title: No-carrier-added synthesis of a 4-methyl-substituted meta-iodobenzylguanidine analogue.
abstract: Radioiodinated meta-iodobenzylguanidine (MIBG) is used in the diagnosis and therapy of various neuroendocrine tumors. As a part of our efforts to develop an MIBG analogue with improved characteristics for these applications, a synthesis of 3-[131I]iodo-4-methylbenzylguanidine ([131I]MeIBG) was developed. Unlabeled MeIBG and the tin precursor, N, N'-(bis-tert-butyloxycarbonyl)-N-(4-methyl-3-trimethylstannylbenzyl) guanidine were synthesized in two steps from 3-iodo-4-methylbenzylalcohol. Radioiodinated MeIBG was synthesized at a no-carrier-added level by the iododestannylation of the tin precursor in about 85% radiochemical yield. The accumulation of [131I]MeIBG (38.9+/-3.0% of input counts) by human neuroblastoma SK-N-SH cells in vitro was 87% that of [125I]MIBG (44.5+/-3.0%) and a number of Uptake-1 inhibiting conditions reduced the uptake of both tracers in this cell line to a similar degree suggesting that introduction of a methyl substituent at the 4-position of MIBG did not adversely affect its biological characteristics.
authors.affiliation: Department of Radiology, Duke University Medical Center, Box 3808 Radiology, Bryan Research Building, Durham, NC 27710, USA. ganesan.v@duke.edu
authors.forename: G
authors.initials: G
authors.lastname: Vaidyanathan
authors.forename: D J
authors.initials: DJ
authors.lastname: Affleck
authors.forename: M R
authors.initials: MR
authors.lastname: Zalutsky
mesh_terms: D019797:3-Iodobenzylguanidine / Q000031:analogs & derivatives* / Q000138:chemical synthesis; D045744:Cell Line, Tumor; D006801:Humans; D007457:Iodine Radioisotopes / Q000737:chemistry*; D007553:Isotope Labeling / Q000379:methods; D009447:Neuroblastoma / Q000000981:diagnostic imaging; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000138:chemical synthesis*
chemical_list: D007457:Iodine Radioisotopes; D019275:Radiopharmaceuticals; D019797:3-Iodobenzylguanidine