Tropical Journal of Pharmaceutical Research

Original Research Article | OPEN ACCESS

Synthesis, characterization, antibacterial, a-glucosidase inhibition and hemolytic studies on some new n-(2,3-dimethylphenyl)benzenesulfonamide derivatives

Muhammad A Abbasi¹ , Mudassar Islam¹, Aziz-ur-Rehman ¹, Shahid Rasool¹, Kaniz Rubab¹, Ghulam Hussain¹, Irshad Ahmad², Muhammad Ashraf³, Muhammad Shahid⁴, Syed Adnan Ali Shah^5,6

¹Department of Chemistry, Government College University, Lahore-54000; ²Department of Pharmacy; ³Department of, Chemistry, The Islamia University of Bahawalpur ,Bahawalpur-63100; ⁴Department of Chemistry and Biochemistry, University of Agriculture, Faisalabad-38040, Pakistan; ⁵Faculty of Pharmacy, Universiti Teknologi MARA, Puncak Alam-42300; ⁶Atta-ur-Rahman Institute for Natural Products Discovery (AuRIns), Level 9, FF3, Universiti Teknologi MARA, Puncak Alam Campus, Bandar Puncak Alam, Selangor Darul Ehsan, Malaysia.

For correspondence:- Muhammad Abbasi Email: abbasi@gcu.edu.pk Tel:+9242111000010

Received: 10 March 2015 Accepted: 5 January 2016 Published: 31 March 2016

Citation: Abbasi MA, Islam M, A, Rasool S, Rubab K, Hussain G, et al. Synthesis, characterization, antibacterial, a-glucosidase inhibition and hemolytic studies on some new n-(2,3-dimethylphenyl)benzenesulfonamide derivatives. Trop J Pharm Res 2016; 15(3):591-598 doi: 10.4314/tjpr.v15i3.22

© 2016 The authors.
This is an Open Access article that uses a funding model which does not charge readers or their institutions for access and distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0) and the Budapest Open Access Initiative (http://www.budapestopenaccessinitiative.org/read), which permit unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited..

Abstract

Purpose: To synthesize a series of new N-(2,3-dimethylphenyl)benzenesulfonamide derivatives with pharmacological analysis.

Methods: N-(2,3-Dimethylphenyl)benzenesulfonamide (3) was synthesized by the reaction between 2,3-dimethylaniline (1) and benzenesulfonyl chloride (2) in aqueous basic medium. Compound 3 was further treated with various alkyl/aralakyl halides (4a-m) to yield new compounds, 5a-m, in a weak basic aprotic polar organic medium. The proposed structures of synthesized compounds were confirmed using proton-nuclear magnetic resonance (1H-NMR), infra-red spectroscopy (IR) and electron impact mass spectrometry (EIMS). The synthesized compounds were screened for in vitro antibacterial, anti-enzymatic and hemolytic activities using standard procedures.

Results: All the synthesized compounds showed moderate to high activity against Gram-positive and Gram-negative bacterial strains. The molecules 5g and 5j exhibited good inhibition of α-glucosidase enzyme with half-maximal inhibitory concentration (IC₅₀) of 59.53 ± 0.01 and 55.31 ± 0.01 μmoles/L, respectively, relative to acarbose with IC₅₀ of 38.25 ± 0.12 μmoles/L. All the compounds exhibited cytotoxicity levels ranging from 27.20 ± 0.24 to 5.20 ± 0.41 %, relative to Triton X-100.

Conclusion: Compound 5f is the most potent antibacterial while 5j is the best α-glucosidase inhibitor; 5e showed the least cytotoxicity.

Keywords: 2,3-Dimethylaniline, Antibacterial activity, Anti-enzymatic activity, ^5;-Glucosidase inhibitor, Hemolytic activity, Sulfonamides

Introduction

Sulfonamides exhibit numerous pharmacological activities [1-3] and sulfonamide antibiotics are among the most common instigators of allergic or hypersensitivity reactions [4-6]. α-Glucosidase (α-D-glucosideglucohydrolase, EC 3.2.1.20)hydrolyzes the 1,4-glycosidic linkage from the non-reducing end of the α-glucosides [7-9].Its inhibitors retard the liberation of D-glucose resulting in delay glucose absorption [10]. The hemolysis takes place due to the stroke of the microbial products and resident parasites on the red blood corpuscles membranes [11,12]. Our group has synthesized many antibacterial and anti-enzymatic potent molecules [13-16] and a series of new compounds was synthesized in the present study to explore their pharmacological behavior.

Methods

General

The chemicals solvents were of commercial grade and were used without purification. Reaction progress and product purity was monitored by pre-coated TLC silica gel G-25-UV254 plates with different solvent systems using ethyl acetate and n-hexane. Melting points were noted on Gallenkamp apparatus by open capillary tube and were uncorrected. FTIR spectra were recorded on MIDAC M 2000 spectrometer. ¹H-NMR spectra were recorded in CDCl₃ on Bruker (400 MHz). Mass spectra (EI-MS) were measured on Finnigan MAT-312 instruments.

