Chemical composition and studying the possible neuroprotective effect of iridoids-rich fraction from Pentas lanceolata leaves using rotenone model of Parkinson’s disease in mice

Abstract Globally Parkinsonism is the most disabling disease that affects the motor coordination in people over 65 years old due to dopaminergic neurodegeneration. Medications that are used for treatment of Parkinson’s disease have serious side effects so bioactive compounds derived from plants have been examined for treatment of Parkinsonism. In this study the iridoids-rich fraction isolated from Pentas lanceolata (PIRF) leaves was investigated for its phytoconstituents. Seven iridoids (1-7) and one flavonol diglycoside (8) were isolated, and their chemical structures were achieved by 1H and 13C nuclear magnetic resonance and ESI-MS spectral data. Compound 1 (6β,7β-epoxy-8-epi-splendoside) and 5 (gaertneroside) were isolated for the first time from Pentas genus as well as compound 8 (kaempferol-3-O-robinobioside). The current study aims to investigate the possible anti-parkinsonian effect of PIRF using a rotenone model of Parkinsonism in mice. Behavioural tests (wire hanging, stair and wooden-walking tests) were done to examine the motor coordination in mice after treatment. Biochemical and histopathological examinations for brain striatum in different groups were also evaluated. Treatment of mice with PIRF had counteracted the effect of rotenone on grip strength and motor coordination as they were restored back to normal levels. Dopamine and AChE levels were elevated again in brain homogenate of PIRF treated groups. Treatment with PIRF masked the inflammatory effect of rotenone as the MCP-1, IL-1β and TNF- α decreased again to their normal content. PIRF also restored the β-amyloid content to its normal level as in the control group. The oxidative stress produced in brain tissues due to rotenone treatment was masked by the antioxidant effect of PIRF. The anti-parkinsonian effect of PIRF could be attributed to their bioactive constituents of iridoids.