Smallanthus sonchifolius leaf attenuates neuroinflammation

Yacon, Smallanthus sonchifolius, has anti-hypertensive, anti-inflammatory, and anti-cancer potential. However, its neuroprotective and anti-neuroinflammatory effects are unknown. Moreover, activation of microglia has been considered a mechanism in the development of Alzheimer's disease. Therefore, the aim of this study was to determine the neuroprotective effects of an ethanolic yacon leaf extract (YLE) on lipopolysaccharide (LPS)-induced neuroinflammation in vitro and in vivo.

The viability of microglial BV2 cells was tested with 2,3-bis[2-methyloxy-4-nitro-5-sulfophenyl]-2H-tetrazolim-5-carboxanilide. The production of nitric oxide (NO) was determined by the Griess reagent. mRNA expression and protein levels of inflammatory mediators were evaluated by the real-time polymerase chain reaction and immunohistochemistry, respectively. In addition, we performed histological analysis in mice treated with an intraperitoneal injection of LPS (250 μg/kg).

Our results showed that treatment with YLE significantly reduced NO production in LPS-stimulated BV2 cells. YLE also decreased mRNA levels of the inflammatory factors tumor necrosis factor alpha, inducible nitric oxide synthase, cyclooxygenase-2, and interleukin-1 beta. In vivo, YLE (40 mg/kg daily for seven days) significantly diminished LPS-induced tissue damage in the dentate gyrus and cornu amonis regions of the hippocampus by regulating the levels of inflammatory factors.

Our findings support the protective effects of YLE against the development of neurodegeneration.