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.

Occurrence of OCPs & PCBs and their effects on multitrophic biological communities in riparian groundwater of the Beiluo River, China.

Persistent Organic Pollutants (POPs) may exert adverse effects on human and ecosystem health. However, as an ecologically fragile zone with strong interaction between river and groundwater, the POPs pollution in the riparian zone has received little attention. The goal of this research is to examine the concentrations, spatial distribution, potential ecological risks, and biological effects of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in the riparian groundwater of the Beiluo River, China. The results showed that the pollution level and ecological risk of OCPs in riparian groundwater of the Beiluo River were higher than PCBs. The presence of PCBs (Penta-CBs, Hexa-CBs) and CHLs, respectively, may have reduced the richness of bacteria (Firmicutes) and fungi (Ascomycota). Furthermore, the richness and Shannon's diversity index of algae (Chrysophyceae and Bacillariophyta) decreased, which could be linked to the presence of OCPs (DDTs, CHLs, DRINs), and PCBs (Penta-CBs, Hepta-CBs), while for metazoans (Arthropoda) the tendency was reversed, presumably as a result of SULPHs pollution. In the network analysis, core species belonging to bacteria (Proteobacteria), fungi (Ascomycota), and algae (Bacillariophyta) played essential roles in maintaining community function. Burkholderiaceae and Bradyrhizobium can be considered biological indicators of PCBs pollution in the Beiluo River. Note that the core species of interaction network, playing a fundamental role in community interactions, are strongly affected by POPs pollutants. This work provides insights into the functions of multitrophic biological communities in maintaining the stability of riparian ecosystems through the response of core species to riparian groundwater POPs contamination.

Mechanistic insights into hormesis induced by erythromycin in the marine alga Thalassiosira weissflogii.

Erythromycin (ERY) is a typical macrolide antibiotic with large production and extensive use on a global scale. Detection of ERY in both freshwaters and coaster seawaters, as well as relatively high ecotoxicity of ERY have been documented. Notably, hormesis has been reported on several freshwater algae under ERY stress, where growth was promoted at relatively lower exposures but inhibited at higher treatment levels. On the contrary, there is limited information of ERY toxicity in marine algae, hampering the risk assessment on ERY in the coaster waters. The presence of hormesis may challenge the current concept of dose-response adopted in chemical risk assessment. Whether and how exposure to ERY can induce dose-dependent toxicity in marine algae remain virtually unknown, especially at environmentally relevant concentrations. The present study used a model marine diatom Thalassiosira weissflogii (T. weissflogii) to reveal its toxicological responses to ERY at different biological levels and decipher the underlying mechanisms. Assessment of multiple apical endpoints shows an evident growth promotion following ERY exposure at an environmentally relevant concentration (1 µg/L), associated with increased contents reactive oxygen species (ROS) and chlorophyll-a (Chl-a), activated signaling pathways related to ribosome biosynthesis and translation, and production of total soluble protein. By contrast, growth inhibition in the 750 and 2500 µg/L treatments was attributed to reduced viability, increased ROS formation, reduced content of total soluble protein, inhibited photosynthesis, and perturbed signaling pathways involved in xenobiotic metabolism, ribosome, metabolism of amino acid, and nitrogen metabolism. Measurements of multiple apical endpoints coupled with de novo transcriptomics analysis applied in the present study, a systems biology approach, can generate detailed mechanistic information of chemical toxicity including dose-response and species sensitivity difference used in environmental risk assessment.

Triclosan toxicity in a model cyanobacterium (Anabaena flos-aquae): Growth, photosynthesis and transcriptomic response.

Exposure to triclosan (TCS) has been reported to reduce photosynthetic pigments, suppress photosynthesis, and inhibit growth in both prokaryotic and eukaryotic algae including Anabaena flos-aquae (a model cyanobacterium). In particular, cyanobacteria are more sensitive to TCS toxicity compared to eukaryotic algae possibly due to the structural similarity to bacteria (target organisms); however, whether TCS exerts its toxicity to cyanobacteria by targeting signaling pathways of fatty acid biosynthesis as in bacteria remains virtually unknown, particularly at environmental exposure levels. With the complete genome sequence of A. flos-aquae presented in this study, the transcriptomic alterations and potential toxic mechanisms in A. flos-aquae under TCS stress were revealed. The growth, pigments and photosynthetic activity of A. flos-aquae were markedly suppressed following a 7-day TCS exposure at 0.5 µg/L but not 0.1 µg/L (both concentrations applied are environmentally relevant). The transcriptomic sequencing analysis showed that signaling pathways, such as biofilm formation - Pseudomonas aeruginosa, two-component system, starch and sucrose metabolism, and photosynthesis were closely related to the TCS-induced growth inhibition in the 0.5 µg/L TCS treatment. Photosynthesis systems and potentially two-component system were identified to be sensitive targets of TCS toxicity in A. flos-aquae. The present study provides novel insights on TCS toxicity at the transcriptomic level in A. flos-aquae.

