Maryam Chinisaz, Azadeh Ebrahim-Habibi, Parichehreh Yaghmaei, Kazem Parivar, Ahmad- Reza Dehpour,
Volume 13, Issue 4 (5-2014)
Abstract
Background: The flexible structure of proteins is one important factor in the formation of ordered aggregates (amyloid fibril). This is a major problem for therapeutic proteins such as insulin. Study on the induction and inhibition of insulin fibrillation process with specific compounds such as aromatic derivatives may provide useful information about means of stabilization of protein structures.
Methods: To induce fibrillation, regular insulin was incubated in phosphate buffer (pH=7.4) during 24 hours. Amyloid formation was investigated by using Congo red absorbance and transmission electron microscopy (TEM). Then nodular amyloidosis was observed in mice upon amyloid fibril injection, after which the excised nodule was studied by Congo red staining and polarized light microscopy. Then, some aromatic compounds effect was investigated on the fibrillation process.
Results: Regular insulin form mature amyloid fibrils at pH=7.4, 37°C after 24 hours. Silibinin had the highest inhibitory effect on that process. Furthermore, Amyloid fibril injection in mice caused nodular amyloidosis.
Conclusion: Regular insulin has a high potential to undergo amyloid aggregation. Nodular amyloidosis confirms fibril formation by insulin under in vitro condition. Silibinin could be considered as a potential compound capable to increase protein structure stability.
Mahsa Soltani-Nobakht , Parichehreh Yaghmaei, Azadeh Ebrahim-Habibi,
Volume 14, Issue 3 (3-2015)
Abstract
Background: Alpha-amylase is the most important enzyme in the digestion of starch. Activators of this enzyme could be potentially used as digestive aids and its inhibitors block the absorption of starch compounds and result in the control of blood sugar levels. This study aimed at the investigation of aromatic compounds on bovine serum alpha-amylase. Methods: Effect of carvacrol, cumyl phenol, tryptamine, tryptophan, N-acetyl-L-tryptophan, Bis phenol A, 2-benzyloxy phenol, 2,6 diisopropyl phenol and 4-chloro-2-isopropyl-5-methyl phenol was investigated on bovine serum alpha-amylase with use of artificial substrate (laboratory kit). Results: Most of tested aromatic compounds showed a similar pattern. All these compounds had 5-30% inhibitory effect on the tested serum with the exception of tryptamine which showed a 20% increase in the enzyme activity. The best inhibitory effect was obtained from cumyl phenol in the range of 30%. Conclusion: This study showed that aromatic compounds with one and two cycles have moderate inhibitory effect on bovine serum alpha-amylase and tryptamine showed a slight activator effect. With regard to these results, indolic and phenolic structures may be effective on alpha-amylase, and in the next step, investigation of these compounds derivatives is suggested.
