Fruits of Polish Medicinal Plants as Potential Sources of Natural Antioxidants: Ellagic Acid and Quercetin

Due to their antioxidant and other beneficial properties, polyphenol-rich plants are important functional foods. The purpose of the study was to evaluate the content of two polyphenols—ellagic acid and quercetin—in fruits of wild medicinal plants of Polish origin, as potential sources of these compounds. The research material was chosen considering both the popularity of the fruits and their recognized medicinal and pharmaceutical properties. All selected fruits—barberry (Berberis vulgaris), blackthorn (Prunus spinosa), chokeberry (Aronia melanocarpa), elderberry (Sambucus nigra), hawthorn (Crataegus monogyna), lingonberry (Vaccinium vitis-idaea), rowanberry (Sorbus aucuparia), and sea-buckthorn (Hippophae rhamnoides syn. Elaeagnus rhamnoides)—are known for therapeutic use in Polish folk medicine. Extracts were analyzed for ellagic acid and quercetin content using UHPLC-ESI-MS/MS. Quantitative results revealed that barberries, blackthorn, and sea-buckthorn contained the highest amounts of ellagic acid, up to 3.29 ± 0.24, 3.50 ± 0.16, and 4.80 ± 0.18 μg/g dw, respectively, while lingonberry provided up to 196.20 ± 3.10 μg/g dw of quercetin, making it a valuable dietary source of this flavonoid. The study confirms that Polish wild medicinal plants are valuable reservoirs of key polyphenols relevant to human health and support their potential inclusion in dietary strategies for disease prevention.