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Protective effect of onion extract against experimental immunesuppression in Wistar rats: biological and molecular study

Adel Alkhedaide
Mohamed Mohamed Soliman
Tamer Ahmed Ismail


Background: The wrong use of drugs results in disturbances in the immunity that affect human health. These drugs have side effects that may lead to death because of lake of immunity. Human beings need to use natural products to strength the immune system and avoid such side effects. Of these products is the onion that used to strength the immune system. This study was conducted to study the protective effect of onion extract on immune-suppressed rats and its impact on the expression level of cytokines, acute phase proteins and antioxidants compared to both control and immune suppressed groups.

Materials and Methods: Forty rats were divided into four groups (10 per group) control group (CNT), immunesuppressed group (DEXA) injected with dexamethasone at a dose of 5 mg per kg intraperitoneally (IP) twice daily for 3 days, onion extract administered group (OE) given orally at a dose of 500 mg per kg for 4 weeks. Group 4 (y), was given onion extract for a week then immune-suppressed with DEXA for 3 days then continued with OE for 3 weeks. Serum and RNA were extracted for examining the biochemical and genetic changes.

Results: Injection of dexamethasone decreased number of leukocytes with increase in the number of neutrophils and the decrease of all other types of white blood cells. Moreover, a decrease in antioxidant levels such as catalase, super oxide dismutase (SOD), and reduced glutathione (GSH) with an increase in the level malondialdehyde (MDA). In parallel, a decrease in serum levels of cytokines, such as TNF and IL-6, together with immunoglobulins (IgG and IgM), were reported in DEXA injected rats that were ameliorated by prior administration of OE. Gene expression analysis revealed that dexamethasone suppressed gene expression of antioxidants together with IL-1 and 8 while increased IL-10 mRNA expression. All of these changes have been normalized to the normal level by OE administration to DEXA injected rats.

Conclusion: The present findings clearly emphasize the medical importance of onions as immune-stimulants at genetic and cellular levels, and that they are good for human health.

Keywords: Onion extract; Dexamethasone; Immune suppression; Protective effect; Gene expression

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eISSN: 0189-6016