Alectosarmentin, a new antimicrobial dibenzofuranoid lactol from the lichen, Alectoria sarmentosa.

From the alcoholic extract of the lichen Alectoria sarmentosa, four compounds showing antimicrobial activity were isolated. Of these, (-)-usnic acid and physodic acid are well known lichen products, 8'-O-ethyl-beta-alectoronic acid [2] is believed to be an artifact formed during isolation and fractionation, and alectosarmentin [1] is a new natural product whose structure was shown, by spectroscopy and chemical transformations, to be that of a dibenzofuranoid lactol. The antimicrobial activity of these substances accounts for the activity of the lichen.