Saliva α-Synuclein and A High Extinction Coefficient Protein: A Novel Approach in Assessment Biomarkers of Parkinson's Disease

BACKGROUND: The pathological hallmark of Parkinson's disease (PD) is the appearance of intracytoplasmic inclusions known as Lewy bodies in which its principal component is α-synuclein. AIM: This study aimed to determine salivary α-synuclein and the extinction coefficient of the saliva protein as biomarkers of PD. MATERIALS AND METHODS: This observational study was done in Department of Pharmacology, College of Medicine in cooperation with Department of Oral Medicine, College of Dentistry at Al-Mustansiriya University in Baghdad, Iraq from September 2013 to March 2014. A total number of 20 PD patients and 20 healthy subjects were enrolled in the study. Unstimulated saliva obtained from each participant obtained for determination of salivary flow rate, saliva protein and α-synuclein using enzyme linked immune sorbent assay (ELISA) technique. RESULTS: Total saliva protein and uncontaminated protein with nucleic acids are significantly higher in PD compared with healthy subjects. The mean extinction coefficient of that protein is 27.25 M.cm(-1) which significantly (P < 0.001) less than corresponding value of healthy subjects (33.48 M.cm(−1) ). Saliva α-synuclein level is significantly less in PD (65 ± 52.2 pg/ml) than healthy subjects (314.01 ± 435.9 pg/ml). CONCLUSIONS: We conclude that saliva α-synuclein serves as a biomarker for PD if its level compared with healthy subjects, and a specific protein with extinction coefficient 27.25 M.cm-1 is detected in saliva of Parkinson's patients.