Antibacterial Activity and Mechanism of Plant Flavonoids to Gram-positive Bacteria Predicted from their Lipophilicities

Abstract

Antimicrobial resistance seriously threatened human health, and new antimicrobial agents are desperately needed. As one of the largest classes of plant secondary metabolite, flavonoids can be widely found in various parts of the plant, and their antibacterial activities have been increasingly paid attention to. Based on the physicochemical parameters and antibacterial activities of sixty-six flavonoids reported, two regression equations between their ACD⁄LogP or LogD7.40 and their minimum inhibitory concentrations (MICs) to gram-positive bacteria were established with the correlation coefficients above 0.93, and then were verified by another sixty-eight flavonoids reported. From these two equations, the MICs of most flavonoids against gram-positive bacteria could be roughly calculated from their ACD⁄LogP or LogD7.40, and their minimum values were respectively predicted as approximately 1.7 or 3.0 μM, more likely fall into the range from 0.9 to 3.4 μM, or from 1.5 to 6.0 μM, respectively. Simultaneously, both tendentiously concave regression curves indicated that the lipophilicity is a key factor for flavonoids against gram-positive. Combined with the literature analyses, the results also suggested that the cell membrane is the main site of flavonoids acting on gram-positive bacteria, and which likely involves the damage of phospholipid bilayers, the inhibition of the respiratory chain or the ATP synthesis, or some others.

In Vitro Antibacterial Activity of Averrhoa bilimbi Leaves Ethanol Extract Against Salmonella typhi

“…18 Flavonoids have several antimicrobial actions, such as inhibiting synthase, which is involved in nucleic acid synthesis, respiratory chain and energy metabolism, cytoplasmic membrane function, and cell envelope synthesis. 19 The bioactive compounds of A. bilimbi seem to cooperate in producing an adequate antibacterial mechanism effect.…”

“…20 A. bilimbi leaf extract also has antibacterial action with the MIC at 30% and the MBC at 35% against Enterococcus faecalis bacteria. 19…”

Research Progress on the Identification and Pharmacological Activity of the Active Components of the Rhododendron Species

“…This review involves an investigation of 29 individual Rhododendron species and a comprehensive and simultaneous study of Rhododendron. In the study of antibacterial activity 72 , it was found that the study on gram-positive bacteria and its activity against gram-positive bacteria were significant, but no visible components were found for gramnegative bacteria. The highly effective substances mentioned in this review will continue to increase in value as pioneers in drug development.…”

Role of Dietary Flavonoids in Preventing COVID-19 Infection and Other Infectious Diseases: A Mini Review

“…Flavonoids not only help fend off infections and reinforce our immune system; however, their use significantly decreases the incidence of antibiotic resistance. 9 As a result, these compounds are now being largely being researched and successfully used as nutraceuticals. Previous researches have depicted that biocompatibility and bio-safety is also an important requirement of the materials used for medical and dental applications whether in case of the treatment of disease or any other invasive procedure.…”