| Kuianchun, a new structural derivative like kuixitong and kuisaiduo from quinoxaline 1,4-dioxide, is a new animal feed additive which was synthesized by Lanzhou institute of animal sciences and veterinary pharmaceutics of Chinese academy of agricultural sciences. The previous study showed that it was less hypotoxicity and residues in edible pork or chicken, was the most potent growth-promoting and antibacterial property than olaquindox and others. In present study, in order to provide new drug candidate for safety of food from animals, provide new reference and scientific data for clinical practice about kuianchun, the pharmacokinetics and excretion path were analysed in target animals with reverse phase high performance liquid chromatography (RP-HPLC), sub-type genes expression of and isoenzymes activity of cytochrome P450 of liver in rats were examined by reverse transcription polymerase chain reaction (RT-PCR) and enzyme assay, reactive oxygen species, nitric oxide, nitric oxide synthase, ahtioxidant enzymes were measured with spectrophotometric method, and cytokines (TNF, IL-2, IL-6) in serum were assayed by radioimmunoassay.RESULTS: (1) A one-compartment body model was observed after oral administration at single dose of 300 mg/kg.body weight (mg/kg.bw) in weanling piglets. A two-compartment body model was observed after injection in vein at dose of 3.0 mg/kg.bw in weanling piglets. A two-compartment body model was observed after oral administration drug at dose of 100 mg/kg.bw.day for 7 days. The bioavailability of kuianchun was 45.56%. 53.76% kuianchun was excreted with feces and 0.31% with urine after oral administration.(2) After wistar male rats were orally administered kuianchun (50, 100, 200,400mg/kg.bw. day) for 7 days, hepatic CYP 2E1 and CYP 3A1 mRNA expression at dose of 200, 400 mg/kg.bw, and CYP 1A1 mRNA expression at dose of 400 mg/kg.bw were down-regulated (P＜0.05). Hepatic cytochrome P450 content was decreased and cytochrome b5 content was increased in drug treated rats (P0.05), and protein level of hepatic microsome was increased with drug doses. Activity of aminopyrine N-demethylase (APND) and erythromycin N-demethylase (EMND) were inhibited, and 7-ethoxyresorufin O-deethylase (EROD) activity was induced by kuianchun, respectively. There were different changes of CYP450 isoforms activity between female and male rats. Glutathione-S-transferase activity of liver microsome was higher at 50,100 mg/kg.bw than that of 200, 400 mg/kg.bw.(3) Catalase (CAT) activity was increased and glutathione (GSH) content was decreased from 2-48h in blood after pigs were orally administered drug at dose of 300 mg/kg.bw, superoxide dismutase (SOD) activity was decreased and malondialdehyde (MDA) content was increased from 5min-1h after injection drug in vein for pigs, other antioxidants were not markedly affected by drug. However, GSH content and CAT activity were not obviously changes after continually oral administration for 30d, glutathione-S-transferase (GST) activity was decreased before 10 day and increased after 20 day, glutathione peroxidase (GSH-Px) activity was decreased, SOD activity was contrary changes to GST. MDA content was increased at dose of 180mg/kg.bw, the level of reactive oxygen species (OH) in liver was increased at all dose, the property against superoxide anion (O2-) was increased at 10d and decreased at 20, 30d. All changes about oxidants and antioxidants were not observed at 10-day after drug retreat at dose of 50,100, 200 mg/kg.bw.(4) In vitro, lipopolysaccharide (LPS), LPS and kuianchun were added in culture medium of celiac macrophage from mice, nitric oxide (NO) content of LPS+kuianchun group was lower than that of LPS group (P＜0.01), there was not dose-defense between doses and NO level change. However, there was not obviously changes on NO, and there was increased in activity of inducible nitric oxide synthase (iNOS) at concentration of 400μg/mL kuianchun after 6 hours.(5) After being continuously administered kuianchun for 14 days, tumor necrosis factor (TNF), interleukin-6 (IL-6) concentration were increased at dose of 631.67mg/kg.diet in male mice, and at dose of 105.56mg/kg.diet in female mice. Interleukin-2 (IL-2) concentration was not affected by drug treatment.(6) There were not obviously changes on blood cell and lymphocyte, and histopathological change was not observed on liver, kidney, spleen, heart and others in rats at 75, 150, 300, 600mg/kg.diet for 40 days.CONCLUAION: (1) The velocity of absorption and distribution of kuianchun was quick in target animals, but bioavailability was lower. The elimination was slow at single high dose or multi-dose. Much of kuianchun was excreted from intestine with feces. (2) CYP450 isoenzyme was inhibited by high dose kuianchun, (3) There was not induction to oxidative stress injury by single dose of kuianchun, but was induction to lipid peroxidation (LPO) and disorder of free radicals by multi-dose. However, these phenomena were not observed after drug was retreated for 10 days. (4) The performance of LPS to induce NO was inhibited by kuianchun. (5) TNF, IL-6 was induced by kuianchun at dose from 105.56～631.67mg/kg.diet in mice, which was different between female and male rats. (6) Any potential adverse effect will not induced by kuianchun to those consumers if target animals, additive dose and drug withdrawal period conform to design for clinical practice. |
