Novel Heterocyclic Compounds: Synthesis, Characterization and Biological Evaluation

 

Mahendrasinh M. Raj¹*, Hemul V. Patel², Lata M. Raj³ and Naynika K. Patel⁴

¹Institute of Science and Technology for Advanced Studies and Research (ISTAR), Vallabh Vidyanagar-388120, Gujarat, India.

²Ashok and Rita Patel Institute of Integrated study and Research in Biotechnology and Allied Sciences (ARIBAS), New Vallabh Vidyanagar-388121, Gujarat, India.

³C.N.P.F Arts and D.N Science College, Dabhoi, Gujarat, India.

⁴Department of Biosciences, Sardar Patel Universty, Vallabh Vidyanagar -388120, Gujarat, India

*Corresponding Author E-mail: mahendramraj@yahoo.com

 

A series of chalcones were prepared by using o- hydroxyl acetophenone. The physical characterization of synthesized compounds was carried out by their Melting point and TLC.  The synthesized compounds were characterized by means of their IR, ¹H-NMR spectral data. All the compounds were tested for their antibacterial and antifungal activities by the cup plate method.

 

 

INTRODUCTION:

Heterocycles with multiple hydrogen bonding sites have gained attention recently for their utility in host-guest systems [1]. Many of these heterocyclic hosts were designed with a preorganized array of hydrogen bonding sites that is complementary to that of a guest molecule. Successful heterocyclic hosts were reported for nucleotide bases [1], ureas,[2] and several other biologically relevant guest molecules [3]. Owing to the great importance of heterocyclic compounds as final products or as reaction intermediates, several different methods are currently used for their construction. Amongst them   chalcones are well known intermediates for synthesizing various heterocyclic compounds. The compounds with the backbone of chalcones have been reported to possess various biological activities such as antimicrobial [4-6], anti-inflammatory [7], antimalarial [8, 9], antileishmanial [10], antioxidant, antitubercular [11, 12], In the present work, we report the reaction of various acetophenone derivatives to form chalcones. The structures of the various synthesized compounds were assigned on the basis of IR, ¹H-NMR spectral data and nitrogen estimation.

 

These compounds were also screened for their antimicrobial activity.

 

EXPERIMENTAL:

Melting points were determined on Stuart apparatus and were uncorrected. IR spectra were recorded on FTIR Perkin Elmer spectrophotometer using KBr disc method. ¹H-NMR spectra were recorded on Bruker-400 MHz FT NMR spectrometer in d6-DMSO. Chemical shifts relative to TMS used as internal standard were obtained in δ unit. Physical and spectral data are shown in tables 1 and 2. The heterocyclic derivatives of chalcone were subjected to antibacterial and antifungal screening using filter paper disc method. The antibacterial activity was tested against various types of bacteria and compared with standard drugs (Steptromycine and Fluconazole) and the results are given in table 3.

 

O-hydroxyacetophenone (0.01 mol) and furfural (0.01 mol) were dissolved in ethanol (25 mL). Sodium hydroxide solution, 10% (25 mL) was added slowly and the mixture stirred overnight at 20-30^o C. The mixture was then washed with cold water until neutral to litmus paper. The crude chalcone (figure-1) was air dried and recrystallized from rectified spirit. The melting point of product was 59^oC and the yield obtained was 83 %.

 

Figure-1:  Synthesis of Chalcone.

 

Synthesis of 2-[2-amino-6-(furan-2-yl)-2H-1,3-oxazin-4-yl]phenol

 

Figure-2:  Synthesis of 2-[2-amino-6-(furan-2-yl)-2H-1,3-oxazin-4-yl]phenol

 

 

Synthesis of 2-({[6-(furan-2-yl)-4-(2-hydroxyphenyl)-2H-1,3-oxazin-2yl]amino}methyl)-1H-isoindole-1,3(2H)-dione.

(0.01mol) product of step-2 in 20 ml methanol was charged in to a three necked flask equipped with a stirrer and dropping funnel and was dissolved completely. To this methanolic solution, (0.01mol) formaldehyde was added drop wise during fifteen minutes. The resultant mixture was stirred for about half an hour to complete reaction of formaldehyde and yield methylol derivative. To this reaction mixture, the methanolic solution of (0.01mol) phthalimide was added drop wise with stirring over the period of half  hour at room temperature and refluxed for one hour at 65-70^oC. After completion of reaction it was allowed to cool and poured in ice water. The solid obtained was filtered off, washed thoroughly with ice water and air dried. The yield of the product is 79% and melting point is 115^oC. The reaction is described in figure- 3.(A).

