PMID-sentid Pub_year Sent_text comp_official_name comp_offsetprotein_name organism prot_offset 11430769-2 2001 In human subjects, orally-administered pure unnatural C-6 isomers, [6R]-5-formyltetrahydrofolate and [6S]-5,10-methenyltetrahydrofolate, were recently shown to be metabolized to the natural isomer, [6S]-5-methyltetrahydrofolate. 5-methyltetrahydrofolate 198-227 complement C6 Homo sapiens 54-57