Relationship between antimicrobial activity and amphipathic structure of ginsenosides

Abstract

Ginsenoside has a wide range of pharmacological activities, but little research has been conducted on its microbial pathogen inhibition and the relationship between its antimicrobial activity and saponin structure. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) or minimum fungicidal concentration (MFC) of a series of ginsenosides were used to investigate the antimicrobial activity of the ginsenosides. And the value of hydrophile–lipophile balance (HLB) was introduced as physicochemical factors to clarify the difference in bacteriostatic activity of saponins. The effects of active ginsenoside Rh2 on the Fusobacterium nucleatum and Bacillus cereus biofilm system were observed by calgary biofilm device (CBD) and fluorescence confocal microscopy (CLSM). The morphological characteristics were examined by using transmission electron microscope (TEM) to explore the cell damage. The antimicrobial effects were in the following order from high to low: saponins containing one glycosyl group > aglycones > two ligands > more than two ligands. Ginsenoside Rh2 and RK3 (hydrophile lipophilic balance value were both 1.15) showed high activity against the tested strains. Correlation analysis shows that HLB is associated with antimicrobial activity (p < 0.01). The antimicrobial activity increased with the HLB value of ginsenosides determined by changes in the length, the number, and the composition of sugar side chains. Specific polar ginsenosides cause bacterial death by destroying the membrane system. Based on their good broad-spectrum antibacterial activity, less polar ginsenosides have potential as bacteriostatic agents.