Valorisation of citrus peels: implications for cardiovascular diseases and diabetes management

Citrus peels, obtained from fruits belonging to the genus Citrus, of family Rutaceae, represents a major agro-industrial waste with significant nutritional and health benefits. These are composed of a variety of compounds, including flavonoids (hesperidin, naringin, quercetin, kaempferol), phenolic acids (caffeic acid, p-coumaric acid, ferulic acid, sinapic acid), essential oils, carbohydrates, amino acids and fatty acids, that can be extracted using green extraction techniques such as pulse electric field, enzyme-assisted extraction and so on. Emerging evidence highlights their numerous therapeutic benefits, including anti-diabetic, antioxidant, anti-inflammatory, anti-hyperlipidaemic and prebiotic effects. These therapeutic effects are provided through multiple pathways such as neutralising of reactive oxygen species, enhancing activity of antioxidant enzymes, suppression of inflammatory cytokines, regulation of blood pressure and blood glucose, lipid metabolism and modulation of gut microbiota. Despite the health-promising effects, existing findings rarely focus on in-vitro and in-vivo studies, primarily for antioxidant and anti-inflammatory activity. Considering the existing research gaps, this review attempts to highlight the significant potential of citrus peels, their nutritional and bioactive composition. Moreover, it examines the mechanism by which citrus peel bioactive compounds exert anti-diabetic and cardioprotective effects by reducing oxidative stress and inflammatory cytokines, with supporting in-vitro and in-vivo studies. In addition, this review investigates the synergistic effect of peels with other compounds, alongside their regulatory effects on lipid profile and gut microflora. Collectively, this review highlights the citrus peels-derived phytoconstituents as a sustainable, economic and environmentally friendly alternative for mitigation of cardiometabolic diseases including diabetes and cardiovascular disorders.