 

Similarly the compounds (B-E) were synthesized using same procedure using p-aminophenol, p-nitroaniline, imidazole and morpholine. The reaction scheme of all these are shown in figure-3 (A-E).

 

Figure-3: Various derivatives of o--hydroxy acetophenone using Urea.

 

 

Synthesis of 2-[2-amino-6-(furan-2-yl)-1,2-dihydropyrimidin-4-yl]phenol

Same procedure described above was used for the synthesis of 2-[2-amino-6-(furan-2-yl)-1,2-dihydropyrimidin-4-yl]phenol. The variation taken was instead of urea we used guanidine hydrochloride. The reaction scheme is shown in figure-4. Compounds (F-H) were synthesized using morpholine, benzatriazole and p-nitroaniline via this route as shown in figure-5.

 

Figure-4: Synthesis of 2-[2-amino-6-(furan-2-yl)-1,2-dihydropyrimidin-4-yl]phenol

 

Figure-5: Various derivatives of o--hydroxy acetophenone using Gunadine hydrochloride

The data of physical characteristics of synthesized compounds are shown in table-1. Percentage of nitrogen was estimated by Kjeldahl method. All the synthesized compounds were characterized by IR and ¹ H NMR.       The spectral data of synthesized compounds are shown in   table-2.

 

 

Table:1 Characterization data of synthesized compounds (A-H).

Compd	Molecular Formula	Mol.Wt gm/mol	M.P (oC)	Yield (%)	Nitrogen (%)
A	C23H17N3O5	415.39	115	79	10.11	8.78
B	C21H19N3O4	377.39	117	72	11.13	9.77
C	C21H18N4O5	406.39	117	73	13.78	11.86
D	C18H20N4O3	340.37	120	74	16.45	14.87
E	C19H21N3O4	355.38	118	76	11.82	9.75
F	C19H22N4O3	354.40	142	76	15.80	13.66
G	C21H18N6O2	386.40	144	78	21.74	18.78
H	C21H19N5O4	405.40	146	75	17.26	15.67

 

Table: 2. Infra Red / ¹H NHR spectral study of the synthesized compounds.

