Inhibitory Effect of Cinnamomum Zeylanicum and Camellia Sinensis Extracts on the Hen EggWhite Lysozyme Fibrillation

Background & Aims: Many neurodegenerative diseases including Alzheimer’s, Parkinson and Huntington diseases are associated with the deposition proteinaceous aggregates known as amyloid fibrils. Currently, there is no approved therapeutic agent for inhibition of fibrillar assemblies. One important approach in the development of therapeutic agents is the use of herbal extracts. At the present comparative study, the effect of Cinnamomum zeylanicum Nees and Camellia sinensis L, extracts on prevention of hen egg white lysozyme (HEWL) amyloidogenesis were studied. Methods: In this experimental study, acidic pH and high temperature were used to drive the protein towards amyloid formation. Lysozyme was dissolved at ۲ mg/mL in ۵۰mM glycine buffer (pH ۲.۵), and then incubated at ۵۷ C for a specified time while stirred gently by Teflon magnetic bars. Measurement of thioflavin T fluorescence intensity and AFM micrography were used to characterize the HEWL fibrillation processes. Data were analyzed through SPSS ۱۶ using descriptive statistics as well as independent t-test. Results: In the absence of the extracts, soluble oligomers became evident after ۲۴ h of incubation, followed by subsequent appearance of mature fibrils after ۴۸h. Upon incubation with various concentrations of Cinnamomum zeylanicum and Camellia sinensis extracts in range of ۰.۱-۱ mg/ml, formation of fibrillar assemblies were dose-dependently inhibited but the extract of Camellia was more efficient (P=۰.۰۲۵). Also, in contrast to Cinnamomum, Camellia extract can stabilize native protein and reverse partial unfolded form into native form and thus, can inhibit all of amyloid formation pathways. Conclusion: The obtained results suggest that poly phenols of the extracts directly insert into amyloidogenic core of early aggregates and inhibit amyloid fibril formation but Camellia extract, due to its specific chemical structure, is probably more effective for aggregation inhibition.