188922-39-6Relevant academic research and scientific papers
Radiolabeled phenethylguanidines: Novel imaging agents for cardiac sympathetic neurons and adrenergic tumors
Raffel, David M.,Jung, Yong-Woon,Gildersleeve, David L.,Sherman, Phillip S.,Moskwa, James J.,Tluczek, Louis J.,Chen, Wei
, p. 2078 - 2088 (2007)
The norepinephrine transporter (NET) substrates [123I]-m- iodobenzylguanidine (MIBG) and [11C]-m-hydroxyephedrine (HED) are used as markers of cardiac sympathetic neurons and adrenergic tumors (pheochromocytoma, neuroblastoma). However, their rapid NET transport rates limit their ability to provide accurate measurements of cardiac nerve density. [11C]Phenethylguanidine ([11C]1a) and 12 analogues ([ 11C]-1b-m) were synthesized and evaluated as radiotracers with improved kinetics for quantifying cardiac nerve density. In isolated rat hearts, neuronal uptake rates of [11C]1a-m ranged from 0.24 to 1.96 mL min-1 (g wet wt)-1, and six compounds had extremely long neuronal retention times (clearance T1/2 > 20 h) due to efficient vesicular storage. Positron emission tomography (PET) studies in nonhuman primates with [11C]-1e, N-[11C]guanyl-m-octopamine, which has a slow NET transport rate, showed improved myocardial kinetics compared to HED. Compound [11C]1c, [11C]-p-hydroxyphenethylguanidine, which has a rapid NET transport rate, avidly accumulated into rat pheochromocytoma xenograft tumors in mice. These encouraging findings demonstrate that radiolabeled phenethylguanidines deserve further investigation as radiotracers of cardiac sympathetic innervation and adrenergic tumors.
Enzymatic peptide synthesis with p-guanidinophenyl and p- (guanidinomethyl)phenyl esters as acyl donors
Sekizaki, Haruo,Itoh, Kunihiko,Toyota, Eiko,Tanizawa, Kazutaka
, p. 846 - 849 (2007/10/03)
Two series of 'inverse substrates', N-Boc-amino acid p-guanidinophenyl and p-(guanidinomethyl)phenyl esters, were prepared as acyl donor components for enzymatic peptide synthesis. The kinetic behavior of these esters toward bovine and Streptomyces griseus (SG) trypsin was analyzed. The spatial requirement of the active site of these enzymes for catalytic efficiency is discussed based on the steric characteristics of the substrates. These substrates were found to couple readily with amino acid p-nitroanilides to produce peptides. SG trypsin was the most efficient catalyst among the enzymes tested (bovine, porcine, and SG trypsin).
