In vitro antioxidant activity of silymarin

Silymarin, a known standardized extract obtained from seeds of Silybum marianum is widely used in treatment of several diseases of varying origin. In the present paper, we clarified the antioxidant activity of silymarin by employing various in vitro antioxidant assay such as 1,1-diphenyl-2-picryl-hydrazyl free radical (DPPH(.)) scavenging, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging activity, total antioxidant activity determination by ferric thiocyanate, total reducing ability determination by Fe3+ - Fe2+ transformation method and Cuprac assay, superoxide anion radical scavenging by riboflavin/methionine/illuminate system, hydrogen peroxide scavenging and ferrous ions (Fe2+) chelating activities. Silymarin inhibited 82.7% lipid peroxidation of linoleic acid emulsion at 30 microg/mL concentration; butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), alpha-tocopherol and trolox indicated inhibition of 83.3, 82.1, 68.1 and 81.3% on peroxidation of linoleic acid emulsion at the same concentration, respectively. In addition, silymarin had an effective DPPH(.) scavenging, ABTS(.)+ scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, ferric ions (Fe3+) reducing power by Fe3+-Fe2+ transformation, cupric ions (Cu2+) reducing ability by Cuprac method, and ferrous ions (Fe2+) chelating activities. Also, BHA, BHT, alpha-tocopherol and trolox, were used as the reference antioxidant and radical scavenger compounds. Moreover, this study, which clarifies antioxidant mechanism of silymarin, brings new information on the antioxidant properties of silymarin. According to the present study, silymarin had effective in vitro antioxidant and radical scavenging activity. It could be used in the pharmacological and food industry because of its antioxidant properties.     

Antioxidant activity of bisbenzylisoquinoline alkaloids from Stephania rotunda: cepharanthine and fangchinoline

In the present study, we determined the antioxidant activity of cepharanthine and fangchinoline from Stephania rotunda by performing different in vitro antioxidant assays, including 1,1-diphenyl-2-picryl-hydrazyl (DPPH) free radical scavenging, 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging, N,N- dimethyl-p-phenylenediamine dihydrochloride (DMPD) radical scavenging, superoxide anion (O₂^?–) radical scavenging, hydrogen peroxide scavenging, total antioxidant activity, reducing power, and ferrous ion (Fe²⁺) chelating activities. Cepharanthine and fangchinoline showed 94.6 and 93.3% inhibition on lipid peroxidation of linoleic acid emulsion at 30 μg/mL concentration, respectively. On the other hand, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), α-tocopherol, and trolox indicated inhibitions of 83.3, 92.2, 72.4, and 81.3% on peroxidation of linoleic acid emulsion at the same concentration (30 μg/mL), respectively. According to the results, cepharanthine and fangchinoline have effective antioxidant and radical scavenging activity.     

Synthesis and antioxidant properties of diphenylmethane derivative bromophenols including a natural product

Bromination of bis(3,4-dimethoxyphenyl)methanone (5) gave four products (6–9) with mono, di, tri, and tetra Br under different conditions. Reduction and demethylation reactions of product 9 with tetra Br were performed, consecutively and a natural product, 5,5′-methylene bis(3,4-dibrombenzene-1,2-diol) (1), was obtained with a 53% yield. Five derivatives, (13–17) (bromophenols), of 1 were also synthesised. The antioxidant and radical scavenging activities of bromophenols 1 and 13–17 were determined by employing various in vitro assays such as 1,1-diphenyl-2-picryl-hydrazyl free radical (DPPH^?), 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid (ABTS^?+), N,N-dimethyl-p-phenylenediamine dihydrochloride radical cation (DMPD^?+), and superoxide anion radical (O₂^?-) scavenging, reducing ability determination by the Fe³⁺-Fe²⁺ and Cu²⁺-Cu⁺ cupric reducing antioxidant capacity (CUPRAC) transformation methods, hydrogen peroxide scavenging, and ferrous ion (Fe²⁺) chelating activities. Moreover, these activities were compared to those of synthetic standard antioxidant compounds such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), α-tocopherol, and trolox. The results showed that the synthesised bromophenols had effective antioxidant power.     

