The neuroprotective effect of Clove essential oil against 6-OHDA-induced cell death in SH- SY5Y and a rat model of Parkinson's disease

Abstract

Parkinson's disease (PD) is the second most prevalent neurological disorder. Natural therapies are becoming more popular for preventing disease onset. Clove essential oil (CEO), a potent antioxidant derived from Syzygium aromaticumbuds, was tested in vitro (SH-SY5Y) and in vivo (PD rat model) for its ability to protect against 6-OHDA-induced cell death. Twenty-four hours of SH-SY5Y cells' exposure to 6-OHDA (100 µM) drastically decreased cell viability. At doses lesser than 20 µg/ml, CEO and its main component eugenol (EG) had no cytotoxic effect on SH-SY5Y. CEO and EG at doses of 2.5-20 µg/ml provided significant neuroprotection against 6-OHDA-induced cell death. A PD rat model was generated by injecting 6-OHDA (21µg/animal) unilaterally into the striatum. An assessment of motor performance can predict neuronal cell loss in the substancia nigra compacta (SNc). Compared to 6-OHDA-lesioned, CEO-treated (10mg/Kg) rats' locomotor performance (actimetry and cylinder tests) improved significantly one and two weeks after 6-OHDA-lesion. Tyrosine hydroxylase (TH) cell count showed a significant decrease in cell death in ipsilateral SNc in both CEO-treated and 6-OHDA-lesioned rats when compared to contralateral. In contrast to the 6-OHDA-lesioned group, the ipsilateral SNc of the CEO-treated group showed a significant high TH cell number. In the present study, the neuroprotective effect of CEO was demonstrated both in vitro and in vivoagainst 6-OHDA cytotoxicity. Therefore, CEO could be used as a food supplement for PD prevention.

Investigating the Therapeutic Potential of Plants and Plant-Based Medicines: Relevance to Antioxidant and Neuroprotective Effects

“…For example, CF was highest in phenolics, flavonoids, and nitrogen (DPPH) free radical scavenging capacities and significantly prevented H 2 O 2 -induced cell death. This is consistent with a previous study that reported that clove essential oil and its major component, eugenol, were protective against 6-hydroxdopamine (OHDA)-induced cell death in SH-SY5Y cells [ 77 ]. In addition, Liu et al [ 78 ] also reported that clove had higher total phenolic content, flavonoid content, and DPPH scavenging capacity than the majority of 68 Chinese herbal samples tested, including black pepper.…”

“…R8 was the only sample that did not reduce cell viability at any concentration; however, pre-treatment with R8 did not significantly improve cell viability in the presence of H 2 O 2 -induced oxidative stress. Several studies have found that phenolic extracts reduce cell viability in the absence of a stressor; for example, Dhanalakshmi et al [ 75 ] found that vanillin, a natural phenolic compound, reduced cell viability at concentrations >1 μM and Hamdi et al [ 77 ] found that clove essential oil was toxic at concentrations >40 μg/mL. Together with the existing studies, these results suggest that plant-derived extracts administered directly to cells without a stressor can have differential effects despite being protective in the presence of a physiological stressor.…”

Multi-Targeting Neuroprotective Effects of Syzygium aromaticum Bud Extracts and Their Key Phytocompounds against Neurodegenerative Diseases

“…Therefore, subsequent cell culture experiments were conducted using concentrations below 50 µg/mL to minimize cell death due to the extract's toxicity. Similar results were obtained in a previous study where no cytotoxicity was observed up to 20 µg/mL when treating SH-SY5Y cells with the clove essential oil [43]. The pure compounds were tested at lower concentrations (0.01, 0.1, 1, 10 µg/mL), where eugenol and TMA displayed significant (* p < 0.05) decreases in cell viability (89.9% and 87.2%, respectively) compared to the control at 10 µg/mL.…”

“…Sci. 2023,24, x FOR PEER REVIEW 8 of 26 cells with the clove essential oil[43]. The pure compounds were tested at lower concentrations (0.01, 0.1, 1, 10 µg/mL), where eugenol and TMA displayed significant (* p < 0.05) decreases in cell viability (89.9% and 87.2%, respectively) compared to the control at 10 µg/mL.…”