Preparation and Antimicrobial Activity of s-Triazine Hydrazones of 7-Hydroxy Coumarin and their Metal Complexes

Metal complexes of 7-hydroxy coumarin hydrazone of s-triazine derivatives derived from 7-hydroxy-8-aceto-N-(4’,6’-dichloro-1’,3’,5’-striazine) coumarin hydrazone and transition metals have been synthesized and screened for their antibacterial, antifungal and antiseptic activity. The geometry of the complexes has been proposed. The ligand system co-ordinates with the metal ion in a bidentate manner through the nitrogen atom of hydrazone group.


Introduction
Coumarins are naturally occurring compounds which are known to have biological activities 1 .Some coumarin derivatives possessing carboxamide moiety are found to have diuretic, analgesic myorelaxant 2 , antifungal 3 and anthelmintic activities 4 .It is suggested that the compounds having antimicrobial activity may act either by killing the microbe or blocking their active site [5][6][7] .
The literature survey reveals that no work has been done on the antimicrobial, antiseptic effect of this hydrazone s-triazine derivative of 7-hydroxy coumarin and it's metal complexes.Hence, this paper reports the synthesis and antibacterial, antifungal activity of 7hydroxy-8-aceto-N-(4',6'-dichloro-1',3',5'-s-triazine) coumarin hydrazones of coumarin ligand and its metal(II) complexes to know whether these biological activity of the ligand is enhanced by the presence of metal ion upon coordination.
Shimadzu 435 FT IR Spectrophtometer by KBr technique.Elemental analysis was done using CARLO ERBA 1106 Micro analyser.
The FT IR spectra were recorded in the range of O-H stretching band at 3650-3400 cm -1 .
IR spectra of all the complexes exhibit a broad band around 3270 cm -1 and a sharp peak in that range.These peaks can be assigned to -OH stretching and bending vibration, which indicates the presence of coordinated water molecule in the complexes The ligand band at 3370 cm -1 corresponding to -NH has been shifted to ±25-40 cm -1 in the complexes, which indicates the coordination of metal and ligand through nitrogen atom 8 .
The ligand band at 1070 cm -1 corresponding to -C-O-C has been shifted to ± 25-35 cm -1 in the complexes, which indicates the coordination through oxygen atom 9 .

Antibacterial activity
The antibacterial activity of the compounds was tested by paper method (also called as agar diffusion method) as described by Bryant 10 .For bacterial activity nutrient agar was used.
The culture of above organism was prepared in distilled water.Then culture was poured over the surface of the media under sterile condition and then it was allowed to stand for few minutes and then remaining culture was drained off from media and dried.5 mm diameter paper discs were prepared and were sterilized in autoclave after dipping the disc in the suspension of the compounds.They were dried to remove the remaining alcohol.
Then these paper discs were put in Petri dish containing culture coated media The paper discs were allowed to settle on media and then all the Petri dishes were incubated for 20 to 24 hours at 37 o C after incubation the zone of inhibition was measured.

Antifungal activity
The fungi used as test organisms is Aspergillus niger.The fungi was grown on slants for 4 to 5 days till maximum sporulation was observed.The spore suspension was prepared by adding 5 to 8 mL of sterile distilled water in the slants and scraping with nicrome wireloop.
The spores suspension was poured on the surface of the media in Petri dish.The testing compounds were taken in cups at concentration of 10 mL per cup with appropriate solvent control.The plates were then incubated at 37 o C for 24 to 48 hours and sensitivity reading was recorded (zone of inhibition).Antimicrobial activity is represented in Table 2.The cultures used for the bacterioststic study were as follow: i) Escherchia coli and staphylococcus aureus for antibacterial activity, ii) Streptococcus pyogenes and P. klebsiella for antiseptic activity and iii) Aspergilius niger for antifungal activity Some drugs taken for comparison are garamycin, ampicillin, penicillin and chloramphenicol.The synthesized compounds were used for study and their activity measured in terms of zones of inhibition given in the Table 3.

Results and Discussion
All parameters which we have discussed above are in well agreement with given structure (Scheme 1).From Table 2, It can be concluded that the Cu(II),Fe(II) and Fe(III) complexes showed higher activity where the other complexes have moderate activity.It is clear that all the compounds have displayed maximum activity against S. aureus Table 3. Zone of inhibition against standard drugs.

7 -Scheme 1 .
Scheme 1. Hydrazone and their chelates.The antimicrobial activity data clearly illuatrates that the metal complexes have significant antibacterial and antifungal activity against tested organism.From Table2, It can be concluded that the Cu(II),Fe(II) and Fe(III) complexes showed higher activity where the other complexes have moderate activity.It is clear that all the compounds have displayed maximum activity against S. aureus Table3.Zone of inhibition against standard drugs.

Table 2 .
Antimicrobial activity of compounds.