Heated glucose is mutagenic to Salmonella typhimurium TA 100 in the absence of S-9 mix. For identifying unknown mutagens in heated glucose (dry solid, 200 degrees C, 20 min), reaction with isopropylideneguanosine (IPG) was followed by isolation and characterization of the mutagen-IPG adduct. Two adducts, glyoxal-IPG and 8-hydroxy-IPG, were identified in the reaction mixture by this technique. To elucidate the mechanism of this hydroxylation reaction, we investigated the abilities of various agents to hydroxylate deoxyguanosine or guanine base in DNA. Various reducing agents, metals, asbestoses, polyphenols, aminophenols, and X-ray were effective for hydroxylation, and an oxygen radical seems to be the reactive species. For sensitive detection of 8-hydroxyguanine, a monoclonal antibody for it was prepared.