Comparison between antioxidant activity of 2,5-disubstituted 1,3,4-oxadiazoles containing heteroaromatic ring and aromatic ring at 2nd position

Abstract

A series of 4-[5-(substitutedphenyl)-1,3,4-oxadiazol-2-yl]-pyridine) and 2-[5-substitutedphenyl)-1,3,4-oxadiazol-2-yl]-benzenamine derivatives were synthesized from substituted esters and hydrazine hydrate in the presence of ethanol to give isonicotinic acid hydrazide and 2-aminobenzohydrazide followed by reaction with phosphorus oxychloride and various aromatic acids. All the compounds were tested for their in vitro antioxidant activity by 1,1-diphenyl-2-picryl hydrazyl (DPPH) method. Compounds containing aromatic group at 2nd position showed significant activity as compared to standard (ascorbic acid) which concludes that the presence of aromatic group increases the free radical scavenging activity.

Synthesis and antioxidant evaluation of some new 2-benzoylamino-5-hetaryl-1,3,4-oxadiazoles

“…The Gewald reaction of 1 with elemental sulfur and cyclohexanone in a warming mixture of ethanol and dimethylformamide (1:1) containing morpholine as a basic catalyst gave N-(5-(2-amino-4,5,6,7-tetrahydrobenzo[b] thiophen-3-yl)-1,3,4-oxadiazol-2-yl)benzamide (5). The IR spectrum of 5 displayed absorption bands at 3446-3388, 3195, 1675 cm -1 due to NH 2 , NH, and amidic C=O functions, respectively.…”

“…Compounds having 1,3,4-oxadiazole skeletons possessed a wide range of therapeutic activities like antifungal [2], antioxidant [3][4][5], antimicrobial [6], antitubercular [7], anti-inflammatory [8,9], antimalarial [10], antihypoglycemic [11], and anticancer [12][13][14] activities as well as potential antihypertensive agents [15], antiviral [16] and anticonvulsant [17] properties. The pharmacological activity of 1,3,4-oxadiazoles can be ascribed to the presence of toxophoric -N=C-O-linkage which may react with the nucleophilic centers of the microbial cell [18].…”

Synthesis and Antioxidant Activity of Bis and Tris Heterocycles

“…71. 35 activity in all the three methods greater than the standard ascorbic acid, whereas the compounds 8b and 14b showed activity equal to the standard ascorbic acid. (2), and 2-((4aryl-1H-imidazol-2-ylcarbamoyl)methylsulfonyl) acetohydrazide (3) were prepared as per the literature procedure [29].…”

“…The oxadiazolylmethylsulfonyloxazolyl‐acetamide displayed noticeable antioxidant activity . The compounds with good antioxidant activity are expected to possess anti‐inflammatory activity . Encouraged by the results and our continued interest in the development of molecules having potential pharmacophoric units the present work is taken up.…”

Synthesis of New 2,5-Di-substituted 1,3,4-Oxadiazoles Bearing 2,6-Di-tert-butylphenol Moieties and Evaluation of Their Antioxidant Activity

“…This stability increases with the extent of delocalisation [13] and enhances antioxidant ability [14]. A number of 1,3,4-oxadiazole derivatives have exhibited various types of biological activity [15,16,17] and antioxidant ability [18,19].…”