Assessment of the antimicrobial effects of sodium hypochlorite on Enterococcus faecalis by D2O-labeled single-cell Raman micro-spectroscopy.

OBJECTIVES: To systematically evaluate the feasibility of D2O-labeled single-cell Raman micro-spectroscopy in drug resistance research and test the susceptibility of Enterococcus faecalis (E. faecalis)to sodium hypochlorite. METHODS: 1) The growth of E. faecalis in different doses of D2O and the regularity of D2O intake were evaluated through absorbance measurement and D2O-labeled single-cell Raman micro-spectroscopy to examine the universality of D2O-labeled single-cell Raman micro-spectroscopy in bacterial resistance research. 2) Broth dilution method and absorbance measurement were performed to determine the minimum inhibitory concentration (MIC) of NaClO against E. faecalis and the MIC based on metabolic activity (MIC-MA) in vitro via D2O-labeled single-cell raman micro-spectroscopy. RESULTS: 1) The growth of E. faecalis was not significantly inhibited by ≤40% D2O in the medium. E. faecalis could actively metabolize D2O and exhibit a C-D ratio in specific areas of Raman micro-spectroscopy results. The C-D ratio of E. faecalis at the stationary phase was positively correlated with D2O concentration. 2) The MIC and MIC-MA of NaClO against E. faecalis were 0.45 and 0.9 g·L-1, respectively. The concentration of MIC-MA was twice that of MIC. CONCLUSIONS: D2O-labeled single-cell Raman micro-spectroscopy is important in screening antimicrobial agents and evaluating the efficacy of antimicrobial agents. It is suitable for evaluating the effect of drugs on bacterial metabolic activities. NaClO showed an effective antimicrobial activity against E. faecalis. E. faecalis ceased propagation yet remained highly metabolically active when it was exposed to NaClO at the MIC level. The metabolic activity of most cells was inhibited only when they were exposed to NaClO at the MIC-MA level.

[Correspondence analysis between traditional commercial specifications and quantitative quality indices of Notopterygii Rhizoma et Radix].

This paper aims to explore a comprehensive assessment method combined traditional Chinese medicinal material specifications with quantitative quality indicators. Seventy-six samples of Notopterygii Rhizoma et Radix were collected on market and at producing areas. Traditional commercial specifications were described and assigned, and 10 chemical components and volatile oils were determined for each sample. Cluster analysis, Fisher discriminant analysis and correspondence analysis were used to establish the relationship between the traditional qualitative commercial specifications and quantitative chemical indices for comprehensive evaluating quality of medicinal materials, and quantitative classification of commercial grade and quality grade. A herb quality index (HQI) including traditional commercial specifications and chemical components for quantitative grade classification were established, and corresponding discriminant function were figured out for precise determination of quality grade and sub-grade of Notopterygii Rhizoma et Radix. The result showed that notopterol, isoimperatorin and volatile oil were the major components for determination of chemical quality, and their dividing values were specified for every grade and sub-grade of the commercial materials of Notopterygii Rhizoma et Radix. According to the result, essential relationship between traditional medicinal indicators, qualitative commercial specifications, and quantitative chemical composition indicators can be examined by K-mean cluster, Fisher discriminant analysis and correspondence analysis, which provide a new method for comprehensive quantitative evaluation of traditional Chinese medicine quality integrated traditional commodity specifications and quantitative modern chemical index.