QS-21, an immunostimulatory saponin, is a powerful vaccine adjuvant that stimulates both Th2 humoral and Th1 cell-mediated immune responses by interacting with antigen presenting cells (APCs) and T cells.

Used as organic synthesis and medicine intermediate.

N-Acetylaspartic acid is a derivative of aspartic acid. It is the second most concentrated molecule in the brain after the amino acid glutamate. It is synthesized in neurons from the amino acid aspartate and acetyl coenzyme A (acetyl CoA).