Synthetic and Antimicrobial Studies of Some New Chalcones of 3-Bromo-4-( p-tolyl sulphonamido ) acetophenone

Eleven new chalcones have been sysnthesised by condensing 3bromo-4-(p-tolyl sulphonamido) acetophenone with different aromatic aldehydes using the method or Rohrman et al. The antimicrobial activity of these chalcones has been tested by adopting “paper disc diffusion plate method”, against various pathogenic fungi(10) and bacteria (9). It has been found that the chalcones have considerable antifungal activity but less antibacterial activity. The results show that these chalcones may find use as antifungal agents.


Introduction Introduction
Sulphonamides are well known for their therapeutic activity 1 , chalcone derivatives also possess anthelmintic 2 2 , germicidal 3 .Antimicobial 4 4--5 5 and carcenogenic 6 6 activities.It was throught worthwhile to synthesise some bromo sulphonamido chalcones and study their antimicrobial activity against various fungi and bacteria.

Preparation of 3-bromo-4-(p-tolyl sulphonamido) acetophenone :
It is also accomplished into two steps: (a) Synthesis of 3-bromo-4-amino acetophenone -It was prepared by acetylation of acetanilide by "Friedel-Craft's reaction" and the acetylated product then subjected to bromination to get bromo-aceto acetanilide.To separate the side chain acetanilide dissolved in pyridine and residue was taken and hydrolysed in presence of alcoholic KOH solution to get 3-bromo-4-amino acetophenone.(b) Condensation of 3-bromo-4-amino acetophenone with p-tolyl sulphonyl chloride -Solution of 3bromo-4-amino acetophenone and p-tolyl sulphonyl chloride in benzene were mixed together and concentrated on water bath.The product was crystallised from ethanol.

Preparation of 3'-bromo-4-(p-tolyl sulphonamido) chalcone
To a solution of 3-bromo-4-(p-tolyl sulphonamido) acetophenone (0.01 mole) and an aromatic Aldehyde (0.01 mole) in minimum quantity of hot aldehyde free alcohol, added 10% (10 ml) of aq.NaOH.The mixture was stirred for 3 hours at 25-30 o C and kept at 0 o C for 24 hrs.The product was filtered and recrysytallised from ethanol.Melting points were recorded on Toshniwal melting point apparatus and are tabulated in T Table able --I.I.The chalcones thus prepared were characterised by halochromium test with conc.H 2 SO 4 and their IR 7 7 and UV 8 8 spectra.

Investigations on the Antimicrobial Activity of the chalcones:
The antimicrobial activity of these chalcones was tested by "paper disc diffusion plate method 9 9 ".For the determination of antifungal activity, about 20 ml of sterilized PDA -(potato-dextrose-agar) and in case of antibacterial screening, oxoid nutrient medium was poured in each sterilised petridish and before gelation of the media, about 2 ml of homogeneous mixture of fungi/bacteria in cool sterilise broth of potato and dextrose/beef extract and peptone respectively was mixed in each petridish.After half an hour, when the media was gelatinized, discs of 6 mm size prepared from Whatman filter paper (No.1) thoroughly moistened with the solution of chalcone (4%) in ethylene glycol were placed over the seeded media and incubated at 32 ±1 o C and 28 ±1 o C for 72 hours in case of fungi and 24 hours in case of bacteria respectively.
Activity of standard antifungal drug, gresiofulvin and antibacterial drug, streptomycin were also checked under the same conditions and concentration.Solvent ethylene glycol also tested for their antimicrobial activity and has shown no activity.
The experiments were performed in duplicate and average zones of inhibition in mm (including the size of the discs have been recorded and tabulated in Tables II Tables II and III III ).

Results and Discussion
On going through the results of antifungal activity ( 4-Nitro-3'-bromo-4'(p-tolyl sulphonamido) chalcone inhibits the growth of Gleosporium sp. as equivalent to the standard gresiofulvin and its activity is 70% against Chaetomium sp.
Remaining chalcones have shown considerable activity against most of the tested fungi; except against Aspergillus niger and Absidium sp.against which all these compounds are inactive.
The results of antibacterial activity has shown that 4-methoxy-3'-bromo-4'(p-tolyl sulphonamido) chalcone have 72.41%activity against Lactobacillus sp. and activity of 2,4-dihydroxy-3'-bromo-4'-(ptolyl sulphonamido)chalcone against Pseudomonas putida is also good 75.86% to the standard 'streptomycin'.None of the chalcones have found to be active against Rhizopus lequminosarum, Serratia bachoria and Salmonella typhi (Table III Table III).On the basis of the results of these antimicrobial efficacies, it can be concluded that these chalcones may find use as antifungal agents.