CHEMICAL AND PHARMACOLOGICAL EVOLUTION OF SOME SYNTHESIZED CHALCONES AND HETROCYCLIC COMPOUNDS

Pharmaceutical chemistry is on quality aspects of medicines and aims to assure fitness for the purpose of centuries medicinal chemistry as a magnanimous field of getting a from the compounds for synthesis of newer and complex molecules possessing medicinal activity while the transit from the earth to a synthetically furnished laboratory. Medicinal chemistry or pharmaceutical chemistry is a discipline at the intersection of chemistry and pharmacology involved designing, synthesizing Chalconesis under third kingdom, theProstita. Based on differences in cellular organization and biochemistry, the kingdom prostita has been divided into two groups, Prokaryotes and Eukaryotes. Bacteria and blue green algae are prokaryotes while fungi, other algae, slime moulds and protozoa are eukaryotes. Anti-fungal drugs are among the most frequently prescribed preparations because of their fungal activity. They are widely used for the treatment of the fungal diseases such as Candidiasis and Apergillosis. These agents prevent from fungal infection. Anti-oxidant drugs are among the most frequently prescribed preparations prevent Oxidation. Broussochalcone A (BCA), isolated from Broussonetia papyrifera Vent. inhibited iron-induced lipid peroxidation in rat brain homogenate in a concentration-dependent manner with an IC 50 of 0.63 ± 0.03 µM which indicated that BCA ( 59 ) was a powerful antioxidant with versatile free radical-scavenging activity. On the other hand, BCA suppressed NO production concentration-dependently, with an IC 50 of 11.3 µM in LPS-activated macrophages (Cheng et al. 2001). In search for new cancer chemopreventive agents some new compounds were isolated from the roots and stolons of licorice (Glycyrrhiza glabra) which were tested in an authentic peroxynitrite anti-oxidant assay in which isoliquiritigenin (60) , and paratocarpin B (61) were found to be the most potent anti-oxidant agents (Chin et al. 2007).

Broussochalcone A (BCA), isolated from Broussonetia papyrifera Vent. inhibited iron-induced lipid peroxidation in rat brain homogenate in a concentration-dependent manner with an IC 50 of 0.63 ± 0.03 µM which indicated that BCA (59) was a powerful antioxidant with versatile free radical-scavenging activity. On the other hand, BCA suppressed NO production concentration-dependently, with an IC 50 of 11.3 µM in LPS-activated macrophages (Cheng et al. 2001). In search for new cancer chemopreventive agents some new compounds were isolated from the roots and stolons of licorice (Glycyrrhiza glabra) which were tested in an authentic peroxynitrite anti-oxidant assay in which isoliquiritigenin (60), and paratocarpin B (61) were found to be the most potent anti-oxidant agents (Chin et al. 2007).
A series of 2"-hydroxy-chalcones were synthesized and tested for their antioxidant and lipoxygenase inhibitory activity and an extensive structure-relationship study revealed that among the tested compounds chalcone 62 possess an appealing pharmacological profile combining high antioxidant and lipid peroxidation activity with potent soybean LOX inhibition (Detsi et al. 2009).
A novel series of nitrogen-containing chalcones were synthesized and screened for anti-inflammatory related activities such as inhibition of cyclo-oxygenase 2 (COX-2), trypsin and β-glucuronidase. The results of the studies reveal that the chalcones with N-methyl piperazine methyl (63) and piperidine methyl (64) substitution seems to be important for inhibition of β-glucuronidase whereas the chalcones with piperidine methyl (65) substitution were observed as effective inhibitors of COX-2 (Bandgar et al. 2010).

Tyrosinase Inhibitor
Tyrosinase (monophenol monooxygenase), also known as polyphenol oxidase (Whitaker, 1995), is a coppercontaining enzyme widely distributed in nature. It catalyzes two reactions involving molecular oxygen in the melanin biosynthesis pathway: the hydroxylation of monophenols to o-phenols (monophenolase activity), and the oxidation of the o-phenols to o-quinones (diphenolase activity) (Seo et al. 2003). Isoliquiritigenin (60) can inhibit both mono-and diphenolase tyrosinase activities with IC 50 was 8.1 µM, when tyrosine was used as substrate, suggesting that chalcones may serve as candidates for skin-lightening agents (Nerya et al. 2003). Different tetrahydroxychalcones, the commercially available Butein (10) and other three which were synthesized and evaluated for the contribution of the different functional groups of the tetrahydroxychalcones to their inhibitory potency on tyrosinase, with a view to optimizing the design of whitening agents and showed that a 2,4-substituted resorcinol subunit on ring B contributed the most to inhibitory potency and found two very active tyrosinase inhibitors, 66 and 67 with IC 50 of 0.2 and 0.02µM, respectively (Khatib et al. 2004 The 4"-(p-toluenesulfonylamino)-4-hydroxychalcone (TSAHC) (69), which bears inhibitory chemotypes for both αglucosidase and tyrosinase, was evaluated for tyrosinase activity and depigmenting ability relative to compounds designed to only target tyrosianse activity and showed that TSAHC significantly decreased three main tyrosinase related protein in melanin biosynthesis, tyrosinase, TRP-1 and TRP-2 (Seo et al. 2010).

