The cultures were grown with shaking at 37 C for 17 h. of mucochloric acid 7 and mucobromic acid 8 as precursors that could provide access to functionalized lactams [14]. These compounds are inexpensive, commercially available, highly functionalized and possess multiple sites for reactivity, particularly the two halogen atoms situated across one double bond adjacent to a pseudo acid functionality. Mucohalic acids have been used for the synthesis of furanones with antibacterial and antibiofilm activities [15,16], anticancer activity [17] and anti-inflammatory activity [18]. Mucohalic acids have also been used for the synthesis of furanone-based natural products such as rubrolide [19,20], as well as their lactam analogues, showing herbicidal (Rac)-Nedisertib [20] and antibiofilm activities [15]. They have also been used as precursors of the antiseizure agent levetiracetam [21]. In this work, a library of 34 lactam compounds was prepared using the reductive amination of mucochloric and mucobromic acids with selected aliphatic and aromatic amines to furnish position compared to the and analogues. The yields for these phenols follow the relative nucleophilicity of the nitrogen. In the derivative, the internal hydrogen bond resulted in the lower nucleophilicity of 12, which required longer reaction times. The introduction of analogue 15, suggesting the impact of the position of the electron-withdrawing group on the nucleophilicity of the aniline group. However, in the reaction of mucobromic acid with carboxy substituted amines, the analogue (27) of 26% and 7%, respectively. Furthermore, the formation of the analogue (27) required more forcing reaction conditions by heating at 30 C instead of room temperature. Compounds 19 and 20, and their mucobromic analogue 29, containing aminophenyl groups, were prepared from protected and position of the MH602 (PAMH602) strain that expresses the gene and the gene and a promoter fused to the green fluorescent protein (GFP) reporter gene were used. Hence, the level of GFP fluorescence is a measure of AHL-mediated QS in this strain. The PAMH602 culture was incubated with varying concentrations (62.5 M, 125 M and 250 M) of the synthesized compounds at 37 C for 15 h, and the fluorescence of GFP at = 535 nm was determined. The optical density (OD) of the cultures at 600 nm was also measured to assess the effect of the compounds on bacterial growth. In these experiments, the halogenated furanone (5) (Fu-30) and another known QS antagonist (TP-5) were used as positive controls. The effects of the compounds on GFP fluorescence and OD are presented in Table 1. Table 1 Mctp1 Percentage inhibition of (Rac)-Nedisertib GFP fluorescence and the reduction of OD by the synthesized lactams against MH602. MH602> 0.05) as the phenol group moved to the position as in derivative 13. The < 0.001) when compared to its (12) and (13) counterparts, suggesting the importance of the position of the phenolic hydroxyl group on activity. Interestingly, no significant difference (> 0.05) in activity was observed when comparing Compound 12 with other potent growth by 84% at 250 M. Therefore, this study showed that the tested compounds inhibit QS with minimal effect on the growth of [24], the ability of our compounds to inhibit pyocyanin production was investigated. Wild-type (PAO1) were grown in the presence of Compounds 12, 13, 19, 23 and 24, and the amount of pyocyanin in the culture supernatants was quantified based on its absorbance at 695 nm following a reported protocol [25]. The ability of the compounds to reduce pyocyanin levels was determined with respect to the levels (Rac)-Nedisertib of pyocyanin in the DMSO-treated positive control (Figure 2). Growth inhibition at OD600 was monitored, and the compounds showed moderate reduction in bacterial growth (22C30%). Open in a separate window Figure 2 Pyocyanin inhibition in PAO1 by the synthesized compounds. Compounds were added to the bacteria at 250 M or 31.25 M and were incubated for 17.
