Synthesis and antioxidant activity of new hydroxy derivatives of chalcones

Synthesis and Antioxidant Activity of 2-Amino-5-R-1,3,4-Oxadiazoles with Hindered Phenol Fragments

“…The oxidation of oleic acid was investigated at 65 °C using a thermostated apparatus upon bubbling of air into a cell for the oxidation at a constant rate of 2-4 mL min -1 . The level of lipid peroxidation was estimated on the concentration of primary oxidation products, hydroperoxides (LOOH) and secondary carbonyl products, which form complexes with thiobarbituric acid (TBARS, thiobarbituric acid reactive species) [14]. Butylated hydroxytoluene was used as a standard.…”

“…[TBARS] = (E•3)/0.156 (2) [TBARS] is the content of carbonyl compounds, nmol L -1 ; E is the absorbance of a sample relative to the control (mixture without oleic acid); 3 is the sample volume, mL; and 0.156 is the extinction of malondialdehyde (1 nmol) dissolved in 1 mL at λ = 532 nm [14].…”

“…Natural antioxidants include endogenous enzymatic (glutathione peroxidase, superoxide dismutase and catalase) [6], non-enzymatic (uric acid, lipoic acid, bilirubin, glutathione, metatonin) [7] and exogenous (carotenoids, vitamin E, A and C, natural flavonoids) [8]. Synthetic antioxidants are represented by a wide range of classes of organic compounds, such as amines [9], benzotriazole derivatives [10], alkylaminothiadiazoles [11] and others, but the most common structures in synthetic antioxidants are flavonoids [12,13], coumarins [14,15], and hindered phenols [16,17]. Despite the fact that the mechanism of oxidation, as well as the mechanism of action of antioxidants, has been studied for several decades, there is no universal approach to the creation of new antioxidants.…”

“…The most rational way to obtain new antioxidants is to combine in one structure a fragment known for its antioxidant properties, for example, hindered phenol and structures with functional groups of various nature or heterocycles [18]. Thus, it was shown that chalcon derivatives with di-tert-butylphenol fragments are effective antioxidants [14]. Also, an increase in the antioxidant properties of phenols under some conditions was achieved by introducing a sulfur atom into the structure of an oxidation inhibitor [19,20].…”

Convenient synthesis of new indeno[1,2-b]pyridine derivatives for antimicrobial and antioxidant evaluation

“…The biological systems contain endogenous antioxidant mechanisms to inactivate the excess ROS which are either enzymatic, like superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase, or non-enzymatic compounds, such as bilirubin and albumin. Thus, the consumption of antioxidants is the most efficient method to avoid many diseases related to the production of high levels (ROS) [10][11][12]. The clinical administration of drugs and the chemoprophylaxis of different diseases that happened via oxidizing agents need the development of the new antioxidants having the predicted antioxidant activity, as well as desired pharmacological properties [10,11].…”