Lab Anim Res.  2014 Dec;30(4):161-168. 10.5625/lar.2014.30.4.161.

Onion peel water extracts enhance immune status in forced swimming rat model

Affiliations
  • 1Center for Animal Resources Development, Wonkwang University, Iksan, Korea. kimoj@wku.ac.kr
  • 2Institute of Animal Experiment & Efficacy Evaluation, Wonkwang University, Iksan, Korea.

Abstract

Onion peel contains a high concentration of quercetin and other flavonoids. In this study, the potential immune-enhancing effects of an onion peel water extract (OPE) supplement were investigated by the rat forced swimming test. OPE was prepared using hot water. Thirty-six male Sprague Dawley rats were fed a pellet diet for 1 week and were then randomly divided into six groups: normal control (NC), forced swimming control (FSC), positive control (quercetin 20 mg/kg), and three groups administered 4, 20, or 100 mg/kg of OPE. Oral drug administration was conducted daily for 4 weeks. All rats, except those of NC group, were forced to swim in water and were considered exhausted when they failed to rise to the water surface to breathe within a 7-s period. Blood lymphocyte counts, immune organ weights, histopathological analysis, and serum interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha, and interleukin (IL)-12 levels were determined. OPE-treated rats consumed more food and had an increased thymic cortex to medulla ratio than that observed in FSC group rats (P<0.05). The area of the white pulp in the spleens of OPE-treated group rats was increased compared with that in FSC group rats (P<0.05). Furthermore, blood lymphocyte numbers and IFN-gamma, TNF-alpha, and IL-12 concentrations were significantly higher in OPE-fed groups than in FSC group (P<0.05). These results suggest that an OPE supplement can improve the immune status by increasing the number of immune-related cells and specific cytokine levels.

Keyword

Allium cepa; onion peel; water extract; immune stimulation; cytokines

MeSH Terms

Administration, Oral
Animals
Cytokines
Diet
Flavonoids
Humans
Interferons
Interleukin-12
Interleukins
Lymphocyte Count
Male
Models, Animal*
Onions*
Organ Size
Physical Exertion
Quercetin
Rats
Rats, Sprague-Dawley
Spleen
Swimming*
Tumor Necrosis Factor-alpha
Water*
Cytokines
Flavonoids
Interferons
Interleukin-12
Interleukins
Quercetin
Tumor Necrosis Factor-alpha
Water
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