Lactic acid is an organic acid. It is a chiral molecule, consisting of two optical isomers, L-lactic acid and D-lactic acid, with the L-isomer being the most common in living organisms. Lactic acid plays a role in several biochemical processes and is produced in the muscles during intense activity. D-Lactic acid is the end product of the enzyme glyoxalase II (or hydroxyacyl-glutathione hydrolase) (EC 3.1.2.6), which converts the intermediate substrate S-lactoyl-glutathione to reduced glutathione and D-lactate