Synthesis of N-(prop-2-yn-1-yl)-1H-indole-2-carboxamide 3To a mixture of 1H-indole-2-carboxylic acid 1 (10 mmol) and propargylamine 2 (10 mmol) in DMF (50 mL), TBTU (13 mmol) and Et3N (13 mmol) were added and the obtained mixture was stirred for 24 h at room temperature (RT). After completion of the reaction, water was added to this reaction mixture and the observed participate was filtered to give pure N-(prop-2-yn-1-yl)-1H-indole-2-carboxamide 3.General procedure for the synthesis of N-phenylacetamide-1,2,3-triazole-indole-2-carboxamide derivatives 5a–nIn the next step, N-(prop-2-yn-1-yl)-1H-indole-2-carboxamide 3 (1 mmol), sodium ascorbate (15 mol %, 0.13 g), and CuSO4 (7 mol%) were added to a stirred mixture of the freshly prepared azide derivatives 4a–n in H2O and t-BuOH (10 ml, 1:1) at RT. After 20–24 h, this reaction mixture was diluted with a mixture of ice and water, precipitated products 5a–n were filtered off, washed with water, and purified by recrystallization in ethanol.
N-((1-(2-oxo-2-(phenylamino)ethyl)-1H-1,2,3-triazol-4-yl)methyl)-1H-indole-2-carboxamide (5a)Yield: 75%. Light brown solid. M.p. 216–218 °C. 1H NMR (301 MHz, DMSO-d6) δ 11.65 (s, 1H), 10.48 (s, 1H), 9.11 (s, 1H), 8.07 (s, 1H), 7.80–6.86 (m, 10H), 5.34 (s, 2H), 4.78–4.44 (m, 2H). 13C NMR (76 MHz, DMSO-d6) δ 164.70, 161.55, 138.89, 136.93, 131.94, 129.38, 127.55, 125.17, 124.22, 123.81, 122.00, 120.19, 120.16, 119.66, 112.78, 103.23, 52.65, 34.87. Anal. Calcd for C20H18N6O2: C, 64.16; H, 4.85; N, 22.45; Found: C 63.91; H 5.02; N 22.29.
N-((1-(2-oxo-2-(m-tolylamino)ethyl)-1H-1,2,3-triazol-4-yl)methyl)-1H-indole-2-carboxamide (5b)Yield: 81%. Light brown solid. M.p. 224–226 °C. 1H NMR (301 MHz, DMSO-d6) δ 11.68 (s, 1H), 10.43 (s, 1H), 9.15 (d, J = 5.6 Hz, 1H), 8.09 (s, 1H), 7.65 (d, J = 7.8 Hz, 1H), 7.57–7.35 (m, 3H), 7.22 (d, J = 6.6 Hz, 3H), 7.06 (t, J = 7.4 Hz, 1H), 6.92 (d, J = 7.4 Hz, 1H), 5.36 (s, 2H), 4.83–4.44 (m, 2H), 2.29 (s, 3H). 13C NMR (76 MHz, DMSO-d6) δ 164.65, 161.61, 138.83, 138.62, 136.97, 131.97, 129.21, 127.59, 125.25, 124.96, 123.84, 122.02, 120.24, 120.21, 116.89, 112.81, 103.29, 52.71, 34.90, 21.63. Anal. Calcd for C21H20N6O2: C, 64.94; H, 5.19; N, 21.64; Found: C 64.80; H 5.41; N 21.76.
N-((1-(2-oxo-2-(p-tolylamino)ethyl)-1H-1,2,3-triazol-4-yl)methyl)-1H-indole-2-carboxamide (5c)Yield: 81%. Light brown solid. M.p. 231–233 °C. 1H NMR (301 MHz, DMSO-d6) δ 11.64 (s, 1H), 10.39 (s, 1H), 9.11 (d, J = 5.7 Hz, 1H), 8.04 (s, 1H), 7.75–7.32 (m, 4H), 7.35–6.89 (m, 5H), 5.31 (s, 2H), 4.60 (d, J = 5.4 Hz, 2H), 2.26 (s, 3H). 13C NMR (76 MHz, DMSO-d6) δ 164.44, 161.53, 136.92, 136.38, 133.19, 131.93, 129.75, 127.54, 125.13, 123.80, 122.00, 120.19, 119.75, 119.65, 112.78, 103.21, 52.61, 34.85, 20.92. Anal. Calcd for C21H20N6O2: C, 64.94; H, 5.19; N, 21.64; Found: C 64.77; H 4.98; N 21.45.
