Experimental phytochemical characterization and OECD guideline evaluation of the acute and 28-day oral toxicity of a hydroethanolic peel extract of Citrus medica L. in Wistar rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Citrus medica peel is traditionally used for inflammatory, respiratory, and gastrointestinal disorders, but safety data for repeated oral exposure remain limited.

AIM OF THE STUDY: This study evaluated the acute and 28-day oral toxicity of a hydroethanolic C. medica peel extract in Wistar rats, per OECD Guidelines 423 (Acute Oral Toxicity) and 407 (Repeated-Dose 28-Day Oral Toxicity).

MATERIALS AND

METHODS

The extract was characterized for total phenolic and flavonoid content and antioxidant activity; marker compounds (e.g., hesperidin, naringin) were not chromatographically profiled. Acute toxicity was assessed via an OECD 423 Limit Test at 2000 mg/kg; the 28-day study used 625, 1250, and 2500 mg/kg/day, assessing clinical, hematological, biochemical, and histopathological endpoints.

RESULTS

The extract contained 111.90 ± 1.63 mg GAE/g phenolics and 74.61 ± 4.12 mg QE/g flavonoids, with moderate antioxidant activity. No mortality occurred at 2000 mg/kg; per OECD 423 decision criteria, the LD50 was estimated to exceed 5000 mg/kg (GHS Category 5). Repeated dosing produced statistically significant (p < 0.05) dose-related hematological and biochemical changes, most pronounced at the high dose, including increased transaminases with hepatocellular hypertrophy (no necrosis or fibrosis) and male-predominant mild renal tubular alterations, with creatinine unchanged.

CONCLUSION

The extract shows low acute toxicity and moderate, sex-dependent subacute (28-day repeated-dose) effects at high doses. The NOAEL was 1250 mg/kg/day in females and 625 mg/kg/day in males; the male LOAEL was 1250 mg/kg/day due to renal tubular degeneration. These findings support the safety of traditional use levels and provide data for the regulatory evaluation of C. medica-derived products.