Targeting and arginine-driven synergizing photodynamic therapy with nutritional immunotherapy nanosystems for combating MRSA biofilms.

The resistance and immune escape of methicillin-resistant Staphylococcus aureus (MRSA) biofilms cause recalcitrant infections. Here, we design a targeting and synergizing cascade PDT with nutritional immunotherapy nanosystems (Arg-PCN@Gel) containing PCN-224 as PDT platform for providing reactive oxygen species (ROS), incorporating arginine (Arg) as nitric oxide (NO) donor to cascade with ROS to produce more lethal ONOO- and promote immune response, and coating with gelatin as targeting agent and persistent Arg provider. The nanosystems adhered to the autolysin of MRSA and inhibited Arg metabolism by down-regulating icdA and icaA. It suppressed polysaccharide intercellular adhesin and extracellular DNA synthesis to prevent biofilm formation. The NO broke mature biofilms and helped ROS and ONOO- penetrate into biofilms to inactivate internal MRSA. Arg-PCN@Gel drove Arg to enhance immunity via inducible NO synthase/NO axis and arginase/polyamine axis and achieve efficient target treatment in MRSA biofilm infections. The targeting and cascading PDT synergized with nutritional immunotherapy provide an effective promising strategy for biofilm-associated infections.

Formulation of a rational dosage regimen of ceftiofur hydrochloride oily suspension by pharmacokinetic-pharmacodynamic (PK-PD) model for treatment of swine Streptococcus suis infection.

BACKGROUND: Our previously prepared ceftiofur (CEF) hydrochloride oily suspension shows potential wide applications for controlling swine Streptococcus suis infections, while the irrational dose has not been formulated. OBJECTIVES: The rational dose regimens of CEF oily suspension against S. suis were systematically studied using a pharmacokinetic-pharmacodynamic model method. METHODS: The healthy and infected pigs were intramuscularly administered CEF hydrochloride oily suspension at a single dose of 5 mg/kg, and then the plasma and pulmonary epithelial lining fluid (PELF) were collected at different times. The minimum inhibitory concentration (MIC), minimal bactericidal concentration, mutant prevention concentration (MPC), post-antibiotic effect (PAE), and time-killing curves were determined. Subsequently, the area under the curve by the MIC (AUC0-24h/MIC) values of desfuroylceftiofur (DFC) in the PELF was obtained by integrating in vivo pharmacokinetic data of the infected pigs and ex vivo pharmacodynamic data using the sigmoid Emax (Hill) equation. The dose was calculated based on the AUC0-24h/MIC values for bacteriostatic action, bactericidal action, and bacterial elimination. RESULTS: The peak concentration, the area under the concentration-time curve, and the time to peak for PELF's DFC were 24.76 ± 0.92 µg/mL, 811.99 ± 54.70 µg·h/mL, and 8.00 h in healthy pigs, and 33.04 ± 0.99 µg/mL, 735.85 ± 26.20 µg·h/mL, and 8.00 h in infected pigs, respectively. The MIC of PELF's DFC against S. suis strain was 0.25 µg/mL. There was strong concentration-dependent activity as determined by MPC, PAE, and the time-killing curves. The AUC0-24h/MIC values of PELF's DFC for bacteriostatic activity, bactericidal activity, and virtual eradication of bacteria were 6.54 h, 9.69 h, and 11.49 h, respectively. Thus, a dosage regimen of 1.94 mg/kg every 72 h could be sufficient to reach bactericidal activity. CONCLUSIONS: A rational dosage regimen was recommended, and it could assist in increasing the treatment effectiveness of CEF hydrochloride oily suspension against S. Suis infections.

Creation of an Anti-Inflammatory, Leptin-Dependent Anti-Obesity Celastrol Mimic with Better Druggability.

