Acta Crystallogr. damage caused by free radicals, such as the DNA repair enzymes, e.g., transferases. Natural antioxidants are present in foods, but synthetic antioxidants may either be added to food to extend its shelf-life, or prepared by extraction from Taurodeoxycholate sodium salt plant sources to be taken as supplements in concentrated form . A number of studies have investigated a range of antioxidant brokers in the hope of obtaining better and more effective treatments against AD . Work has tended to focus on dietary antioxidants such as vitamins A, C, and E. Though these appear to have some benefits, results have proved frustratingly inconclusive . Studies of many other dietary antioxidants polyphenols have also shown promise but, once more, their Rabbit Polyclonal to FIR worth is usually yet unproven . Researchers have recently investigated the potential health benefits Taurodeoxycholate sodium salt of polyphenols in organic product . Increased consumption of polyphenols has been associated with a reduced risk of cardiovascular disease and possibly malignancy and stroke. Laboratory findings have shown that oxidative stress may play an important role to the pathogenesis of AD. Therefore, the risk of AD disease might be decreased by intake of antioxidants that neutralize the unfavorable effects of oxidative stress . The present work reports the synthesis, characterization, antioxidants activities and X-ray crystal structures of Schiff bases derived from the condensation reaction of gallic hydrazide with pyridine and acetophenone derivatives, together with their acetylcholinesterase inhibition and antioxidant activity. 2. Results and Discussion 2.1. Chemistry The reaction of gallic hydrazide (1) with selected hydroxyacetophenones and pyridine derivatives resulted in the formation of the corresponding polyphenolic compounds: stacking involving the monohydroxyphenyl ring, Trp 286 and Tyr 341 and a cation-interaction between the protonated nitrogen atom of the amide and Trp 286. Furthermore, hydrophobic interactions between 2 and the rich aromatic residues (Asp 74, Tyr 124, Trp 286, Leu 289 and Tyr 341) along the gorge appear to direct the trihydroxyphenyl moiety into the ABP, thus enabling the phenolic hydroxyl groups to form a network of hydrogen bonds with Ser 293, Phe 295 and Arg 296. Molecular modeling of the complexes formed between the enzyme and compounds 3 and 6 suggested the involvement of a similar set of interactions as for the complex with compound 2 (see Physique 3 and Physique 4). In the case of the complex with compound 3, the model showed, at the PAS, a hydrogen bond between the 2-hydroxyl group and Asp 74, a conversation between carbon 6 in the aromatic ring and Trp 286, a cation-interaction between the protonated nitrogen atom of the amide and Tyr 341 and a hydrogen bond between the amide nitrogen atom and Tyr 124 and, in the ABP, hydrogen bonds between two of the hydroxyl groups in Taurodeoxycholate sodium salt the trihydroxyphenyl moiety and Ser 293 and Arg 296. The complex with compound 6 showed, at the PAS, stacking between the pyridinyl ring and Trp 286 and hydrogen bonds between the amide nitrogen atom and the carbonyl group and Arg 296 and, in the ABP, hydrogen bonds between of the hydroxyl groups in the trihydroxyphenyl moiety and Tyr 337 and Phe 338. Figure 3 Open in a separate window Representations of the molecular model of the complex formed between compound 3 and hAChE. (a) 3D representation of the ligand-enzyme binding interactions. Compound 3 is usually represented as a dark grey sticks and hydrogen bonds as green dashed lines; (b) 2D schematic representation of the hydrogen bonding and hydrophobic interactions. This analysis suggests that the hAChE inhibition activity of compounds 2, 3 and 6 is probably due to their ability to.