Estimation of some total secondary metabolites and profile of polyphenols of grape seeds by HPLC techniques

Grape seeds, as by-products of grape processing, are valuable sources of phytochemicals that contribute to human health. This study involved a comprehensive chemical analysis of grape seeds from six Vitis vinifera cultivars to identify their phytochemical components. The seeds were collected from the local market of Najaf AL Ashraf, Iraq, during the ۲۰۲۳ harvest season, shade-dried, ground, and extracted with ۹۹.۸% methanol via maceration with shaking for ۲۴ hours. HPLC analysis of the methanolic extracts revealed several phenolic and flavonoid compounds, including catechin, epicatechin, gallic acid, quercetin, and rutin, with varying retention times and concentrations. Quantification was performed using external calibration curves for each standard (R² > ۰.۹۹۹), validated by intra-day and inter-day precision, recovery studies, and limits of detection (LOD) and quantification (LOQ) determined via signal-to-noise ratios. Among the cultivars, V. vinifera cv. Black magic exhibited the highest concentrations of all detected compounds, with catechin being the most abundant. Additionally, the total contents of phenolic compounds (Folin-Ciocalteu), flavonoids (aluminum chloride), anthocyanins (pH differential), alkaloids (BCG), tannins (gelatin precipitation), saponins (gravimetric), terpenoids (colorimetric, linalool standard), and steroids (Zak's method) were quantitatively estimated. The results showed significant variation in the overall chemical content across the six studied cultivars (p< ۰.۰۵, ANOVA).

کلیدواژه ها:

Grape seeds ، Vitis vinifera ، Secondary metabolites ، Polyphenols ، HPLC ، Bioactive compounds