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.