N-((1-(2-((2,3-dimethylphenyl)amino)-2-oxoethyl)-1H-1,2,3-triazol-4-yl)methyl)-1H-indole-2-carboxamide (5d)Yield: 83%. Light brown solid. M.p. 205–207 °C. 1H NMR (301 MHz, DMSO-d6) δ 11.66 (s, 1H), 9.87 (s, 1H), 9.12 (s, 1H), 8.06 (s, 1H), 7.78–6.77 (m, 8H), 5.39 (s, 2H), 4.62 (s, 2H), 2.26 (s, 3H), 2.12 (s, 3H). 13C NMR (76 MHz, DMSO-d6) δ 164.95, 161.57, 137.61, 136.95, 135.73, 131.95, 131.50, 127.74, 127.56, 125.77, 125.15, 123.81, 123.72, 122.00, 120.23, 120.20, 112.79, 103.25, 52.36, 34.89, 20.60, 14.48. Anal. Calcd for C22H22N6O2: C, 65.66; H, 5.51; N, 20.88; Found: C 65.38; H 5.37; N 20.72.
N-((1-(2-((2,6-dimethylphenyl)amino)-2-oxoethyl)-1H-1,2,3-triazol-4-yl)methyl)-1H-indole-2-carboxamide (5e)Yield: 85%. Light brown solid. M.p. 208–210 °C. 1H NMR (301 MHz, DMSO-d6) δ 11.64 (s, 1H), 9.77 (s, 1H), 9.11 (d, J = 5.8 Hz, 1H), 8.05 (s, 1H), 7.63 (d, J = 7.7 Hz, 1H), 7.46 (d, J = 8.0 Hz, 1H), 7.31–6.92 (m, 6H), 5.38 (s, 2H), 4.70–4.45 (m, 2H), 2.17 (s, 6H). 13C NMR (76 MHz, DMSO-d6) δ 164.55, 161.55, 136.93, 135.55, 134.68, 131.94, 128.22, 127.54, 127.22, 124.98, 123.81, 122.00, 120.21, 120.20, 112.78, 103.22, 52.04, 34.87, 18.50. Anal. Calcd for C22H22N6O2: C, 65.66; H, 5.51; N, 20.88; Found: C 65.41; H 5.74; N 20.98.
N-((1-(2-((4-ethylphenyl)amino)-2-oxoethyl)-1H-1,2,3-triazol-4-yl)methyl)-1H-indole-2-carboxamide (5f)Yield: 82%. Light brown solid. M.p. 203–205 °C. 1H NMR (301 MHz, DMSO-d6) δ 11.65 (s, 1H), 10.41 (s, 1H), 9.12 (s, 1H), 8.06 (s, 1H), 7.71–7.38 (m, 4H), 7.31–7.00 (m, 5H), 5.32 (s, 2H), 4.62 (s, 2H), 2.71–2.37 (m, 2H), 1.16 (t, J = 7.2 Hz, 3H). 13C NMR (76 MHz, DMSO-d6) δ 164.44, 161.55, 139.64, 136.93, 136.57, 131.94, 128.56, 127.55, 125.07, 123.81, 122.00, 120.20, 119.84, 119.74, 112.78, 103.23, 52.63, 34.87, 28.06, 16.11. Anal. Calcd for C22H22N6O2: C, 65.66; H, 5.51; N, 20.88; Found: C 65.43; H 5.32; N 21.01.
N-((1-(2-((4-methoxyphenyl)amino)-2-oxoethyl)-1H-1,2,3-triazol-4-yl)methyl)-1H-indole-2-carboxamide (5g)Yield: 81%. Light brown solid. M.p. 209–211 °C. 1H NMR (301 MHz, DMSO-d6) δ 11.66 (s, 1H), 10.37 (s, 1H), 9.12 (s, 1H), 8.07 (s, 1H), 7.80–7.33 (m, 4H), 7.32–6.82 (m, 5H), 5.31 (s, 2H), 4.62 (s, 2H), 3.73 (s, 3H). 13C NMR (76 MHz, DMSO-d6) δ 164.17, 161.56, 155.98, 136.94, 131.98, 131.94, 127.55, 125.20, 123.82, 122.01, 121.32, 121.23, 120.21, 114.47, 112.78, 103.25, 55.61, 52.60, 34.87. Anal. Calcd for C21H20N6O3: C, 62.37; H, 4.98; N, 20.78; Found: C 62.14; H 5.21; N 20.63.
