Synthesis, Characterization and Antibacterial Activity of a New Series of s-Triazines Derived with Quinolines

8-Hydroxy quinoline was synthesized using Skraup reaction. This was condensed with trichloro-s-triazine. The product of the above reaction was allowed to react with triazole derivative. Finally, urea derivatives were allowed to react and the products were characterized by conventional and instrumental methods. Their structures were determined and important biochemical properties were studied


Introduction
Nitrogen containing heterocycles play an important role, not only for life science industry but also in many other industrial fields related to special and fine chemistry.Among them 1,3,5-triazines represent a widely used lead structure with multitude of interesting applications in numerous fields 1 Several derivatives of s-triazine show antibacterial 2 ,antimicrobial 3 , and herbicidal activities 4 .The replacement of a chlorine atom in cyanuric chloride by basic group is greatly facilitated by the ring nitrogen atom of the symmetrically built s-triazine nucleus.2,4,6-trichloro-s-triazine derivatives prepared 5,6 by replacement of one chlorine atom at 0-5 o C, second one at 35-45 o C and third one at 80-100 o C.Quinoline and their derivatives are receiving increasing importance due to their wide range of biological activities as antimalarial, antihypertensive, antiinflammatory, antibacterial, antiasthmatic, antiplatelet activity and as tyrokinase inhibiting activity [7][8][9][10] .In addition, quinolines have also been employed in the study of bioorganic and bioorganometallic processes 11 .Benzotriazole (BT) is an anticorrosive agent well known for its use in antifreeze fluids.It is highly persistent in the environment; therefore, BT is frequently found in runoff emanating from large airports as well as in the surrounding groundwater.Its derivatives such as 5-chloro-1H-benzotriazole, 1-hydroxy benzotriazole and 5-Me-1H-benzotriazole could be used as nitrification inhibitors for fertilizers to increase their effectiveness and reduce the leaching of nitrate-N.Benzotriazole derivatives also are pharmaceutically important.
N-Alkylated benzotriazole derivatives show antibacterial and antifungal activity 12 .Their N-alkyl derivatives were tested in vitro against the protozoa Acanthamoeba Castellanii 13 .Among other urea derivatives, phenyl urea derivatives are widely used particularly in pharmaceutical chemistry.Urea derivatives possess wide therapeutic activities such as antithyroidal, hyponotic and anaesthetic 14 , anthelmintics, anti antimalerial 15 , anti HIV 16 and analgesic activity, antibacterial and diuretic.

Experimental
The reagent grade chemicals were obtained from commercial sources and purified by either distillation or recrystallization before use.Purity of synthesized compounds has been checked by thin layer chromatography.Melting points were determined by open capillary method and are uncorrected.IR spectra are recorded on FT-IR Perkin-Elmer spectrophotometer RX1 using KBr disc. 1 H-NMR spectra are recorded in DMSO-d 6 on a Bruker DRX-400 MHz using TMS as internal standard.The chemical shifts are reported as parts per million (ppm) and mass spectra were determined on Jeol SX-102 (FAB) spectrometer.

Preparation of 8-[(4,6-dichloro-1,3,5-triazine-2-yl)oxy]quinoline(1)
To a stirred solution of cyanuric chloride (9.22 g, 0.05 mole) in acetone at low temperature, the solution of 8-hydroxy quinoline (7.25 g, 0.05 mole) in acetone was added and neutral pH was maintained by adding 10% NaHCO 3 solution.The stirring was continued at the same temperature for three hours.Then stirring was stopped and solution was mixed with crushed ice.The product obtained was filtered and dried.The crude product was purified by recrystallization from DMF to give 85% yield of the title compound.Melting point 245 0 C

Preparation of 8-{[4-(1H-benzotriazole-1-yl)]-6-chloro-1,3,5-trizin-2-yl]oxy}quinoline(2)
To a stirred solution of (1) (14.60 g, 0.05 mole) in acetone at 35 0 C the solution of 1Hbenzotriazole (5.95 g, 0.05 mole) in acetone was added drop wise and neutral pH was maintained by adding 10% NaHCO 3 solution.The temperature was gradually raised to 45 0 C during two hours.Then stirring was stopped and solution was poured into cold water.The solid product thus obtained was filtered and dried.The crude product was purified by recrystallization from DMF to give 75% yield of the title compound.Melting point >300 0 C

