Construction, petro-collecting/dispersing capacities, antimicrobial activity, and molecular docking study of new cationic surfactant-sulfonamide conjugates

Abstract

Surfactants with their diverse activities have been recently involved in controlling the spread of new coronavirus (COVID-19) pandemic as they are capable of disrupting the membrane surrounding the virus. Using hybrids approach, we constructed a novel series of cationic surfactant-sulfonamide conjugates (3a-g) through quaternization of the as-prepared sulfonamide derivatives (2a-g) with n-hexadecyl iodide followed by structural characterization by spectroscopy (IR and NMR). Being collective properties required in petroleum-processing environment, the petro-collecting/dispersing capacities on the surface of waters with different degrees of mineralization, and the antimicrobial performance against microbes and sulfate-reducing bacteria (SRB) that mitigate microbiological corrosion were investigated for the synthesized conjugates. Among these conjugates, 3g (2.5% aq. solution) exhibited the strongest ability to disperse the thin petroleum film on the seawater surface, whereas K_D is 95.33% after 96 h. In diluted form, 3f collected the petroleum layer on distilled water surface (K_max = 32.01) for duration exceeds 4 days. Additionally, almost all compounds revealed high potency and comparable action with standard antimicrobials, especially 3b and 3f, which emphasize their role as potential biocides. Regarding biocidal activity against SRB, 3g causes a significant reduction in the bacterial count from 2.8 × 10⁶ cells/mL to Nil. Moreover, the conducted molecular docking study confirms the strong correlation between RNA polymerase binding with bioactivity against microbes over other studied proteins (threonine synthase and cyclooxygenase-2).

Keywords: Biocidal activity; Cationic surfactants; Molecular docking; Petro-collecting; Petro-dispersing; Sulfonamides.

Graphical abstract

Fig. 1

Chemical structures of some bioactive sulfonamides, BAC, and our conjugates.

Scheme 1

Synthetic route for the cationic surfactant-sulfonamide conjugates.

Fig. 2

Zoomed ¹H NMR spectrum (region: 2.85–4.15 ppm) of compound 3e.

Fig. 3

Petro-collecting capacities of the synthesized conjugates 3a-f.

Fig. 4

Petro-dispersing properties of the synthesized conjugates 3f and 3g toward Red sea crude slicks of different thicknesses.

Fig. 5

Representation for the surfactant action on the bacterial cell membrane.

Fig. 6

Representative hydrophobic interactions of E. coli RNA polymerase with A) compound 3b, B) compound 3a, and C) compound 3e analyzed by LigPlot + software.

Fig. 7

In-depth ligand-protein interaction profile for A) compound 3b, B) compound 3a, and C) compound 3e against E. coli RNA polymerase. D) Binding energy (BE, Kcal/mol), inhibition concentration (IC, mM) and ligand efficiency (LE) for compounds 3a and 3b.