Metabolomic profiles in a green alga (Raphidocelis subcapitata) following erythromycin treatment: ABC transporters and energy metabolism.

A recent study showed that erythromycin (ERY) exposure caused hormesis in a model alga (Raphidocelis subcapitata) where the growth was promoted at an environmentally realistic concentration (4 µg/L) but inhibited at two higher concentrations (80 and 120 µg/L), associated with opposite actions of certain signaling pathways (e.g., xenobiotic metabolism, DNA replication). However, these transcriptional alterations remain to be investigated and verified at the metabolomic level. This study uncovered metabolomic profiles and detailed toxic mechanisms of ERY in R. subcapitata using untargeted metabolomics. The metabolomic analysis showed that metabolomic pathways including ABC transporters, fatty acid biosynthesis and purine metabolism were associated with growth promotion in algae treated with 4 µg/L ERY. An overcompensation was possibly activated by the low level of ERY in algae where more resources were reallocated to efficiently restore the temporary impairments, ultimately leading to the outperformance of growth. By contrast, algal growth inhibition in the 80 and 120 µg/L ERY treatments was likely attributed to the dysfunction of metabolomic pathways related to ABC transporters, energy metabolism and metabolism of nucleosides. Apart from binding of ERY to the 50S subunit of ribosomes to inhibit protein translation as in bacteria, the data presented here indicate that inhibition of protein translation and growth performance of algae by ERY may also result from the suppression of amino acid biosynthesis and aminoacyl-tRNA biosynthesis. This study provides novel insights into the dose-dependent toxicity of ERY on R. subcapitata.

Transcriptional response of a green alga (Raphidocelis subcapitata) exposed to triclosan: photosynthetic systems and DNA repair.

Recent studies show that triclosan (TCS) exposure causes reduction in pigments, suppression of photosynthesis, and induction of oxidative stress at the physiological level, resulting in morphological alteration and growth inhibition in algae including Raphidocelis subcapitata (R. subcapitata, a freshwater model green alga). However, the underlying molecular mechanisms remain to be elucidated, especially at environmentally relevant concentrations. The present study uncovered the transcriptional profiles and molecular mechanisms of TCS toxicity in R. subcapitata using next-generation sequencing. The algal growth was drastically inhibited following a 7-day exposure at both 75 and 100 µg/L TCS, but not at 5 µg/L (environmentally realistic level). The transcriptomic analysis shows that molecular signaling pathways including porphyrin and chlorophyll metabolism, photosynthesis - antenna proteins, and photosynthesis were suppressed in all three TCS treatments, and the perturbations of these signaling pathways were exacerbated with increased TCS exposure concentrations. Additionally, signaling of replication-coupled DNA repair was only activated in 100 µg/L TCS treatment. These results indicate that photosynthesis systems were sensitive targets of TCS toxicity in R. subcapitata, which is distinct from the inhibition of lipid synthesis by TCS in bacteria. This study provides novel knowledge on molecular mechanisms of TCS toxicity in R. subcapitata.

[Biocompatibility evaluation of electrospun PLCL/fibrinogen nanofibers in anterior cruciate ligament reconstruction].