Procedure for the synthesis of N-(2,3-dimethylphenyl)benzenesulfonamide (3)

An equimolar mixture of 2,3-dimethylaniline (1, 0.02 mol) was dispersed in 25 mL waterfollowed by the addition ofbenzenesulfonyl chloride (2, 0.02 mol). The pH of the suspension was maintained at 9-10 during the whole reaction by adding Na₂CO₃ at RT. The reaction solution was stirred for 3 h. After complete reaction, the concentrated HCl (2-3 mL) was added slowly to adjust the pH to 2. Product formation was confirmed by TLC. The reaction mixture was kept still for 3-5 min. The off-white precipitates were collected by filtration, washed with distilled water and dried to acquire the compound 3.

General procedure for the synthesis of N-alkyl/aralakyl substituted sulfonamides (5a-m)

The calculated amount of 3 (0.7 mmol; 0.2 g) was taken in a round bottom flask (50 mL), then N,N-dimethyl formamide (DMF) was added to dissolve it followed by the addition of lithium hydride LiH (0.004 g). The mixture was stirred for 45 min at RT and then alkyl/aralakyl halides (4a-m; 0.7 mmol) were added to the mixture. The solution was further stirred for 3-4 h. The progress of reaction was monitored by TLC. The product was precipitated by adding cold water, filtered, washed with distilled water and dried.

Evaluation of antibacterial activity

The antibacterial activity was performed in sterile 96-wells microplates under aseptic environments by the methods of Kaspady et al [17] and Yang et al [18].

α-Glucosidase assay

The α-glucosidase inhibition activity was performed according to the method of Chapdilaine et al [10].

Determination of hemolytic activity

Hemolytic activity was studied by the reported method of Powell et al [11,19]. 3.0 mL fresh heparin added human blood obtained from volunteers after guidance from the Department of Clinical Medicine and Surgery, University of Agriculture, Faisalabad, Pakistan. The study protocol was approved by the institutional ethical committee (approval no. DGS/8786-89, dated 09-03-2015), University of Agriculture, Faisalabad, Pakistan and was conducted in accordance with 1964 Declaration of Helsinki and its subsequent amendments [20].

Data analysis

All the measurements were performed in triplicate and statistical analysis was carried out by Microsoft Excel 2010. The results are presented as mean ± SEM with CL 80 % (for antibacterial), 85 % (for α-glucosidase) and 95 % (for hemolytic analysis). MIC (minimum inhibitory concentration and IC₅₀ (50 % inhibitory concentration) were calculated using EZ-Fitz software (Perrella Scientific Inc. Amherst, USA).

Results

The new N-substituted derivatives of N-(2,3-dimethylphenyl)benzenesulfonamide were synthesized according to the protocol sketched in Scheme-1.

The antibacterial activities are given in Table-1 while inhibition against α-glucosidase enzyme and hemolytic activity are tabulated in .

Spectral characteristics of synthesized compounds (3, 5a-m)

N-(2,3-Dimethylphenyl)benzenesulfonamide (3)

Yield: 98 %; off-white solid; mp. 118-119 °C; Molecular formula: C₁₄H₁₅NO₂S; Molecular weight: 261; Analysis. Calcd: C, 64.32; H, 5.74; N, 5.36; S, 12.25. Found: C, 64.03; H, 6.40; N, 5.52; S, 11.73;IR (cm^-1) υ_max:3208(N-H), 3042 (Ar C-H), 2924(Alkane C-H), 1583(Ar C=C), 1324 (S=O); ¹H-NMR (400 MHz, CDCl₃, δ in ppm): 7.69 (2H, d, J = 7.6Hz, H-2', H-6'), 7.53 (1H, t, J = 7.6 Hz, H-4'), 7.41 (2H, t, J = 7.6 Hz, H-3', H-5'), 7.13 (1H, d, J = 7.6Hz, H-6), 6.96 (1H, t, J = 7.6Hz, H-5), 6.46 (1H, d, J = 8.4Hz, H-4), 2.18 (3H, s, CH₃-2), 1.91 (3H, s, CH₃-3); EI-MS (m/z): 261 (M⁺, 28.2%), 141, 120 (BP, 100%), 105, 77, 51.

