Also available in 1 mL, 1 mg, 2 mg, 10 mg, 25 mg, 50 mg, 100 mg, 500 mg and bulk. Please contact Fisher for quotes. 2,3-dihydroxy-3-methylbutanoic acid is a natural metabolite of the branched-chain amino acid leucine. It acts by activating the mTOR signaling pathway to promote the synthesis of new muscle proteins and reduce the breakdown of existing proteins, thereby increasing muscle mass and improving recovery from exercise. Purity 99.03%