Florfenicol induces more severe hemotoxicity and immunotoxicity than equal doses of chloramphenicol and thiamphenicol in Kunming mice

A review on the antibiotic florfenicol: Occurrence, environmental fate, effects, and health risks

Florfenicol, as a replacement for chloramphenicol, can tightly bind to the A site of the 23S rRNA in the 50S subunit of the 70S ribosome, thereby inhibiting protein synthesis and bacterial proliferation. Due to the widespread use in aquaculture and veterinary medicine, florfenicol has been detected in the aquatic environment worldwide. Concerns over the effects and health risks of florfenicol on target and non-target organisms have been raised in recent years. Although the ecotoxicity of florfenicol has been widely reported in different species, no attempt has been made to review the current research progress of florfenicol toxicity, hormesis, and its health risks posed to biota. In this study, a comprehensive literature review was conducted to summarize the effects of florfenicol on various organisms including bacteria, algae, invertebrates, fishes, birds, and mammals. The generation of antibiotic resistant bacteria and spread antibiotic resistant genes, closely associated with hormesis, are pressing environmental health issues stemming from overuse or misuse of antibiotics including florfenicol. Exposure to florfenicol at μg/L-mg/L induced hormetic effects in several algal species, and chromoplasts might serve as a target for florfenicol-induced effects; however, the underlying molecular mechanisms are completely lacking. Exposure to high levels (mg/L) of florfenicol modified the xenobiotic metabolism, antioxidant systems, and energy metabolism, resulting in hepatotoxicity, renal toxicity, immunotoxicity, developmental toxicity, reproductive toxicity, obesogenic effects, and hormesis in different animal species. Mitochondria and the associated energy metabolism are suggested to be the primary targets for florfenicol toxicity in animals, albeit further in-depth investigations are warranted for revealing the long-term effects (e.g., whole-life-cycle impacts, multigenerational effects) of florfenicol, especially at environmental levels, and the underlying mechanisms. This will facilitate the evaluation of potential hormetic effects and construction of adverse outcome pathways for environmental risk assessment and regulation of florfenicol.

Pharmacokinetics and Pharmacodynamics of Florfenicol in Plasma and Synovial Fluid of Pigs at a Dose of 30 mg/kgbw Following Intramuscular Administration

A major problem of our time is the ever-increasing resistance to antimicrobial agents in bacterial populations. One of the most effective ways to prevent these problems is to target antibacterial therapies for specific diseases. In this study, we investigated the in vitro effectiveness of florfenicol against S. suis, which can cause severe arthritis and septicemia in swine herds. The pharmacokinetic and pharmacodynamic properties of florfenicol in porcine plasma and synovial fluid were determined. After a single intramuscular administration of florfenicol at 30 mg/kg_bw, the AUC_0-∞ was 164.45 ± 34.18 µg/mL × h and the maximum plasma concentration was 8.15 ± 3.11 µg/mL, which was reached in 1.40 ± 0.66 h, whereas, in the synovial fluid, these values were 64.57 ± 30.37 µg/mL × h, 4.51 ± 1.16 µg/mL and 1.75 ± 1.16 h, respectively. Based on the MIC values of the 73 S. suis isolates tested, the MIC₅₀ and MIC₉₀ values were 2 µg/mL and 8 µg/mL, respectively. We successfully implemented a killing-time curve in pig synovial fluid as a matrix. Based on our findings, the PK/PD breakpoints of the bacteriostatic (E = 0), bactericidal (E = -3) and eradication (E = -4) effects of florfenicol were determined and MIC thresholds were calculated, which are the guiding indicators for the treatment of these diseases. The AUC_24h/MIC values for bacteriostatic, bactericidal and eradication effects were 22.22 h, 76.88 h and 141.74 h, respectively, in synovial fluid, and 22.42 h, 86.49 h and 161.76 h, respectively, in plasma. The critical MIC values of florfenicol against S. suis regarding bacteriostatic, bactericidal and eradication effects in pig synovial fluid were 2.91 ± 1.37 µg/mL, 0.84 ± 0.39 µg/mL and 0.46 ± 0.21 µg/mL, respectively. These values provide a basis for further studies on the use of florfenicol. Furthermore, our research highlights the importance of investigating the pharmacokinetic properties of antibacterial agents at the site of infection and the pharmacodynamic properties of these agents against different bacteria in different media.

