Fermentation enhances Ginkgo biloba protective role on gamma-irradiation induced neuroinflammatory gene expression and stress hormones in rat brain

• The protective role of fermented Ginkgo biloba leaf (FGb) extract was studied in γ-irradiated rats.
• Radiation induced brain injury proved by elevation in MDA, TNF-α, IL-1β and stress hormone levels.
• FGb exhibits significant amelioration of the studied parameters.
• Fermentation could improve the bioactivities of Ginkgo biloba leaf extract.
• FGb exhibits potent in-vivo antioxidant, anti-apoptotic and anti-inflammatory activities.

Ionizing radiation has attracted a lot of attention due to its beneficial and possible harmful effects to the human population. The brain displays numerous biochemical and functional alterations after exposure to irradiation, which induces oxidative-stress through generation of reactive oxygen species (ROS). The present study evaluated the neuro-protective role of fermented Ginkgo biloba (FGb) leaf extract, compared to non-fermented G. biloba (Gb) leaf extract against γ-irradiation (6 Gy) in the rats' brain. The changes of the Gb phytochemical constituents after fermentation, using Aspergillus niger were evaluated by Gas Chromatography–Mass Spectrometry. The results showed a significant decrease in superoxide dismutase (SOD), glutathione peroxidase (GPx) activities and elevation of the calcium level in the brain cytosolic fraction of γ-irradiated rats. Further, significant increases in the malondialdehyde (MDA), the stress hormones (catecholamines); epinephrine (EN), norepinephrine (NE) and dopamine (DA) levels and the interleukin-1-beta (IL-1β) and tumor necrosis factor-alpha (TNF-α) gene expression relative ratio in parallel with a significant decrease in the glutathione (GSH) content and DNA fragmentation in the brain tissues of the γ-irradiated rats were observed. The pre-treatment with Gb extract significantly amended these biochemical parameters. Meanwhile, the pre-treatment with the FGb showed more improvement, compared to Gb, of these biochemical parameters in the brain of γ-irradiated rats, which could be attributed to the enhancement of its antioxidant activity after fermentation. These findings suggested that fermentation enhances the protective effect of Gb in the brain on the neuroinflammation, release of the stress hormones, apoptosis and oxidative damage induced by γ-irradiation. In conclusion: fermentation improved the bio-activities of Gb leaf extract and thus enhanced the in-vivo antioxidant, anti-apoptotic and anti-inflammatory activities, leading to amelioration of the stress hormones and Ca level. Accordingly, the fermentation enhances the protective role of Gb against γ-irradiation induced physiological disturbance in the rat's brain.