Modulation of Endoplasmic Reticulum Stress by Selected Polyphenols from <em>Sambucus ebulus</em> Fruit

Background: Endoplasmic reticulum (ER) stress occurs when misfolded or unfolded proteins ac-cumulate in the organelle and contributes to the pathogenesis of various diseases. A previous study from our research group showed that aqueous extract from the Sambucus ebulus 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 chry-santhemin. The present review summarizes the effects of these phtyochemicals on ER stress. Methods: We queried the PubMed and ScienceDirect databases for primary studies discussing ER stress markers influenced by neochlorogenic acid, chlorogenic acid, idaein, epicatechin, resvera-trol, and chrysanthemin. Results: 43 articles were selected for review. No sufficient data was found regarding neochloro-genic acid and idaine in the context of ER stress. Other polyphenols, at low concentrations, reduce ER stress markers following exposure to stress agents in various experimental models. Interstingly, high doses of resveratrol activate pro-apoptotic signaling in cancer cell lines. Conclusions: A causal relationship between the polyphenols in the extract and ER stress modu-lation 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 thera-peutic applications of these phytochemicals for conditions associated with chronic cellular stress.