MATERIALS AD METHDS CHAPTER 2. MATERIALS AD METHDS 2.1: SYTHESIS, IDETIFICATI AD CHARACTERIZATI The Benzotriazole derivatives were synthesized using raw materials as below (Table 4). Table 4. Chemical and raw material used in synthesis The synthetic scheme for synthesis of 2-(1H-1,2,3-benzoriazol-1yl)-- Phenylacetamide derivatives from Ia to Va involves synthesis of Benzotriazole Department of Pharmaceutical Sciences, JJT University Rajasthan Page 14
MATERIALS AD METHDS heterocyclic nucleus on which substitution of ethyl chloroacetate was done to get ethyl 1-H-benzotriazol-1-yl aceate. The ester so produced was converted to acetyl chloride derivative with thionyl chloride. Then subsequent substitution of various amines would produce 2-(1H-1,2,3-benzoriazol-1yl)--Phenylacetamide derivatives(figure 4). H 1H -benzotriazo le (a) C H 3 ethyl chloroacetate H 3 C ethyl 1H -benzotriazol-1-ylacetate (b) S Thionyl chloride 1H -benzotriazol-1-yl acetyl chloride (c) H 2 R Aromatic amine H R 2-(1 H -1,2,3-benzotriazol-1-yl)- -phenylacetamide derivatives (Ia to Va) Figure 4: Reaction pathway for synthesis of 2-(1H-1,2,3-benzotriazol-1-yl)-phenylacetamide derivatives.2. Procedure of Synthesis of Benzotriazole (a): 10.8 gm of -phenylenediamine was added to mixture of 12g (11.5 ml) of glacial acetic acetic acid and 30 ml of water, which was cooled to 15 o C, stir. Then solution of 7.5g of sodium nitrite in 15 ml water was added in portion. The temperature rises slowly to 85 o C and then cooled slowly. When temperature was 45 o C the mixture was chilled at ice bath for 30 min. Pale brown solid separated by the filtration. The recrystallization was done using benzene as solvent. Synthesis of ethyl 1H-benzotriazol-1-ylacetate (b): A mixture of Benzotriazole of 0.1M, ethyl chloroacetate of 0.1M and 0.3g of K 2 C 3 in 60 ml of acetone was stirred for 10 hrs. The solvent was separated. A solid mass produced was then needle shaped brown crystals were obtained after recrystallization from the mixture of chloroform and ether (8:2%V/V).The yield obtained was 60% and M.P. was 40 o C. Department of Pharmaceutical Sciences, JJT University Rajasthan Page 15
MATERIALS AD METHDS Synthesis of 1H-benzotriazol-1-ylacetyl chloride(c): A 250-ml, three-necked flask, equipped with a magnetic stirbar, condenser, thermometer, and addition funnel, was charged with 10.0 g Benzotriazole and 34 ml of chloroform (CHCl 3 ). At 25 C, 22 ml (600 mm) of thionyl chloride and 1 drop of dimethylformamide (DMF) were added, followed by heating the mixture at 68 C for 3 hr. After the initial suspension turns into a yellow solution, the heating source was removed and the acid chloride precipitated as a pale red solid. After cooling the reaction mixture to 25 C, the solid was collected via filtration using a Buchner funnel, washed with CHCl 3, and dried in a vacuum desiccator for 15 hr to give 5.12 g (90%) of as a white powder. 2.21. Substitution of aromatic amines on (c) to get the below derivatives. Synthesis of 2-(1H-benzotriazol-1-yl)--(naphthalen-1-yl) acetamide(ia): the compound (c) was treated with 1-aminonapthalien in equimolar concentration and refluxed for 4 hrs in benzene solvent. Characterized by Physical, Chemical properties. TLC, Spectral data FTIR (KBr cm-1),1h-mr, Mass spectral were studied. Synthesis of 2-(1H-benzotriazol-1-yl)--(4-sulfamoylphenyl) acetamide (IIa): the compound (c) was treated with equimolar 4-aminobenzenesulfonamide and refluxed for 4 hrs in benzene solvent. Characterized by Physical, Chemical properties. TLC, Spectral data FTIR (KBr cm-1),1h-mr, Mass spectral were studied.. Synthesis of 2-(1H-benzotriazol-1-yl)--(4-hydroxyphenyl)acetamide (IIIa): the compound (c) was treated with equimolar 4-aminophenol and refluxed for 4 hrs in benzene solvent. Characterized by Physical, Chemical properties. TLC, Spectral data FTIR (KBr cm-1),1h-mr, Mass spectral were studied.. Synthesis of 