HARDIK ARVINDBHAI PATEL, KIRAN MANUBHAI PATEL, DHRUBO JYOTI SEN AND DILIPKUMAR RAMJIBHAI CHAVDA
The idea has been generated for CNS depression from the rational drug design from the structure of benzodiazepines and barbiturates in which there are closed chain urea moiety having two nitrogens in heterocyclic rings. Our objective was to synthesis such molecule in which this type of linkage must be in closed chain as well as in side chain. The synthesised molecule has three variables of three hetero atoms O/S/N and the CNS depression study has been done with respect to the standard sedative drug and found that the CNS depression activity persists in only urea moiety and there was no CNS depression activity in thiourea and guanidine linkage, but the sleeping time potentiation has been found in all the three compounds are as follows: Compound-A: X=O (urea derivative) > Compound-C: X=NH (guanidine derivative) > Compound-B: X=S (thiourea derivative) because electronegativity of oxygen for urea X:O=3.5 and of sulfur for thiourea X:S=2.4 and of nitrogen for guanidine X:NH=3.1. So the X=O shows the maximum electronegativity with two lone pair of electrons whereas X=S has also two lone pairs but X=NH has one lone pair of electrons, but in case of NH moiety the electronegativity of hetero element (N) is in between the hetero elements (O) for X:O and (S) for X:S. So, the affinity for GABA receptor binding capacity for urea is maximum to block the chloride channel.
