Pharmacognosy

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Browsing Pharmacognosy by Author "A. Bekhit, Adnan(PhD)"

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    Synthesis and Biological Screening of Some Pyrazole Derivatives as Antimalarial and Antileishmanial Agents
    (Addis Ababa University, 2012-06) Tuha, Abdu; A. Bekhit, Adnan(PhD)
    Malaria and leishmania are very common parasitic diseases of the developing world and drug resistance has hindered their efficient control. Pyrazole derivatives were synthesized using aldol condensation and subsequent cyclization reactions. The compounds were synthesized in a good yield (71.39%-95.23%). The compounds were purified by recrystallization and their chemical structure was characterized by elemental microanalysis, IR, and 1HNMR spectroscopy. In vivo antimalarial and in vitro antileishmanial activity was conducted using four day suppression test and Alamar blue reduction method, respectively. The results for antimalarial activity conducted using P. berghei infected mice at a dose level of 48.46μmol/kg/day showed that all the synthesized compounds have lower activity than the standard drug chloroquine phosphate. Compound IIc, 1-phenyl-4-(3-(thiophen-2-yl)-4,5- dihydro-1H-pyrazol-5-yl)-3-p-tolyl-1H-pyrazole, showed relatively the highest % suppression, 63.40%. The result for antileishmanial activity test revealed that all the synthesized compounds except compound IIb had better antileishmanial activity than the standard drug miltefosine (IC50= 3.1911 μg/ml). All of the synthesized compounds except compounds III and IIIb exhibited lower antileishmanial activity compared to the standard drug amphotericin B deoxycholate (IC50=0.0460 μg/ml). Compound IIIb, phenyl pyrazoline with propanoyl side chain, 1-(3-phenyl-5-(1-phenyl-3-p-tolyl-1H-pyrazol-4-yl)-4,5- dihydropyrazol-1-yl)propan-1-one, was found to be the most active (IC50= 0.0112) and two hundred eighty five and four fold more active than the standards miltefosine and amphotericin B deoxycholate, respectively. Keywords: pyrazole, in vivo antimalarial activity, in vitro antileishmanial activity.