Novel molecular matrices have been derived from coumarin-4-acetic acids and β-phenylethylamines using the Bischler-Napieralski protocol which has led to the synthesis of analogues of tetrahydropapaverine in which the dimethoxybenzene moiety has been replaced by substituted coumarins. One carbon homologation has led to cyclization at the C3 position of coumarin generating the protoberberine skeleton. Structures have been confirmed by diffraction studies. The results showed that compounds 6e, 6f, 7e and 7f were found to be very effective against DNA samples of Gram positive bacterium Staphylococcus aureus and fungus Aspergillus niger. A series of novel coumarin analogues of 1,2,3,4-tetrahydroisoquinoline and protoberberine alkaloids have been synthesized from coumarin-4-acetic acids. The DNA cleavage study has been performed on Gram positive, Gram negative bacteria and fungi strains. © 2010 Elsevier Masson SAS. All rights reserved.