Obesity is characterized by an excessive body mass, but is also closely associated with metabolic syndrome. And, so far, only limited pharmacological treatments are available for obesity management. Celastrol, a pentacyclic triterpenoid from a traditional Chinese medicine (Tripterygium wilfordii Hook.f.), has shown remarkable potency against obesity, inflammation and cancer, but its high toxicity, low natural abundance and tedious chemical synthesis hindered its translation into clinics. In the present work, a triterpenoid library was screened for compounds with both high natural abundance and structural similarity to celastrol; from this library, glycyrrhetinic acid (GA), a compound present in extremely high yields in Glycyrrhiza uralensis Fisch. ex DC., was selected as a possible scaffold for a celastrol mimic active against obesity. A simple chemical modification of GA resulted in GA-02, a derivative that suppressed 68% of food intake in diet-induced obesity mice and led to 26.4% weight loss in 2 weeks. GA-02 plays a role in obesity treatment by re-activating leptin signaling and reducing systemic and, more importantly, hypothalamic inflammation. GA-02 was readily bioavailable with unnoticeable in vitro and in vivo toxicities. The strategy of scaffold search and modification on the basis of bio-content and structural similarity has proved to be a green, economic, efficient and practical way of widening the medicinal applications of "imperfect" bioactive natural compounds.

Discovery of novel nitrogenous heterocyclic-containing quinoxaline-1,4-di-N-oxides as potent activator of autophagy in M.tb-infected macrophages.

As a continuation of our research on antimycobacterial agents, a series of novel quinoxaline-1,4-di-N-oxides (QdNOs) containing various nitrogenous heterocyclic moieties at the R6 position were designed and synthesized. Antimycobacterial activities, as well as the cytotoxic effects, of the compounds were assayed. Four compounds (6b, 6f, 6n, and 6o), characterized by 2-carboxylate ethyl or benzyl ester, 6-imidazolyl or 1,2,4-triazolyl, and a 7-fluorine group, exhibited the most potent antimycobacterial activity against M.tb strain H37Rv (MIC ≤ 0.25 µg/mL) with low toxicity in VERO cells (SI = 169.3-412.1). Compound 6o also exhibited excellent antimycobacterial activity in an M.tb-infected macrophage model and was selected for further exploration of the mode of antimycobacterial action of QdNOs. The results showed that compound 6o was capable of disrupting membrane integrity and disturbing energy homeostasis in M.tb. Furthermore, compound 6o noticeably increased cellular ROS levels and, subsequently, induced autophagy in M.tb-infected macrophages, possibly indicating the pathways of QdNOs-mediated inhibition of intracellular M.tb replication. The in vivo pharmacokinetic (PK) profiles indicated that compounds 6o was acceptably safe and possesses favorable PK properties. Altogether, these findings suggest that compound 6o is a promising antimycobacterial candidate for further research.

Dosage Regimen Formulation and Therapeutic Effect Evaluation of Cyadox Nanosuspension Against Dairy Cow Mastitis Caused by Staphylococcus aureus.

AIMS: In this study, the dosage regimen establishment of cyadox nanosuspension against dairy cow mastitis caused by Staphylococcus aureus (S. aureus) was used as example to provide a general reference for the other novel nanocrystal preparations. METHODS: The effect of cyadox against S. aureus isolates from dairy cows were firstly estimated and then the dosing regimen of nanosuspension after intramammary administration was optimized according to the model of ex vivo pharmacokinetic (PK) and pharmacodynamic (PD). The therapeutic efficacy of the predicted dosage regimen was evaluated. RESULTS: The results demonstrated that cyadox has a concentration-dependent effect on S. aureus. The smallest and highest values of minimum inhibitory concentration (MIC) against 80 isolates was 8 and 64 µg/mL, respectively. The corresponding MIC 50 and MIC 90 was 16 and 32 µg/mL, respectively. The MIC against the pathogenic S. aureus SAHZ156001 in broth and milk were 16 and 32 µg/mL, respectively. The AUC 0-last and C max of cyadox in milk were 4442.877 µg*h/mL and 753.052 µg/mL, respectively. According to the inhibitory sigmoid E max modeling and dosage equation, the daily doses were predicted 1.6, 6.6, and 12.2 mL/gland to achieve bacteriostatic, bactericidal, and elimination effects. The dosage internal was daily administration for continuous three days. CONCLUSION: The clinical experiment showed that the efficient rates were 100, 100, and 90.9%, and the curative rates were 100, 81.8, and 63.6% in 12.2, 6.6 and 1.6 ml/gland groups, respectively. These results showed that cyadox nanosuspension had a good prospect as intramammary infusion to cure dairy cow mastitis infected by S. aureus. This study will be helpful for providing reference for nanocrystal preparation dosage regimen formulation.

Activated FXR promotes xenobiotic metabolism of T-2 toxin and attenuates oxidative stress in broiler chicken liver.