N-(2,3-Dimethylphenyl)-N-ethylbenzenesulfo-namide (5a)

Yield: 99 %; light mustard solid; mp. 85.8 °C; Molecular formula: C₁₆H₁₉NO₂S; Molecular weight: 289; Analysis. Calcd: C, 66.43; H, 6.56; N, 4.84; S, 11.07. Found: C, 64.90; H, 6.29; N, 4.52; S, 11.02;IR (cm^-1) υ_max:3065 (Ar C-H), 2934 (Alkane C-H), 1583 (Ar C=C), 1341 (S=O); ¹H-NMR (400 MHz, CDCl₃, δ in ppm): 7.67 (2H, d, J = 7.6Hz, H-2', H-6'), 7.55 (1H, t, J = 7.6Hz, H-4'), 7.46 (2H, t, J = 7.6Hz, H-3', H-5'), 7.08 (1H, d, J = 7.6Hz, H-6), 6.92 (1H, t, J = 7.6Hz, H-5), 6.39 (1H, d, J = 8.0Hz, 1H, H-4), 3.86-3.77 (1H, m, H_a-1''), 3.31-3.23 (1H, m, H_b-1''), 2.28 (3H, s, CH₃-2), 2.26 (3H, s, CH₃-3), 1.02 (3H, t, J = 7.2Hz, CH₃-2''); EI-MS (m/z): 289 (M⁺, 9.3%), 148 (BP, 100%), 141, 120, 105, 77, 51.

N-(2,3-Dimethylphenyl)-N-propan-1-ylbenzenesulfonamide (5b)

Yield: 99 %; light pink solid; mp. 79 °C; Molecular formula: C₁₇H₂₁NO₂S; Molecular weight: 303; Analysis. Calcd: C, 67.32; H, 6.93; N, 4.62; S, 10.56. Found: C, 66.35; H, 6.70; N, 4.61; S, 10.57; IR (cm^-1) υ_max:3071 (Ar C-H), 2978 (Alkane C-H), 1586 (Ar C=C), 1336 (S=O); ¹H-NMR (400 MHz, CDCl₃, δ in ppm): 7.66 (2H, d, J = 7.2Hz, H-2', H-6'), 7.56 (1H, t, J = 7.6Hz, H-4'), 7.46 (2H, t, J = 7.6Hz, 2H, H-3', H-5'), 7.08 (1H, d, J = 7.6Hz, H-6), 6.91 (1H, t, J = 7.6Hz, H-5), 6.89 (1H, d, J = 8.0Hz, H-4), 3.69-3.62 (1H, m, H_a-1''), 3.18-3.12 (1H, m, H_b-1''), 2.27 (3H, s, CH₃-2), 2.25 (3H, s, CH₃-3), 1.53-1.33 (2H, m, H-2''), 0.83 (3H, t, J = 7.2Hz, CH₃-3''); EI-MS (m/z): 303 (M⁺, 12.0%), 141, 120 (BP, 100%), 105, 77, 51.

N-(2,3-Dimethylphenyl)-N-(1-methylethyl) benzenesulfonamide (5c)

Yield: 53 %; light pink solid; mp. 103.1 °C; Molecular formula: C₁₇H₂₁NO₂S; Molecular weight: 303; Analysis. Calcd: C, 67.32; H, 6.93; N, 4.62; S, 10.56. Found: C, 66.56; H, 6.69; N, 4.37; S, 10.70; IR (cm^-1) υ_max:3066 (Ar C-H), 2977 (Alkane C-H), 1584 (Ar C=C), 1335 (S=O); ¹H-NMR (400 MHz, CDCl₃, δ in ppm): 7.72 (2H, d, J = 7.6Hz, H-2', H-6'), 7.53 (1H, t, J = 7.6Hz, H-4'), 7.44 (2H, t, J = 7.2Hz, H-3', H-5'), 7.13 (1H, d, J = 7.6Hz, H-6), 6.96 (1H, t, J = 7.6Hz, H-5), 6.56 (1H, d, J = 7.9Hz, H-4), 4.63-4.56 (1H, m, H-1''), 2.28 (3H, s, CH₃-2), 2.23 (3H, s, CH₃-3), 1.02 (3H, d, J = 6.4Hz, CH₃-2''), 0.92 (3H, d, J = 6.4Hz, CH₃-3''); EI-MS (m/z): 303 (M⁺, 33.4%), 141, 120 (BP, 100%), 105, 77, 51.

N-(2,3-Dimethylphenyl)-N-butan-1-ylbenzene-sulfonamide (5d)

