The findings make for encouraging reading as the extract sesaminol is found in the sesame seed shell waste product produced during the manufacture of sesame seed oil.
“Currently there is no preventive medicine for Parkinson's disease,” states Osaka City University’s Associate Professor Akiko Kojima-Yuasa. “We only have coping treatments.”
Along with sesaminol’s antioxidant effects, research also points to the extract’s anti-cancer effect that works by reducing the expression of proteins linked to the development and progression of cancer.
Sesaminol has been also linked to the inhibition of cell growth processes and promoting the degradation of unneeded or damaged proteins.
The extract’s role in PD focuses on its ability to prevent or reduce the oxidative stress that contributes to the degeneration of substantia nigra neurons, the part of the brain that plays an important role in movement.
Using in vitro PD models, Professor Kojima-Yuasa’s team began adding 6-hydroxydopamine (6-OHDA), a neurotoxin used to selectively destroy brain neurons, to human neuroblastoma (SH-SY5Y) cells.
The team found the viability of SH-SY5Y cells decreased dose-dependently following 6-OHDA treatment, but the addition of sesaminol restored viability to the control level.
In addition, 6-OHDA increased intracellular reactive oxygen species production, and the addition of sesaminol significantly suppressed this increase.
Nrf2 expression, which controls genes for detoxifying and building an antioxidant defence in the liver, was observed in the control group, but increased activity was observed in the 6-OHDA group.
Further findings revealed the sesaminol group showed strong expression of Nrf2 in the cytoplasm and nucleus.
The in vivo experiment also provided further encouragement as the team discovered that impairment of movement due to PD was the result of damaged neurons producing less dopamine than needed.
Having demonstrated this in mice with PD, Professor Kojima-Yuasa’s team fed them a diet containing sesaminol for 36 days, resulting in an increase in dopamine levels and subsequent increases in motor performance and intestinal motor function soon followed.
Gut-brain axis role?
Suspecting involvement from the gut, the team noted in the experimental group, a “shortening of the intestinal mucosal layer and damage to the mucosal surface were observed in the rotenone group.
“However, intestinal mucosal abnormalities were hardly observed in the sesaminol group. These results suggest that sesaminol prevents the progression of PD pathology from the intestine.”
“The results of the in vivo test suggests that sesaminol reducing α-synuclein expression in the substantia nigra, which suppresses motor dysfunction and the decline of intestinal motor function,” they added.
Going forwards, Professor Kojima-Yuasa and her team are ready to take their work to the clinical trial phase and connect the consumption/production chain in a way that, as she puts it, “prevents diseases with natural foods to greatly promote societal health.”
Published online: doi.org/10.1016/j.heliyon.2020.e05342
“Sesaminol prevents Parkinson's disease by activating the Nrf2-ARE signaling pathway”
Authors: Haruka Kaji et al