N-((1-(2-((3-chlorophenyl)amino)-2-oxoethyl)-1H-1,2,3-triazol-4-yl)methyl)-1H-indole-2-carboxamide (5h)Yield: 70%. Light brown solid. M.p. 211–213 °C. 1H NMR (301 MHz, DMSO-d6) δ 11.64 (s, 1H), 10.07 (s, 1H), 9.11 (s, 1H), 8.06 (s, 1H), 7.77–7.02 (m, 9H), 5.44 (s, 2H), 4.60 (s, 2H). 13C NMR (76 MHz, DMSO-d6) δ 165.41, 161.53, 136.92, 134.62, 131.92, 130.09, 128.03, 127.53, 127.16, 126.69, 126.30, 124.95, 123.80, 121.99, 120.21, 120.19, 112.77, 103.20, 52.36, 34.84. Anal. Calcd for C20H17ClN6O2: C, 58.76; H, 4.19; N, 20.56; Found: C 58.54; H 3.98; N 20.69.
N-((1-(2-((4-chlorophenyl)amino)-2-oxoethyl)-1H-1,2,3-triazol-4-yl)methyl)-1H-indole-2-carboxamide (5i)Yield: 74%. Light brown solid. M.p. 225–227 °C. 1H NMR (301 MHz, DMSO-d6) δ 11.64 (s, 1H), 10.63 (s, 1H), 9.12 (s, 1H), 8.06 (s, 1H), 7.76–6.84 (m, 9H), 5.34 (s, 2H), 4.61 (s, 2H).13C NMR (76 MHz, DMSO-d6) δ 164.91, 161.55, 137.83, 136.92, 131.92, 129.30, 127.82, 127.54, 125.23, 123.81, 121.99, 121.33, 121.23, 120.20, 112.78, 103.23, 52.63, 34.86.Anal. Calcd for C20H17ClN6O2: C, 58.76; H, 4.19; N, 20.56; Found: C 58.59; H 4.37; N 20.33.
N-((1-(2-((2,4-dichlorophenyl)amino)-2-oxoethyl)-1H-1,2,3-triazol-4-yl)methyl)-1H-indole-2-carboxamide (5j)Yield: 74%, Light brown solid. M.p. 233–235 °C. 1H NMR (301 MHz, DMSO-d6) δ 11.66 (s, 1H), 10.17 (s, 1H), 9.14 (s, 1H), 8.38–6.71 (m, 10H), 5.48 (s, 2H), 4.64 (s, 2H).13C NMR (76 MHz, DMSO-d6) δ 165.59, 161.60, 136.95, 133.84, 131.92, 130.22, 129.52, 128.14, 127.56, 127.48, 127.17, 125.12, 123.84, 122.01, 120.26, 120.22, 112.80, 103.31, 52.45, 34.91.Anal. Calcd for C20H16Cl2N6O2: C, 54.19; H, 3.64; N, 18.96; Found: C 53.96; H 3.82; N 19.18.
N-((1-(2-((4-bromophenyl)amino)-2-oxoethyl)-1H-1,2,3-triazol-4-yl)methyl)-1H-indole-2-carboxamide (5k)Yield: 81%. Light brown solid. M.p. 236–238 °C. 1H NMR (301 MHz, DMSO-d6) δ 11.63 (s, 1H), 10.63 (s, 1H), 9.11 (s, 1H), 8.11–7.04 (m, 10H), 5.34 (s, 2H), 4.60 (s, 2H). 13C NMR (76 MHz, DMSO-d6) δ 164.88, 161.55, 138.23, 136.92, 132.21, 131.90, 127.53, 125.29, 123.82, 121.99, 121.71, 121.62, 120.21, 115.87, 112.78, 103.25, 52.76, 34.91. Anal. Calcd for C20H17BrN6O2: C, 52.99; H, 3.78; N, 18.54; Found: C 52.79; H 4.01; N 18.31.
N-((1-(2-((3-nitrophenyl)amino)-2-oxoethyl)-1H-1,2,3-triazol-4-yl)methyl)-1H-indole-2-carboxamide (5l)Yield: 79%. Brown solid. M.p. 254–256 °C. 1H NMR (301 MHz, DMSO-d6) δ 11.65 (s, 1H), 10.99 (s, 1H), 9.12 (t, J = 5.6 Hz, 1H), 8.61 (s, 1H), 8.09 (s, 1H), 8.01–7.84 (m, 2H), 7.65 (t, J = 7.9 Hz, 2H), 7.47 (d, J = 8.2 Hz, 1H), 7.13 (dt, J = 44.7, 6.9 Hz, 3H), 5.41 (s, 2H), 4.63 (d, J = 5.6 Hz, 2H). 13C NMR (76 MHz, DMSO-d6) δ 165.63, 161.58, 148.44, 139.97, 136.94, 131.93, 130.87, 127.56, 125.66, 125.15, 123.82, 122.00, 121.83, 120.20, 118.77, 113.85, 112.78, 103.26, 52.65, 34.88. Anal. Calcd for C20H17N7O4: C, 57.28; H, 4.09; N, 23.38; Found: C 56.99; H 4.31; N 23.59.
