Abstract
An hexane extract from the roots of A. tinctoria was subjected to fractionation. Microbiologie examination of the resulting fractions revealed that the antimicrobial properties of the extract residue in its naphthaquinone pigments, which were shown to be alkannin esters. Preliminary studies indicate that alkannin itself [la, R = R' = H] is also active.
Although acylation of alkannin does not appear to affect its antimicrobial properties, alkylation of the phenolic hydroxyl groups leads to complete loss of activity, as does also polymerization.
Key Word Index
Alkanna tinctoria - Naphthaquinones - Antimicrobial Effects - Boraginaceae
