Traditional Chinese Medicinal Plant Extract Protects against PD

A team of Korean neurodegenerative disease researchers has identified a naturally occurring drug that prevents the death of dopamine-producing neurons that characterizes Parkinson's disease.

Parkinson's disease is a degenerative brain disorder caused by the death of dopaminergic neurons in the middle cerebral brain. It is a disease with a higher incidence in the elderly population, exhibiting symptoms such as tremors, stiffness, reduced motor capability, and postural instability.

RNF146 (RING finger protein 146) is an E3 ubiquitin ligase enzyme that specifically recognizes and polyubiquitinates poly (ADP-ribose) (PAR)-conjugated substrates for proteasomal degradation. RNF146 has been shown to be neuroprotective against PAR polymerase-1 (PARP1)-induced cell death during stroke.

To discover the mechanism that underlies the neuroprotective effect of RNF146, a team of Korean investigators used a high-throughput screen based on a luciferase construct harboring the RNF146 promoter to evaluate compounds in the natural materials library of the Natural Medicine Bank of the Korea Foundation.

The investigators reported in the October 11, 2017, online edition of the journal Oncotarget that they had identified the licorice extract liquiritigenin as a potent RNF146 inducer. RNF146 expression and the RNF146 inducer liquiritigenin could prevent cell death elicited by Parkinson’s disease-associated and PARP1-activating stimuli.

The investigators further reported that RNF146 expression by liquiritigenin was mediated by estrogen receptor activation and contributed to cytoprotective effect of liquiritigenin. In addition, RNF146 expression by liquiritigenin in mouse brains provided dopaminergic neuroprotection in a 6-hydroxydopamine Parkinson's disease mouse model.

Contributing author Dr. Yun-Il Lee, a senior researcher at Daegu Gyeongbuk Institute of Science and Technology, said, "Neuronal death is involved in a variety of signaling systems in vivo. Therefore, it is essential to identify a new mechanism that is able to control the system comprehensively and we have found additional possibilities in licorice extract. I would like to contribute to the treatment of degenerative brain diseases such as Parkinson's disease by conducting advanced researches, comprehensive research and clinical studies."

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Daegu Gyeongbuk Institute of Science and Technology