Research Envisaged
Pyrazole derivatives have aroused considerable interest of chemists due to their versatile practical applications as well as their wide range of biochemical properties. Pyrazole have been reported to posses a broad spectrum of biological activities namely , antifungal,antioxidant, activities. Some pyrazole derivatives are also showing CNS depressant and analgesic activities in animal models. Due to its wide range of biological activity pyrazole ring constitutes a relavent synthetic target in pharmaceutical industry. (Nowakowska, 2007;Dimmock et al. 1999;Batovska and Todorova, 2010).
The stability and broad range of promising pharmacological properties inspired chemists to synthesize and study more chalcone derivatives since structural modifications can lead to different bioactivity. Extensive literature survey revealed that pyrazole derivatives in particular has received a considerable interest in recent years. In the present work the effort is made to develop a convenient method for the synthesis of substituted chalcones. Understanding the importance of chalcones for their antimicrobial activity, some novel substituted chalcone derivatives were synthesized by structural modification on the chalcone rings. Finally the synthesized compounds were screened for their antimicrobial activity and other activities.
IR spectra were refcorded on a FT-IR Shimadzu DZU 8400S spectrophotometerin KBr disks and Elemental analysis were done on a Perkin-Elmer 2400C, H, N analyzer and values were found to be within the acceptable limits of the calculated values.
The 1 H-NMR spectra of the synthesized compounds in CDCl 3 /DMSO were recorded at 400 MHz by Bruker Advance II 400 NMR spectrometer. Chemical shift values are given in scale using tetramethylsilane (TMS) as an internal standard. Significant 1 H-NMR data are written in order: number of protons, multiplicity (b, broad; s, singlet; d, doublet; dd, double doublet; t, triplet; m, multiplet), coupling constants in Hertz, assignment.The FAB mass spectra (at room temperature) were recorded on TOF MS ES + mass spectrometer. All these above analysis were done at SAIF, Punjab University, Chandigarh. Progress of reaction and purity of synthesized compounds was ascertained by thin layer chromatography (A) using Silica gel G and Iodine vapors as detecting agent.

Synthesis of intermediates Synthesis 3-N-(N'-p-chlorophenylurenyl)acetophenone
Synthesis of methyl ketone derivative was carried out by making m-amino acetophenone react with the pchlorophenyl isocyanate. A mixture of the m-aminoacetophenone (2.7 g, 20 mmol) and p-chlorophenyl isocyanate (3 g, 20 mmol) was dissolved in dry acetone (100 mL). The mixture was stirred for 6-7 hr at room temperature, filtered, and the crude compound urenylacetophenone was recrystallized using ethanol (Sonmez et al., 2011).

Synthesis of 3'-N [(2'', 5''-dichlorophenyl) sulfonyl-amide] acetophenone
The intermediate compound 3"-N[(2"",5""-dichlorophenyl) sulfonyl-amide] acetophenone was synthesized adopting the procedure described by Leon et al. (2007) with some modifications (Figure ). A mixture of 3-aminoacetophenone (2.7 g, 20 mmol) and 2, 5-dichloro-benzene sulfonyl chloride (4.9 g, 20 mmol) in 5 mL of chloroform was stirred at room temperature (rt) for 3-6 hr. The resulting precipitate was washed with acetone, filtered, and the crude material obtained was recrystallized in acetonitrile to give pure compound 3"-N[(2"",5""-dichlorophenyl) sulfonyl-amide] acetophenone..  To the solution of the appropriate chalcone 1a-1p (4 mmole) in 10 mL of n-butanol, (0.55 g, 4 mmole) of nicotinic acid hydrazide was added and the reaction mixture was refluxed for 8-10 hr. The excess of solvent was removed under reduced pressure and the reaction mixture was cooled on an ice bath. The products precipitated out at low temperature were washed five times with 50 mL distilled water, reconstituted in minimum amount of methanol and dried under reduced pressure. This product was further purified by crystallization from the ethanol-DMF mixture (1:1). Purity of the products was checked by TLC using mixture of acetone and petroleum ether (