Results and Discussion
s-Triazine has three active chlorine atoms at position 2,4,6, which can be replaced by bases.Various s-triazine derivatives were prepared as shown in the scheme 1. O-H stretching peak at 3610 cm -1 disappeared in the product and characteristic C-O-C peak appeared at 1255 cm -1 .andfinal product was also confirmed by missing of C-Cl stretching peak at 750-700 cm -1 .The major characteristic absorption bands are observed at 3400 cm -1 and 1491 cm -1 (broad, N-H stretching of secondary amine), 1653 cm -1 (NH-CO-NH stretching), 821 cm -1 (C 3 N 3 stretching in s-triazine ring).
The 1 H NMR spectra of compound 3a showed the following chemical shifts.The δ at 7.30-7.50ppm is 5H of phenyl ring.A δ observed at 9.14 ppm is 2H of urea moiety (-NH-CO-NH-) appeared by the merge of two signals.More over the structure of compound 3a has been assigned on the basis of elemental analysis (Table 1) supporting the gross formula C 25 H 17 N 9 O 2. This was also confirmed by the mass spectrum, which gave a quasimolecular ion [MH] + peak at m/z 476.Presence of 9-nitronen atoms (from elemental analysis) makes it must to have odd molecular weight.458 peak is the base peak which is due to loss of H 2 O from the 476 peak.477 peak is 27.77% of 476 peak indicating the presence of 25 carbon atoms in the molecule (3a).

Antimicrobial activity
Antimicrobial activity testing was carried out by using broth dilution method.Each purified compound is dissolved in dimethyl sulfoxide (DMSO), sterilized by filtration using sintered glass filter and store at 4 0 C.All the synthesized compounds were screened for their antibacterial and antifungal activities (Table 2 & 3) against the E. coil, P. auregenosa, S.aures, S. pyogenus and the fungi C. albicans, A. niger, and A. clavatus.The compounds were tested at 500, 250, 100 and 50 µg/mL concentration using nutrient agar tubes.The highest dilution showing at least 99% inhibition is taken as MBC (minimal bacterial concentration).Control experiment was carried out under similar condition by using gentamycine, ampicillin, chloramphenicol for antibacterial activity and nystatin, greseofulvin for antifungal activity as standard drugs.
Out of ten synthesized heterocyclic compounds, compound 3b showed equal antibacterial activity as chloramphenicol (against E. coli.) and compound 3f (against E. coli) and 3j (against S. pyogenus) showed equal antibacterial activity as ampicillin.Compound 3a, 3b and 3f showed marginal higher antibacterial activity against P. aeruginosa compared to the other compounds.Against the organism S. aureus, compound 3f and 3j showed comparable antibacterial activity similar to standard drug.
(2) Out of ten synthesized compounds 3f showed equal antifungal activity as greseofulvin (against C. albicans) and less activity against the two other organisms.Compound 3f contains methyl group in meta position, Compound 3f and 3i showed marginal higher antifungal activity against A. niger compared to the other compounds, however less than the standard drugs.The ten compounds against A. clavatus seemed much less effective as antifungal.

Conclusion
Ten cyanuric chloride derivatives were synthesized and characterized for their structure elucidation.Various chemical and spectral data supported the structures thought of.Antibacterial and antifungal studies of these compounds indicated that compound 3b, 3f, 3j were found to be equal active against some bacteria compared to standard antibiotic drugs.However, they could not exhibit appreciable antifungal action.

Table 1 .
Physical and analytical data of title compound and its other substitute derivatives (3a-3j) ClScheme 1. Synthetic route to s-triazine derivatives(3)

.
Antibacterial activity of synthesized compounds 3a to 3j

Table 3 .
Antifungal activity of synthesized compounds 3a to 3j