Bioactive Compounds and Pharmacological Effects of Citrus Limonoids

Citrus limonoids are a class of highly oxygenated tetranortriterpenoid secondary metabolites predominantly found in the seeds, peel and albedo of citrus fruits. Core members such as limonin, nomilin and obacunone exist as aglycones or as glycosidic conjugates and exhibit a spectrum of biological activities. Key pharmacological effects include antioxidant and anti-inflammatory actions mediated by free-radical scavenging and modulation of proinflammatory signalling pathways, anticancer properties through induction of apoptosis and cell-cycle arrest, antimicrobial and antiviral activities against a range of pathogens, antidiabetic effects via enzyme inhibition and insulin-sensitising actions, and neuroprotective benefits through attenuation of oxidative stress in neuronal models. Limonoids also promote phase II detoxifying enzyme activity and display insecticidal properties of interest to agriculture. Despite promising in vitro and in vivo data, challenges remain in enhancing bioavailability and optimising structural features. Practical applications have emerged in nutraceuticals, functional foods and sustainable valorisation of citrus by-products. Advances in extraction technologies, structural modification and mechanistic studies continue to shape the potential of limonoids as therapeutic leads and dietary supplements.

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Bioactive Compounds and Pharmacological Effects of Citrus Limonoids publication trend

The graph below shows the total number of articles in bioactive compounds and pharmacological effects of citrus limonoids across all publications each year (not limited to Nature Index journals).

Technical terms

Citrus limonoids: Highly oxygenated tetranortriterpenoid secondary metabolites found in citrus fruit tissues.

Aglycone: The non‐sugar moiety of a glycoside, often determining biological activity.

Glycoside: A compound in which a sugar unit is covalently bonded to a non-sugar aglycone.

Phase II detoxifying enzymes: Enzymes that conjugate xenobiotics to increase their solubility and excretion.

Structure–activity relationship: The relationship between a compound’s chemical structure and its biological effects, used to guide optimisation.

References

1. The Chemistry and Pharmacology of Citrus Limonoids. Molecules (2016).
2. In vivo induction of phase II detoxifying enzymes, glutathione transferase and quinone reductase by citrus triterpenoids. BMC Complementary Medicine and Therapies (2010).
3. A Green Extraction Method to Achieve the Highest Yield of Limonin and Hesperidin from Lime Peel Powder (Citrus aurantifolia). Molecules (2022).
4. Nomilin and Its Analogues in Citrus Fruits: A Review of Its Health Promotion Effects and Potential Application in Medicine. Molecules (2022).