The basic structure of PGA consists of D- and L-glutamicacidmonomers which are connected by amid linkagesbetween α-amino and γ-carboxyl groups. Large number ofcarboxyl along the molecule chain of PGA can form hydrogenbonding in a molecule or between diferent molecules. Thusithashighwaterabsorb-abilityandmoisture-retaining capability.PGAhasgoodbiocompatibilityandcanincreasethecontent of skin natural moisturizing factor (N.M.F). It is agoodnaturalhydratingingredient.Atthesametime,PGA-LMW can control tyrosinase function, is a mild skinbrightening raw material.Accordingtothemolecular weight,FredaPGA can bedivided into many diferent types, such as PGA-HMW (highmolecularweight)(about1000KDa),PGA-LMW(lowmolecular weight) (about 100KDa), and PGA-Oligo (oligomolecular weight) (about 10KDa).