Antibiotic resistance of bacteria lead to create different way in the pathogen bacteria handling such us inhibit their quorum sensing mechanism. The goal of this study is to search quorum sensing inhibitor of seven Indonesia medicinal plants. The experiment was conducted by extracting the plants using ethyl acetate subsequently tested on reporter carrying luxR homologous and luxCDABE genes. Reporter luminescence used as indicator of quorum sensing inhibition. The results show that ethyl acetate extracts of buah adas (Foeniculum vulgare), bunga lawang (Illicium verum), selasih (Ocimum basilicum), temu ireng (Curcuma aeruginosa), temu giring (Curcuma heyneana), dan temu lawak (Curcuma xanthorriza) mampu menginhibisi quorum sensing pada Pseudomonas aeruginosa. Further analysis was done by observing several metabolites which directly influenced by quorum sensing. The experiment was design by growth Pseudomonas aeruginosa at LB medium occurring fennel
seeds ethyl acetate extract in the various concentration. Number of biofilms, rhamnolipid and activity of LasA produced by Pseudomonas aeruginosa were then measured. The experiment shown LasA activity inhibition reaching 100% was obtained at growth media containing 1.52 mg / ml extract. There was a decrease at inhibition activity when the extract concentration was added above this value. Meanwhile, 19% inhibition of rhamnolipid production occurred at concentrations of ethyl acetate extract of 2.03 mg / ml in growth media. Different results obtained in the production of biofilm which is induced by fennel seeds ethyl acetate extract at the level 123%
