Modulation of Endoplasmic Reticulum Stress by Selected Polyphenols from Sambucus ebulus L. Fruit

When misfolded or unfolded proteins accumulate in the endoplasmic reticulum (ER), ER stress occurs, which contributes to the pathogenesis of various diseases. A previous study from our research group showed that aqueous extract from the Sambucus ebulus L. fruit has anti-inflammatory properties, possibly by reducing ER stress. The extract was found to contain high levels of neochlorogenic acid, chlorogenic acid, idaein, epicatechin, resveratrol, and chrysanthemin. The present review summarizes the effects of these phytochemicals on ER stress. We queried the PubMed and ScienceDirect databases for primary studies discussing ER stress markers influenced by neochlorogenic acid, chlorogenic acid, idaein, epicatechin, resveratrol, and chrysanthemin. Forty-two articles were selected for review. No sufficient data were found regarding neochlorogenic acid and idaein in the context of ER stress. Other polyphenols, at low concentrations, reduce ER stress markers following exposure to stress agents in various experimental models. Interestingly, high doses of resveratrol activate pro-apoptotic signaling in cancer cell lines. A causal relationship between the polyphenols in the extract and ER stress modulation was identified. The PERK pathway was most strongly associated with the effects of the listed compounds. Although further research is needed, recent findings suggest potential therapeutic applications of these phytochemicals for conditions associated with chronic cellular stress.