An assessment of the in vitro neuroprotective properties of selected Algerian and South African medicinal plant extracts

In this study eleven Algerian and two South African medicinal plant extracts were selected and screened to evaluate their neuroprotective potential in attenuating characteristic biochemical features of Parkinson's disease (PD). Pretreatment with non-cytotoxic Pistacia atlantica Desf. (PA), Globularia alypum L. (GA), Zizyphus lotus Desf. (ZL) and Withania frutescens Pauquy (WF) at 100 µg/mL significantly reduced starvation-induced apoptosis. Aspalathus linearis (AL) and Corallina officinalis L. (CO) displayed significant anti-oxidant potential. Extracts testing positive for anti-oxidant/anti-apoptotic activity were further screened to evaluate their neuroprotective properties against known PD-inducing neurotoxins: 6-OHDA (100µM), rotenone (5µM) and paraquat (600µM). GA (25 µg/mL), PA (100 µg/mL) and ZL (100 µg/mL) pretreatment reduced 6-OHDA neurotoxicity whilst PA (100 µg/mL) and WF (100 µg/mL) were effective in reducing rotenone neurotoxicity. No neuroprotection was observed in the paraquat model, suggesting selected extracts are specific in reducing neurotoxicity of mitochondrial complex I inhibitors. Autophagy induction, as a measure to clear disease-causing protein aggregation, was also investigated. Peganum harmala (PH) and WF induced lysosomal accumulation and increased microtubule-associated protein 1 light chain 3-II (LC3-II) levels. Transmission electron microscopy imaging was conducted and confirmed autophagic vesicle presence for both PH and WF treatments. Our results suggest in addition to the neuroprotective properties displayed by GA, PA, ZL and WF the autophagy inducing potential of PH and WF can be further primed to an extent where its neuroprotective properties solely exist as studies have shown that autophagy upregulation may be a therapeutic approach in removing misfolded/aggregated proteins [1, 2].

Keywords: neuroprotective, autophagy, parkinson's disease

References:

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