The study aimed to evaluate the safety and function of poly(lactic-acid-co-ε-caprolactone) (PLCL)/fibrinogen nanofibers (P/F-Ns), and provide theoretical basis for the clinical application. The surface morphology, mechanical properties, the hydrophilicity and the fibrinogen content of P/F-Ns were tested by scanning electron microscope, the material testing machine, the contact angle meter and the microplate reader, respectively. The cell adhesion, proliferation and ligament remodeling genes expression of Hig-82 cells on P/F-Ns were conducted through cell counting kit-8 (CCK-8) and real-time quantitative PCR analyses, respectively. The results showed that with the increase of the fibrinogen content, the pore sizes and hydrophilicity of three P/F-Ns increased, but the mechanical properties decreased. Cell adhesion and proliferation tests showed that P/F-N-2 held the best ability to promote cell adhesion and proliferation. The ligament remodeling genes expressions of Hig-82 cells on P/F-N-1, P/F-N-2 and P/F-N-3 were all up-regulated compared to P/F-N-0 on days 3 and 7. All the three P/F-Ns containing fibrinogen (P/F-N-1, P/F-N-2 and P/F-N-3) had better biocompatibility compared to P/F-N-0, and could be efficiently applied to the reconstruction of anterior cruciate ligament.

Prioritizing pharmaceuticals based on environmental risks in the aquatic environment in China.

In last two decades, the number of detected activated pharmaceutical ingredients (APIs) in the natural environment worldwide has increased due to their widespread use in daily life. However, given the large number of APIs that are currently in use (approximate 850 are on the market in China), it is impractical to investigate the occurrence, ecotoxicological effects, and perform environmental risk assessment for all drugs. Therefore, it is crucial to rank and prioritize APIs in the environment to identify the compounds of high concern. In China, since information on API usage is not available, an attempt was made to use the number of products per API (the number of pharmaceutical commodities that contain a particular API) on the market multiplied by its daily dose (average daily dose of medication for adults used for the primary therapeutic purpose) to replace the usage in the exposure modeling. Coupled with the hazard assessment, including acute and chronic toxicity of aquatic ecological effects and potential effects related to the therapeutic mode of action, risk scores were estimated and used for ranking. Application of the approach was illustrated for 259 APIs with product number no less than 4. A list of 20 APIs was finally identified as a potential priority, including drugs of cardiovascular, nervous system, respiratory system, musculoskeletal system and antibiotics. In the future, this approach could be applied to prioritize APIs in other countries/regions where information on API usage are limited or non-existent.

Transcriptomic analysis suggests the inhibition of DNA damage repair in green alga Raphidocelis subcapitata exposed to roxithromycin.

Macrolide antibiotics are common contaminants in the aquatic environment. They are toxic to a wide range of primary producers, inhibiting the algal growth and further hindering the delivery of several ecosystem services. Yet the molecular mechanisms of macrolides in algae remain undetermined. The objectives of this study were therefore to: 1. evaluate whether macrolides at the environmentally relevant level inhibit the growth of algae; and 2. test the hypothesis that macrolides bind to ribosome and inhibit protein translocation in algae, as it does in bacteria. In this study, transcriptomic analysis was applied to elucidate the toxicological mechanism in a model green alga Raphidocelis subcapitata treated with 5 and 90 µg L-1 of a typical macrolide roxithromycin (ROX). While exposure to ROX at 5 µg L-1 for 7 days did not affect algal growth and the transciptome, ROX at 90 µg L-1 resulted in 45% growth inhibition and 2306 (983 up- and 1323 down-regulated) DEGs, which were primarily enriched in the metabolism of energy, lipid, vitamins, and DNA replication and repair pathways. Nevertheless, genes involved in pathways in relation to translation and protein translocation and processing were dysregulated. Surprisingly, we found that genes involved in the base excision repair process were mostly repressed, suggesting that ROX may be genotoxic and cause DNA damage in R. subcapitata. Taken together, ROX was unlikely to pose a threat to green algae in the environment and the mode of action of macrolides in bacteria may not be directly extrapolated to green algae.

Involvement of oxidative stress in the sensitivity of two algal species exposed to roxithromycin.

Algal species Raphidocelis subcapitata and Chlorella vulgaris are commonly used to test the chemicals with an antibacterial mode of action during marketing authorization process. However, significant differences in the sensitivity toward antibiotic exposure have been reported. The selection of an inappropriate test species would thus underestimate the environmental hazard of target chemicals and pose a potential threat to the ecosystem. Since oxidative stress is a crucial factor determining the inhibition of algal growth, an investigation on oxidative stress and antioxidant defense mechanisms in these two species was performed to explore its roles in species sensitivity. Here, roxithromycin (ROX), a macrolide antibiotic extensively used to treat respiratory, urinary and soft tissue infections, was used for testing. After 7 days exposure to ROX at the low (0.01 mg L-1) and high (0.09 mg L-1) concentrations, R. subcapitata was inhibited while the growth of C. vulgaris was stimulated. We investigated the roles of oxidative stress in algae by measuring the oxidative stress biomarkers (MDA), non-enzymatic antioxidants (GSH), and antioxidant enzymes (SOD, CAT, GP, GST). The results suggested that when the growth of algae is inhibited, MDA content as well as activities of oxidative stress enzymes would increase, and thus, activating the antioxidant system. On the contrary, it was inferred that when the growth is stimulated, MDA content and oxidative stress enzymes activities would decrease.

