Abstract

Alloxan and ninhydrin affect insulin release by first stimulation and then inhibition of subsequent glucose-induced insulin release from the β-cells in the islets of Langerhans. The structures of D-glucose and D-mannose, the two hexoses that protect against them and initiate insulin release, were analyzed and found to share with alloxan and ninhydrin common molecular properties. These common molecular properties were: An oxygen at C(1); a hydroxyl at C(2), either axial or equatorial; an equatorial oxygen at C(3); and at position 5 an electron density. Further structural analysis revealed that alloxan and ninhydrin would require little, if any, additional volume than that required for recognition of the active hexoses, D-glucose and D-mannose at a common site. Other hexoses (1-deoxy-D-glucose, 2-deoxy-D-glucose, D-allose, D-galactose, lyxose, xylose, 6-deoxy-D-glucose, and L-glucose) which either did not protect against alloxan and ninhydrin or did not initiate insulin release were found to vary in their structure from the active hexoses. Based on the presently available evidence, a hypothesis was advanced that alloxan, ninhydrin, and the active hexoses interact at a common receptor to initiate the first phase of insulin release.