Compound	Infra Red (cm-1)	1H – NMR (δ ppm)
A	3218 (N-H str.), 2965 (C-H Ar str.), 2855 (C-H str.), 1715 (C=O Amide Str.), 1340(C=N str.), 880 (C-H Ar. def.), 1254(C-O str.), 1443(-C=C- Ar. str.), 1620 (-NH2).	7.34-7.74 (m, 12H, Ar-H), 8.44 (3H, NH), 3.99 (s, 3H, OCH3), 3.60 (s, 2H, CH3)
B	3310 (N-H str.), 2940 (C-H Ar str.), 2910 (C-H str.), 1725 (C=O Amide Str.), 1350(C=N str.), 880 (C-H Ar. def.), 1264(C-O str.), 1435(-C=C- Ar. str.), 1630 (-NH2).	7.42-7.82 (m, 12H, Ar-H), 8.30 (3H, NH), 3.88 (s, 3H, OCH3), 3.59 (s, 2H, CH3)
C	3428 (N-H str.), 2965 (C-H Ar str.), 2865 (C-H str.), 1735 (C=O Amide Str.), 1310(C=N str.), 880 (C-H Ar. def.), 1250(C-O str.), 1455(-C=C- Ar. str.), 1650 (-NH2).	7.33-7.69 (m, 12H, Ar-H), 8.42 (3H, NH), 3.95 (s, 3H, OCH3), 3.99 (s, 2H, CH3)
D	3510 (N-H str.), 2965 (C-H Ar str.), 2855 (C-H str.), 1750 (C=O Amide Str.), 1290(C=N str.), 880 (C-H Ar. def.), 1242(C-O str.), 1460(-C=C- Ar. str.), 1635 (-NH2).	7.60-7.95 (m, 12H, Ar-H), 8.59 (3H, NH), 3.29 (s, 3H, OCH3), 3.88 (s, 2H, CH3)
E	3522 (N-H str.), 2965 (C-H Ar str.), 2855 (C-H str.), 1770 (C=O Amide Str.), 1315(C=N str.), 880 (C-H Ar. def.), 1274(C-O str.), 1438(-C=C- Ar. str.), 1670 (-NH2).	7.40-7.85 (m, 12H, Ar-H), 8.35 (3H, NH), 3.45 (s, 3H, OCH3), 3.78 (s, 2H, CH3)
F	3410 (N-H str.), 2985 (C-H Ar str.), 2855 (C-H str.), 1670 (C=O Amide Str.), 1560 (C=N str.), 880 (C-H Ar. def.), 1254(C-O str.), 1443(-C=C- Ar. str.), 1655 (-NH2)..	7.56-7.75 (m, 12H, Ar-H), 8.73(3H, NH), 3.59 (s, 3H, OCH3), 3.65 (s, 2H, CH3)
G	3428 (N-H str.), 2995 (C-H Ar str.), 2745 (C-H str.), 1735 (C=O Amide Str.), 1320(C=N str.), 880 (C-H Ar. def.), 1250(C-O str.), 1455(-C=C- Ar. str.), 1650 (-NH2).	7.38-7.70 (m, 12H, Ar-H), 8.55 (3H, NH), 3.70 (s, 3H, OCH3), 3.95 (s, 2H, CH3)
H	3522 (N-H str.), 2865 (C-H Ar str.), 2635 (C-H str.), 1770 (C=O Amide Str.), 1325(C=N str.), 880 (C-H Ar. def.), 1274(C-O str.), 1438(-C=C- Ar. str.), 1670 (-NH2).	7.28-7.88 (m, 12H, Ar-H), 8.50 (3H, NH), 3.66 (s, 3H, OCH3), 3.85 (s, 2H, CH3)

 

 

 

Antimicrobial activity:

The synthesised compounds (A-H) were screened for their in vitro antimicrobial activity against Escherichia coli, Pseudomonas aeruginosa and antifungal activity against Aspergillus niger, Aspergillus flavus, by measuring the zone of inhibition in mm. The antimicrobial activity was performed by filter paper disc plate method [13,14] at concentration 100μg/mL and reported in Table-3. Muller Hinton agar & Sabouroud Dextrose agar were employed as culture medium and DMSO was used as solvent control for antimicrobial activity. Streptomycin and Fluconazole were used as standard for antibacterial and antifungal activities respectively.

 

Table: 3. In-vitro antibacterial and antifungal activity of synthesized compounds.

Compound	Zone of inhibition at 100 µg/mL (in mm.)
	Antibacterial		Antifungal
	E c.	P.a.	A.n.	A. f
A	17	16	12	14
B	10	10	14	13
C	16	14	08	10
D	11	12	14	10
E	10	14	13	14
F	10	12	11	14
G	14	12	11	10
H	16	15	13	12
Streptomycin	19	19	-	-
Fluconazole	-	-	16	15

 

RESULT AND DISCUSSION:

All synthesized compounds as well as the reactions that carried out were characterized and monitored by TLC, melting point, nitrogen estimation, IR and ¹H NMR and they all gave satisfactory results as shown in table-2.

 

The compounds were evaluated for their antibacterial activity against various types of bacteria. The compounds  A-H have shown significant antibacterial and antifungal activity in comparison against Streptomycin and Fluconazole at 100µg/mL. Compounds A, C, G and H showed higher antibacterial activity where as other compounds showed moderate to good activity. The antifungal activity in all the synthesized compounds found very good compare to antibacterial activity. Compounds B, D and H showed highest antifungal activity compare to all other compounds. The furfural was reacted with substituted acetophenones to obtain chalcones. Further various seven derivatives were obtained by the described procedure. All the synthesized compounds have shown promising antibacterial and antifungal activities. With suitable molecular modifications the compounds may show better activities.

 

ACKNOWLEDGEMENT:

The authors are thankful to Charutar Vidya Mandal (CVM) Vallabh Vidyanagar’s institutes ISTAR and ARIBAS for providing research facilities. The Authors are also thankful to Sophisticated Instrumentation Center for Applied Research and Testing (SICART) for providing IR and NMR spectral facilities.

