Protective Efficacy of Spilanthes acmella Murr. Extracts and Bioactive Constituents in Neuronal Cell Death.

Spilanthes acmella Murr., a well-known Thai traditional medicine, has been used for treatment of toothache, rheumatism, and fever. Diverse pharmacological activities of S. acmella Murr. have been reported. In this study, antioxidative and neuroprotective effects of S. acmella Murr. extracts as well as bioactive scopoletin, vanillic acid, and trans-ferulic acid found in the aerial parts of this plant species have been described. Protective effect of S. acmella Murr. extracts and bioactive compounds on dexamethasone-induced neuronal cell death was investigated. Different plant crude ethyl acetate (EtOAc) and methanol (MeOH) extracts including pure compounds of S. acmella Murr. were evaluated in human neuroblastoma SH-SY5Y cells. Cytotoxic effects were performed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Mechanisms involved in the antioxidant effects of S. acmella Murr. regarding the activation of antioxidant marker proteins such as superoxide dismutase 2 (SOD2) and sirtuin 3 (SIRT3) were determined using 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA) assay, Western blot analysis, and immunocytochemistry. Dexamethasone significantly caused the decrease of SH-SY5Y cell viability. Conversely, the increases in reactive oxygen species (ROS), autophagy, and apoptosis were observed in dexamethasone-treated cells. S. acmella Murr. MeOH and EtOAc extracts, as well as the bioactive compounds, reversed the toxic effect of dexamethasone by increasing the cell viability, SIRT3 protein expression but reducing the ROS, autophagy, and apoptosis. This study demonstrated that S. acmella Murr. may exert its protective effects against ROS through SOD2 and SIRT3 signaling pathways in dexamethasone-induced neurotoxicity. S. acmella Murr. may be a candidate therapy for neuroprotection.

Neuroprotective effect of Spilanthes acmella Murr. on pesticide-induced neuronal cells death.

OBJECTIVE: To investigate protective effects of Spilanthes acmella (S. acmella) Murr. extracts against pesticide-induced neuronal cells death and to elucidate the underlying molecular mechanism in dopaminergic (SH-SY5Y) cells lines. METHODS: Cell viability of SH-SY5Y cells was studied by treating the cells with various concentration of pirimicarb for 24 h. Neuroprotective effect of S. acmella Murr. extracts was investigated by adding the plant extracts to the medium for 24 h prior to the incubation with 100 µM H2O2 or with pirimicarb for 24 h. Control-untreated cells were incubated with the culture medium. Cell viability was measured by MTT assay, calpain and calpastatin expressions were analyzed by Western blotting and immunocytochemistry. RESULTS: Pretreatment of SH-SY5Y cells with S. acmella Murr. extracts (1 µg/mL) for 24 h significantly increased the dopaminergic neurons in pirimicarb-induced neurotoxicity. In addition, pretreatment with the S. acmella Murr. extracts led to decreased calpain but increased calpastatin protein levels. CONCLUSION: S. acmella Murr. extracts exerted neuroprotective effect, via an alteration of calcium homeostasis, against pirimicarb induced neurotoxicity. The S. acmella Murr. might be a potential natural candidate with neuroprotective activity.