Bioprospecting Underutilized Plant By-Products for Antioxidant Natural Extracts: A Review

Underutilized plant by-products are an overlooked source of natural extracts that contain antioxidant bioactive compounds and therapeutic potential. Oxidative stress significantly contributes to the development of various chronic diseases. In this context, natural extracts rich in bioactive compounds derived from underutilized plant by-products emerge as promising options for developing antioxidant-based therapies that target oxidative stress-related molecular pathways involved in the pathogenesis of chronic disease. The valorization of by-products through the recovery of antioxidant-rich extracts is particularly appealing, as non-edible plant parts often contain higher levels of bioactive compounds than their edible counterparts. This review provides a comprehensive overview of antioxidant natural extracts and their major bioactive components, including polyphenols (particularly flavonoids and phenolic acids), terpenoids, alkaloids, and other redox-active compounds.