Investigation of Aloin effects on hen egg-white lysozyme fibril formation

Amyloid fibrils are extracellular aggregates found in organs and tissues which are composed of beta plates. The mechanism of fibril formation is the spontaneous accumulation of proteins and peptides due to misfolding. Amyloid fibrils have been found in many diseases, such as type ۲ diabetes, Alzheimer’s, and Parkinson's. These beta-sheet deposits cause cell damage and death. Since proteins can form amyloid fibrils at different biophysical conditions, hen egg-white lysozyme (HEWL) was applied as a model protein for in vitro fibril formation in the presence and absence of Aloin. Aloin is extracted from the leaves of the Aloe Vera plant. Aloe Vera gel is used in the food and cosmetics industry. Aloin has low stability as a solution and should be kept away from light and in a cool place. Aloin has anti-oxidation, and anti-tumor properties, and no molecular level studies were done about its’ anti fibrillation effects on HEWL. Experiments were done using UV-vis (concentration determination) spectroscopy, fluorescence spectroscopy and atomic force microscopy (AFM). The increase in fluorescence intensity in the presence of thioflavin T showed that HEWL could form amyloid fibrils at pH ۲ and ۵۷°C over time. Fibrils were also observed by AFM. Therefore, as a next step, fibril formation was detected in the presence of different Aloin concentrations over time. Fluorescence intensity of HEWL decreased in the presence of Aloin. It means that Aloin has inhibitory effect on HEWL fibril formation. However, more studies are needed to know the general inhibitory effect of Aloin on protein fibril formation.

کلیدواژه ها:

Thioflavin T ، Amyloid fibrils ، Atomic force microscopy