Fig. 7: Antibacterial sensitivity study.

A The minimum inhibitory concentration (MIC) against Gram-positive bacteria (S. aureus MTCC1430) was determined. Each set represents the MIC assay in the presence of five different novel test compounds and Chloramphenicol antibiotic (positive control). The bacterial growth data are presented as mean values ± SEM of optical density at 600 nm. Error bars signify the standard error of the mean (SEM) for experiments performed in three biological replicates. Red graph with (●), orange graph with (■), pink graph with (▲), blue graph with (▼), brown graph with (♦) and green graph with (○) represent assay in varying concentration of 3a’, 3a, 3h, 3h’, 3c’ (structures are exhibited in lower panel) and Chloramphenicol, respectively. It was observed that 3h, 3h’, and 3c’ were found ineffective against S. aureus. Whereas 3a showed mild bacterial growth inhibition compared to 3a’, which showed the highest growth inhibition, even better than that of Chloramphenicol—the well-known marketed antibiotic. The determined MIC value of Chloramphenicol was 19.17 ± 1.4 µg/mL, whereas the determined MIC of 3a’ compound was 10 µg/mL. B Antibacterial sensitivity test of 3h, 3a’, 3c’ against gram-positive bacteria (S. aureus MTCC 1430). ‘Blank’ tube contained only Mueller Hinton broth (MHB), the other three experimental tubes marked as 3h, 3a’ and 3c’ contained 50 µg/mL of test compounds, i.e., 3h, 3a’ and 3c’, respectively, in MHB and bacteria of 0.5 McFarland standard. None of the tested compounds was able to inhibit bacterial growth, except 3a’. +ve (positive) control tube contained bacteria in MHB. ─ve (negative) control contained bacteria in 5% of DMSO and MHB. C Antibacterial sensitivity test of 3h, 3c’, 3a’ against gram-negative bacteria (E. coli DH5-Alpha). Blank, +ve control, ─ve control, and the concentration of tested compounds were the same as in (B). None of these compounds exhibited bacterial growth inhibition in the case of gram-negative bacteria.