The amendatory effect of hesperidin and thymol in allergic rhinitis: an ovalbumin-induced rat model.

Allergic rhinitis is an immunoglobulin-E (Ig-E)-mediated response driven by type 2 helper T cells. Hesperidin and thymol are biological agents that possess antioxidant and anti-inflammatory characteristics. The purpose of this study was to investigate the effects of hesperidin and thymol in rats with ovalbumin-induced allergic rhinitis. Thirty adult Sprague-Dawley rats were randomly assigned into five groups, each containing six animals. The first group constituted the negative control group, while the remaining groups were exposed to an ovalbumin-induced model of allergic rhinitis. In the provocation stage, 4 mL/kg saline was administered to the positive control group, 10 mg/kg desloratadine to the reference group, 100 mg/kg hesperidin to the hesperidin group, and 20 mg/kg thymol to the thymol group, all by gastric lavage for 7 days. Nasal symptoms were scored on day 22. Rats were then sacrificed, and intracardiac blood specimens were collected to measure plasma total Ig-E, IL-5, IL-13, total antioxidant capacity (TAC), and total oxidant status (TOS) levels. Nasal tissues were extracted for histopathological and immunochemical examination. Nasal symptom scores were highest in the positive control group, while hesperidin and thymol ameliorated these symptoms to the same extent as desloratadine. Ig-E, IL-5, IL-13, and TOS levels increased, while TAC levels decreased significantly in the allergic rhinitis group compared to the other groups. Significant improvement in these parameters was observed in both the hesperidin and thymol groups. At histopathological and immunohistochemical examination of the nasal cavity, severe allergic inflammation and severe TNF-α expression was determined in rats from the allergic rhinitis group. Mild inflammatory changes and mild TNF-α expression were observed in all three treatment groups. Both hesperidin and thymol were effective in suppressing allergic symptoms and inflammation in the treatment of allergic rhinitis.