Impacts of Oral Florfenicol Medication and Residues on the Kidney and Liver of Nile Tilapia Oreochromis niloticus (L.)

Florfenicol (FFC), an approved aquaculture antibiotic, is administered in feed at doses of 10-15 mg kg biomass^-1 day^-1 for 10 successive days. In this study, healthy Oreochromis niloticus were fed with 0-10 times the therapeutic dose of 15 mg kg biomass^-1 day^-1 for 10 days and tracked for 43 days post dosing. Assessments of residue accrual and depletion, oxidative stress, serum biochemistry, histopathology and extent of kidney and liver damages were made. FFC dosing reduced the feed intake significantly. The therapeutic dose produced no mortalities on day 10. Dose-dependent alterations in serum biochemistry were noted upon dosing. Several histopathological alterations were observed in the kidney and liver, which vindicated the toxic potentials of FFC. The residual FFC and florfenicol amine (FFA) accrual, depletion and oxidative stress responses, such as increased malondialdehyde, total nitric oxide, ferric reducing antioxidant power and reduced glutathione S-transferase activity, were documented. The dietary FFC persuaded the physiological state of O. niloticus, the effects of which normalized sparsely with time upon cessation of dosing at the higher doses. The study provided a brief outlook on the physiological responses upon oral FFC administration, which should be kept in mind during its application for fish health safety purposes.

Biological Responses of Nile tilapia Oreochromis niloticus as Influenced by Dietary Florfenicol

Antibiotics are used in the treatment of bacterial diseases in commercial aquaculture. In this study, we the biological responses of Oreochromis niloticus juveniles upon dietary florfenicol (FFC) administration at 15 mg (1×) and 45 mg kg biomass^-1 day^-1 (3×) for 10 days in terms of feed intake, survival, biomass, hematological, erythro-morphological, serum biochemical, and histopathological aberrations as compared with controls. FFC caused a dose-dependent reduction in feed intake, survival, and biomass, with marked variations in hematology, hematological indices, and erythrocytic cellular and nuclear abnormalities, suggesting its apparent cytotoxic and nucleotoxic effects. The serum biomarkers increased significantly in a dose-dependent manner, except for calcium and chloride, which decreased significantly. The therapeutic dose (1×) group exhibited marked histopathological aberrations, such as renal tubular epithelial degeneration and a widened lumen in the kidney, as well as glycogen-type vacuolation and cytoplasmic degeneration in the liver during the dosing period. The extent of kidney and liver tissue damage was more prominent in the 3× group. The 1× serum biomarker levels became normal, with the exception of alkaline phosphatase, within 3 weeks of suspension of dosing. The recovery of the measured parameters and histopathological and erythro-morphological changes suggested that the therapeutic dietary biological responses induced by FFC are reversible and safe for O. niloticus.

Determination of extractable and non-extractable florfenicol residues as florfenicol amine in eggs by UPLC-MS/MS

Some florfenicol (FF) metabolites have a strong binding affinity towards biomolecules in the edible tissues of some food animals. These bound FF residues cannot be extracted directly from edible tissues with organic solvents and are present in higher concentrations even than solvent extractable residues. In this study, an ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was established to detect the total residues of FF in eggs, by quantifying the metabolite florfenicol amine (FFA). The sample was hydrolyzed at 95-100 °C for 4 hours to release sample-matrix bound residues and convert them all into FFA. The hydrolyzed sample was washed with ethyl acetate to remove interfering substances, extracted with ethyl acetate under alkaline conditions, purified by solid phase extraction and quantified by UPLC-MS/MS. The recoveries of FFA in eggs ranged from 91.2 to 102.4%, with an RSD ≤ 10.9%. The LOD and LOQ were 0.5 and 1.0 μg/kg, respectively. This method can be applied to the quantification of total FF residues in eggs.

