Radiation-induced reactions of ketoacids in aqueous solutions and their possible role in chemical evolution

摘要

Chemical evolution is the process through which simple compounds generate organic compounds essential for the development of life. The stability of organic compounds is an essential factor in the evaluation of plausible scenarios for the formation of organic molecules in the primitive Earth. In this context, we studied the steady-state gamma-radiolysis of alpha-ketoacids (aKA) of prebiotic importance in aqueous solutions at high irradiation doses. These compounds participate in a variety of pathways in the metabolism of living organisms. The acids under study have the general formula R-(C=O)CO2H (R=CH3 pyruvic acid; R=CH2CO2H oxalacetic acid; R=CH2CH2CO2H alpha-ketoglutaric acid). We carried out the irradiation in a Co-60 gamma source, with doses up to 300 kGy. For the analysis, we used various spectroscopic and chromatographic analytical methods. The gamma irradiation of alpha-ketoacids formed appreciable amounts the saturated carboxylic acid with one C-atom less compared to the target compound and the dimeric products.