2-(1H-benzotriazol-1-yl)--(4-nitrophenyl)acetamide (IVa): the compound (c) was treated with equimolar 4-nitroaniline and refluxed for 4 hrs in benzene solvent. Characterized by Physical, Chemical properties. TLC, Spectral data FTIR (KBr cm-1),1h-mr, Mass spectral were studied.. Synthesis of 4-[(1H-benzotriazol-1-ylacetyl) amino] benzoic acid (Va): the compound (c) was treated with equimolar 4-aminobenzoic acid and refluxed for 4 hrs in benzene solvent. Characterized by Physical, Chemical properties. TLC, Spectral data FTIR (KBr cm-1),1h-mr, Mass spectral were studied. Department of Pharmaceutical Sciences, JJT University Rajasthan Page 16
MATERIALS AD METHDS H 1H -ben zotriazo le (a) C H 3 ethyl chloroacetate H 3 C ethyl 1H -benzotriazol-1-ylacetate (b) S Thionyl chloride 1H -b en zotriazol-1 -yl acetyl chloride (c) H H 2 R Amino acid R H (1 H -benzotriazol-1-ylacetyl)carbamic acid derivatives (Ib to Vb) Figure 5: Reaction pathway for synthesis of [(1H-benzotriazol-1-ylacetyl) amino] acetic acid Derivatives. The synthetic scheme for synthesis of Ib to Vb derivatives involves synthesis of Benzotriazole heterocyclic nucleus on which substitution of ethyl chloroacetate was done to get ethyl 1-H-benzotriazol-1-yl aceate. The ester so produced was converted to acetyl chloride derivative with thionyl chloride. Then subsequent substitution of various amino acids would produce 2-(1H-1,2,3-benzoriazol-1yl)--carbamic acid derivatives. 2.22. Substitution of amino acids on (c) to get the below derivatives (Figure 5). Synthesis of [(1H-benzotriazol-1-ylacetyl) amino] acetic acid (Ib): the compound (c) was treated with glycine in equimolar concentration and refluxed for 4 hrs in benzene solvent. Characterized by Physical, Chemical properties. TLC, Spectral data FTIR (KBr cm-1),1h-mr, Mass spectral data were studied. Synthesis of 2-[(1H-benzotriazol-1-ylacetyl)amino]propanoic acid (IIb): the compound (c) was treated with equimolar alanine and refluxed for 4 hrs in benzene solvent. Characterized by Physical, Chemical properties. TLC, Spectral data FTIR (KBr cm-1),1h-mr, Mass spectral data were studied. Synthesis of 2-[(1H-benzotriazol-1-ylacetyl) amino]-3-(4- hydroxyl phenyl) propanoic acid (IIIb): the compound (c) was treated with equimolar tyrosine and refluxed for 4 hrs in benzene solvent. Characterized by Physical, Chemical properties. TLC, Spectral data FTIR (KBr cm-1),1h-mr, Mass spectral data were studied.. Department of Pharmaceutical Sciences, JJT University Rajasthan Page 17
MATERIALS AD METHDS Synthesis of 2- [(1H- benzotriazol-1-ylacetyl) amino]-5-carbamimid amido pentanoic acid (IVb): the compound (c) was treated with equimolar arginine and refluxed for 4 hrs in benzene solvent. Characterized by Physical, Chemical properties. TLC, Spectral data FTIR (KBr cm-1),1h-mr, Mass spectral data were studied. Synthesis of 4-[(1H-benzotriazol-1-ylacetyl)amino]benzoic acid (Va): the compound (c) was treated with equimolar cysteine and refluxed for 4 hrs in benzene solvent. Characterized by Physical, Chemical properties. TLC, Spectral data FTIR (KBr cm-1),1h-mr, Mass spectral data were studied. 2.3 ATIBACTERIAL ACTIVITY Synthesized Benzotriazole derivatives were subjected for the antibacterial activity. The determination of antibacterial activity followed here was a relative method and not absolute. Responses of an organism to synthesized derivatives were compared with responses to the standard preparation of known composition and concentration. This determination indicates whether the organism is sensitive or resistant to the agent. The organism being sensitive means that the organism is inhibited by the antimicrobial agent at clinically attainable concentration, resistant means that the growth of the organism is not inhibited and intermediate means that special consideration needed to be followed if the agent is to be used effectively. Different techniques of determination of antibacterial activities are Diffusion