New insights into thiamphenicol biodegradation mechanism by Sphingomonas sp. CL5.1 deciphered through metabolic and proteomic analysis

Biological treatment is an efficient and economical process to remove thiamphenicol (TAP) residues from the environment. The discovery of TAP-degrading bacteria and the decryption of its biodegradation mechanism will be beneficial to enhance the biological removal of TAP. In this study, Sphingomonas sp. CL5.1 was found to be capable of catabolizing TAP as the sole carbon, nitrogen, and energy source. This strain could degrade 93.9% of 25 mg/L TAP in 36 h, and remove about 11.9% of the total organic carbon of TAP. A novel metabolism pathway of TAP was constructed, and the enzymes involved in TAP metabolism in strain CL5.1 were predicted via proteomic and metabolic analysis. TAP was proposed to be transformed to O-TAP via oxidation of C₃-OH and DD-TAP via dehydration of C₃-OH and dehydrogenation of C₁-OH. A novel glucose-methanol-choline (GMC) family oxidoreductase CapO was predicted to be involved in the oxidation of C₃-OH. O-TAP was supposed to be further cleaved into DCA, glycine, and PMB. Glycine might be a pivotal direct nitrogen source for strain CL5.1, and it could be involved in nitrogen metabolism through the glycine cleavage system or directly participate in the biosynthetic processes.

Salvia miltiorrhiza polysaccharides alleviates florfenicol induced kidney injury in chicks via inhibiting oxidative stress and apoptosis

Florfenicol (FFC) is a commonly used antibiotic in animal husbandry, which is easy to cause organs damage in a variety of animals. It has been proved to have nephrotoxicity and affect the yield and quality of meat products. Salvia miltiorrhiza polysaccharides (SMPs) have been proved to have the pharmacological effects of regulating immunity and protecting the liver of animals, and its alleviative effect on renal injury is unclear. In order to investigate the alleviating effect of SMPs on drug nephrotoxicity and determine its potential molecular mechanism, we took chicks as the research object, FFC as the induced drug, and established the model by adding SMPs in drinking water. The chicks were randomly divided into control group, FFC model group (0.15 g/L FFC), FFC + low, medium and high dose of SMPs groups (0.15 g/L FFC + 1.25, 2.5, 5 g/L SMPs) and SMPs group (5 g/L SMPs). The results showed that, SMPs increased the average weight gain and renal index of chicks, alleviated the pathological changes of renal structure induced by FFC, decreased the contents of uric acid, blood urea nitrogen and creatinine in serum and malondialdehyde in renal tissue, increased the levels of glutathione, superoxide dismutase and catalase in renal tissue, up-regulated the relative expression levels of nuclear factor erythroid 2 related factor 2 (Nrf2), heme oxygenase-1 (HO-1) and nicotinamide adenine dinucleotide phosphate: quinone oxidoreductase-1 (NQO-1) mRNA and protein, and down-regulated the relative expression levels of p53, Caspase-3 and Caspase-6 mRNA and protein and the apoptosis rate of renal histiocytes. It is concluded that SMPs could significantly alleviate the renal injury induced by FFC, and its mechanism may be related to improving renal antioxidant capacity and inhibiting abnormal apoptosis of renal histiocytes.

