Phytochemical profile of ethanolic extracts of Chimonanthus salicifolius S. Y. Hu. leaves and its antimicrobial and antibiotic-mediating activity

Abstract

The aim of this study was to determine the phytochemical profiles in the ethanol elutions of Chimonanthus salicifolius S. Y. Hu. leaves (EECS) and study its antibacterial activity. The ethanol extracts of C. salicifolius S. Y. Hu. leaves were prepared by ethanol gradient elution orderly and analyzed by HPLC-DAD. Three bacterial and four fungal species were used to evaluate the antimicrobial activities of the EECS by the broth microdilution method. Results showed that the MIC values against bacteria ranged from 0.35 mg/mL to 11.25 mg/mL (Escherichia coli CVCC1490, Staphylococcus aureus, and Bacillus subtilis). The C. salicifolius S. Y. Hu. leaves exhibited MIC values ranging from 2.81 mg/mL to 45 mg/mL against both the strains of yeast (Saccharomyces cerevisiae CICC 1540, Saccharomyces cerevisiae CICC 1340) and against strains of Cephalckiscus Fiagans (Penicillium digitatum AS3.5752, Aspergillus niger) with the MIC values ranging from 2.81 mg/mL to 11.25 mg/mL, respectively. Remarkable antibacterial potential was marked with low minimal inhibitory concentration (MIC) for the 50%, 70% and 95% ethanolic fractions against bacteria. The HPLC analysis revealed quercetin and kaempferol as major ingredients in the screening EEs. Interestingly, the content of quercetin and kaempferol varied with the concentration of elution ethanol. The synergistic and additive effects of the selected EEs were frequently observed against E. coli, S. aureus and B. subtilis when combined with standard antibiotics (aminoalcohol, aminoglycosides and β-lactam antibiotics). In conclusion, the EECS possessed the property of modifying antibiotics against bacteria. Synergistic combination can be used to reduce the use of antibiotics or look forward to dealing with drug-resistant bacteria, and also provide theoretical underpinning as natural food preservatives and medicinal plants.