 

REFERENCES:

1.       Goodman, MS.; Rose, SD. Molecular recognition of a pyrimidine dimer and photosensitized dimer splitting by a macrocyclic bis(diaminopyridine)J. Am. Chem. Soc. 1991, 113, 9380-9382.

2.       Hung, C.; Hopfner, T.; Thummel, RP. Molecular recognition: consideration of individual hydrogen-bonding interactions J. Am. Chem. Soc. 1993, 115, 12601-12602.

3.       Schmidtchen, FP.; Gleich, A.; Schummer, Selective molecular hosts for anions A. Pure Appl. Chem. 1989, 61, 1535-1547.

4.       Y. Rajendra prasad, A. Lakshmana Rao and R.Rambabu, Synthesis and Antimicrobial Activity ofSome Chalcone Derivatives, E.J. Chem., 2008 ,5 (3),461-466.

5.       Silvia N. López, María V. Castelli, Susana A. Zacchino, José N. Domínguez, Gricela Lobo, JaimeCharris-Charris, Juan CG. Cortés, Juan C. Ribas,  Cristina Devia, Ana M. Rodríguez, Ricardo D. Enriz, In vitro antifungal evaluation and structure-activity relationships of a new series of chalcone derivatives and synthetic analogues, with inhibitory properties against polymers of the fungal cell wall, Bioorg. Med. Chem. 2001,9,1999-2013.

6.       Bhagyesh Baviskar, Sureshbhi Patel, Bhushan Baviskar, S.S. Khadabadi, Mahendra Shiradkar, Design and Synthesis of Some Novel Chalcones as Potent Antimicrobial Agent, Asian J. Res. Chem., 2008,1(2),67-69.

7.       Felipe Herencia, M. Luisa Ferrandiz, Amalia Ubeda, Jose N. Domínguez, Jaime E. Charris, Gricela M. Lobo, M. Jose Alcaraz, Synthesis and anti- inflammatory activity of chalcone derivatives, Bioorg. Med. Chem. Lett., 1998,8,1169-1174.

8.       Xiang Wu, Prapon Wilairat, Mei-Lin Go, Anti malarial Activity Of Ferrocenyl Chalcones, Bioorg. Med. Chem. Lett. 2002,12(17),2299-2302.

9.       Anu Agarwal, Kumkum Srivastava, S.K. Puri, Prem M.S. Chauhan,Synthesis of 4-pyrido-6-aryl-2- substituted amino pyrimidines as a new class of antimalarial agents, Bioorg. Med. Chem., 2005 ,13, 6226-6232.

10.     Todigoppula Narender, Tanvir Khaliq, Shweta, Nishi, Neena Goyal, Suman Gupta. Synthesis of chrominochalcone and evaluation of their in vitro antileishmanial activity, Bioorg. Med. Chem., 2005,13,6543-6550.

11.     Jen-Hao Cheng, Chi-Feng Hung, Shyh-Chyun Yang, Jih-Pyang Wang, Shen-Jeu Won, Chun-Nan Lin, Synthesis And Cytotoxic, Anti-Inflammatory, And Anti-Oxidant Activities Of 2′,5′-Dialkoxyl chalcones As Cancer Chemopreventive Agents, Bioorg. Med. Chem., 2008,16(15),7270-7276.

12.     Yuh-Meei Lin, Yasheen Zhou, Michael T. Flavin, Li-Ming Zhou, Weiguo Nie, Fa-Ching Chen, Chalcones and flavonoids as anti-Tuberculosis agents, Bioorg. Med. Chem., 2002,10,2795-2802.

13.     Sivakumar PM, Prabu Seenivasan V, Vanaja Kumar, Mukesh Doble, Synthesis, antimycobacterial activity evaluation, and QSAR studies of chalcones derivatives Bioorg. Med. Chem. Lett., 2007,17,1695-1700.

14.     Saisivam S, and Kishan VB, Standard method of antifungal activity, Ind J.Microbio., 2006, 46(2),P.13-19.

 

 

Received on 17.05.2013       Modified on 12.06.2013

Accepted on 17.06.2013      © AJRC All right reserved