DNB-001

The removal rate of some antibiotics in urban sewage by conventional treatment is low, which leads to an increase in antibiotic resistant bacteria in natural water environments. To reduce the ecological harm of antibiotics to the water in towns, a risk control technique for degradation of microantibiotics by the co-metabolism of antibiotic resistant denitrifying bacteria was proposed. Using sodium acetate as an electron donor and maintaining the concentration of ofloxacin (OFLX) at 1 μg·g^-1, gradually increasing the dominant growth of antibiotic degradation bacteria, denitrifying bacteria (DnB₁), trace antibiotics and sodium acetate, and denitrifying bacteria (DnB₂) with the presence of sodium acetate and nitrogen elements were cultured. The degradation effect of antibiotics through denitrification and the effects of antibiotics on denitrification of resistant denitrifying bacteria and the changes to the microbial community were investigated. The results showed that DnB₂ had a significant degradation effect on OFLX compared to DnB₁. The degradation to OFLX by DnB₁ and DnB₂ was 0.31 μg·g^-1 and 16.14 μg·g^-1, respectively. Increased OFLX concentration inhibited DnB₁ denitrification activity in the short term. The denitrification process of DnB₂ was less affected by OFLX. At the same time, high-throughput sequencing using the Illumina MiSeq platform was used. Based on the operational taxonomic unit information formed by the clustering of sequencing results, the diversity of each sample was compared and analyzed. The research results show that the relative abundance and diversity of the microbial community of DnB₁ are higher than those of DnB₂.

The metabolism and disposition of KR31378 (a benzopyran derivative and a novel neuroprotective agent) were investigated following single oral or intravenous administration of [(14)C]-KR31378 to rats. [(14)C]-KR31378 was rapidly absorbed after oral dosing with an oral bioavailability of greater than 71%. The maximum plasma concentration and area under the curve of total radioactivity in rat plasma increased proportionally to the administered dose. KR31378 was distributed over all organs and tissues except for brain, eyeball and testis, and declined by first order kinetics up to 24 h after dosing. Excretion of the radioactivity was 29.5% of the dose in the urine and 58.5% in the feces within 2 days after oral administration. Biliary excretion of the radioactivity in bile duct-cannulated rats was about 66.0% for the first 24 h. KR31378 was extensively metabolized by ring hydroxylation, O-demethylation, oxidation and reduction with subsequent N-acetylation and O-glucuronide conjugation. N-acetylated conjugates (M2, M10, M11, M12, M14, and M15) were identified as the predominant metabolites in rats.