Synthesis of Novel Benzothiazole-Profen Hybrid Amides as Potential NSAID Candidates

Abstract

Herein, we report the synthesis of a series of new compounds by combining 2-aminobenzothiazole with various profens. The compounds were characterized using techniques such as ¹H- and ¹³C-NMR, FT-IR spectrometry, and high-resolution mass spectrometry (HRMS), with detailed HRMS analysis conducted for each molecule. Their biological activities were tested in vitro, revealing significant anti-inflammatory and antioxidant effects, comparable to those of standard reference compounds. Lipophilicity was experimentally determined through partition coefficient (R_M) measurements. To understand their binding affinity, molecular docking studies were perfsormed to analyze interactions with human serum albumin (HSA). The stability of these predicted complexes was further evaluated through molecular dynamics simulations. The results highlight the compounds' promising biological activity and strong affinity for HSA. The new hybrid molecule between 2-ABT and ketoprofen 3b demonstrates significant promise based on the experimental data and is further supported by in silico calculations. Compound 3b exhibits the best hydrogen peroxide scavenging activity among the tested compounds, with an IC₅₀ of 60.24 μg/mL. Furthermore, 3b also displays superior anti-inflammatory activity, with an IC₅₀ of 54.64 μg/mL, making it more effective than the standard ibuprofen (76.05 μg/mL).

Keywords: amides; benzothiazole; hybrid molecules; in vitro biological activity; lipophilicity; molecular docking; molecular dynamics; profens.

Figure 1

Structural formulas of benzothiazole, 2-aminobenzothiazole, and 2-aminobenzimidazole.

Figure 2

New 2-ABZ-NSAID conjugates as potential drug candidates.

Scheme 1

Synthetic approach for the synthesis of benzothiazole–profen hybrids 3a–e.

Figure 3

Results of the HPSA of 2-ABT derivatives 3a–e. Values are presented as IC₅₀, µg/mL. Ascorbic acid (AA) and quercetin (Qrc) were used as standards. Different letters for the same method indicate a significant difference at the p < 0.05 level by Duncan’s test. Duncan’s test compares the average values of the groups and classifies them by significance levels. Group average values that do not differ significantly are united into homogeneous subgroups.

Figure 4

Results of the HRSA of 2-ABT derivatives 3a–e. Values are presented as IC₅₀, µg/mL. Ascorbic acid (AA) and quercetin (Qrc) were used as standards. Different letters for the same method indicate a significant difference at the p < 0.05 level by Duncan’s test. Duncan’s test compares the average values of the groups and classifies them by significance levels. Group average values that do not differ significantly are united into homogeneous subgroups.

Figure 5

Results of the IAD of 2-ABT derivatives 3a–e. Values are presented as IC₅₀, µg/mL. Ibuprofen (Ibu) was used as a standard. Different letters for the same method indicate a significant difference at the p < 0.05 level by Duncan’s test. Duncan’s test compares the average values of the groups and classifies them by significance levels. Group average values that do not differ significantly are united into homogeneous subgroups.

Scheme 2

General fragmentation pathway of the newly synthesized 2-ABT derivatives 3a–e.

Figure 6

The top-ranked conformation of compound 3b[R] (carbon atoms depicted in magenta) bound in Sudlow’s site I of albumin. Among the current series of compounds, 3b[R] showed the strongest binding to this site. Two ion–dipole interactions (depicted in red) are predicted to appear between the amide oxygen atom and Hys242 sidechain and between the ketone oxygen atom and Arg257.

Figure 7

The top-ranked conformation of compound 3e[S] (carbon atoms depicted in magenta) bound in Sudlow’s site II of albumin. Among the current series of compounds, 3e[S] showed the strongest binding to this site. A hydrogen bond (depicted in red) is predicted to appear between the amide oxygen atom as an acceptor and the Tyr411 sidechain as a donor.

Figure 8

The top-ranked conformation of compound 3b[R] (carbon atoms depicted in magenta) bound in site III of albumin. Among the current series of compounds, 3b[R] showed the strongest binding to this site. An ion–dipole interaction (depicted in red) is predicted to appear between the amide oxygen atom and Arg117 sidechain, and a hydrogen bond (depicted in red) is predicted to appear between the ketone oxygen atom as an acceptor and Tyr161 as a donor.

Figure 9

The top-ranked conformation of compound 3e[S] (carbon atoms depicted in magenta) bound in the cleft site of albumin. Among the current series of compounds, 3e[S] showed the strongest binding to this site. An ion–dipole interaction (depicted in red) is predicted to appear between the amide oxygen atom and Lys190 sidechain and a π–π stacking (depicted in red) is predicted to appear between the terminal phenyl of 3e[S] and Tyr452.