Antimicrobial, immunological and biochemical effects of florfenicol and garlic (Allium sativum) on rabbits infected with Escherichia coli serotype O55: H7

Florfenicol (FFC) is a synthetic broad-spectrum antibiotic and garlic has a bactericidal action against coliforms. This study was carried out to compare the antimicrobial, immunological and biochemical effects of florfenicol and garlic, for their ability to treat enteropathogenic Escherichia coli serotype O55: H7 infection in rabbits. Four groups (G1-G4) were included. G1 group was the negative control; G2 group was the infected with a field-isolated strain of E. coli and untreated; G3 group was the infected+treated with FFC for 5 days; and G4 group was the infected+treated with garlic tablets for 14 days. The rabbits were observed for clinical signs, growth performance and mortality rates. Garlic-infused disks had a larger clear zone of inhibition than other antibiotic disks. Garlic treatment improved growth performance, biochemical parameters, and immunological response and reduced the fecal shedding and histopathological lesions in E. coli O55: H7 infected rabbits compared to the other groups. Colonization of E. coli more rapidly declined in G3 & G4 than in G2. Hepatic and intestinal gene expressions; tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) were significantly elevated in G2 compared to the other groups, and their levels were elevated more in G3 than in G4. Serum interferon-gamma (IFN-γ) and phagocytic activity were significantly elevated in G4 compared to G3. G3 revealed macrocytic hypochromic anaemia that was confirmed histopathologically by moderate haematopoiesis of the bone marrow. In conclusion, garlic powder can reduce rabbit colibacillosis, like FFC, and can enhance the immune status of rabbits.

Synergistic use of florfenicol and Salvia miltiorrhiza polysaccharide can enhance immune responses in broilers

To explore the effect of florfenicol (FFC) combined with Salvia miltiorrhiza polysaccharide (SMPs) on immune function of Broilers. One hundred and twenty-one-day-old chicks were chosen and divided into 6 groups. The group A received standard basal diet only, the group B received a basal diet with FFC (0.15 g/L diet), and the group C, D, E received a basal diet with FFC (0.15 g/L diet) and SMPs (1.25 g/L, 2.5 g/L, 5 g/L diet)，the group F received a basal diet with SMPs (5 g/L diet). FFC can significantly inhibit the growth performance of broilers, but has no significant damage to the immune function of broilers. The combination of FFC and SMPs can improve the growth performance of broilers, increase the number of leukocyte subtypes in blood (P < 0.05), increase the number of Newcastle disease (ND) and avian influenza (AI) antibodies in blood, the number of immunoglobulins, and the content of cytokines (P < 0.05). In addition, it significantly improve the lymphocyte conversion rate of broiler peripheral blood (P < 0.05). So that, synergistic use of FFC and SMPs can enhance immune responses in Broilers.

In Vitro Selective Growth-Inhibitory Activities of Phytochemicals, Synthetic Phytochemical Analogs, and Antibiotics against Diarrheagenic/Probiotic Bacteria and Cancer/Normal Intestinal Cells

A desirable attribute of novel antimicrobial agents for bacterial diarrhea is decreased toxicity toward host intestinal microbiota. In addition, gut dysbiosis is associated with an increased risk of developing intestinal cancer. In this study, the selective growth-inhibitory activities of ten phytochemicals and their synthetic analogs (berberine, bismuth subsalicylate, ferron, 8-hydroxyquinoline, chloroxine, nitroxoline, salicylic acid, sanguinarine, tannic acid, and zinc pyrithione), as well as those of six commercial antibiotics (ceftriaxone, ciprofloxacin, chloramphenicol, metronidazole, tetracycline, and vancomycin) against 21 intestinal pathogenic/probiotic (e.g., Salmonella spp. and bifidobacteria) bacterial strains and three intestinal cancer/normal (Caco-2, HT29, and FHs 74 Int) cell lines were examined in vitro using the broth microdilution method and thiazolyl blue tetrazolium bromide assay. Chloroxine, ciprofloxacin, nitroxoline, tetracycline, and zinc pyrithione exhibited the most potent selective growth-inhibitory activity against pathogens, whereas 8-hydroxyquinoline, chloroxine, nitroxoline, sanguinarine, and zinc pyrithione exhibited the highest cytotoxic activity against cancer cells. None of the tested antibiotics were cytotoxic to normal cells, whereas 8-hydroxyquinoline and sanguinarine exhibited selective antiproliferative activity against cancer cells. These findings indicate that 8-hydroxyquinoline alkaloids and metal-pyridine derivative complexes are chemical structures derived from plants with potential bioactive properties in terms of selective antibacterial and anticancer activities against diarrheagenic bacteria and intestinal cancer cells.

