Nutraceutical Potential and Toxicological Concerns of Citrus Fruit Phytoconstituents: A Review

Citrus refers to a genus of flowering shrubs and trees belonging to the Rutaceae family. Citrus fruits are among themost widely cultivated and consumed fruits globally, serving as important sources of nutrients and nutraceuticals.Major species include Citrus sinensis (sweet orange), Citrus limon (lemon), Citrus paradisi (grapefruit), Citrus medica(citron), Citrus aurantium (sour orange), Citrus maxima (pummelo), Citrus reticulata (tangerine), and Citrusclementina (clementine). These fruits are valued not only for their refreshing juices but also for their bioactive-richby-products (peels, pulp, and seeds), which exhibit diverse pharmacological properties. This review was conductedthrough a structured literature search of major scientific databases, including Scopus, Web of Science, PubMed, andGoogle Scholar, covering publications from 2000 to 2024. Keywords such as “citrus phytochemicals,” “citrusflavonoids,” “limonoids,” “citrus essential oils,” “bioactivity,” and “toxicity” were used. Peer-reviewed experimental,clinical, and review articles published in English were included, with emphasis on studies addressing both healthbenefits and toxicological outcomes of citrus-derived compounds. Reported biological activities include antidiabetic,anticancer, antihypertensive, antihypercholesterolemic, anti-obesity, antiviral, antifungal, antibacterial, anti-inflammatory, and antioxidant effects. These health-promoting properties are largely attributed to the diversephytoconstituents present in citrus fruits, including flavonoids, limonoids, carotenoids, coumarins, and essential oils.However, despite these benefits, emerging evidence indicates that excessive intake or high concentrations of certaincitrus phytochemicals may elicit toxic effects, highlighting important safety concerns. This review critically examinesboth the nutraceutical benefits and potential toxicities of citrus phytoconstituents, emphasizing their dual biologicalroles. Furthermore, it underscores the need for mechanistic and dose–response studies to better define toxicitypathways and establish safe consumption thresholds