The asymmetric synthesis of amino acid precursors from complex organics have been performed. A gaseous mixture of carbon monoxide, ammonia and water (molecules which are among those identified in the interstellar medium) was irradiated with 3.0MeV protons to obtain amino acid precursors within high-molecular-weight complex organics of up to 3000Da. The amino acid precursor products synthesized were then irradiated with right (R-) or left (L-) ultraviolet circularly polarized light (UV–CPL) obtained from a synchrotron radiation (SR) source. Glycine was a predominant product, and number of chiral amino acids including alanine were identified following acid hydrolysis. R-UV–CPL preferentially produced d-alanine, while L-UV–CPL produced more l-alanine. Enantiomeric excesses (% D–% L) of + 0.44% and − 0.65% were obtained by R-UV–CPL and L-UV–CPL, respectively. These results imply that the origins of chirality in meteoritic amino acids could be accounted for by the formation of asymmetric amino acid precursors from extraterrestrial complex organics by CPL in space.