Compound danshen dripping pills normalize a reprogrammed metabolism of myocardial ischemia rats to interpret its time-dependent efficacy in clinic trials: a metabolomic study.

INTRODUCTION: Clinical trials of Compound danshen dripping pills (CDDP) indicated distinct improvement in patients with chronic stable angina. Daily fluctuation of therapeutic effect agreed with a peak-valley PK profile during a 4-week CDDP regimen, but stabilized after 8-week treatment. OBJECTIVES: This article aims to explore the underlying mechanism for the time-dependent drug efficacy of the up-down fluctuation or stabilization in clinic trials. METHODS: A rat model of myocardial ischemia was established via isoproterenol induction. Metabolomics was employed to analyze the energy-related substances both in circulatory system and myocardium in the myocardial ischemia model. RESULTS: CDDP treatment ameliorated myocardial ischemia, reversed the reprogramming of the metabolism induced by ISO and normalized the level of most myocardial substrates and the genes/enzymes associated with those metabolic changes. After 1- or 2-week treatment, CDDP regulated plasma and myocardial metabolome in an analogous, time-dependent way, and modulated metabolic patterns of ischemic rats that perfectly matched with the fluctuated or stabilized effects observed in clinical trials with 4 or 8-week treatment, respectively. CONCLUSION: Metabolic modulation by CDDP contributes to the fluctuated or stabilized therapeutic outcome, and is a potential therapeutic approach for myocardial ischemia diseases.

Effects of prenatal exposure to triclosan on the liver transcriptome in chicken embryos.

Triclosan (TCS), a commonly used antimicrobial compound, has recently been detected in the eggs of wild avian species. Exposure to TCS in rodents is known to interfere with thyroid hormone (TH), disrupt immune responses and cause liver disease. However, no attempt has been made to clarify the effects of TCS in avian species. The aim of this study is therefore to evaluate the toxic effects of in ovo exposure to TCS and explore the molecular mechanism by transcriptome analysis in the embryonic liver of a model avian species, chicken (Gallus gallus). Embryos were treated with graded concentration of TCS (0.1, 1 and 10 µg/g egg) at Hamburger Hamilton Stage (HHS) 1 (1st day), followed by 20 days of incubation to HHS 46. At the administration of 10 µg TCS/g egg, embryo mortality increased from 20% in control to 37% accompanied with 8% attenuation in tarsus length. While liver somatic index (LSI) in TCS treatments was enhanced, statistical difference was only observed at the treatment of 0.1 µg TCS/g egg in females. The up-regulation of several crucial differentially expressed genes (DEGs) in transcriptome analysis suggested that TCS induced xenobiotic metabolism (e.g. CYP2C23a, CYP2C45 and CYP3A37 in males; CYP2C45 in females) and activated the thyroid hormone receptor (THR) - mediated downstream signaling (e.g. THRSPB and DIO2 in males; THRSPB in females). In females, TCS may further activate the lipogenesis signaling (e.g. ACSL5, ELOVL2) and repress the lipolysis signaling (e.g. ABHD5, ACAT2). A battery of enriched transcription factors in relation to these TCS-induced signaling and phenotypes were found, including activated SREBF1, PPARa, LXRa, and LXRb in males and activated GLI2 in females; COUP-TFII was predicted to be suppressed in both genders. Finally, we developed adverse outcome pathways (AOPs) that provide insights into the molecular mechanisms underlying the alteration of phenotypes.

Effects on the hepatic transcriptome of chicken embryos in ovo exposed to phenobarbital.