Yield: 98 %; light pink solid; mp. 54.7 °C; Molecular formula: C₁₈H₂₃NO₂S; Molecular weight: 317; Analysis. Calcd: C, 68.13; H, 7.25; N, 4.41; S, 10.09. Found: C, 66.91; H, 6.87; N, 4.09; S, 10.18; IR (cm^-1) υ_max:3070 (Ar C-H), 2955 (Alkane C-H), 1583 (Ar C=C), 1335 (S=O); ¹H-NMR (400 MHz, CDCl₃, δ in ppm): 7.65 (2H, d, J = 7.2Hz, 2H, H-2', H-6'), 7.56 (1H, t, J = 7.6Hz, H-4'), 7.45 (2H, t, J = 7.6Hz, H-3', H-5'), 7.08 (1H, d, J = 7.2Hz, H-6), 6.91 (1H, t, J = 7.6Hz, H-5), 6.39 (1H, d, J = 8.0Hz, H-4), 3.74-3.67 (1H, m, H_a-1''), 3.20-3.13 (1H, m, H_b-1''), 2.28 (3H, s, CH₃-2), 2.25 (3H, s, CH₃-3), 1.52-1.41 (2H, m, H-2''), 1.30-1.26 (2H, m, H-3''), 0.92 (3H, t, J = 7.2Hz, CH₃-4''); EI-MS (m/z): 317 (M⁺, 22.5%), 141 (BP, 100%), 120, 105, 77, 57, 51.

N-(2,3-Dimethylphenyl)-N-(1-methylpropyl) benzenesulfonamide(5e)

Yield: 41 %; pinkish white solid; m.p. 92.6 °C; Molecular formula: C₁₈H₂₃NO₂S; Molecular weight: 317; Analysis. Calcd: C, 68.13; H, 7.25; N, 4.41; S, 10.09. Found: C, 66.65; H, 6.88; N, 4.64; S, 10.34;IR (cm^-1) υ_max: 3062 (Ar C-H), 2973 (Alkane C-H), 1585 (Ar C=C), 1337 (S=O); ¹H-NMR (400 MHz, CDCl₃, δ in ppm): 7.71 (2H, d, J = 7.6Hz, H-2', H-6'), 7.53 (1H, t, J = 7.2Hz, H-4'), 7.44 (2H, t, J = 7.6Hz, H-3', H-5'), 7.12 (1H, d, J = 7.2Hz, H-6), 6.95 (1H, t, J = 7.6Hz, H-5), 6.54 (1H, d, J = 8.0Hz, H-4), 4.29-4.23 (1H, m, H-1''), 2.26 (3H, s, CH₃-2), 2.23 (3H, s, CH₃-3), 1.01 (3H, d, J = 6.8 Hz,H-4''), 0.90-0.85 (2H, m, H-2''), 0.74 (3H, t, J = 7.2Hz, CH₃-3''); EI-MS (m/z): 317 (M⁺, 16.7%),147 (BP, 100%), 141, 120, 105, 77, 57, 51.

N-(2,3-Dimethylphenyl)-N-pentylbenzenesul-fonamide (5f)

Yield: 93 %; pinkish white solid; mp. 72.3 °C; Molecular formula: C₁₉H₂₅NO₂S; Molecular weight: 331; Analysis. Calcd: C, 68.88; H, 7.55; N, 4.22; S, 9.66. Found: C, 68.26; H, 7.16; N, 4.52; S, 9.95;IR (cm^-1) υ_max: 3069 (Ar C-H), 2959 (Alkane C-H), 1585(Ar C=C), 1332 (S=O); ¹H-NMR (400 MHz, CDCl₃, δ in ppm): 7.65 (2H, d, J = 7.2Hz, H-2', H-6'), 7.55 (1H, t, J = 7.6Hz, H-4'), 7.45 (2H, t, J = 7.2Hz, H-3', H-5'), 7.08 (1H, d, J = 7.2Hz, H-6), 6.91 (1H, t, J = 7.6Hz, H-5), 6.39 (1H, d, J = 8.0Hz, H-4), 3.73-3.65 (1H, m, H_a-1''), 3.20-3.13 (1H, m, H_b-1''), 2.28 (3H, s, CH₃-2), 2.25 (3H, s, CH₃-3), 1.51-1.45 (2H, m, H-2''), 1.26-1.20 (4H, m, H-3'', H-4'' ), 0.81 (3H, t, J = 6.8Hz, CH₃-5''); EI-MS (m/z): 331 (M⁺, 34.1%), 141, 120, 105, 77 (BP, 100%), 71, 51.

N-(2,3-Dimethylphenyl)-N-(1-methylbutyl) benzenesulfonamide (5g)

Yield: 89 %; light brownish liquid (extracted with chloroform); Molecular formula: C₁₉H₂₅NO₂S; Molecular weight: 331; Analysis. Calcd: C, 68.88; H, 7.55; N, 4.22; S, 9.66. Found: C, 68.23; H, 7.46; N, 4.19; S, 8.92;IR (cm^-1) υ_max: 3070 (Ar C-H), 2936 (Alkane C-H), 1580 (Ar C=C), 1341 (S=O); ¹H-NMR (400 MHz, CDCl₃, δ in ppm): 7.71 (2H, d, J = 7.6Hz, H-2', H-6'), 7.53 (1H, t, J = 7.2Hz, H-4'), 7.44 (2H, t, J = 7.6Hz, H-3', H-5'), 7.12 (1H, d, J = 7.2Hz, H-6), 6.95 (1H, t, J = 7.6Hz, H-5), 6.64 (1H, d, J = 7.6Hz, H-4), 4.36-4.33 (1H, m, H-1''), 1.32-1.23 (2H, m, H-2''), 1.15-1.12 (2H, m, H-3''), 1.01 (3H, d, J = 6.8Hz, CH₃-5''), 0.77 (3H, t, J = 7.2Hz, CH₃-4''); EI-MS (m/z): 331 (M⁺, 1.1%), 141, 120, 105, 77 (BP, 100%), 71, 56, 51.

