Antibacterial Activity and Mechanisms of Plant Flavonoids against Gram-Negative Bacteria Based on the Antibacterial Statistical Model.

The antimicrobial quantitative structure-activity relationship of plant flavonoids against Gram-positive bacteria was established in our previous works, and the cell membrane was confirmed as a major site of action. To investigate whether plant flavonoids have similar antibacterial effects and mechanisms against both Gram-negative and Gram-positive bacteria, here, the minimum inhibitory concentrations (MICs) of 37 plant flavonoids against were determined using the microdilution broth method, and then the correlation between their lipophilic parameter ACD/LogP or LogD value and their MIC was analyzed. Simultaneously, the correlation between the ACD/LogP or LogD value and the MIC of 46 plant flavonoids reported in the literature against was also analyzed.

Quinone Pool, a Key Target of Plant Flavonoids Inhibiting Gram-Positive Bacteria.

Plant flavonoids have attracted increasing attention as new antimicrobial agents or adjuvants. In our previous work, it was confirmed that the cell membrane is the major site of plant flavonoids acting on the Gram-positive bacteria, which likely involves the inhibition of the respiratory chain. Inspired by the similar structural and antioxidant characters of plant flavonoids to hydro-menaquinone (MKH), we deduced that the quinone pool is probably a key target of plant flavonoids inhibiting Gram-positive bacteria.

Stachydrine, a Bioactive Equilibrist for Synephrine, Identified from Four Chinese Herbs.

Four Chinese herbs from the genus, namely Aurantii Fructus Immaturus (), Aurantii Fructus (), Citri Reticulatae Pericarpium Viride () and Citri Reticulatae Pericarpium (), are widely used for treating various cardiovascular and gastrointestinal diseases. Many ingredients have already been identified from these herbs, and their various bioactivities provide some interpretations for the pharmacological functions of these herbs. However, the complex functions of these herbs imply undisclosed cholinergic activity.

Antimicrobial Quantitative Relationship and Mechanism of Plant Flavonoids to Gram-Positive Bacteria.

Antimicrobial resistance (AMR) poses a serious threat to human health, and new antimicrobial agents are desperately needed. Plant flavonoids are increasingly being paid attention to for their antibacterial activities, for the enhancing of the antibacterial activity of antimicrobials, and for the reversing of AMR. To obtain more scientific and reliable equations, another two regression equations, between the minimum inhibitory concentration (MIC) () and the lipophilicity parameter ACD/LogP or LogD (), were established once again, based on the reported data.