This work aimed at evaluating the toxic effects of in ovo exposure to phenobarbital (PB) and unveiling the mode of action by transcriptome analysis in the embryonic liver of a model avian species, chicken (Gallus gallus). Embryos were initially treated with saline or 1 µg PB /g egg at Hamburger Hamilton Stage (HHS) 1 (1st day), followed by 20 days of incubation to HHS 46. At 21st day, chicks that pipped successfully were euthanized and dissected for assessing the PB caused effects on phenotypes and the liver transcriptome in both genders. In the PB treatment group, a 7% attenuation in tarsus length was found in females. While no adverse phenotypic effect on the liver somatic index (LSI) was observed, PB caused significant changes in the expressions of 52 genes in males and 516 genes in females (False Discovery Rate < 0.2, p value < 0.05, and absolute fold change > 2). PB exposure modulated the genes primarily enriched in the biological pathways of the cancer, cardiac development, immune response, lipid metabolism, and skeletal development in both genders, and altered expressions of genes related to the cellular process and neural development in females. However, mRNA expressions of chicken xenobiotic receptor (CXR)-mediated CYP genes were not induced in the PB treatment groups, regardless of males and females. On the contrary, PB exposure repressed the mRNA expressions of CYP2AC2 in males and CYP2R1, CYP3A37, and CYP8B1 in females. Although transcription factors (TFs) including SREBF1 and COUP-TFII were predicted to be commonly activated in both genders, some TFs were activated in a gender-dependent manner, such as PPARa in males and BRCA1 and IRF9 in females. Taken together, our results provided an insight into the mode of action of PB on the chicken embryos.

In ovo exposure to triclosan alters the hepatic proteome in chicken embryos.

The occurrence of triclosan (TCS) in the eggs of wild avian species is an emerging concern. We previously evaluated the effects of in ovo exposure to TCS on the liver transcriptome of chicken embryos and proposed adverse outcome pathways (AOPs). However, the key molecular events identified to be affected need to be verified at the protein level. Herein, we investigated the changes in the spectrum of hepatic proteins in TCS-treated chicken embryos by proteomic analysis to validate the key signaling pathways involved in the AOPs. We identified and quantified 894 unique proteins using matrix-assisted laser desorption/ionization time-of-flight/time-of-flight tandem mass spectrometry. In the 0.1 (low dose), 1 (median dose), and 10 µg triclosan/g egg (high dose) groups, TCS caused significant changes in the levels of 195, 233, and 233 proteins in males and 237, 188, and 156 proteins in females, respectively (fold changes > 1.3 or < 0.7). TCS exposure modulated the expression of proteins, predominantly involved in signaling pathways of lipid and energy metabolism in both genders. Among the proteins associated with TCS metabolism in the liver, phase I (e.g., CYP2C23a) and phase II (e.g., UGT1A1) enzymes mediated by chicken xenobiotic receptor, were only induced in males. In consonance with the malondialdehyde levels, which were increased upon TCS exposure in females in a dose-dependent manner, a battery of antioxidant enzymes, notably SOD2, GST, GSTz1, and PRDX1, was decreased and SOD1 and GSTK1 were increased in the embryos. Taken together, this proteome analysis complements the transcriptome profiling reported in our previous study and authenticates the AOPs proposed for chicken embryos in ovo exposed to TCS.

Orally Administered Berberine Modulates Hepatic Lipid Metabolism by Altering Microbial Bile Acid Metabolism and the Intestinal FXR Signaling Pathway.

Previous studies suggest that the lipid-lowering effect of berberine (BBR) involves actions on the low-density lipoprotein receptor and the AMP-activated protein kinase signaling pathways. However, the implication of these mechanisms is unclear because of the low bioavailability of BBR. Because the main action site of BBR is the gut and intestinal farnesoid X receptor (FXR) plays a pivotal role in the regulation of lipid metabolism, we hypothesized that the effects of BBR on intestinal FXR signaling pathway might account for its pharmacological effectiveness. Using wild type (WT) and intestine-specific FXR knockout (FXRint-/-) mice, we found that BBR prevented the development of high-fat-diet-induced obesity and ameliorated triglyceride accumulation in livers of WT, but not FXRint-/- mice. BBR increased conjugated bile acids in serum and their excretion in feces. Furthermore, BBR inhibited bile salt hydrolase (BSH) activity in gut microbiota, and significantly increased the levels of tauro-conjugated bile acids, especially tauro-cholic acid(TCA), in the intestine. Both BBR and TCA treatment activated the intestinal FXR pathway and reduced the expression of fatty-acid translocase Cd36 in the liver. These results indicate that BBR may exert its lipid-lowering effect primarily in the gut by modulating the turnover of bile acids and subsequently the ileal FXR signaling pathway. In summary, we provide the first evidence to suggest a new mechanism of BBR action in the intestine that involves, sequentially, inhibiting BSH, elevating TCA, and activating FXR, which lead to the suppression of hepatic expression of Cd36 that results in reduced uptake of long-chain fatty acids in the liver.

