Nature’s Remedy: Evaluating the Combined in Vitro and in Vivo Anti-inflammatory Potential of Citrus limon Peel Extracts

Abstract

Chronic inflammation contributes to many disorders, encouraging the search for natural agents with safer therapeutic potential. Citrus limon is highly recognised for its plant chemical richness as well as its capacity to modulate oxidative and inflammatory pathways. It is frequently used in traditional medicine. This study aimed to characterise the phytochemical constituents of C. limon peel extracts in both methanolic and water-based forms and to compare their anti-inflammatory effects through in vitro and in vivo approaches. Phytochemical analysis revealed that the methanolic extract contained higher levels of total polyphenols (92.07 ± 1.22 mg GAE/g) and flavonoids (65.37 ± 2.9 mg QE/g) than the aqueous extract (53.01 ± 1.16 mg GAE/g and 46.79 ± 2.3 mg QE/g). The extract’s effects on inflammation were explored through tests for protein denaturation (bovine serum albumin [BSA]and egg albumin) and erythrocyte membrane stabilisation. The methanolic extract exhibited lower IC₅₀ values for BSA denaturation (53.97 ± 5.56 µg/mL), egg albumin (84.95 ± 1.77µg/mL), and membrane stabilisation (65.99 ± 4.66 µg/mL) compared with the aqueous extract (94.51 ± 0.98, 142 ± 2.48 , and 114.6 ± 1.35µg/mL). For the in vivo test, paw edema was induced by carrageenan. The methanolic extract (200 mg/kg) significantly reduced edema progression at the sixth hour to 5.46 ± 0.36%, compared with 11.04 ± 0.37% for the aqueous extract, approaching the efficacy of diclofenac (10 mg/kg, 6.62 ± 0.29%). Overall, the methanolic peel extract of C. limon demonstrated superior anti-inflammatory activity, supported by lower IC₅₀ values and stronger inhibition of edema.