Antimicrobial and antioxidative activities of 1-adamantylthio derivatives of 3-substituted pyridines

Abstract

Diverse biological activities of sulfur containing pyridines were reported. To investigate for new lead compounds, thus, 1-adamantylthiopyridines bearing 3-substituents (OEt, OAc, NAc2, Br and OH) were prepared and evaluated for antimicrobial and antioxidative activities. The antimicrobial assay against 27 strains of microorganisms was performed using agar dilution method. The results show that all the tested 2-(1-adamantylthio)-3-ethoxypyridine (4a), 2-(1-adamantylthio)-3-acetoxypyridine (4b), N-acetyl-2-(1-adamantylthio)-3-acetamidopyridine (4c), 2-(1-adamantylthio)-3-bromopyridine (4d), 2-(1-adamantylthio)-5-hydroxypyridine (5) and 3-(1-adamantylthio)-5-bromopyridine (6) exhibit antigrowth activity on Streptococci at 30 µg/mL. Particularly, the thiopyridines 4c, 5 and 6 are the most active compounds, displaying complete inhibition against ß-hemolytic Streptococcus group A at 30 µg/mL. These pyridyl sulfides 4a-d, 5 and 6 represent a new group of antimicrobial agents. Antioxidative activity was analyzed using the DPPH assay. The sulfides 4a-d, 5 and 6 show only a weak antioxidative activity. In contrast the 2-(1-adamantylthio)-3-bromopyridine (4d) shows the highest radical scavenging activity.