Anti-encephalitogenic effects of cucumber leaf extract

- Cucumber leaf extract is rich in cucurbitacins and phenolics.
- Cucumber leaf extract inhibits encephalitogenic T cells.
- Cucumber leaf extract inhibits macrophages and dendritic cells.
- Cucumber leaf extract is not toxic to zebrafish.
- Cucumber leaf extract inhibits generation of encephalitogenic T cells in vivo.

Cucumber (Cucumis sativus) fruit has been used in cuisine worldwide, while its leaves are rich in immunomodulatory compounds. Cucumber leaf extract (CLE) was characterized by the predominance of triterpenoids cucurbitacins and significant levels of phenolics. Effects of CLE on CD4+ T helper (Th) cells and macrophages, as the major encephalitogenic cells in the autoimmunity of the central nervous system were investigated in our study. CLE potently inhibited production of major pathogenic Th cytokines: interferon-gamma and interleukin-17, as well as of nitric oxide and reactive oxygen species in macrophages. Antigen-presenting activity of macrophages and dendritic cells was also affected by CLE. The effects of CLE were co-incident with modulation of NFκB and p38 MAPK signaling. Concentrations of CLE used in vitro did not show toxic effects on zebrafish embryos. Moreover, CLE inhibited generation of encephalitogenic cells in vivo. These results demonstrate that CLE deserve further investigation on its anti-encephalitogenic therapeutic properties.