Abstract

Background: Ginkgo biloba extract (GbE) is known to contain several bioactive compounds and exhibits free radical scavenging activity. Parkinson's Disease (PD) is a neurodegenerative disorder characterized by the loss of dopaminergic neurons and is associated with oxidative stress, neuroinflammation and apoptosis.

Objective: The current study aimed to investigate the neuroprotective effect of GbE in a rat model of PD induced by rotenone (ROT; a neurotoxin).

Methods: Twenty-four male albino rats were randomly divided into four groups of six rats each: normal control, GbE treated, toxin control (ROT treated) and GbE+ROT group.

Results: Oral administration of ROT (2.5 mg/kg b.w.) for 50 days caused an increased generation of lipid peroxidation products and significant depletion of reduced glutathione, total thiol content and activities of enzymatic antioxidants, i.e., superoxide dismutase and glutathione peroxidase in the brains of treated rats. Furthermore, ROT caused an elevation in acetylcholinesterase, interleukin-1β, interleukin- 6 and tumor necrosis factor-α and a significant reduction in dopamine in the stratum and substantia nigra. Immunohistochemical results illustrated that ROT treatment reduced the expression of tyrosine hydroxylase (TH). GbE treatment (150 mg/kg b.w./day) significantly reduced the elevated oxidative stress markers and proinflammatory cytokines and restored the reduced antioxidant enzyme activities, DA level and TH expression. These results were confirmed by histological observations that clearly indicated a neuroprotective effect of GbE against ROT-induced PD.

Conclusion: GbE mitigated ROT-induced PD via the inhibition of free-radical production, scavenging of ROS, and antioxidant enhancement.

Keywords: Ginkgo biloba; Parkinson's disease; ROT treatment; neuroprotection; oxidative stress; rotenone.

Wireworm has become a major problem causing extensive crop loss in many potato production areas in Canada. Wireworm control methods includes the use of chemical pesticides. However, pesticides can affect human health and the environment, and their use has consequently been questioned and prohibited in many countries. Therefore, the use of environmentally friendly plant protection techniques, including crop rotation as an alternative to chemical control measures have been promoted to minimize crop damage. In that context, buckwheat is used as a rotation crop to mitigate wireworm damage in potatoes. But so far, less is known about how buckwheat contributes to mitigate disease. This study was designed in a context of integrated pest management, with primary objectives to:(1) determine the microbial diversity in the buckwheat rhizosphere in comparison with other rotation crops; and (2) determine the correlation between the buckwheat rhizosphere microbiome structure and wireworm density. To achieve these objectives, 16S rRNA metagenomic sequencing was performed to determine the microbial diversity in bulk and rhizosphere soils of buckwheat and barley grown at two locations during two growing seasons. A pilot wireworm trapping study was also performed to assess the wireworm population following buckwheat and barley as rotation crops. The study identified 27 phyla in the two crops of which Proteobacteria, Bacteroidetes, Actinobacteria were the most abundant and species identification was confidently achieved in 7 phyla including Proteobacteria, Actinobacteria, Acidobacteria, Bacteroidetes, Firmicutes, Deinococcus-Thermus and Crenarchaeota. Interestingly, Methylophilus flavus, Saccharopolyspora tripterygii and Deinococcus yunweiensis were three operational taxonomic units (OTUs) found at the species level to be unique to the buckwheat rhizosphere soil at both locations and purported as non-pathogenic entophytic bacteria and beneficial for sustainable agriculture. Moreover, after two years, a reduction in wireworm density was observed in both crops although, the direct link associating the reduced wireworm density and the observed microbial diversity and the operating mechanisms in each crop remain to be elucidated. Taken together, changes were observed in the soil microbial communities associated with specific rotation crops and a reduction in wireworm density was correlatively observed. Thus, our study showed that the root system of buckwheat influences the structure of the microbiome in the rhizosphere as .hypothesized