Technique. Photometry or Turbid metric method. Under the present study Diffusion technique was followed: ne-dimensional technique is diffusion in test-tube or in capillaries. Here 6-8 mm tube containing a soft agar medium was inoculated with test organism. The test solution was placed on top. The diameter of clear zone obtained was measured after incubating overnight in a water bath. In a radial or 2D technique, Petri dishes of agar were prepared by pouring melted agar media previously inoculated with selected microorganisms. After the solidification of agar cups were made with help of borer and cups were filled with solution of suitable concentration of sample and standard respectively and incubated at 37 o C for 24 hours. The antimicrobial agent diffuses through the agar around its cup and produces a characteristic zone of inhibition of the microorganism sensitive to the sample, the diameter of which can be measured. Department of Pharmaceutical Sciences, JJT University Rajasthan Page 18
MATERIALS AD METHDS In 3D diffusion technique consists of disc method. Here a culture of known concentration was spread on appropriate agar medium. Filter paper discs containing predetermined concentration of an antimicrobial agent were placed on the seeded agar plates in a set pattern with equally spacing between the discs. The plates were then incubated for 16-18 hours at 36 o C, after which the organism s sensitivity was measured on a basis of the size of the zone of inhibition. 2.4. METHDLGY: Culture: Two Gram +ve and two Gram -ve bacteria were chosen for screening. Gram positive organism: Staphylococcus aureus (ATCC 29737) Bacillus subtilis (ATCC 6633) Gram negative organism: Escherichia coli (ATCC 10536) Salmonella typhi. Two fungi were used; Aspergillus niger, and Candida albicans Media: utrient Agar Media from Himedia was used with composition (Table 5): Table 5: Composition of the utrient Agar media 28 gm of media was dissolved in 1000 ml of distilled water by heating and was sterilized by autoclaving at 121 o C at 15 lb/inch 2 pressure for 15 minutes. 1) Standard: orfloxacin was used as standard antibiotics for the comparison (Table 6). Department of Pharmaceutical Sciences, JJT University Rajasthan Page 19
MATERIALS AD METHDS Table 6: Standards used for antimicrobial activity 2) Apparatus: Sterile Petri plates, 1 ml syringes, micropipette, inoculating loop, nonabsorbent cotton, spirit lamp. 3) Compounds screened: Ia, IIa, IIIa, IVa, Va, Ib, IIb, IIIb, IVb, and Vb. Procedure: utrient agar 8.4 gm of was dissolved in 300 ml of distilled water by heating. Then it was sterilized by autoclaving at 121 o C temperature at 15 lb/inch 2 for 15 minutes. Adjust ph at 25 C for 7.4 ± 0.2 To sterilized utrient agar media of 150 ml, 0.5 ml of bacterial suspension was added, mixed and poured into the sterilized Petri plates and allowed to solidify. Plates were allowed to dry for 15 minutes. The media on solidification was bored with the help of the 6 mm borer and the analogues synthesized were added to the bore at 10 mcg/ml, 20 mcg/ml, 40mcg/ml, 60 mcg/ml, 80 mcg/ml and 100 µg/ml concentrations. The standard orfloxacin of 10µg/ml was also placed in all the plates for the comparison. Culture plates were incubated at 37 o C and observed at 20 to 24 hours and May continued to incubate for 48 hours. Zone of inhibition by sample were measured and compared with the standard (Figure 6). 2.5. MIIMAL IHIBITRY CCETRATI (MIC) METHD The antibacterial activities of synthesized compounds were tested in vitro on strains of four microorganisms, Escherichia coli, Bacillus subtilis, Staphylococcus aureus and Salmonella typhi two fungal organisms Aspergillus niger, and Candida albicans. The MIC was determined by agar diffusion method subjecting solution of sample in proper concentration. Department of Pharmaceutical Sciences, JJT University Rajasthan Page 20