N-(2,3-Dimethylphenyl)-N-benzylbenzene-sulfonamide (5h)

Yield: 88 %; shiny pinkish white solid; mp. 80.8 °C; Molecular formula: C₂₁H₂₁NO₂S; Molecular weight: 351; Analysis. Calcd: C, 71.79; H, 5.98; N, 3.98; S, 9.11. Found: C, 70.32; H, 5.72; N, 3.66; S, 9.26;IR (cm^-1) υ_max: 3054 (Ar C-H), 2927 (Alkane C-H), 1585 (Ar C=C), 1330 (S=O); ¹H-NMR (400 MHz, CDCl₃, δ in ppm): 7.71 (2H, d, J = 7.6Hz, H-2', H-6'), 7.59 (1H, t, J = 7.6Hz, H-4'), 7.48 (2H, t, J = 7.2Hz, H-3', H-5'), 7.18-7.09 (5H, m, H-2'' to H-6''), 7.01 (1H, d, J = 7.6Hz, H-6), 6.88 (1H, t, J = 7.6, H-5), 6.41 (1H, d, J = 8.0Hz, H-4), 4.96 (1H, d, J = 13.6 Hz, H_a-7''), 4.24 (1H, d, J = 13.6 Hz, H_b-7''), 2.14 (3H, s, CH₃-2), 1.88 (3H, s, CH₃-3); EI-MS (m/z): 351 (M⁺, 13.4%), 141, 120, 105, 91 (BP, 100%), 77, 51.

N-(2,3-Dimethylphenyl)-N-(2-chlorobenzyl) benzenesulfonamide (5i)

Yield: 98 %; pinkish white solid; mp. 109 °C; Molecular formula: C₂₁H₂₀ClNO₂S; Molecular weight: 385; Analysis. Calcd: C, 65.45; H, 5.19; N, 3.63; S, 8.31. Found: C, 65.01; H, 5.38; N, 3.80; S, 7.71;IR (cm^-1) υ_max: 3063 (Ar C-H), 2927 (Alkane C-H), 1582 (Ar C=C), 1342 (S=O), 576 (C-Cl); ¹H-NMR (400 MHz, CDCl₃, δ in ppm): 7.72 (2H, d, J = 7.6Hz, H-2', H-6'), 7.60 (1H, t, J = 7.6Hz, H-4'), 7.49 (2H, t, J = 7.6Hz, H-3', H-5'), 7.33 (1H, dd, J = 7.2, 3.2 Hz, H-3''), 7.19 (1H, dd, J = 6.4, 2.8Hz, H-6''), 7.13-7.09 (2H, m, H-4'', H-5''), 7.00 (1H, d, J = 7.6 Hz, H-6), 6.87 (1H, t, J = 7.6 Hz, H-5), 6.52 (1H, d, J = 7.6Hz, H-4), 5.08 (1H, d, J = 14.0 Hz, H_a-7''), 4.53 (1H, d, J = 14.0 Hz, H_b-7''), 2.13 (3H, s, CH₃-2), 1.91 (3H, s, CH₃-3); EI-MS (m/z): 387 ([M+2]⁺, 6.1%), 385 (M⁺, 17.9%), 141, 120, 125 (BP, 100%), 105, 90, 77, 51.

N-(2,3-Dimethylphenyl)-N-(4-chlorobenzyl) benzenesulfonamide (5j)

Yield: 50 %; pinkish white solid; mp. 104.8 °C; Molecular formula: C₂₁H₂₀ClNO₂S; Molecular weight: 385; Analysis. Calcd for: C, 65.45; H, 5.19; N, 3.63; S, 8.31. Found: C, 64.86; H, 5.45; N, 3.35; S, 8.18; IR (cm^-1) υ_max:3066 (Ar C-H), 2923 (Alkane C-H), 1584 (Ar C=C), 1342 (S=O), 581 (C-Cl); ¹H-NMR (400 MHz, CDCl₃, δ in ppm): 7.69 (2H, d, J = 7.6Hz, H-2', H-6'), 7.59 (1H, t, J = 7.2Hz, H-4'), 7.48 (2H, t, J = 7.6Hz, H-3', H-5'), 7.15 (2H, d, J = 8.4 Hz, H-3'', H-5''), 7.05 (2H, d, J = 8.4Hz, H-2'', H-6''), 7.02 (1H, d, J = 8.0 Hz, H-6), 6.88 (1H, t, J = 7.6 Hz, H-5), 6.39 (1H, d, J = 7.6Hz, H-4), 4.91 (1H, d, J = 13.6 Hz, H_a-7''), 4.21 (1H, d, J = 13.6 Hz, H_b-7''), 2.15 (3H, s, CH₃-2), 1.89 (3H, s, CH₃-3); EI-MS (m/z): 387 ([M+2]⁺, 5.2%), 385 (M⁺, 15.4%), 141, 120, 125 (BP, 100%), 105, 90, 77, 51.

