A facile and inexpensive preparation of 1,3-dicaffeoylquinic acid (cynarin) from the leaves Cynara cardunculus L. (Asteraceae) without the use any chromatographic steps is described. The procedure was based on separation of the fraction rich in 1,5-dicaffeoylquinic acid, isomerisation of 1,5-dicaffeoylquinic acid to cynarin and, owing to its higher polarity, the simple isolation of cynarin from the reaction mixture. Cynarin inhibited HIV-1 replication in MT-2 cell culture at nontoxic concentrations similar to other previously tested dicaffeoylquinic acids, which have been recently established as a potent and highly selective class of HIV-1 integrase inhibitors.