Background. Raspberries (Rubus idaeus L.) hold significant importance in the food industry. Raspberry pomace, commonly regarded as a waste product during fruit processing, is a rich source of biologically active components. This study aimed to assess the detailed profile of polyphenols in fresh and freezedried raspberry pomace. Furthermore, we examined its potential to protect normal human gastric epithelial cells against oxidative stress in an H₂O₂-induced stress model. A qualitative and quantitative analysis of phenolic compounds was performed using the  high-performance liquid chromatography coupled with mass spectrometry (HPLC-MS) method. Cell viability was assessed based on the integrity of lysosomal membranes (neutral red NR  assay) and mitochondrial dehydrogenase activity (MTT). Additionally, the reducing potential (FRAP), the ability to scavenge free radicals in the DPPH^• test and studies on ABCHP021X cells  based on the H₂DCFDA test were evaluated.
Results and conclusion. It was found that the extract from freeze-dried raspberry pomace is a rich source of various polyphenolic compounds, including ellagitannins, epicatechin and  anthocyanins. The extract was characterized by high antioxidant potential and exhibited a protective effect on human gastric epithelial cells against H₂O₂-induced cytotoxicity. Cell incubation  with the extracts prior to oxidative stress induction attenuated H₂O₂-induced cytotoxicity in a concentration-dependent manner, and at a concentration of 250 µg/cm³ , it abolished the  detrimental effects of H₂O₂. Additionally, the extract at this concentration restored the redox status in cells with induced oxidative stress and reduced ROS levels to values similar to the control. Thus, raspberry pomace extracts may be considered a valuable food supplement.