N-(2,3-Dimethylphenyl)-N-(4-bromobenzyl) benzenesulfonamide (5k)

Yield: 98 %; off-white solid; mp. 106.3 °C; Molecular formula: C₂₁H₂₀BrNO₂S; Molecular weight: 430; Analysis. Calcd: C, 58.60; H, 4.65; N, 3.25; S, 7.44. Found: C, 58.19; H, 4.72; N, 3.41; S, 7.12;IR (cm^-1) υ_max:3065 (Ar C-H), 2924 (Alkane C-H), 1586 (Ar C=C), 1342 (S=O), 585 (C-Br); ¹H-NMR (400 MHz, CDCl₃, δ inppm): 7.69 (2H, d, J = 7.2Hz, H-2', H-6'), 7.59 (1H, t, J = 7.6Hz, H-4'), 7.48 (2H, t, J = 7.6Hz, H-3', H-5'), 7.30 (2H, d, J = 8.4 Hz, H-3'', H-5''), 7.02 (1H, d, J = 8.0 Hz, H-6), 6.99 (2H, d, J = 8.4Hz, H-2'', H-6''), 6.88 (1H, t, J = 7.6 Hz, H-5), 6.39 (1H, d, J = 8.0Hz, H-4), 4.89 (1H, d, J = 13.6 Hz, H_a-7''), 4.20 (1H, d, J = 14.0 Hz, H_b-7''), 2.16 (3H, s, CH₃-2), 1.90 (3H, s, CH₃-3); EI-MS (m/z): 432 ([M+2]⁺, 7.8%), 430 (M⁺, 8.2%), 141, 120, 169, 105, 90, 77 (BP, 100%), 51.

N-(2,3-Dimethylphenyl)-N-(phenylethyl)ben-zenesulfonamide (5l)

Yield: 89 %; pinkish white solid; mp. 103.5 °C; Molecular formula: C₂₂H₂₃NO₂S; Molecular weight: 365; Analysis. Calcd for: C, 72.32; H, 6.30; N, 3.83; S, 8.76. Found: C, 71.71; H, 6.12; N, 3.95; S, 8.90; IR (cm^-1) υ_max:3064 (Ar C-H), 2922 (Alkane C-H), 1582 (Ar C=C), 1342 (S=O); ¹H-NMR (400 MHz, CDCl₃, δ inppm): 7.64 (2H, d, J = 8.0Hz, H-2', H-6'), 7.54 (1H, t, J = 7.2Hz, H-4'), 7.44 (2H, t, J = 8.0Hz, H-3', H-5'), 7.22 (2H, d, J = 7.6 Hz, H-3'', H-5''), 7.17 (1H, t, J = 6.8 Hz, H-4''), 7.11 (1H, d, J = 7.2 Hz, H-6), 7.06 (2H, d, J = 7.2Hz, H-2'', H-6''), 6.95 (1H, t, J = 7.6 Hz, H-5), 6.47 (1H, d, J = 8.0Hz, H-4), 4.00-3.93 (1H, m, H_a-8''), 3.46-3.36 (1H, m, H_b-8''), 2.88-2.82 (1H, m, H_a-7''), 2.68-2.62 (1H, m, H_b-7''), 2.29 (3H, s, CH₃-2), 2.21 (3H, s, CH₃-3); EI-MS (m/z): 365 (M⁺, 25.8%), 141, 120, 105, 104, 77 (BP, 100%), 51.

N-(2,3-Dimethylphenyl)-N-allylbenzenesulfo-namide (5m)