MATERIALS AD METHDS 2.51. Preparation of double strength nutrient media Formula: Peptone 1 gm. Yeast 0.3 gm. Sodium Chloride 0.5 gm. Distill water 50 ml. The components were dissolved in water, ph of the solution was adjusted to 7.4 ± 0.2 and the media was sterilized by autoclaving at 15 lb/psi for 15 mins. 2.52. Preparation of micro organism suspension- Microorganisms from culture were transferred to 5 ml of sterile normal saline (0.09%) solution. 2.53. Determination of Minimal Inhibitory Concentration: To the sterile test tubes 1 ml of sterile media was added, followed by 1 ml o serially diluted sample solution. A 0.1 ml of suspension of respective microorganism in normal saline solution was added, and then incubated at 37 ± 2 o C for 18 to 24 hrs. The growths in the tubes were recorded visually for turbidity and inhibition was determined by lowest concentrations of sample that prevented the development of turbidity. The procedure was repeated to confirm the MIC. Figure 6: Antibacterial activity 2.6. ATIXIDAT ACTIVITY The evaluation of 2-(1H-1,2,3-benzotriazol-1-yl)--phenylacetamide and [(1Hbenzotriazol-1-ylacetyl)amino]acetic acid derivatives (Table 1)for antioxidant activity Department of Pharmaceutical Sciences, JJT University Rajasthan Page 21
MATERIALS AD METHDS following Radical activity of itric oxide or Griess reaction assay (Scheme 2). The nitroprusside used in the reaction produce nitric oxide at physiological ph which interacts with oxygen to produce nitrite ion. The synthesized derivatives contain carbonyl and amine functional groups which interact with nitric oxide resulting in reduced production of nitrite ion, a strong oxidizing agent. The remaining nitrite ion oxidizes the sulphonilamde to form diazonium salt which couples with - (naphthalene-1-yl)ethylenedime (ED) to form 4-[(E)-{4-[(2- aminoethyl)amino]naphthalene-11 yl}diazenyl]benzenesulfonamde a purple colored complex(figure 7). Thus formed complex was measured spectrophotometrically at 548nm H 2 H H 2 H+ H H 2 - + S S -(naphthalen-1-yl)ethane-1,2-diamine H 2 H 2 4-aminobenzenesulfonamide S H 2 4-[(E)-{4-[(2-aminoethyl)amino]naphthalen-1-yl}diazenyl]benzenesulfonamide Figure 7: Reaction pathway of 4-[(E)-{4-[(2-aminoethyl) amino] naphthalen-1- yl}diazenyl]benzenesulfonamide complex formation with Griess reagent 2.7. EXPERIMETAL METHDS: 2.71. Materials and Methods: All the reagents used were analytical grade. DMS was used as solvent, Griess Reagent Prepared with 0.2% naphthylenediamine dihydrochloride, and 2% sulphonilamide in 5% phosphoric acid. Phosphate buffer saline (PBS) and Sodium nitroprusside (10mM) were prepared. All absorbance was measured with Digital Spectrophotometer Model VSI- SP1. Absorption of radical scavenging activity was recorded at 548nm using DMS as blank and Ascorbic acid as standard or control using formula given below. Department of Pharmaceutical Sciences, JJT University Rajasthan Page 22
MATERIALS AD METHDS 2.72. Procedure: Test solutions of Benzotriazole derivatives were prepared in range of 25µgml -100µg/ml in DMS. 1ml of test solution of each concentration transferred to 10ml volumetric flasks. 5ml of Phosphate Buffer Salt (PBS) solution was added and 2ml of Sodium itroprusside (SP) solution was added. Similarly Standard Ascorbic acid was treated with PBS and SP in volumetric flask. All the mixtures were incubated at 25 o C for 150 minutes. The Griess reagent of 3ml was added to all the solutions. Chromophore developed was measured spectrophotometrically. For each concentration minimum three observations were recorded and mean of the observations were used for the calculation. The percentage of scavenging activity of derivatives was calculated with Absorption of different concentrations. The derivatives like IIa, IIIa and IIb showed remarkable Scavenging activity when compared to ascorbic acid (Figure 6). Greater the values of scavenging activity better the antioxidant activity (Table 20), Standard Error of the Mean (SEM) was calculated for each derivative and found to be within the normal range. The Benzotriazole derivatives like II a, III a and IIb showed comparable percentage of nitric oxide scavenging activity with standards reference ascorbic acid. The other derivatives show medium activity. 