Antibacterial Difference of Plant Flavonoids to Gram-Negative and -Positive Bacteria
Yu Yan, Xuexue Xia, Aiman Fatima, Li Zhang, Ganjun Yuan, Fengxian Lian, Yu Wang · Preprints.org · 2024
The antibacterial activities of plant flavonoids have increasingly paid a more attention to. In our previous works, the antimicrobial quantitative structure-activity relationship was established for plant flavonoids against gram-positive bacteria, and its major action site was confirmed as the cell membrane. To understand the antimicrobial difference of plant flavonoids to gram-negative and -positive bacteria, here the minimum inhibitory concentrations (MICs) of thirty-seven plant flavonoids to Escherichia coli were determined using microdilution broth method, and then the correlation between their lipophilic parameter ACD/LogP or LogD7.40 values and their MICs were analyzed. Combined with those correlations analyses from forty-six plant flavonoids reported, the results showed that there is also correlation between their LogP values and MICs to Gram-negative bacteria, while it is difficult to predict the MIC of plant flavonoids against gram-negative from their lipophilic parameters like against Gram-positive bacteria. Simultaneously, the antibacterial activities of plant flavonoids to Gram-negative bacteria are generally weak. After compared the character of regression curves established from plant flavonoids against gram-negative and -positive bacteria, it was found that the antibacterial activities of most plant flavonoids to Gram-negative bacteria are greater than to Gram-positive bacteria when their LogP values are less than about 3.0, but less than which when their LogP values are more than about 3.6. Moreover, different from mainly acting on the cell membrane of Gram-positive bacteria, there are probably multiple action modes of plant flavonoids against Gram-negative bacteria, and among them the cell membrane is also an important action.