Step-I complexes of 4-substituted thiazolidinone derivative is prepared

:  preparation of Schiff’s Base:

                            A mixture of
2-hydrazinobenzothiazole (1.65gm, 10 mmole) , aromatic aldehyde (10m mole) in
ethanol (20 ml) and a few drops of piperdine was refluxed on a water bath for
four hours. It was cooled to room temperature and poured into crushed ice.The
solid separated was filtrated, dried and recrystallised from ethanol.   M.P.218oC,
yield-2.1gm (70%), (Found S,  12.11%, C14H11N3S
requires S, 12.6%)

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3-(Benzothiazolyl-2′) amino-2-phenyl- 4-thiazolidinone:

                           Mercaptoacetic acid
(0.1 gm,1m mole) was added to a well stirred solution of the hydrazono
derivative of benzaldehyde (0.26 gm,1 m mole) in dry Benzene (15 ml).The
mixture is stirred for 6 hours and refluxed for four hours during which the
desired compound precipitated .It was filtrated ,dried and recrystallised from
ethanol. M.P. 215oC, yield-0.22 gm (68%), (Found: S, 19.59%  C16H13N3OS2
requires S,19.57%). IR(KBr ?cm-1):
746.45 (C-S str), 1487.12 (C=C str) 1556.55
(C=N str), 1714.72(C=O str), 3030.17(Ar-H str), 3226.91(N-H str).

2-(Benzothiazolyl-2′)hydrazono-3-phenyl 5-arylidene-4-thiazolidinone (Compound-K)                                      A mixture
of 3-(benzothiazolyl-2′)ammino-2-phenyl 4-thiazolidinone (0.32 gm, 1 m mole),
benzaldehyde (0.1 gm, 1 m mole), fused sodium acetate (0.2 gm) in glacial
acetic acid (10ml) was heated under reflux for four hour. It was cooled and
poured into ice cold water .The yellow solid separated was filtered, washed in
water ,dried and recrystalised from ethanol. m.p. 210oC ,yield-0.24
gm (60%). (Found: S, 18.20% C23H17N3OS2
requires S, 18.18%). In this method compound K is prepared. Similarly compound
L is prepared by taking P-Anisaldehyde in place of Benzaldehyde during the
fourth step.The  compounds M and N is
prepared by replacing benzaladehyde and taking O-chlorophenyl as a substituent
in the first step and further step is  same as that of  first two compounds.

phase solubility study  :

aqueous phase solubility of different substituted 4-thiazolidinone derivatives
at various conc. of ?-cyclodextrin
has been studied by Higuchi Connors method 15. An accurate
amount of the substance are taken in a conical flask with different concentrations of   ?-cyclodextrin(0-10mM)  exceeding their aqueous solubility are shaking
in a rotatory flask shaker at room temperature .The shaking process will
continue for a periods of 48 hour till it attains equilbrium.These solution is
then filtrated through the whatmann filter paper and are analyzed by UV visible
spectrometer. At the end, absorbance of various values of at ?max were plotted against different
concentrations of ?-cyclodextrin as given in fig 1.  

  Synthesis of Inclusion complexes:

inclusion complexes of 4-substituted thiazolidinone derivative is prepared
according to co-precipitation method16-18. Required concentrations of
compound solution are prepared and added drop wise to a previously stirred
?-cyclodextrin solution. Stir the mixture at room temperature for 48 hour and
filtered. Then the content is cooled for another 48 hour in a refrigerator. At
the end, the precipitate is filtered through G-4 crucible, washed with
distilled water and dried in air for 24hour.

Evaluation of
Antibacterial activity

                                  The antibacterial activity of compounds was studied as
per cup-plate method 19,20. The solutions of the test compounds were prepared
in dimethyl sulphoxide (DMSO) at 500?g/ml. The bacterial strains of Escherichia
coli (MTCC 40), Staphylococcus
aureus  (MTCC
87) and Proteus Vulgaris (MTCC 426)  were inoculated into 100ml of the sterile nutrient
broth and incubated at 37±1°C for 24 hour. The density of the bacterial
suspension was standardized by McFarland method. Well of uniform diameter (6mm)
were made on agar plates, after inoculating them separately with the test
organisms aseptically. The drug (500?g/ml) and the test compounds (500?g/ml)
were introduced with the help of micropipette and the plates were placed in the
refrigerator at 8-10°C for proper diffusion of drug into the media. After two
hour of cold incubation, the Petri plates were transferred to incubator and
maintained at 37±2°C for 18-24 hour. Then the Petri plates were observed for
zone of inhibition by using venire scale. The results were reported by
comparing the zone of inhibition shown by the test compounds with standard drug
(Tetracycline). The results were the mean value of zone of inhibition of three
sets measured in millimetre and the data were
presented in Fig.3 to 5

Evaluation of Antioxidant

                     In the present study DPPH
(2, 2-Diphenyl-1-picrylhydrazyl) scavenging assay method is used for screening
the antioxidant activity of the synthesized compounds as suggested by Tagashira
and Ohtake 21. Test sample solution is prepared in 100µg/ml concentration in
ethanolic DPPH. After vortexing, the mixture is incubated for 10 minutes at
room temperature. The absorbances of the samples are measured at 517 nm. The
activity of the sample is calculated by finding the difference of absorbance
between a test sample and a control. Butylated Hydroxyl Toluene (BHT) is used
as reference substance (Table-4).


              The formation of inclusion
complexes of the compounds with ?-cyclodextrin is confirmed from the changes in
melting point, colour and spectral characteristics with respect to their
compounds (Table 1&2).The colours of the compounds is yellow,pale
yellow,brown and light brown respectively.But their corrspodending inclusion
complexes  are different colours.The
melting point of the compounds are 170oC, 175oC, 225oC
and 232oC   respectively,
whereas the melting point of their corresponding inclusion complexes are 182oC,183oC,
229oC and  237oC
respectively. It is due to the fact that extra amount of thermal energy is
required to bring the molecules out of the cavity of the ?-cyclodextrin .The
percentage of yield of the compounds is found to be declined in the formation
of inclusion complexes as compared to the original compounds.

1:Physical  properties of compounds and
their inclusions