Preparation of Some New Pyrazolo[1,5‐a]pyrimidines and Evaluation of Their Antioxidant, Antibacterial (MIC and ZOI) Activities, and Cytotoxic Effect on MCF‐7 Cell Lines

Abstract

AbstractThis study aims to synthesize some novel pyrazolo[1,5‐a]pyrimidine derivatives, and investigate their biological activities. These compounds exhibited good to high antioxidant activities [2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) radical scavenging capabilities]. Among them, Ethyl 5‐(2‐ethoxy‐2‐oxoethyl)‐7‐hydroxy‐2‐methylpyrazolo[1,5‐a]pyrimidine‐3‐carboxylate (3h) showed the highest antioxidant activity [Half‐maximal Inhibitory Concentration (IC50)=15.34 μM] compared to ascorbic acid (IC50=13.53 μM) as a standard compound. Their antibacterial activities were investigated against two Gram‐positive bacteria (Bacillus subtilis, and Staphylococcus aureus) and two Gram‐negative bacteria (Pseudomonas aeruginosa, and Escherichia coli). The results showed that Ethyl 7‐hydroxy‐5‐phenylpyrazolo[1,5‐a]pyrimidine‐3‐carboxylate (3i) has the best antibacterial activity against Gram‐positive B. subtilis [Zone of Inhibition (ZOI)=23.0±1.4 mm, Minimum Inhibitory Concentration (MIC)=312 μM]. Also, the cytotoxicity of these compounds was assessed against breast cancer cell lines [human breast adenocarcinoma (MCF‐7)], which 7‐Hydroxy‐2‐methyl‐5‐phenylpyrazolo[1,5‐a]pyrimidine‐3‐carbonitrile (3f) displayed the most cytotoxicity (IC50=55.97 μg/mL), in contrast with Lapatinib (IC50=79.38 μg/mL) as a known drug.