Aspalathin and linearthin from Aspalathus linearis (Rooibos) protect SH-SY5Y cells from MPP plus -induced neuronal toxicity

Aspalathus linearis is a plant endemic to the Western Cape province of South Africa and is widely consumed as a beverage due to its numerous health benefits. It is rich in antioxidants and bioactive polyphenolic com-pounds including aspalathin, nothofagin and the recently reported linearthin. This study investigates the potential neuroprotective effects of the total extract of A. linearis (rooibos RB), and its bioactive compounds, aspalathin (ASP) and linearthin (LIN) in an in vitro model of Parkinson's disease, using the SH-SY5Y neuro-blastoma cells and the 1-methyl-4-phenylpyridinium (MPP+) neurotoxin. The effect of increasing concentra-tions, 12.5, 25, and 50 mg/mL of RB as well as 2.5, 5, and 10 mg/mL of ASP or LIN on the viability of SH-SY5Y cells was investigated using the MTT assays. For neuroprotection experiments, cells were pre-treated with extracts or compounds for 2 h before exposure to 2000 mM MPP+ and thereafter cell viability was performed. The mechanism of neuroprotection was determined by the measurement of lactate dehydrogenase release (LDH), reactive oxygen species (ROS) production, adenosine triphosphate (ATP) and caspase 3/7 activities in the cells. Results show that the deleterious effects of MPP+ were attenuated by pre-treatment with either RB or the bioactive compounds ASP and LIN as evidenced by increased cell viability, reduced ROS accumulation, increased ATP levels, as well as the inhibition of apoptosis. These findings suggest that rooibos and its bioac-tive compounds are potential nutraceuticals that could enhance the function of neurons and in turn, slower the progression of neurodegeneration (c) 2023 SAAB. Published by Elsevier B.V. All rights reserved.