Dr. Gerd Kempermann from the Technische Universität Dresden and the German Center for Neurodegenerative Diseases and colleagues found that high concentrations of quercetin or DHBA stimulate the generation of new neurons, a process called neurogenesis.
“As apples are one of the most widely consumed fruits worldwide, resulting in a generalized exposure across cultures, we investigated whether they contain substances that sustain or promote adult hippocampal neurogenesis,” they said.
“We took a two-pronged approach, first studying quercetin, the most abundant flavonoid in apple peel, and second extending our investigation to identify additional pro-neurogenic factors in the fruit.”
The researchers found that laboratory-grown stem cells from adult mouse brains generated more neurons and were protected from cell death when quercetin or DHBA were added to the cultures.
The researchers found that laboratory-grown stem cells from adult mouse brains generated more neurons and were protected from cell death when quercetin or DHBA were added to the cultures.
Subsequent tests in mice showed that in distinct structures of the adult brain associated with learning and memory, stem cells multiplied and generated more neurons when the mice were given high doses of quercetin or DHBA.
The effects on neurogenesis were comparable to effects seen after physical exercise, a known stimulus for neurogenesis.
“We found that quercetin, the most abundant flavanol in apple peel, was anti-proliferative at high concentrations but pro-neurogenic at low concentrations,” the scientists said.
“This was confirmed in vivo, with intraperitoneally delivered quercetin promoting survival and neuronal differentiation, without affecting proliferation.”
“We found that DHBA significantly increased neural precursor cell proliferation and neurogenesis,” they added.
“This work shows that both flavonoids and DHBA are pro-neurogenic, not only by activating precursor cell proliferation but also by promoting cell-cycle exit, cellular survival, and neuronal differentiation.”