5. Biological Activity:

5.1. Evaluation of Antibacterial activity

The compounds prepared herein were screened for their potential biological activities such as, antibacterial activity1 using both Staphylococcus aureus (gram positive)(TabIe-l) and Salmonella typhimurium (gram negative) bacteria.The concentrations of the substrates used were 500, 200, 100, 10 and 0.lpg/ml.57
Cephalexin was used as standard compound.
5.1.1. Antimicrobial activity:
Compounds were screened in vitro for their antibacterial activity against S. aureus,and S. typhi (Table-1) .The minimum inhibitory concentration (MIC) was determinedusing tube dilution method according to the Standard procedure DMSO was used as asolvent and blank. Cephalexin (MIC: 5 pg/ ml) was used as the antibacterial standard.
Tube Dilution Method: In this method, equal volumes of nutrient broth were takenup in six test tubes; same volume of sample was added to the first test tube and thendecreasing dilutions were prepared. A sample control and a solvent control were alsomaintained. Finally, same volumes of a 24 hr old culture (106 cfu/ml) were added toall the test tubes and then incubated at 37°C for 24 hr. Next day a loopful of themixture was streaked on to a fresh nutrient agar plate to find out the minimuminhibitory concentration (MIC pg/ ml).

Table 3: Antimicrobial activity data (MIC jigm/mL)
(STAPHYLOCOCCUS AUREUS)
Symbols:
Total inhibition, no growth of organism = –
Poor growth compared to controls = P
Medium growth compared to controls = +
Confluent growth, no inhibition = ++

SAMPLE
ID
STRUCTURE
CONCENTRATION
0.1
?g
/ml 1
?g
/ml 10
?g
/ml 100
?g
/ml 200
?g
/ml 500
?g
/ml Approx
MIC
3
+
+ +
+ + P P _ 500
?g
/ml
4a +
+ +
+ + P P _ 500
?g
/ml
4b +
+
+ p _ _ 200
?g
/ml
4c +
+ +
+ + P _ 500
?g
/ml
4d
+
+ +
+ + P _ _ 200
?g
/ml
4e +
+
P P _ _ 200
?g
/ml
4f
+
+ +
+ + + _ _ 200
?g
/ml
4g
+
+
+ P _ _ 200
?g
/ml
4h
+
+ +
+ + + + P >1000
?g
/ml
4i
+
+ +
+ +
+ P _ _ 200
?g
/ml
4j
+
+ +
+ + + P P 1000
?g
/ml
4k
+
+ +
+ +
+ + P _ 500
?g
/ml
4l +
+ +
+ + + P _ 500
?g
/ml
4m
+
+ +
+ + P P _ 500
?g
/ml

3.1. CONCLUSION

All the compounds synthesised herein were screened for their potential biological activity such as, antibacterial activity against Staphylococcus aureus (gram positive) and Salmonella typhimuiium (gram negative) bacterial strains. The in vitro activity studies showed promising results towards the testing. Cephalexin was used as a reference standard for antibacterial testing, The compounds tested for antibacterial activity against Salmonella typhimuiium showed promising activity, however, they were found to have poor activity against Staphylococcus aureus.