Syzygium cumini (L.) Skeels has Thermostable and Selective Anti-Bacillus anthracis Activity

IntroductionGastrointestinal (GI) anthrax caused by Bacillus anthracis remains a neglected disease in many parts of the Americas, Asia, and Africa. The symptoms include dysentery, stomachache, bloating of the stomach, vomiting, fever, chills, etc. Current study evaluated several edible plants traditionally indicated for GI disease/symptoms in the Indian subcontinent for their anti-B. anthracis activity. Materials & MethodsAqueous extracts of plant parts were assessed for anti-B. anthracis activity using standard antimicrobial susceptibility testing assays. Most promising extracts were evaluated for desirable activity under conditions relevant to their usage, including extremes of temperature, pH, presence of bile salt, impact on gut microflora, and interaction with FDA-approved drugs for anthrax treatment. The bioactive components separated by bioactivity-guided thin-layer-chromatography were subjected to GC-MS characterization. ResultsAqueous Syzygium cumini (L.) Skeels or Jamun extract (AJE) was most potent and reduced the viable colony-forming units (CFU) by 6-logs within 2 hours of exposure at [≥]1.9%w/v concentration. It displayed both desirable selectivity towards gut microflora and thermostability (>90% and [~]80% of anti-B. anthracis activity were retained on incubation at 50{degrees}C for 20 days and at 95{degrees}C for 12h, respectively). AJE and FDA-approved antibiotics for anthrax displayed synergy. GC-MS analysis of AJE identified various previously-identified antimicrobials belonging to categories of alkaloids, flavonoids, phenols, etc. ConclusionAJE has potent and selective anti-B. anthracis activity with the desired degree of thermotolerance, compatibility with gut microflora, and recommended antibiotics. Further studies exploring the bioactive components in AJE and their potential application in preventing anthrax and anthrax-like diseases may be undertaken.