Isolation and Identification of α-Ketoaldehydes in Calf and Rabbit Livers

Carbonyl compounds in calf liver stored at 4°C for 5~6 hr after slaughter were investigated, with emphasis on α-ketoaldehydes. After conversion of carbonyls into their 2,4-dinitrophenylhydrazones (2,4-DNPs), they were fractionated by preparative thin-layer chromatography (TLC); at least, twenty-three fractions were separated, among which eighteen fractions contained 2,4-DNPs of α-dicarbonyls. From some of the fractions, crystalline 2,4-DNPs were isolated, and identified by TLC and infrared spectra: pyruvaldehyde, 3-deoxypentosulose, xylosulose, 3-deoxyglucosulose, 2,3-diketogulonic acid or/and dehydroascorbic acid, and formaldehyde were identified, and glucosulose was tentatively identified.

The carbonyl pattern, obtained from rabbit liver frozen in liquid nitrogen immediately after slaughter, was also similar as that from calf liver, and further, the amount of each α-ketoaldehydes remained at the almost same level during storage at 4°C for 24 hr. These results indicate that the identified α-ketoaldehydes are constituents or metabolic intermediates in calf and rabbit livers.

The formation mechanisms of the carbonyls in tissues are discussed.