Yield: 88 %; brownish white solid; mp. 60.5 °C; Molecular formula: C₁₇H₁₉NO₂S; Molecular weight: 301; Analysis. Calcd: C, 67.77; H, 6.31; N, 4.65; S, 10.63. Found: C, 66.83; H, 6.08; N, 4.30; S, 10.72;IR (cm^-1) υ_max: 3063(Ar C-H), 2946 (Alkane C-H), 1580 (Ar C=C), 1705 (Alkene C=C), 1341 (S=O); ¹H-NMR (400 MHz, CDCl₃, δ in ppm): 7.68 (2H, d, J = 7.6Hz, H-2', H-6'), 7.56 (1H, t, J = 7.2Hz, H-4'), 7.47 (2H, t, J = 7.6Hz, H-3', H-5'), 7.07 (1H, d, J = 7.6 Hz, H-6), 6.90 (1H, t, J = 7.6 Hz, H-5), 6.39 (1H, d, J = 7.6Hz, H-4), 5.76-5.69 (1H, m, H-2''), 4.97 (1H, dd, J = 6.4, 2.8 Hz, H_b-3''), 4.30 (1H, dd, J = 7.6, 2.8 Hz, H_a-3''), 3.87 (2H, d, J = 6.4 Hz, H-1''), 2.26 (3H, s, CH₃-2), 2.23 (3H, s, CH₃-3); EI-MS (m/z): 301 (M⁺, 20.9%), 141, 120, 105, 77 (BP, 100%), 51.

Antibacterial activity

The synthesized compounds were evaluated against two Gram-positive and four Gram-negative bacterial strains using ampicillin and ciprofloxacin as standards. (). The compounds showed moderate to significant activity against bacterial strains except compounds, 5a, 5d and 5e. The compound 3 was active against one strain of gram-positive bacteria only. The preliminary screening showed that compound, 5c, 5f, 5g, 5i, 5l and 5m were the most active ones against gram-positive and compounds, 5b, 5f, 5j and 5k were more active against gram-negative bacterial strains.

Anti-enzymatic activity

The screening against α-glucosidase enzyme demonstrated that the most of compounds were active with good inhibitory potential except 5a, 5b, 5c and 3 (Table-2). The molecules 5g and 5j were found to be excellent inhibitors with their IC₅₀ values of 59.53 ± 0.008 and 55.31 ± 0.01 μmoles/L respectively, relative to acarbose a reference standard with IC₅₀ value 38.25 ± 0.12μmoles/L.

Hemolytic activity

The compounds 5a, 5b, 5d, 5h and 5j exhibited cytotoxic activity with percent lysis of 27.2 ± 0.24, 22.4 ± 0.21, 21.7 ± 0.68, 18.2 ± 0.56 and 18.9 ± 0.23 respectively, which was much lower than the positive control triton X-100 (0.1 % v/v) which has percent lysis value of 100.The compound 5e was the least cytotoxic in this series with percent lysis of 5.2 ± 0.41.

Discussion

Sulfonamide 3 was obtained as off-white powder. Although its structure has been established by the x-ray crystallography [21] but more structural details are presented here for the first time. Its molecular formula, C₁₄H₁₅NO₂S, was determined through CHNS analysis with percentage of elements as C: 64.03 %; H: 6.40 %; N: 5.52 % and S: 11.73 %.

The molecular formula was also supported by EI–MS, showing a [M]⁺ ion peak at m/z 261 and by the integration curves in its ¹H-NMR spectrum indicating the number of protons for each peak. The signals in ¹H-NMR spectrum, appearing at δ 7.69 (d, J = 7.6Hz, 2H, H-2', H-6'), 7.53 (t, J = 7.6 Hz, 1H, H-4') and 7.41 (t, J = 7.6 Hz, 2H, H-3', H-5') were typical for the protons of the benzenesulfonyl group present in the molecule. Furthermore, the signals resonating at δ 7.13 (d, J = 7.6Hz, 1H, H-6), 6.96 (t, J = 7.6Hz, 1H, H-5), 6.46 (d, J = 6.39Hz, 1H, H-4), 2.18 (s, 3H, CH3-2) and 1.91 (s, 3H, CH3-3) were assigned to the protons of substituted aniline ring. FT-IR supported the structure by absorption bands at 3208 (N-H), 3042 (Ar C-H), 2924 (Alkane C-H), 1583 (Ar C=C) and 1324 (S=O) cm^-1. On the basis of above accumulative manifests, the structure of 3 was confirmed as N-(2,3-dimethylphenyl)benzenesulfonamide. Similarly, the structures of other compounds, 5a-m, were characterized.

The antibacterial activity results declared the compound 5f bearing aliphatic straight chain with moderate length at nitrogen atom was the most active molecule against all the bacterial strains used in this study. The compounds with sulfamoyl moiety have been introduced as valuable biologically active compounds and in accordance with our previous findings [13-16], the overview of synthesized compounds hereby showed that N-substitution of sulfamoyl group with aliphatic chains and halogenated aromatic compounds presented best activity because of best fit to active site of enzyme and better π-π interactions. The two molecules, 5g and 5j, showed good activity against α-glucosidase probably because of branched long alkyl chain in 5g and p-substituted halogenated aralkyl group in 5j, presented better binding interactions with the active site of enzyme. The compound 5e was the least cytotoxic in this series but it was inferred that all the compounds can be used as possible therapeutic agents.