Florfenicol induces oxidative stress and hepatocyte apoptosis in broilers via Nrf2 pathway

In order to explore the mechanism of liver injury induced by florfenicol (FFC) in broilers, one hundred and twenty broilers were randomly divided into six groups, twenty broilers in each group. Except for control group, the other five groups were given different doses of FFC (0.15 g/L, 0.3 g/L, 0.6 g/L, 1.2 g/L and 1.8 g/L) in drinking water. After five days of continuous use, blood was collected from the subpterional vein and the chickens' liver were obtained. Chicken weight gain and liver indices were calculated; blood routine analysis was performed; the oxidative stress and apoptosis of hepatocytes was detected. The results showed that compared with the control group, except for 0.15 g/L FFC, the other doses of FFC significantly decreased the weight gain, white blood cell (WBC) and platelet (PLT) contents in blood, 0.3 g/mL FFC and 1.8 g/L FFC significantly reduced the content of hemoglobin (RGB) (P < 0.05); all doses of FFC significant decreased red blood cell (RBC) increased Alanine aminotransferase (ALT) and Aspartate aminotransferase (AST) contents in serum of chickens (P < 0.05), and significantly decreased the contents of albumin (ALB) and total protein (TP) in serum (P < 0.05), but had no significant effect on alkaline phosphatase (ALP) contents(P > 0.05). FFC significantly increased malondialdehyde (MDA) content in serum and liver tissues, but decreased glutathione (GSH), Superoxide dismutase (SOD) and catalase (CAT) content (P < 0.05), and significantly inhibited the mRNA transcription and protein expression of antioxidant proteins nuclear factor-erythroid 2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1) and NAD(P)H dehydrogenase quinone-1 (NQO-1)(P < 0.05). FFC also inhibited the content and the transcription level of cytochrome P4501A1(CYP1A1) and CYP2H1 in liver (P < 0.05). At the same time, FFC significantly promoted the apoptotic rate of hepatocytes and the mRNA transcription and protein expression of caspase-3 and caspase-6 (P < 0.05). With the increase of FFC concentration, liver injury became more and more serious, which affected liver function in chickens by inhibiting enzyme activity in Nrf2-ARE pathway to increase oxidative stress and promoting apoptotic protein expression to accelerate hepatocyte apoptosis.

Growth and cardiovascular development are repressed by florfenicol exposure in early chicken embryos

Florfenicol (FLO) is one of the most popular antibacterial drugs used in veterinary clinics and aquaculture. The drug was found to decrease the hatchability of eggs laid by treated hens in veterinary clinics and research work. However, the pathological changes in developing embryos and their cardiovascular system and the mechanism underlying FLO-induced embryonic death remain unclear. In the present study, fertilized eggs laid by hens treated with a therapeutic dose of FLO were collected and incubated. Results showed that FLO exposure repressed embryonic development and induced early embryonic death. As a result, FLO decreased the hatchability and increased the proportion of weak chicks. Moreover, FLO exposure led to embryonic lethality and inhibited the development of chick embryos as characterized by decreased weights, lagging distribution of Hamburger–Hamilton stages, and dysplastic eyes. Pathological examination indicated that FLO exposure affected the normal development of the heart in 4.5-day-old chick embryos, as characterized by shorter transverse cardiac diameter, disordered arrangement of trabecular muscles in ventricles, and reduced thickness of ventricular walls. Furthermore, FLO decreased blood vascular densities and downregulated the expression levels of key angiogenesis-related genes, including the vascular endothelial growth factor and fibroblast growth factor, in the yolk sac membrane. These findings indicated that FLO exposure restricted vascular development during early embryonic development. In summary, our data suggest that the restricted growth and abnormal cardiovascular development may be responsible for FLO-induced early embryonic death. Thus, these findings can be useful for guiding the proper use of FLO and in laying a foundation for further studies on the mechanism of FLO-induced embryonic toxicity.

