AUTHOR=Yadav Mukesh Kumar , Mailar Karabasappa , Nagarajappa Masagalli Jagadeesh , Chae Sung-Won , Song Jae-Jun , Choi Won Jun 

TITLE=Ruthenium Chloride—Induced Oxidative Cyclization of Trans-Resveratrol to (±)-ε-Viniferin and Antimicrobial and Antibiofilm Activity Against Streptococcus pneumoniae

JOURNAL=Frontiers in Pharmacology

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/pharmacology/articles/10.3389/fphar.2019.00890

DOI=10.3389/fphar.2019.00890

ISSN=1663-9812

ABSTRACT=<p>Polyphenol ε-viniferin (<bold>2</bold>) is a protective phytochemical found in several plant families. Here, we report a simple and effective method for the synthesis of (±)-ε-viniferin (<bold>2</bold>) as major product and (±)-(E)-ω-viniferin (<bold>3</bold>) as a minor product. Synthesized viniferin compounds and standard viniferin were analyzed for antibacterial and antibiofilm activity against Gram-positive bacteria <italic>Streptococcus pneumoniae</italic>. The minimum inhibitory concentrations (MICs) of (±)-ε-viniferin (<bold>2</bold>) and standard viniferin were 20 µm. However, the MICs of (±)-(E)-ω-viniferin (<bold>3</bold>) and compound <bold>8</bold> were 40 µm. Although viniferin significantly (p &lt; 0.05) reduced pre-established <italic>in vitro</italic> biofilms and killed bacteria within the biofilm, it was unable to prevent biofilm formation at sub-MIC concentrations. The time kill experiment revealed that viniferin killed bacteria and reduced 2.8 log<sub>10</sub> bacteria at 2 × MIC concentration after 24 h. Scanning electron microscope (SEM) analysis and live/dead biofilm staining of pre-established biofilms revealed that viniferin treatment disrupts membrane integrity of biofilm bacteria. Crystal violet absorption, total protein, and DNA and RNA release revealed that viniferin alters bacterial cell permeability, eventually killing bacteria.</p>