Conclusion

All the compounds have been structurally identified by spectral data and screened for antibacterial, α-glucosidase and hemolytic analysis. The synthesized compounds exhibit cytotoxicity and antibacterial potentials.

References

Naseer M, Chohan M, Zahid H. Synthesis, characterization and reactivity towards first-row d-transition metals and biological significance of new pyridinyl derived N-substituted sulfonamides. Appl Organometal Chem 2007; 21: 826-835.

Rambabu N, Modi VB, Goswami KJ. Synthesis and characterization of N-(4-(4-chlorophenyl)-6-(3,4-dimethylphenyl)pyrimidin-2-yl)-4-(2,6-diphenyl-4-thioxo-2H-1,3,5-oxadiazin-3(4H)-yl)benzenesulfonamide. Der Pharma Chemica 2012; 4(1): 511-516.

Caballero RD, Torres-Lapasió JR, Baeza-Baeza JJ, García-Alvarez-Coque MC. Micellar chromatographic procedure with direct injection for the determination of sulfonamides in milk and honey samples. J Liq Chrom Rel Technol 2001; 24(1): 117-131.

Lackner H, Doring G, Garre K. NMR spectroscopic identification of sulfonamides from urine. Forensic Sci 1974; 4: 219-231.

Chen A, Wang G, Cao Q, Wang Y, Zhang Z, Sun Y, Wang H, Xu C, Zhou Q, Han P, Liu M, Yang Y, Xing W, Mitchelson K, Cheng J. Development of an antibody hapten-chip system for detecting the residues of multiple antibiotic drugs. J Forensic Sci 2009; 54(4): 953-960.

Rieder MJ, Krause R, Bird IA. Time-course of toxicity of reactive sulfonamide metabolites. Toxicol 1995; 95: 141-146.

Chiba S. Molecular mechanism of α-glucosidase and glucoamylase. Biosci Biotech Biochem 1997; 61: 1233-1239.

Baron AD. Postprandial hyperglycemia and alpha-glucosidase inhibitor. Diabetes Res Clin Pr 1998; 40(Suppl.):51-55.

Lebovitz HE. Alpha-glucosidase inhibitors. Endocrinology and Metabolism. Clin North Am 1997; 26: 539-551.

Chapdilaine P, Tremblay RR, Dube JY. p-Nitrophenol-α-D-Glucopyranoside as substrate for measurement of maltase activity in human semen. Clin Chem 1978; 24: 208-211.

Sharma P, Sharma JD. In vitro hemolysis of human erythrocytes by plant extracts with antiplasmodial activity. J Ethnopharmacol 2001; 74: 239-243.

Dausset J, Contu L. Drug induced hemolysis. Ann Rev Med 1967; 18: 55-70.

Abbasi MA, Aziz-ur-Rehman, Muhmood T, Khan KM, Ashraf M, Ejaz SA, Arshad S. Synthesis structural characterization and biological screening of various sulfa drugs derived from 2-anisidine. J Chem Soc Pak 2013; 35(2): 404-410.

Abbasi MA, Ahmad S, Aziz-ur-Rehman, Rasool S, Khan KM., Ashraf M, Nasar R, Ismail T. Sulfonamide derivatives of 2-amino-1-phenylethane as suitable cholinesterase inhibitors. Trop J Pharm Res 2014; 13(5): 739-745.

Abbasi MA, Saeed A, Aziz-ur-Rehman, Khan KM, Ashraf M, Ejaz SA. Synthesis of brominated 2-phenitidine derivatives as valuable inhibitors of cholinesterases for the treatment of Alzheimer’s disease. Iran J Pharm Res 2014; 13(1): 87-94.

Irshad M, Abbasi MA., Aziz-ur-Rehman, Rasool S, Siddiqui SZ, Ahmad I, Ashraf M, Lodhi MA, and Jamal SB. O- and N-Substituted derivatives of planetol as valuable bioactive compounds. Asian J Chem 2014; 26 (4): 1151-1160.

Kaspady M, Narayanaswamy VK, Raju M, Rao GK. Synthesis, antibacterial activity of 2,4-disubstituted oxazoles and thiazoles as bioesters. Lett Drug Des Discov 2009; 6: 21-28.

Yang CR, Zang Y, Jacob MR, Khan SI, Zhang YJ, Li XC. Antifungal activity of C-27 steroidal saponins. Antimicrob Agents Ch 2006; 50(5): 1710-1714.

Powell WA, Catranis CM, Maynard CA. Design of self-processing antimicrobial peptide for plant protection. Lett Appl Microbiol 2000; 31(2): 163-168.

World Medical Association. World Medical Association Declaration of Helsinki; Ethical principles for medical research involving human subjects. Clin Rev Edu 2013; 310(20): 2191-2194.

Gowda BT, Foro S, Babitha KS, Fuess H. N-(2,3-Dimethylphenyl)benzenesulfonamide. Acta Cryst 2009; E65: o366.