Aim: Major side effects of cyclophosphamide administration are immunosuppression and myelosuppression. The immunomodulatory effects of plant bioactive compounds on chemotherapy drug-induced immunosuppression may have significant effects in cancer treatment. For this reason, we investigated the immunomodulatory effect of myricetin, apigenin, and hesperidin in cyclophosphamide-induced immunosuppression in rats. Methods: In our study, a total of 64 rats were used, and divided into eight equal groups. These groups were: control, cyclophosphamide, cyclophosphamide + myricetin (100 mg/kg), cyclophosphamide + myricetin (200 mg/kg), cyclophosphamide + apigenin (100 mg/kg), cyclophosphamide + apigenin (200 mg/kg), cyclophosphamide + hesperidin (100 mg/kg), and cyclophosphamide + hesperidin (200 mg/kg). Myricetin, apigenin, and hesperidin pretreatments were performed for 14 d, while cyclophosphamide application (200 mg/kg) was performed only on the 4th day of the study. Levels of humoral antibody production, quantitative hemolysis, macrophage phagocytosis, splenic lymphocyte proliferation, and natural killer cell cytotoxicity were determined. In addition, we measured pro-inflammatory cytokines, and followed lipid peroxidation and antioxidant markers and examined the histology of bone marrow, liver and spleen in all groups. Results: During cyclophosphamide treatment, all three phytochemicals increased the levels of humoral antibody production, quantitative hemolysis, macrophage phagocytosis, splenic lymphocyte proliferation, antioxidant markers, and natural killer cell cytotoxicity. Moreover, the agents decreased the levels of pro-inflammatory cytokines and mediators, reduced lipid peroxidation markers, and reduced tissue damage in liver, spleen, and bone marrow. Conclusion: Our study demonstrated that myricetin, apigenin, and hesperidin can reduce the immunosuppressive effect of cyclophosphamide by enhancing both innate and adaptive immune responses, and these compounds may be useful immunomodulatory agents during cancer chemotherapy.

Diosmin is an unsaturated flavonoid glycoside, presents in citrus fruits. The aim of this study is to investigate the molecular mechanism of diosmin with respect to the NF-κB and MAPKs signaling pathways. Firstly, 10, 20, 30, 40 and 50 µM diosmin were treated to lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. The anti-inflammatory effects of diosmin was displayed via measuring prostaglandin E2 (PGE2), nitric oxide (NO), interleukines (IL-6, IL-12), tumor necrosis factor α (TNF-α) production, cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), IL-6, IL-12, TNF-α mRNA levels, and phosphorylation levels of nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor alpha (IκB-α) and mitogen-activated protein kinases (MAPKs); JNK, ERK, and p38 in LPS induced RAW264.7 macrophages. Our study showed that especially high concentrations of diosmin decreased NO, PGE2, IL-6, IL-12, TNF-α production and mRNA levels of these mediators (p < 0.05). The expression of phosphorylated-JNK was significantly suppressed by diosmin at 40 and 50 µM concentrations. Furthermore, diosmin significantly inhibited the expression of phosphorylated-ERK, p38, and p-IκB-α in a dose-dependent manner. Our results suggest that diosmin is a potent anti-inflammatory agent and has potential for development into a therapeutic agent for inflammation-associated disorders.