Novel insights into the anti-asthmatic effect of Raphanus sativus L. (Raphani Semen): Targeting immune cells, inflammatory pathways and oxidative stress markers

Raphanus sativus L. is a well-known medicinal plant with traditional therapeutic applications in various common ailments including inflammation and asthma. This study aimed to evaluate the chemical composition and anti-asthmatic potential of the hydro-methanolic extract of the leaves of R. sativus L. (Rs.Cr) using various in vitro and in vivo investigations. The Rs.Cr was subjected to preliminary phytochemical analysis and HPLC profiling. The safety was assessed through oral acute toxicity tests in mice. The antiasthmatic effect of the extract was studied using milk-induced leukocytosis and ovalbumin (OVA)-induced allergic asthma models established in mice. While mast cell degranulation and passive paw anaphylaxis models were established in rats. Moreover, effect of the extract was studied on various oxidative and inflammatory makers. The antioxidant effect of the extract was also studied by in vitro DPPH method. The HPLC profiling of Rs.Cr showed the presence of important polyphenols in a considerable quantity. In toxicity evaluation, Rs.Cr showed no sign of morbidity or mortality with LD50 < 2000 mg/kg. The extract revealed significant mast cell disruption in a dose-dependent manner compared to the intoxicated group. Similarly, treatment with Rs.Cr and dexamethasone significantly (p < 0.001) reduced paw edema volume. Subcutaneous injection of milk at a dose of 4 mL/kg, after 24 h of its administration, showed an increase in the leukocyte count in the intoxicated group. Similarly, mice treated with dexamethasone and Rs.Cr respectively showed a significant decrease in leukocytes and eosinophils count in the ovalbumin-induced allergic asthma model. The extract presented a significant (p˂0.001) alleviative effect on the levels of SOD and GSH, MDA, IL-4, IL-5, and IL-13 in a dose-dependent manner as compared to the intoxicated group. Furthermore, the histological evaluation also revealed a notable decrease in inflammatory and goblet cell count with reduced mucus production. The current study highlights mechanism-based novel insights into the anti-asthmatic potential of R. sativus that also strongly supports its traditional use in asthma.