Monoglucosyl and monogalactosyl diglycerides (MGDGs) with medium-long length acyl chains, identified as active components in Euphorbiaceae, were synthesized. They were examined for antimicrobial activity against Gram-positive, Gram-negative bacteria and fungi. MGDGs with two octanoyl groups at both 1- and 2-positions showed the most potent activity. The stereoselectivity of pancreatic lipase was investigated in vitro where the preference for the 1 position in MGDGs is strictly related to the length of the acyl chains.