To observe the effects of Centella asiatica (C. asiatica) methanolic extract on α-synuclein aggregation and its expression in rotenone-exposed zebrafish. Zebrafish (Danio rerio) were exposed to 5 μg/L rotenone for 28 days and co-incubated with 2.5, 5.0 and 10.0 μg/mL of C. asiatica methanolic extract. The medium was changed every 48 h for maintain the concentration of rotenone and extract. After 28 days zebrafish were sacrificed on the ice block and protein was isolated from zebrafish brain for ELISA of dopamine and Western blotting of α-synuclein. Immunohistochemistry was conducted to observe the α-synuclein expressions from histopathological preparation of zebrafish brain. The head were soaked in 10% formaline for less than 24 h and embedded onto paraffin block, then sliced for immunohistochemistry using anti α-synuclein antibody. We also measured zebrafish motility for 5 min in each week. C. asiatica has important bioactive compounds such as asiaticoside that has anti-inflammatory and antioxidant properties. It may inhibit cascade reaction due to oxidative stress induced by rotenone. Decreasing reactive oxygen species proposed probability of radical attack to α-synuclein protein that caused aggregation and increase of its expression. The motility of zebrafish was also maintained in C. asiatica groups due to the increasing dopamine level in rotenone-induced zebrafish. High level of reactive oxygen species inactivated enzyme for dopamine synthesis such as tyrosine hydroxylase, and oxidized dopamine itself. Oxidized dopamine increased α-synuclein aggregation. Thus, the dopamine level decreased in rotenone-induced zebrafish, but C. asiatica increased dopamine level. C. asiatica has a potential to be developed as an anti-Parkinson’s disease treatment due to its capability for minimized the sign of Parkinson’s such as α-synuclein aggregation and expression, increasing motility and dopamine as well.
(By: Husnul Khotimah, Mulyohadi Ali, Sutiman B. Sumitro, Muchamad Aris Widodo
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