Synthesis of trisubstituted pyrazolines (2a-2p) General method for synthesis of 1, 3, 5-trisubstituted pyrazolines (2a-2p)
1,3,5-trisubstituted pyrazolines (2a-2p) were synthesized according to the scheme depicted in Figure 4.6 (Ozdemir et al., 2008).In this method, chalcone and nicotinic acid hydrazide were refluxed in n-butanol in order to synthesize the desired product (Kini and Gandhi, 2008). Factors such as the structure and position of the substituents have profoundly influenced the rate of the reaction. The generally accepted interpretation of this reaction, involves the initial formation of an aryl hydrazone with subsequent nucleophilic attack of nitrogen upon the carbon-carbon double bond at  position. Hence the electropositive nature of  carbon may control the overall rate of the reaction. The electropositive nature of  carbon is controlled by the aromatic ring directly connected to it. Halogens being electron withdrawing in nature significantly increase the positive character of  carbon lead to faster reaction while electron donating alkyl and alkoxy groups contributed for slower reaction. To the solution of the appropriate chalcone 1a-1p (4 mmole) in 10 mL of n-butanol, (0.55 g, 4 mmole) of nicotinic acid hydrazide was added and the reaction mixture was refluxed for 8-10 hr. The excess of solvent was removed under reduced pressure and the reaction mixture was cooled on an ice bath. The products precipitated out at low temperature were washed five times with 50 mL distilled water, reconstituted in minimum amount of methanol and dried under reduced pressure. This product was further purified by crystallization from the ethanol-DMF mixture (1:1). Purity of the products was checked by TLC using mixture of acetone and petroleum ether (40:60 V/V) as mobile phase.

Results And Discussion:-
All the synthesized substituted chalcone and pyrazoline derivatives remitted in products with good yield. Purity of all the synthesized compounds was checked by their melting point as well as TLC. The structure of synthesized compounds has been established and confirmed by spectral and elemental data obtained viz, FT-IR, 1 HNMR and Mass. The synthesized compounds were screened for , Antioxidant ,Antifungal activity.

Antioxidant Activity Nitric oxide Scavenging Activity:
Among all the compounds tested, B05 and B06 showed moderate antioxidant activity and remaining compounds showed mild activity as compared to that of standard Ascorbic acid.

Average of triplicate ± Standard deviation # Clotrimazole -no zone of inhibition
It is observed fro te table 5.2 that all the compounds exhibited considerable inhibitory action specially against A. niger and R. oryzae. However, their action has been found to be very weak against A. flavus. Compounds 2m, 2o, 2p, 3i and 3p have shown high potency specially against A. niger, R. oryzae and A. flavus.

Summary And Conclusion:-
With increasing resistance to available antimicrobial drugs, intensive drug discovery efforts aimed at developing new antimicrobial drugs or modifying existing agents are ongoing. In this context, chalcones and Pyrazoline are promising candidates, as these individually possess multifarious pharmacological profiles including antimicrobial activities with different mode of action. The substitution on these two pharmacophores into novel scaffolds and evaluation of their biological activities have not yet been reported. The strategy to synthesis of designed compounds 2a-2p and 3a-3phas been shown in Fig   Fig. 6.1:-The synthesis of the designed compounds 1a-1p, 2a-2p, 3a-3p In the first step, syntheses of chalcones 1a-1p were carried out by Claisen-Schmidt reaction and products were purified by recrystallization from methanol (60-70% yield). In the second step, chalcones and nicotinic acid hydrazide or thiosemicarbazide were refluxed in n-butanol or hot ethanol respectively, in order to synthesize the desired products. Purity of the compounds was checked on TLC plates (silica gel G) which were visualized by exposing to iodine vapours.
Physico-chemical characterization, melting point, FT-IR, 1 H-NMR mass spectral and elemental analysis of the synthesized compounds were done. The results showed that the observed values are in full agreement with the expected values and confirm the anticipated structures of synthesized compounds. The IR spectra of synthesized compounds showed absorption bands which are characteristic of the anticipated structure of the synthesized compounds. The NMR spectra of synthesized compounds showed signals for both aliphatic and aromatic protons, characteristic of the anticipated structure of the synthesized compounds. The fragmentation patterns obtained in the mass spectra also confirm the anticipated structures of the synthesized compounds.
All the synthesized compounds were found to be soluble in most of the organic solvents (chloroform, DMSO, ethyl acetate, acetone and dichloromethane) and insoluble in water.
It is also observed from the The analgesic activity of the sixteen chalcones (2a-2p) has been evaluated by using acetic acid induced writhing method using aspirin as the standard drug. The observed analgesic activity of chalcones and pyrazoline derivatives by writhing method is presented in Table 5.4 and Fig 5.2.
The synthesized compounds (2a-2p) showed analgesic activity (percent inhibition) ranging from 16.48 to 70.39%. It was noted that compounds 2a, 2b, 2h, 2o and 2p showed significant analgesic activity throughout the test period. The activity of compound 2o and 2p are very much comparable to that of standard reference drug aspirin. It indicates that they are effective against acetic acid induced writhing model.
In conclusion, novel pyrazoline derivatives (2a-2p, 3a-3p) were synthesized and their antileishmanial activity against Leishmania donovani was evaluated. Compound 2p and 3p showed better activity in comparison to Pentamidine and Sodium Stibogluconate. As a consequence of the above results and considerations, these molecules can serve as promising prototypes for the development of potent antileishmanial agents.
These observations indicated that these chalcone and 2-pyrazoline derivatives constitute attractive chemical scaffold for the establishment of new chemical entities with antimicrobial, anti-inflammatory and analgesic activities.