To determine the possible roles of two essential trace elements and ascorbic acid concerning amyloidal beta-sheet formation in diabetes mellitus

Abstract

Amylin is a peptide hormone that is made and co-secreted along with insulin. Human amylin is the main component of amyloid beta-sheet found in the pancreas of majority of diabetic patients. Amyloidogenesis causes destruction of pancreatic β-cells. The subsequent lack of insulin leads to increased blood and urine glucose.In this article, the fluorimetric assay was used to examine the role of ascorbic acid and two essential trace elements including zinc and iron on beta-amyloid formation of human peptide of amylin hormone under near-physiological circumstances.Results obtained from in vitro study showed that after 120 h incubation by shaker incubator at 37°C, zinc element at 10 μM inhibited amylin 10 μM from amyloid fibril formation by 9.1% (p<0.05) while the similar value of iron element promoted the formation of β-sheet structure by 13.1% (p<0.05). The obtained data also demonstrated that ascorbic acid with concentration of 150 μM had inhibitory effects on formation of beta-amyloid sheet significantly (p<0.05). It may be concluded that if islet amyloid is cytotoxic to β-cells then zinc and ascorbic acid should protect these cells against degeneration in diabetic patients. Key words: Vitamin C, diabetes mellitus, amylin hormone, zinc, iron.