Sea Buckthorn Leaves as a Potential Source of Antioxidant Substances

Each year, agro-foods produce thousands of tonnes of by-products that contain high-value, unique nutrients. The application of plant by-products enables agro-food corporations to obtain value from them and avoid using natural resources. The idea of the bio economy protects against environmental pollution and leads to a cheap source of bioactive components, which can be transformed into value-added products for other industries. The numerous publications on the positive impact of sea buckthorn (SBT, Hippophae rhamnoides L., Elaeagnaceae family) and its products on human health mainly concern its fruits and seeds. However, there are few data relating to the properties of SBT leaves. The leaves of SBT can be a rich source of nutrients and biologically active substances. In this investigation, we report the study of the leaves of four SBT cultivars. We determined their antioxidant capacities, measured total polyphenols and total flavonoids, and quantified their major polyphenols and alkaloids. The results show that SBT leaves are a source of antioxidants and alkaloids. Additionally, in this raw material, we identified the presence of individual flavonols (rutoside and quercetin), individual anthocyanidins (cyaniding, delphinidin, and peonidin), and chelerythrine by high-performance thin-layer chromatography (HPTLC) for the first time. Through these types of studies, we aim to revalue this raw material, which is not well known in the world. Considering its nutritional properties, we seek to increase the use of its high-value, unique nutrients in food processing, medicine, and animal nutrition, in accordance with the goals of a closed-loop bioeconomy.