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Chemical modifications together with density functional theory study on the targets supplied us with some valuable clarifications about the required properties needed for the target compounds to be more active against free radicals.

Screening of 18 bacterial honey isolates revealed that all the isolates were levansucrase producers. The most potent isolate that achieved the highest activity (45.66 U/ml) was identified as Bacillus subtilis NRC based on morphological examination and 16S rRNA. The results recorded the necessity of starch (5 g/L), baker's yeast (12.5 g/L), and AlCl 3 (5 mM) in improvement of the enzyme productivity. The Bacillus subtilis levansucrase was eluted as a single protein in one purification step. The enzyme molecular weight was (14 kDa). It showed its optimum activity at 45°C and could retain 60% of its activity after incubation at 50°C for 2 h. Its optimum activity was obtained at pH 8.2 and the enzyme showed great pH stability in both acidic and alkaline ranges.Unlike, most levansucrases all tested metals had an adverse effect in enzyme activity. The enzyme had antioxidant activities and were characterized as spherical micro-and nanoparticles by transmission electron microscopy. The effect of growth conditions and medium composition in levan structure and its fibrinolytic activity was evaluated. K E Y W O R D S

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Previously, a series of 2-phenoxy-benzo[g]triazoloquinazolines 1–16 were synthesized and fully characterized. The antioxidant activity of the target molecules 1–16 was evaluated using three different assays namely 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging, ferric reduction antioxidant power (FRAP) and reducing power capability (RPC). The results revealed that some benzotriazoloquinazolines showed good activity and have the capacity to scavenge free radicals. In particular, compounds 1 and 14 have shown the highest activity. The butylated hydroxyl toluene (BHT) used as standard agent.Density functional theory was carried out to explain the relative importance of CO, CS and NH groups on the radical scavenging activity of the target benzotriazoloquinazolines. The finding in present study shows that the active compounds can be used as template for further development of more potent antioxidant agents.

A series of 2-methylthio-pyrido-triazolopyrimidines (1-17) were prepared by the reaction of dimethyl-N-cyanoimidodithiocarbonate with hydrazinopyridine carboxylic acid as starting reactants. Their chemical structures were affirmed with HREI-MS, IR and NMR analyses. The target compounds (1-17) were evaluated for their antioxidant activity using 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging, ferric reduction antioxidant power (FRAP) and reducing power capability (RPC). The results revealed that some pyrido-triazolopyrimidines showed good activity as antioxidant agents, in particular, compounds 12 and 15 were found to possess good antioxidant activity. Butylated hydroxyl toluene (BHT) was used as reference drug.