In vitro assessment of the glucose-lowering effects of berberrubine-9-O-ß-D-glucuronide, an active metabolite of berberrubine.

Berberrubine (BRB) is the primary metabolite of berberine (BBR) that has shown a stronger glucose-lowering effect than BBR in vivo. On the other hand, BRB is quickly and extensively metabolized into berberrubine-9-O-ß-D-glucuronide (BRBG) in rats after oral administration. In this study we compared the pharmacokinetic properties of BRB and BRBG in rats, and explored the mechanisms underlying their glucose-lowering activities. C57BL/6 mice with HFD-induced hyperglycemia were administered BRB (50 mg·kg-1·d-1, ig) for 6 weeks, which caused greater reduction in the plasma glucose levels than those caused by BBR (120 mg·kg-1·d-1) or BRB (25 mg·kg-1·d-1). In addition, BRB dose-dependently decreased the activity of α-glucosidase in gut of the mice. After oral administration of BRB in rats, the exposures of BRBG in plasma at 3 different dosages (10, 40, 80 mg/kg) and in urine at different time intervals (0-4, 4-10, 10-24 h) were dramatically greater than those of BRB. In order to determine the effectiveness of BRBG in reducing glucose levels, we prepared BRBG from the urine pool of rats, and identified and confirmed it through LC-MS-IT-TOF and NMR spectra. In human normal liver cell line L-O2 in vitro, treatment with BRB or BRBG (5, 20, 50 µmol/L) increased glucose consumption, enhanced glycogenesis, stimulated the uptake of the glucose analog 2-NBDG, and modulated the mRNA levels of glucose-6-phosphatase and hexokinase. However, both BBR and BRB improved 2-NBDG uptake in insulin-resistant L-O2 cells, while BRBG has no effect. In conclusion, BRB exerts a stronger glucose-lowering effect than BBR in HFD-induced hyperglycemia mice. Although BRB significantly stimulated the insulin sensitivity and glycolysis in vitro, BRBG may have a greater contribution to the glucose-lowering effect because it has much greater system exposure than BRB after oral administration of BRB. The results suggest that BRBG is a potential agent for reducing glucose levels.

Risk assessment of triclosan in the global environment using a probabilistic approach.

The occurrence of antimicrobial agent triclosan (TCS) in the global aquatic and terrestrial environment is an emerging concern. While risk assessment for TCS is available in certain countries, no studies have attempted to assess the risk of TCS worldwide. This could be due to lack of method to characterize the global exposure. The present study therefore proposed a probabilistic-based approach to approximate the percent-ranked measured environmental concentrations (MECs) by estimating exposure concentration distribution (ECD) for different environmental compartments on a global scale, incorporating approximate 1200 single MECs. Hazard of TCS was assessed from species sensitivity distribution as well as predicted no effect concentrations (PNECs) derived from ecotoxicological and toxicological endpoints. We draw on experiences from previous risk assessment exercises and present a holistic approach for characterizing the risk of TCS to microorganism in sewage treatment plant, aquatic and soil organisms, avian and mammalian species, and humans. Using the approach, we estimated risk of TCS to organisms dwelling in sediment and living in surface waters, and the risk quotients (MEC/PNEC) were within the range of 0.95 - 33.3 and 0.49 - 9.5, respectively. While the risk quotients for other environmental compartments were below a value of 1, there are large uncertainties likely due to an insufficient dataset of exposure and hazard of TCS.

Assessment of the Risks of Mixtures of Major Use Veterinary Antibiotics in European Surface Waters.

