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

• Published in: South African journal of botany 2023-06, Vol.157, p.53-63
• Main Authors: Omoruyi, Sylvester I., Akinfenwa, Akeem O., Ekpo, Okobi E., Hussein, Ahmed A.
• Format: Article
• Language: English
• Subjects: Aspalathin; Aspalathus linearis; Linearthin; Neuroprotection; Parkinson's diseases; Rooibos
• ISSN: 0254-6299; 1727-9321
• DOI: 10.1016/j.sajb.2023.03.042

•Aspalathus linearis and its bioactive compounds aspalathin and linearthin protect SH-SY5Y cells from MPP+-induced neurotoxicity is SH-SY5Y cells.•Aspalathus linearis, aspalathin and linearthin prevent ROS accumulation in cells following MPP+ toxicity.•Aspalathus linearis, aspalathin and linearthin improve ATP production in cells following MPP+ toxicity.•Aspalathus linearis, aspalathin and linearthin rescue SH-SY5Y cells from MPP+-induced apoptosis.•Cell morphology improved following pre-treatment with aspalathus linearis, aspalathin and linearthin. 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 compounds 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 neuroblastoma cells and the 1-methyl-4-phenylpyridinium (MPP+) neurotoxin. The effect of increasing concentrations, 12.5, 25, and 50 µg/mL of RB as well as 2.5, 5, and 10 µg/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 µM 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 bioactive compounds are potential nutraceuticals that could enhance the function of neurons and in turn, slower the progression of neurodegeneration.