Cuscuta chinensis flavonoids alleviate bisphenol A-induced apoptosis of testicular cells in male mice offspring

Bisphenol A (BPA) is a widespread environmental endocrine disruptor that has multiple effects on reproductive organ development. To investigate the effect of Cuscuta chinensis flavonoids (CCFs) on testicular apoptosis induced by BPA in male mice offspring, pregnant mice were administered intragastrically with BPA and CCF at gestation day (GD) 0.5-17.5. The testes of male offspring (F1 males) were collected at post-natal day (PND) 21 and PND 56 for the detection of related indicators. The results showed that compared with the BPA group, the testicular index in CCF groups was significantly increased at PND 21 (p < .01). For the mice of different concentrations of CCF groups, the expression levels of bax, caspase-9 and caspase-7 proteins were significantly decreased at PND 21 and PND 56, while the expression level of bcl-2 protein was significantly increased, and testicular apoptotic cells were also decreased significantly (p < .01 or p < .05). Forty mg/kg CCF has no significant difference compared with the control group. The results indicated that CCF could protect the testis development of F1 male mice by alleviating the apoptosis of testicular cells induced by BPA.

A reliable and cost-efficient TLC-HPLC method for determining total florfenicol residues in porcine edible tissues

It is still a challenge to solve the matrix interferences in veterinary drug residue analysis. In this study, we reported a thin layer chromatography (TLC)-high-performance liquid chromatography (HPLC) method for determining total florfenicol (FF) residues, expressed as florfenicol amine (FFA), in porcine edible tissues. The tissue homogenate were acid-hydrolyzed to liberate the bound residues and convert them into FFA. The hydrolysates were washed with ethyl acetate and subsequently extracted with ethyl acetate under alkaline conditions. The supernatants were concentrated through evaporation, defatted with hexane, purified by TLC and analyzed by HPLC at 225 nm. The optimal developing solvent for TLC purification was ethyl acetate-acetone-ammonium hydroxide mixtures (2:8:0.5, v/v/v). The method was fully validated according to decision 2002/657/EC, and could be used for the routine monitoring of FF residues in pig. TLC showed excellent purification efficiency, and was expected to solve the matrix interferences in veterinary drug residue analysis.

A reliable, simple and cost-efficient TLC-HPLC method for simultaneously determining florfenicol and florfenicol amine in porcine urine: application to residue surveillance

Violative residues of florfenicol (FF) in porcine edible tissues pose a potential risk for human health. In this study, urine was selected as target matrix for routine residue monitoring of FF in pig, and a thin layer chromatography (TLC)-high-performance liquid chromatography (HPLC) method was developed for simultaneously determining FF and florfenicol amine (FFA) in porcine urine. The urine samples were extracted with ethyl acetate under alkaline environment. The extracts were enriched through evaporation, purified by TLC and analysed by HPLC at 225 nm. A Waters Symmetry C₁₈ column was used for the separation of the two analytes. The mobile phase was acetonitrile-phosphate buffer mixtures (33.3: 66.7, v/v), and was pumped at 0.6 mL/min. The TLC-HPLC method was well validated and successfully applied to residue depletion study. Good analytical specificity was confirmed by the lack of interfering peaks at the retention times of FF and FFA. The standard curves showed good linearity (FF: y = 143064x - 1045.3, r= 0.9999; FFA: y = 275826x + 1888.8, r= 0.9999) over the range of 0.0625-8 μg/mL. The precision ranged from 0.83% to 11.66% and 2.19% to 8.75% for intraday and interday determination, respectively. The corresponding accuracy ranged from -13.38% to 10.78% and -12.15% to 7.14%, respectively. The limits of quantification (LOQs) for FF and FFA were 0.125 μg/mL. The residue depletion study showed that the concentrations of FF and FFA in urine were higher than those in edible tissues at three time points. This method was reliable, simple and cost efficient, and could be used to monitor FF residues in porcine edible tissue without slaughtering animals. TLC showed excellent purification efficiency and is expected to solve matrix interferences in veterinary drug residue analysis.

