A Comprehensive Study of the Use of Cu(I)/4,4'-Dicarboxy-2,2'-biquinoline Complexes to Measure the Total Reducing Capacity: Application in Herbal Extracts.
نویسندگان
چکیده
A method for the determination of total reducing capacity (TRC) based on the reduction of Cu(II) to Cu(I) by antioxidants in a buffered solution (pH 7.0) containing 4,4'-dicarboxy-2,2'-biquinoline acid (BCA) was developed. Absorbance values at 558 nm characteristic of the Cu(I)/BCA complexes formed were used to determine the TRC of aqueous extracts of twelve Brazilian plants. The TRC values obtained with the suggested method correlated well with values obtained using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) method (r² = 0.959). They were also compared with the total polyphenol content (using the Folin-Ciocalteu reagent) and the good agreement (r² = 0.919) indicates that the polyphenols should be responsible for this reducing capacity. The method proposed here (and successfully applied in plant extracts) can be used to measure the TRC of aqueous samples derived from other plants (e.g., teas, juices, beers and wines) and even in biological samples (e.g., serum, urine and follicular fluid). To achieve a structure-activity relationship of the proposed reaction, the reduction capability of 25 standard antioxidants (phenolic derivatives, flavonoids, stilbenoids, vitamins, etc.) was individually evaluated and the apparent molar absorptivity values (at 558 nm) obtained were compared and discussed.
منابع مشابه
Free radical scavenging capacity and antioxidant activity of methanolic and ethanolic extracts of plum (Prunus domestica L.) in both fresh and dried samples
Objectives: Consumption of fruits, such as plums and prunes, is useful in treating blood circulation disorder, measles, digestive disorder, and prevention of cancer, diabetes, and obesity. The paper presents a description of antioxidant and antiradical capacity of plum (Prunus domestica L.) in both fresh and dried samples. Materials and Methods: Samples were mixed with methanol and ethanol (as ...
متن کاملDi-μ-iodido-bis[(dimethyl 2,2′-biquinoline-4,4′-dicarboxylate-κ2 N,N′)copper(I)]
In the centrosymmetric dinuclear title complex, [Cu(2)I(2)(C(22)H(16)N(2)O(4))(2)], the Cu(I) atom is coordinated in a distorted tetra-hedral geometry by an N,N'-bidentate dimethyl 2,2'-biquinoline-4,4'-dicarboxyl-ate ligand and two symmetry-related I atoms, which act as bridges to a symmetry-related Cu(I) atom. The distance between the Cu(I) atoms within the dinuclear unit is 2.6723 (11) Å.
متن کاملSynthesis of Binuclear Monohydroxo Bridged Copper(II) Complexes with 1,10-Phenanthroline and 4,4'-Dimethyl-2,2'-Bipyridine
Tow new compound of type [(chelate)2Cu-OH-Cu(chelate)2] X3.nH2O, where chelate=1,10-phenanthroline; X=Cl¯(n=3.5) and chelate=4,4'-dimethyl-2,2'-bipyridine; (n=5) have been synthesized and their properties investigated. The complexes show room temperature magnetic moment order of 1.0 B.M. per copper atom. The X-band ESR spectrum of powdered sample...
متن کاملAntioxidant activities of two sweet pepper Capsicum annuum L. varieties phenolic extracts and the effects of thermal treatment
Objectives: Sweet peppers Capsicum annuum L. (C. annuum) are an excellent source of vitamins A and C as well as phenolic compounds, which are important antioxidant components that may reduce the risk of diseases. The objective of this study was to evaluate their antioxidant activity under various temperatures. Materials and Methods: To compare the antioxidant activity in various temperatures (2...
متن کاملSynthesis, Characterization and Crystal Structure Determination of Copper (II) Complexes with 2,2′-Dimethyl-4,4′-bithiazole
Copper(II) complex [Cu(dmbt)2(H2O)](ClO4)2 (1) was prepared from the reaction of copper(II) perchlorate hexahydrate with 2,2'-dimethyl-4,4'-bithiazole (dmbt) ligand in methanol at ambient temperature. The complex was quantitatively and qualitatively characterized by elemental analysis, absorption and infrared spectrometries. Complex [Cu(DMSO)5](ClO4)2 (2) was also synt...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Molecules
دوره 20 12 شماره
صفحات -
تاریخ انتشار 2015