Lemon Juice and Peel Constituents Potently Stabilize Rat Peritoneal Mast Cells.

Background/aims: Lemons (Citrus limon ) contain various nutrients and are among the most popular citrus fruit. Besides their antioxidant, anticancer, antibacterial, and anti-inflammatory properties, clinical studies have indicated their anti-allergic properties.

Methods: Using the differential-interference contrast (DIC) microscopy, we examined the effects of lemon juice and peel constituents, such as citric acid, ascorbic acid, hesperetin and eriodictyol, on the degranulation from rat peritoneal mast cells. Using fluorescence imaging with a water-soluble dye, Lucifer Yellow, we also examined their effects on the deformation of the plasma membrane.

Results: Lemon juice dose-dependently decreased the number of degranulated mast cells. At concentrations equal to or higher than 0.25 mM, citric acid, hesperetin, and eriodictyol significantly reduced the number of degranulating mast cells in a dose-dependent manner, while ascorbic acid required much higher doses to exert significant effects. At 1 mM, citric acid, hesperetin, and eriodictyol almost completely inhibited exocytosis and washed out the Lucifer Yellow trapped on the mast cell surface, while ascorbic acid did not.

Conclusion: This study provides in vitro evidence for the first time that lemon constituents, such as citric acid, hesperetin, and eriodictyol, potently exert mast cell-stabilizing properties. These properties are attributable to their inhibitory effects on plasma membrane deformation in degranulating mast cells.