(E)-2,6-Di-tert-butyl-4-(4-(diethylamino)styryl)pyrylium (trifluoromethanesulfonate)

(E)-2,6-Di-tert-butyl-4-(4-(diethylamino)styryl)pyrylium (trifluoromethanesulfonate) (Compound 4a) is a Gram-negative outer membrane permeabilizer with synergistic antibacterial activity through the blockage on LptA/LptC interaction via targeting Met47 in LptA. (E)-2,6-Di-tert-butyl-4-(4-(diethylamino)styryl)pyrylium (trifluoromethanesulfonate) potentiates pol B against both wild-typed and MDR A. baumannii and E. coli strains. (E)-2,6-Di-tert-butyl-4-(4-(diethylamino)styryl)pyrylium (trifluoromethanesulfonate) can be used as antibiotic adjuvants against MDR Gram-negative bacteria.