Antimycobacterial Mechanism of Vanillin Involves Disruption of Cell-Surface Integrity Virulence Attributes, and Iron Homeostasis

• Published in: International journal of mycobacteriology Vol. 5; no. 4; pp. 460 - 468
• Main Authors: Sharma, Sharda, Pal, Rahul, Hameed, Saif, Fatima, Zeeshan
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Ltd 01.12.2016; Medknow Publications and Media Pvt. Ltd; Wolters Kluwer Medknow Publications
• Subjects: Antitubercular Agents - pharmacology; Bacteriolysis; Benzaldehydes - pharmacology; Biofilm; Biofilms - drug effects; Biofilms - growth & development; Cell Adhesion - drug effects; Cell Membrane - drug effects; Cell Membrane - physiology; Flavoring essences; Homeostasis - drug effects; Humans; Hydrolysis; Infectious Disease; Iron; Iron - metabolism; MDR; Medical Education; Membrane; Microbial Sensitivity Tests; Microscopy, Electron, Transmission; Mycobacterium; Mycobacterium smegmatis - pathogenicity; Mycobacterium smegmatis - physiology; Tuberculosis; Vanillin; Virulence - drug effects; India; Mycobacterium; Biofilm; Membrane; Iron; MDR; Vanillin; Anti-TB drugs
• ISSN: 2212-5531; 2212-554X
• DOI: 10.1016/j.ijmyco.2016.06.010

Abstract Objective/Background Tuberculosis (TB) remains a global threat, claiming one-third of the population annually. The ever increasing emergence of multidrug-resistant TB (MDR-TB) is the major impediment to effective anti-TB therapy. Under such circumstances, deciphering the antimycobacterial potential of natural compounds has gained considerable prominence. This study evaluated the antimycobacterial activity of vanillin (Van), a natural food-flavoring agent and preservative, along with its potential mechanisms of action. [Methods] Drug susceptibilities were performed using broth microdilution, spot, and filter-disc assays. Membrane damage was studied by nitrocefin hydrolysis and electron microscopy. Virulence attributes were assessed by biofilm formation and cell adherence. Iron availability was estimated by enzymatic (ferroxidase) assay. [Results] We found that the antimycobacterial activity of Van against Mycobacterium smegmatis (a surrogate of Mycobacterium tuberculosis ) is 125 μg/mL. Additionally, we observed disruption of membrane homeostasis in the presence of Van, as revealed by enhanced membrane permeability and transmission electron microscopy images showing a disturbed cell envelope. Concomitant with our findings, we also observed that Van leads to enhanced drug susceptibility to membrane targeting known anti-TB drugs. Furthermore, Van affects significant virulence traits of Mycobacterium by inhibiting biofilm formation and cell adhesion. Finally, we observed that Van disrupted iron homeostasis as displayed by hypersensitivity to iron deprivation. [Conclusion] The results established for the first time that Van could be an effective antimycobacterial agent that could be exploited further in treating mycobacterial infections.