Acetyltryptophan,DL- functions readily as a component of the food in place of the free amino acid - a greater amount of acetyltryptophane,DL- than dl-tryptophane may be available to man. Acetyltryptophan,DL- is used as an additive in the protein microbubbles, used in various biomedical applications such as contrast imaging, targeted drug and gene delivery, delivery of drugs through blood brain barrier (BBB) and IV O2 delivery etc. In the breast cancer biomarkers search, lower levels of endogenous metabolite Acetyltryptophan, DL- was identified in the fluid from the affected breasts compared to the control breast fluid.