Biol. Pharm. Bull. 28(7) 1161—1164 (2005)

such as growth inhibition and mutagenesis in Escherichia coli, of dihydropyrazines (DHPs). The DHPs revealed single strand-cleavage on the covalently closed circular DNA of plasmid pBR322, especially in the presence of Cu . Since the participation of Cu enhanced the cleaving activity, it is likely that the effects of DHPs on E. coli also would be influenced. Here, we examined the effects of DHPs on E. coli upon the addition of Cu . Pyrazine derivatives have been detected in the urine of humans with diabetes mellitus, which suggests that DHPs, which are precursors of pyrazines, might be involved in diabetes mellitus, although this remains unconfirmed. DHPs also are produced from the accumulation of the heme precursor, 5-aminolevulinic acid (ALA), in lead poisoning and some types of porphyries. We have reported that DHPs induce apoptosis of cultured cells, and, therefore investigated other potential biological effects caused by DHPs. The sugar origin of DHPs and their prevalence in the human body suggests that these compounds may be involved in various internal injuries in vivo.