Effects of single veterinary antibiotics on a range of aquatic organisms have been explored in many studies. In reality, surface waters will be exposed to mixtures of these substances. In this study, we present an approach for establishing risks of antibiotic mixtures to surface waters and illustrate this by assessing risks of mixtures of three major use antibiotics (trimethoprim, tylosin, and lincomycin) to algal and cyanobacterial species in European surface waters. Ecotoxicity tests were initially performed to assess the combined effects of the antibiotics to the cyanobacteria Anabaena flos-aquae. The results were used to evaluate two mixture prediction models: concentration addition (CA) and independent action (IA). The CA model performed best at predicting the toxicity of the mixture with the experimental 96 h EC50 for the antibiotic mixture being 0.248 µmol/L compared to the CA predicted EC50 of 0.21 µmol/L. The CA model was therefore used alongside predictions of exposure for different European scenarios and estimations of hazards obtained from species sensitivity distributions to estimate risks of mixtures of the three antibiotics. Risk quotients for the different scenarios ranged from 0.066 to 385 indicating that the combination of three substances could be causing adverse impacts on algal communities in European surface waters. This could have important implications for primary production and nutrient cycling. Tylosin contributed most to the risk followed by lincomycin and trimethoprim. While we have explored only three antibiotics, the combined experimental and modeling approach could readily be applied to the wider range of antibiotics that are in use.

Effects of Antibiotics on the Growth and Physiology of Chlorophytes, Cyanobacteria, and a Diatom.

The occurrence of antibiotics in surface waters has been reported worldwide with concentrations ranging from ng L-1 to low µg L-1 levels. During environmental risk assessments, effects of antibiotics on algal species are assessed using standard test protocols (e.g., the OECD 201 guideline), where the cell number endpoint is used as a surrogate for growth. However, the use of photosynthetic related endpoints, such as oxygen evolution rate, and the assessment of effects on algal pigments could help to inform our understanding of the impacts of antibiotics on algal species. This study explored the effects of three major usage antibiotics (tylosin, lincomycin, and trimethoprim) on the growth and physiology of two chlorophytes (Desmodesmus subspicatus and Pseudokirchneriella subcapitata), a cyanobacteria (Anabaena flos-aquae), and a diatom (Navicula pelliculosa) using a battery of parameters, including cell density, oxygen evolution rate, total chlorophyll content, carotenoids, and the irradiance-photosynthesis relationship. The results indicated that photosynthesis of chlorophytes was a more sensitive endpoint than growth (i.e., EC50 derived based on the effects of tylosin on the growth of D. subspicatus was 38.27 µmol L-1 compared with an EC50 of 17.6 µmol L-1 based on photosynthetic rate), but the situation was reversed when testing cyanobacteria and the diatom (i.e., EC50 derived based on the effects of tylosin on the growth of A. flos-aquae was 0.06 µmol L-1; EC50 0.33 µmol L-1 based on photosynthetic rate). The pigment contents of algal cells were affected by the three antibiotics for D. subspicatus. However, in some cases, pigment content was stimulated for P. subcapitata, N. pelliculosa, and A. flos-aquae. The light utilization efficiency of chlorophytes and diatom was decreased markedly in the presence of antibiotics. The results demonstrated that the integration of these additional endpoints into existing standardised protocols could provide useful insights into the impacts of antibiotics on algal species.

Simultaneous determination of caffeic acid and its major pharmacologically active metabolites in rat plasma by LC-MS/MS and its application in pharmacokinetic study.

A simple, sensitive and selective high-performance liquid chromatography electrospray ionization tandem mass spectrometry (LC-MS/MS) method was developed for simultaneous determination and pharmacokinetic study of caffeic acid (CA) and its active metabolites. The separation with isocratic elution used a mobile phase composed of methanol and water (containing 0.1% formic acid) at a flow rate of 0.2 mL/min. The detection of target compounds was done in selected reaction monitoring (SRM) mode. The SRM detection was operated in the negative electrospray ionization mode using the transitions m/z 179 ([M - H](-) ) → 135 for CA, m/z 193 ([M - H](-) ) → 134.8 for ferulic acid and isoferulic acid and m/z 153 ([M - H](-) ) → 108 for protocatechuic acid. The method was linear for all analytes over the investigated range with all correlation coefficients 0.9931. The lower limits of quantification were 5.0 ng/mL for analytes. The intra- and inter-day precisions (relative standard deviation) were <5.86 and <6.52%, and accuracy (relative error) was between -5.95 and 0.35% (n = 6). The developed method was applied to study the pharmacokinetics of CA and its major active metabolites in rat plasma after oral and intravenous administration of CA.