2.8. Characterization The Benzotriazole derivatives from Ia to Va and Ib to Vb synthesized were scaled for yield and purified by recrystallization with suitable solvent system. The purified compounds were identified / characterized by following methods: 1. Physical properties 2. Melting point determination. 3. Thin Layer Chromatography. 4. Infra-Red Spectroscopy. 5. uclear Magnetic Resonance Spectroscopy. 6. Mass Spectrometry. 2.81. Melting point determination: The melting point of the synthesized compounds were determined in open capillary using LABHSP melting point apparatus and recorded in o C without Department of Pharmaceutical Sciences, JJT University Rajasthan Page 23
MATERIALS AD METHDS correction. It was widely used physical constant in the characterization of an organic compound. 2.82. Thin Layer Chromatography: Thin layer chromatography was performed on precoated silica gel plates (604 GF 254 Merck) with suitable solvent system. The R f values were recorded accordingly. This technique was widely employed for the identification of the organic compounds with characteristic R f value. This method was also applied to determine the progress of the reaction and to examine the purity of the end product. After the development of chromatogram, the spots were detected by placing the plate in UV chamber. In all the synthesized derivatives, single spots were seen, indicating the purity of the compound. 2.83. Infrared Spectroscopy: The infrared spectroscopy is one of the most powerful analytical techniques, which is used for chemical identification. The most important advantages of infrared spectroscopy over the other usual methods of structural analysis is that it provides useful information about the functional groups present in the molecule quickly. The infrared spectrum for the synthesized compounds were recorded using Agilent Technologies CARY 630 FTIR and SHIMADZU-FTIR 8400 spectrometer using potassium bromide pellet technique. 2.84. uclear Magnetic Resonance Spectroscopy: It is the branch of spectroscopy in which radiofrequency waves induces transitions between magnetic energy levels of nuclei of a molecule. The magnetic energy levels are created by keeping nuclei in a magnetic field. Without the magnetic field the spin states of nuclei are degenerated i.e., possess the same energy & the energy level transition is not possible. The energy level transition is possible with the application of external magnetic field which requires different R f radiation to put them into resonance. This is a measurable phenomenon. It is a powerful tool for the investigation of nuclei structure. 1 H MR spectrum of the synthesized compounds were taken using BRUKERSPECTRSPI-400MHz spectrometer using tetra methyl silane as an internal standard. 1 H MR spectra were recorded with DMS (d 6 ) as a solvent and the chemical shift data were expressed as delta values related to TMS in ppm. Department of Pharmaceutical Sciences, JJT University Rajasthan Page 24
MATERIALS AD METHDS 2.55. Mass spectroscopy: Mass spectrometer performs three essential functions. The ions of particular mass-to-charge ratio were detected by a device which can count the number of ions striking it. The detector s output was amplified and fed to a recorder. The trace from the recorder is a mass spectrum- a graph of particles detected as a function of mass-tocharge ratio. The MS of the synthesized compound was taken using GCMS QP5050 SHIMADZU instrument. Theoretically organic compounds with heterocyclic structure with amine or amide substitutions would rarely give stable molecular peaks. Department of Pharmaceutical Sciences, JJT University Rajasthan Page 25