Editor's Note
In this study, the authors extracted and purified the flavonoids (TFCH) from the peel of  Citrus changshan-huyou  ( Qu Zhi Ke, QZK ) and established an obesity-induced non-alcoholic fatty liver disease (NAFLD) model of rats. TFCH was given orally for 8 weeks, and its anti-NAFLD effects and potential mechanism were evaluated. The authors conclude that QZK  is a new source of  Citrus  flavonoids for therapeutic use, and TFCH is a promising representative of Citrus flavonoids for anti-NAFLD therapy.
Background

Citrus flavonoids, consisting of naringin, narirutin, neohesperidine, etc., have therapeutic activities for the treatment of lipometabolic disorders. The peel of  Citrus changshan-huyou  ( Qu Zhi Ke , QZK ) is a new source of flavonoids, but attracted little attention so far.

Hypothesis

QZK  should possess therapeutic effects against lipometabolic disorders due to the flavonoids it contains.

Study design

In this study, we extracted and purified the flavonoids of  QZK  (TFCH) and established an obesity-induced non-alcoholic fatty liver disease (NAFLD) model of rats. TFCH was given orally for 8 weeks, and its anti-NAFLD effects and potential mechanism were evaluated.

Methods

The flavonoid chemoprofile of TFCH was determined by using HPLC. High-fat diet was employed to induce NAFLD model in rats, and six groups were set up: negative control group, reference treatment group, model group, low-dose TFCH (25 mg/kg), intermediate-dose TFCH (50 mg/kg), and high-dose TFCH (100 mg/kg). Serum and liver levels of inflammatory cytokines and NAFLD markers were measured biochemically. The relative mRNA expressions of liver 
T-bet, GATA3 , and  TNF-α  were tested by real time PCR (qPCR) analysis. The protein expression of p38 and the phosphorylation of NF-κB, ERK1/2, and p38 in liver were tested by Western blot analysis.

Results

The histopathological observation showed that TFCH attenuated hepatic lesions with significantly decreased NAFLD activity scores. The biochemical data showed that TFCH significantly suppressed both systemic and intrahepatic inflammation by inhibiting IL-1β, IL-6, IL-12, TNF-α, and IFN-γ, and the qPCR analysis revealed a Th1/Th2 related anti-inflammatory mechanism of TFCH. Western blot results clarified that TFCH exerted hepatoprotective and anti-inflammatory effects by suppression of phosphorylated NF-κB and MAPKs, indicating a mechanism associated with NF-κB and MAPK signaling pathways.

Conclusion

QZK  is a new source of  Citrus  flavonoids for therapeutic use, and TFCH is a promising representative of  Citrus  flavonoids for anti-NAFLD therapy.

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