The transmission of T-2 toxin and its metabolites into the edible tissues of poultry has potential effects on human health. The bile acid and xenobiotic system composes an intricate physiological network of chemoprotective and transporter-related functions, which ensures the detoxification and removal of harmful xenobiotic and endobiotic compounds from the body. This study revealed that cholic acid (CA), as one of the bile acids, promoted the metabolism of T-2 toxin in vivo by inducing the xenobiotic metabolism enzymes expression, thereby increasing the stress resistance and attenuating the oxidative stress. This study also indicated that dietary supplementation of 1% CA alleviated the mortality caused by T-2 toxin. Liver histology results demonstrated that CA supplementation significantly reduced inflammatory cell infiltration, sinusoidal expansion and congestion. Biochemistry results showed that the elevations of plasma alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities and the increase in concentration of hydrogen peroxide (H2O2) in liver induced by the T-2 toxin were decreased by dietary supplementation of 1% CA. Additionally, CA supplementation led to the increase in superoxide dismutase (SOD) activity, but the decrease in catalase (CAT) activity in broiler chicken livers. Based on these findings, we propose that activation of FXR promotes T-2 toxin xenobiotic metabolism, and FXR plays a hepatoprotection role in liver injury induced by T-2 toxin.

The antibacterial activities of aditoprim and its efficacy in the treatment of swine streptococcosis.

Aditoprim (ADP) has potential use as an antimicrobial agent in animals. However, its pharmacodynamic properties have not been systematically studied yet. In this study, the in vitro antibacterial activities of ADP and its main metabolites were assayed, and the in vivo antibacterial efficacy of ADP for the treatment of swine streptococcosis was evaluated. It was shown that Salmonella and Streptococcus from swine, Escherichia coli and Salmonella from chickens, E. coli, Streptococcus, Mannheimia, Pasteurella from calves, Streptococcus and Mannheimia from sheep, and E. coli, Flavobacterium columnare, Acinetobacter baumannii and Yersinia ruckeri from fishes were highly susceptible to ADP. Haemophilus parasuis from swine, Staphylococcus aureus, Aeromonas punctate, Mycobacterium tuberculosis, Streptococcus agalactiae from fishes, and Klebsiella from calves and sheep showed moderate susceptibility to ADP, whereas E. coli, Actinobacillus pleuropneumonia, Pasteurella, S. aureus, Clostridium perfringens from swine, S. aureus, C. perfringens from chickens, and S. aureus from calves were resistant to ADP. The main metabolites of ADP showed equal activity to that of their parent compound, and the prevention and therapeutic dosages of ADP recommended for swine streptococcosis were 10 and 20~40 mg/kg b.w., respectively. This study firstly showed that ADP had strong antibacterial activity and had potential to be used as a single drug in the treatment of bacterial infectious diseases.

Synthesis and potential anticonvulsant activity of new N-3-substituted 5,5-cyclopropanespirohydantoins.

Thirteen new 5-cyclopropanespirohydantoins with various N-3 substituents were synthesized and their pharmacological activity was determined with the objective to better understand their structure-activity relationship (SAR) for anticonvulsant activity. The anticonvulsant effects of these compounds were evaluated by maximal electroshock seizure (MES) test and subcutaneous pentylenetetrazole (scPTZ) test models in mice. All compounds substituted with cyclopropyl group at fifth position of hydantoin ring showed better protection against MES test. Compounds 5b, 5d, 5e, 5g and 5j were found to be the most potent compounds of this series and compared with the reference drug phenytoin sodium in MES test. Compound 5j also showed equipotent activity with the standard drug sodium valproate at the doses of 20 and 40 mg kg(-1) in scPTZ test.

Cytotoxic withanolides from the flowers of Datura metel.

Chemical investigation of a methanol extract of the flowers of Datura metel has led to the isolation of 10 new withanolides, withametelins I-P (1-8), 1,10-seco-withametelin B (9), and 12beta-hydroxy-1,10-seco-withametelin B (10), together with seven known withanolides. The structures of 1-10 were elucidated by means of spectroscopic methods, and the absolute stereochemistry of 1 was confirmed by single-crystal X-ray analysis. Compounds 1, 3, 4, and 6 exhibited cytotoxic activities against A549 (lung), BGC-823 (gastric), and K562 (leukemia) cancer cell lines, with IC50 values ranging from 0.05 to 3.5 microM.