Development and comparison of liquid-liquid extraction and accelerated solvent extraction methods for quantitative analysis of chloramphenicol, thiamphenicol, florfenicol, and florfenicol amine in poultry eggs

Accelerated solvent extraction was investigated as a novel alternative technology for the separation and quantitative analysis of chloramphenicol, thiamphenicol, florfenicol, and florfenicol amine from poultry eggs, and the results were compared with the results of liquid-liquid extraction. Rapid quantification of the target compounds was carried out by ultra-performance liquid chromatography-electrospray ionization tandem triple quadrupole mass spectrometry. This optimized method was validated according to the requirements defined by the European Union and the United States Food and Drug Administration. Finally, the new approach was successfully applied to the quantitative determination of these analytes in 90 commercial poultry eggs from local supermarkets.

Development of an Accelerated Solvent Extraction-Ultra-Performance Liquid Chromatography-Fluorescence Detection Method for Quantitative Analysis of Thiamphenicol, Florfenicol and Florfenicol Amine in Poultry Eggs

A simple, rapid and novel method for the detection of residues of thiamphenicol (TAP), florfenicol (FF) and its metabolite, florfenicol amine (FFA), in poultry eggs by ultra-performance liquid chromatography-fluorescence detection (UPLC-FLD) was developed. The samples were extracted with acetonitrile-ammonia (98:2, v/v) using accelerated solvent extraction (ASE) and purified by manual degreasing with acetonitrile-saturated n-hexane. The target compounds were separated on an ACQUITY UPLC^® BEH C₁₈ (2.1 mm × 100 mm, 1.7 μm) chromatographic column using a mobile phase composed of 0.005 mol/L NaH₂PO₄, 0.003 mol/L sodium lauryl sulfate and 0.05% trimethylamine, adjusted to pH 5.3 ± 0.1 by phosphoric acid and acetonitrile (64:36, v/v). The limits of detection (LODs) and limits of quantification (LOQs) of the three target compounds in poultry eggs were 1.8–4.9 µg/kg and 4.3–11.7 µg/kg, respectively. The recoveries of the three target compounds in poultry eggs were above 80.1% when the spiked concentrations of three phenicols were the LOQ, 0.5 maximum residue limit (MRL), 1.0 MRL and 2.0 MRL. The intraday relative standard deviations (RSDs) were less than 5.5%, and the interday RSDs were less than 6.6%. Finally, this new detection method was successfully applied to the quantitative analysis of TAP, FF and FFA in 150 commercial poultry eggs.

Florfenicol-induced Mitochondrial Dysfunction Suppresses Cell Proliferation and Autophagy in Fibroblasts

Florfenicol (FLO) is one of the most popular antibiotics used in veterinary clinic and aquaculture. FLO can inhibit both bacterial and mitochondrial protein synthesis. However, the effects of FLO on mitochondrial function and cellular homeostasis remain unclear. Here we show that FLO inhibits expression of mitochondrial DNA-encoded proteins, decreases mitochondrial membrane potential, and promotes generation of reactive oxygen species (ROS) in vitro. As a result, activities of mitochondrial respiratory chain complex I and IV and the cellular ATP level are decreased and mitochondrial morphology is damaged. FLO represses cell growth and proliferation by suppression of phosphorylation of p70S6K through AMPK/mTOR/p70S6K pathway. Furthermore, FLO also induces G0/G1 cell cycle arrest via increase of p21 levels through activating ROS/p53/p21 pathway. Moreover, the clearance of damaged mitochondria by autophagy is impaired, leading to cell proliferation inhibition and promotes cell senescence. In addition, FLO-induced upregulation of cytosolic p53 may contribute to mitophagy deficiency via regulation of Parkin recruitment. In summary, our data suggest that florfenicol is an inhibitor of mitochondrial protein synthesis that can induce noticeable cytotoxicity. Thus, these findings can be useful for guiding the proper use of FLO and the development of safe drugs.