RESUMO
The root bark of Illicium henryi has been used in traditional Chinese medicine to treat lumbar muscle strain and rheumatic pain. Its ethanol extract (EEIH) has been previously reported to attenuate lipopolysaccharide (LPS)-induced acute kidney injury in mice. The present study aimed to evaluate the in vitro antioxidant activities and in vivo protective effects of EEIH against LPS-induced acute liver injury (ALI) in mice as well as explore its molecular mechanisms. The mice were injected intraperitoneally (i.p.) with EEIH at the doses of 1.25, 2.5, and 5.0 mg/kg every day for 5 days. One hour after the last administration, the mice were administered i.p. with LPS (8 mg/kg). After fasting for 12 h, blood and liver tissues were collected to histopathological observation, biochemical assay, enzyme-linked immunosorbent assay (ELISA), quantitative real-time polymerase chain reaction (qRT-PCR), and Western blot analyses. EEIH possessed 2,2-diphenyl-1-picrylhydrazil (DPPH) and 2,2'-azino-bis-(3-ethylbenzothiozoline-6-sulfonic acid) disodium salt (ABTS) radical scavenging activities and ferric-reducing antioxidant capacity in vitro. The histopathological examination, serum biochemical analysis, and liver myeloperoxidase (MPO) activity showed that EEIH pretreatment alleviated LPS-induced liver injury in mice. EEIH significantly dose-dependently decreased the mRNA and protein expression levels of inflammatory factors TNF-α, IL-1ß, IL-6, and COX-2 in liver tissue of LPS-induced ALI mice via downregulating the mRNA and protein expressions of toll-like receptor 4 (TLR4) and inhibiting the phosphorylation of nuclear factor-κB (NF-κB) p65. Furthermore, EEIH markedly ameliorated liver oxidative and nitrosative stress burden in LPS-treated mice through reducing the content of thiobarbituric acid reactive substances (TBARS), inducible nitric oxide synthase (iNOS), and nitric oxide (NO) levels, restoring the decreased superoxide dismutase (SOD) and reduced glutathione (GSH) levels, and up-regulating nuclear factor erythroid 2 related factor 2 (Nrf2). These results demonstrate that EEIH has protective effects against ALI in mice via alleviating inflammatory response, oxidative and nitrosative stress burden through activating the Nrf2 and suppressing the TLR4/NF-κB signaling pathways. The hepatoprotective activity of EEIH might be attributed to the flavonoid compounds such as catechin (1), 3',4',7-trihydroxyflavone (2), and taxifolin (7) that most possibly act synergistically.
RESUMO
The root bark of Illicium henryi has been used in traditional Chinese medicine to treat various diseases. Its ethanol extract (EEIH) was found to contain a large number of phenols and possess in vitro antioxidant activities. The present study aimed to investigate its protective effect against lipopolysaccharide (LPS)-induced acute kidney injury (AKI) in mice. BALB/c mice were intraperitoneally pretreated with EEIH for five days, and then LPS injection was applied to induce AKI. Blood samples and kidney tissues were collected and used for histopathology, biochemical assay, enzyme-linked immunosorbent assay (ELISA), quantitative real-time polymerase chain reaction (qRT-PCR), and Western blot analyses. EEIH not only significantly dose-dependently attenuated histological damage and reduced renal myeloperoxidase (MPO) activity (from 9.77 ± 0.73 to 0.84 ± 0.30 U/g tissue) but also decreased serum creatinine (from 55.60 ± 2.70 to 27.20 ± 2.39 µmol/L) and blood urea nitrogen (BUN) (from 29.95 ± 1.96 to 16.12 ± 1.24 mmol/L) levels in LPS-treated mice. EEIH also markedly dose-dependently inhibited mRNA expression and production of TNF-α (from 140.40 ± 5.15 to 84.74 ± 5.65 pg/mg), IL-1ß (from 135.54 ± 8.20 to 77.15 ± 5.34 pg/mg), IL-6 (from 168.74 ± 7.23 to 119.16 ± 9.35 pg/mg), and COX-2 in renal tissue of LPS-treated mice via downregulating mRNA and protein expressions of toll-like receptor 4 (TLR4) and phosphorylation of nuclear factor-κB (NF-κB) p65. Moreover, EEIH significantly dose-dependently reduced malondialdehyde (MDA) (from 5.43 ± 0.43 to 2.80 ± 0.25 nmol/mg prot) and NO (from 1.01 ± 0.05 to 0.24 ± 0.05 µmol/g prot) levels and increased superoxide dismutase (SOD) (from 22.32 ± 2.92 to 47.59 ± 3.79 U/mg prot) and glutathione (GSH) (from 6.57 ± 0.53 to 16.89 ± 0.68 µmol/g prot) levels in renal tissue induced by LPS through upregulating mRNA expression of nuclear factor erythroid 2 related factor 2 (Nrf2). Furthermore, EEIH inhibited LPS-induced intracellular reactive oxygen species (ROS) production from RAW264.7 cells in a concentration-dependent manner. These results suggest that EEIH has protective effects against AKI in mice through regulating inflammation and oxidative stress.