title: Synthesis and evaluation of substituted diphenyl-1,3,4-oxadiazole derivatives for central nervous system depressant activity.
abstract: BACKGROUND
  Substituted 1,3,4-oxadiazoles are of considerable pharmaceutical interest. 2,5-Substituted diphenyl-1,3,4-oxadiazoles are associated with diverse biological activities by the virtue of -N = C-O- grouping. In the view of wide range of biological properties associated with 1,3,4-oxadiazole, we have synthesized substituted derivatives of 1,3,4-oxadiazole (XIII-XXII), a versatile hydrophobic molecule possessing preliminary CNS properties, with the hope to potentiate the biological activities with lesser or limited amount of toxicities.
  
  
  METHODS
  The synthesis was based on ester substitution of substituted benzohydrazide in presence of hydrazine hydrate followed by cyclization in presence of phosphorus oxychloride. All the synthesized compounds were evaluated for their potential CNS depressant activities. Statistical analysis of the anticonvulsant, antidepressant, and antianxiety activity of the synthesized compounds on animals was evaluated using one-way analysis of variance (ANOVA).
  
  
  RESULTS
  Two compounds 5-(4-nitrophenyl)-2-(4-chlorophenyl)-1,3,4-oxadiazole (XIV) and 5-(4-nitrophenyl)-2-(4-nitrophenyl)-1,3,4-oxadiazole (XV) were found to be the most promising compounds of the series in antidepressant, anticonvulsant and antianxiety activity with no neurotoxicity when compared with standard.
  
  
  CONCLUSIONS
  Among the synthesized compounds, it was found that incorporation of electron withdrawing group at C2 and C5 position of the oxadiazole ring led to high degree of pharmacological activity. Thus compounds 5-(4-nitrophenyl)-2-(4-chlorophenyl)-1,3,4-oxadiazole (XIV) and 5-(4-nitrophenyl)-2-(4-nitrophenyl)-1,3,4-oxadiazole (XV) showed excellent CNS depressant activities. The result of the present investigation may encourage us to develop and/or improve similar other related compounds and it may be assumed that further modifications may produce compounds of better activity with lesser side effects.
authors.affiliation: Department of Pharmaceutical Technology, Meerut Institute of Engineering & Technology, NH-58, Baghpat By-pass Crossing, Delhi-Haridwar Highway, Meerut-250005, India. poonamsingh048@gmail.com.
authors.forename: Poonam
authors.initials: P
authors.lastname: Singh
authors.forename: Pramod Kumar
authors.initials: PK
authors.lastname: Sharma
authors.forename: Jitendra Kumar
authors.initials: JK
authors.lastname: Sharma
authors.forename: Anshu
authors.initials: A
authors.lastname: Upadhyay
authors.forename: Nitin
authors.initials: N
authors.lastname: Kumar