Catalysis-based enantioselective total synthesis of the macrocyclic spermidine alkaloid isooncinotine

A concise and efficient total synthesis of the spermidine alkaloid (-)-isooncinotine (1) incorporating a 22-membered lactam ring is outlined. The approach is largely catalysis-based, involving a selective iron-catalyzed alkyl–aryl cross-coupling reaction of a difunctionalized pyridine substrate, a heterogeneous asymmetric hydrogenation step to set the chiral center of the target, and a highly integrated ring-closing metathesis/hydrogenation sequence to forge the saturated macrocyclic edifice in a single operation

Radioimmunoassay of Human Intestinal Goblet Cell Mucin INVESTIGATION OF MUCUS FROM DIFFERENT ORGANS ANI) SPECIES

radioimmulnoassay for the (quanititative imieassuremiienit of humiiani goblet cell mucin (GCM) in ordier to stu(ly intestinal imiutcus in human and other species. The assay used 3H-labeled mucin as the aintigen, rabbit antisera, and sheep anti-rabbit IgG aintiserat as the second antibody. A number of applications of the assay were investigated. A survey of human tissues revealed that Imlucinls of the rectumil, coloni, aind smiiall intestine had identical affinity for the rabbit antibody, whereas lung, eyelid conjunctiva, esophagus, and stomsach reacted less strongly. GCCM coineentrattion ranged from 1.9 to 14,ug mucin protein/ing tissue protein in the small and large intestinie, respectively. The radioiiiiinunioassay was also found to be useful as a imarker during the isolationi of GCM froIml huimlaIn ileal extracts, where it indicated that a 10,000-fold purification had l)een achieved. Antigenic determninants of the imiucin did not rely upon ABH blood grouip-specific terimiinal sugars in oligosaccharide chains. A comparison of imulcinis aimoing various species revealed a partial species specificity of the GCCM antiblody. Human GCXI cross-reacted writh dog, monkey, and rabbit mucins, l)ut not with imucins of rat, pig, toad, and oyster. Organ distribution of crossreactive imuticiins in rabbit tissues indicated a pLattern that was (qucalitatively similar to that seen in humiian tissues. Possible imlplications of these findings for auitoimin-une diseases are briefly discuissed