Investigation of Polyphenol Composition and the Bioactivities of Shoots, Seeds, and Skins of Georgian Grape (Vitis vinifera L.) Varieties

Introduction: Grape-derived products constitute a significant and affordable source of natural bioactive compounds, particularly polyphenols. Regular consumption of these substances is associated with reduced cases of various degenerative and long-term illnesses, largely due to their potent antioxidant properties that combat oxidative stress. This study aimed to explore the phenolic composition of grape-derived products from three Georgian grape varieties and evaluate their antioxidant and anti-inflammatory activities. Methods: Phenolic compounds were assessed qualitatively and quantitatively using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The ORAC (oxygen radical absorbance capacity) and the DCFH-DA assay on WS1 human fibroblasts were used to evaluate antioxidant activity. Anti-inflammatory activity was assessed via nitrite quantification in RAW 264.7 macrophages treated with extracts. Results: Saperavi seeds demonstrated highest value for phenolic composition, as well as antioxidant activity with an IC₂⁽ value of 18 μg/mL and ORAC of 0.9 μmol TE/mg. Anti-inflammatory properties were most prominent in seed extracts of Kisi (53% inhibition), Rkatsiteli (41.7%), and Saperavi (39.5%). Discussion: Polyphenol profiles varied by grape tissue; Saperavi seeds were rich in flavanols, while skins contained anthocyanins, such as delphinidin-3-O-glucoside. Antioxidant and antiinflammatory activities also differed by variety; notably, Kisi seeds showed highest NO inhibition. These results highlighted tissue- and variety-dependent polyphenol distribution and bioactivity. Conclusion: Grape-derived products, particularly seeds and skins, are rich in polyphenols with strong antioxidant and anti-inflammatory activities. This evidence valorizes grape by-products as sustainable sources of natural bioactives suitable for functional food and pharmaceutical applications. conclusion: Grape-derived products, particularly seeds and skins, are rich in diverse phenolic compounds with strong antioxidant and anti-inflammatory activities. These findings support the valorization of grape by-products as sustainable sources of natural bioactives for functional food and pharmaceutical applications.