ABSTRACT
The genus Citrus species have been widely used in the relief of arthritic pain in traditional medicine. Citrus limon pith was one of the constituents of herbal decoctions taking daily for prevention against Coronavirus disease during covid-19 era. This study investigated the immunomodulatory activity of the aqueous extract of the pith of C. limon using cyclophosphamide-induced myelosuppression and delayed type hypersensitivity reaction in Wistar rats. Thirty-six rats were divided into six groups of six animals each. Three groups served as the control while the remaining three groups were given 150, 300, 600 mg/kg of extract respectively via oral route for 13 days. Groups II to VI were administered cyclophosphamide 30 mg/kg i.p on day 11, 12, and 13. On the 14th day, blood samples were collected for haematological parameters analysis. Delayed type hypersensitivity reaction was carried out using 24 animals divided into four groups of six animals each. Phytochemical screening revealed the presence of triterpenoids, flavonoids, and carbohydrates. LD50 was found to be greater than 3000 mg/kg. C. limon extract on cyclophosphamide-induced myelosuppression showed a statistically significant (P<0.05) increase in the white blood cells (WBC), platelets and lymphocytes counts at all extract doses. In the delayed type of hypersensitivity reaction, percentage increase in inflammation was 24.3%, 31.5% and 43% at extract doses of 150, 300 and 600 mg/kg. The findings of this study have shown that the aqueous extract of the pith of C. limon possessed immunostimulatory activity. © 2023 Shorinwa and Otu and the authors.