N-((1-(2-((4-nitrophenyl)amino)-2-oxoethyl)-1H-1,2,3-triazol-4-yl)methyl)-1H-indole-2-carboxamide (5m)Yield: 69%. Brown solid. M.p. 259–261 °C. 1H NMR (301 MHz, DMSO-d6) δ 11.64 (s, 1H), 11.09 (s, 1H), 9.12 (s, 1H), 8.43–7.71 (m, 5H), 7.62 (d, J = 7.7 Hz, 1H), 7.45 (d, J = 8.0 Hz, 1H), 7.12 (d, J = 44.2 Hz, 3H), 5.43 (s, 2H), 4.61 (s, 2H). 13C NMR (76 MHz, DMSO-d6) δ 165.87, 161.55, 144.98, 143.03, 136.92, 131.91, 127.53, 125.58, 125.21, 123.82, 121.99, 120.20, 119.52, 119.48, 112.78, 103.23, 52.75, 34.86. Anal. Calcd for C20H17N7O4: C, 57.28; H, 4.09; N, 23.38; Found: C 57.02; H 4.28; N 23.17.
N-((1-(2-((2-methyl-4-nitrophenyl)amino)-2-oxoethyl)-1H-1,2,3-triazol-4-yl)methyl)-1H-indole-2-carboxamide (5n)Yield: 73%. Brown solid. M.p. 229–231 °C. 1H NMR (301 MHz, DMSO-d6) δ 11.63 (s, 1H), 10.04 (s, 1H), 9.11 (s, 1H), 8.35–7.79 (m, 5H), 7.62 (d, J = 7.6 Hz, 1H), 7.45 (d, J = 7.9 Hz, 1H), 7.27–6.93 (m, 3H), 5.49 (s, 2H), 4.61 (s, 2H), 2.41 (s, 3H). 13C NMR (76 MHz, DMSO-d6) δ 165.77, 161.54, 143.91, 142.59, 136.92, 131.92, 131.73, 127.53, 126.00, 124.82, 123.81, 123.67, 122.32, 121.99, 120.21, 120.19, 112.77, 103.22, 52.61, 34.88, 18.30. Anal. Calcd for C21H19N7O4: C, 58.19; H, 4.42; N, 22.62; Found: C 58.01; H 4.66; N 22.35.In vitro α-glucosidase and α-amylase inhibition assaysIn vitro assays (inhibition effects and kinetics) of the new compounds 5a–n performed according to pervious reported work15 (Supplementary Information S1).Docking studyMolecular modeling of the selected compounds 5c, 5f, 5j, and 5k, and molecular dynamics of the most potent compound 5k done on modeled α-glucosidase based on our pervious reported works15,20. Coordinates of active site of the modeled α-glucosidase was placed as follows:Center of the grid box: x = 12.5825, y = − 7.8955, and z = 12.519 ÅDimensions of the active site box: 40 × 40 × 40 Å.Free binding energy calculationsThe evaluation of the binding free energy of the protein–ligand complex was conducted utilizing the g_mmpbsa program21,22,23. Developed specifically for this purpose, g_mmpbsa facilitates the computation of the various constituents contributing to the binding free energy employing the molecular mechanics/Poisson-Boltzmann surface area (MM/PBSA) methodology. This computational tool enables the determination of the binding energy components pertinent to the protein–ligand complex which can be described as:$$\begin{gathered} {\text{Free binding energy }} = {\text{ molecular mechanics interaction energy }}\left( {{\text{MMIE}}} \right) \, + {\text{solvation energy }}\left( {{\text{SE}}} \right) \hfill \\ {\text{MMIE }} = {\text{ van der Waals energy }} + {\text{Electrostatic energy}} \hfill \\ {\text{SE }} = {\text{ polar solvation energy }}\left( {{\text{PSE}}} \right) \, + {\text{nonpolar solvation energy }}\left( {\text{SASA energy}} \right) \hfill \\ {\text{PSE }} = {\text{ PSE}}_{{{\text{complex}}}} – \, \left( {{\text{PSE}}_{{{\text{protein}}}} + {\text{PSE}}_{{{\text{ligand}}}} } \right) \hfill \\ {\text{SASA}}_{{{\text{energy}}}} = {\text{ SASA}}_{{{\text{complex}}}} {-} \, \left( {{\text{SASA}}_{{{\text{protein}}}} + {\text{SASA}}_{{{\text{ligand}}}} } \right) \hfill \\ \end{gathered}$$
Design, synthesis, in vitro, and in silico anti-α-glucosidase assays of N-phenylacetamide-1,2,3-triazole-indole-2-carboxamide derivatives as new anti-diabetic agents
