Synthesis and antimicrobial evaluation of amino sugar-based naphthoquinones and isoquinoline-5,8-diones and their halogenated compounds

In this work two series of glycoconjugate and non-glycoconjugate amino compounds derived from
isoquinoline-5,8-dione and 1,4-naphthoquinone and their halogenated derivatives were synthesized and
evaluated for antimicrobial activity against Gram-positive and Gram-negative bacteria strains of clinical
importance. This study revealed that glycoconjugate compounds derived from halogeno-substituted
naphthoquinones were more active against Gram-negative strains. These molecules were also more active
than isoquinoline-5,8-dione analogs with minimum inhibitory concentration (MIC = 4-32 μg/mL) within Clinical
and Laboratory Standard Institute MIC values (CLSI 0.08-256 μg/mL). Interestingly the minimal bactericidal
concentration (MBC) values of the most active compounds were equal to MIC classifying them as
bactericidal agents against Gram-negative bacteria. Sixteen compounds among eighteen carbohydratebased
naphthoquinones tested showed no hemolytic effects on health human erythrocytes whereas more
susceptibility to hemolytic cleavage was observed when using non-glycoconjugate amino compounds.