Selective Synthesis of Some New Carbohydrate Derivatives: Antimicrobial Screening Studies against Human and Phytopathogens

Methyl 4,6-O-benzylidene-a-D-glucopyranoside (1) was selectively converted to methyl 4,6-0-benzylidene-2-0-(2,6- dichlorobenzoyl)-a-D-glucopyranoside (2) by reaction with 2,6-dichlorobenzoyl chloride using direct method in good yield. Using a wide variety of acylating agents, a series of 3-O-acyl derivatives (2-10) of this 2-substitution product were also prepared. These synthesized derivatives were screened for in vitro antimicrobial activity against ten human pathogenic bacteria and three fungal phytopathogens. The study revealed that the acylated derivatives exhibit promising antibacterial and antifungal activities. The acylated derivatives were found to be more effective against the fungal strains than those of the bacterial pathogens. However, a good number of methyl 4,6-O-benzylidene-a-D-glucopyranoside derivatives exhibited better antimicrobial activity than the standard antibiotics.