine oxidase (PAO). N1-Acetylspermidine hydrochloride selectively elevates its level in human colorectal adenocarcinomas. N1-acetylspermidine shows cleavage efficiency at apurinic sites in DNA.