Apoptotic, antioxidant and antiradical effects of majdine and isomajdine from Vinca herbacea Waldst. and kit

In the present study, apoptotic, antioxidant and antiradical effects of majdine and isomajdine from Vinca herbacea Waldst. and Kit were studied. For testing the possible apoptotic effects of majdine and isomajdine from V. herbacea, DNA fragmentation assay was conducted on the rat brain cortical tissue homogenates, in vitro. Also their possible effects on mitochondrial activity were tested by using the same tissue samples of rats. In addition, the antioxidant activity of isomajdine and majdine was determined using various in vitro antioxidant assays, including 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS(?+)) radical scavenging and N,N-dimethyl-p-phenylenediamine (DMPD(?+)) radical scavenging, ferric ions (Fe(3+)) and cupric ions (Cu(2+)) reducing abilities and ferrous ions (Fe(2+)) chelating activity. On the other hand, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), α-tocopherol and trolox (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid) were used as reference antioxidants.     

Antioxidant and radical scavenging properties of curcumin

Curcumin (diferuoyl methane) is a phenolic compound and a major component of Curcuma longa L. In the present paper, we determined the antioxidant activity of curcumin by employing various in vitro antioxidant assays such as 1,1-diphenyl-2-picryl-hydrazyl free radical (DPPH*) scavenging, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging activity, N,N-dimethyl-p-phenylenediamine dihydrochloride (DMPD) radical scavenging activity, total antioxidant activity determination by ferric thiocyanate, total reducing ability determination by the Fe(3+)-Fe(2+) transformation method, superoxide anion radical scavenging by the riboflavin/methionine/illuminate system, hydrogen peroxide scavenging and ferrous ions (Fe(2+)) chelating activities. Curcumin inhibited 97.3% lipid peroxidation of linoleic acid emulsion at 15 microg/mL concentration (20 mM). On the other hand, butylated hydroxyanisole (BHA, 123 mM), butylated hydroxytoluene (BHT, 102 mM), alpha-tocopherol (51 mM) and trolox (90 mM) as standard antioxidants indicated inhibition of 95.4, 99.7, 84.6 and 95.6% on peroxidation of linoleic acid emulsion at 45 microg/mL concentration, respectively. In addition, curcumin had an effective DPPH* scavenging, ABTS*(+) scavenging, DMPD*(+) scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, ferric ions (Fe(3+)) reducing power and ferrous ions (Fe(2+)) chelating activities. Also, BHA, BHT, alpha-tocopherol and trolox, were used as the reference antioxidant and radical scavenger compounds. According to the present study, curcumin can be used in the pharmacological and food industry because of these properties.     

Comparison of in vitro antioxidant and antiradical activities of L-tyrosine and L-Dopa

Summary. Phenolic compounds are interesting because of their antioxidant properties. In the present study, the antioxidant properties of L-tyrosine as a monophenolic and L-Dopa as a diphenolic amino acid were investigated by using different antioxidant assays: (i) 1,1-diphenyl-2-picryl-hydrazyl free radical (DPPH^•) scavenging; (ii) 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical cation decolorization assay; (iii) total antioxidant activity by ferric thiocyanate method; (iv) ferric ions (Fe³⁺) reducing power; (v) superoxide anion radical (O₂ ^•−) scavenging; (vi) hydrogen peroxide (H₂O₂) scavenging, and (vii) ferrous ions (Fe²⁺) chelating activities. Butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), α-tocopherol and trolox, a water-soluble analogue of tocopherol, were used as the reference antioxidant compounds. At the same concentration (20 μg/mL), L-tyrosine and L-Dopa showed 30.6 and 67.9% inhibition of lipid peroxidation of linoleic acid emulsion, respectively. On the other hand, BHA, BHT, α-tocopherol and trolox indicated inhibitions of 74.4, 71.2, 54.7 and 20.1% on the peroxidation of linoleic acid emulsion, respectively, at the above-mentioned concentration. In addition, L-tyrosine and L-Dopa had an effect on DPPH radical scavenging, ABTS radical scavenging, superoxide anion radical scavenging, H₂O₂ scavenging, total ferric ions reducing power and metal chelating on ferrous ions activities.     

Antioxidant activity of L-adrenaline: a structure-activity insight

L-adrenaline belongs to a group of the compounds known as catecholamines, which play an important role in the regulation of physiological process in living organisms. The antioxidant activity and antioxidant mechanism of L-adrenaline was clarified using various in vitro antioxidant assays including 1,1-diphenyl-2-picryl-hydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), N,N-dimethyl-p-phenylenediamine (DMPD(+)), and superoxide anion radicals (O(2)(-)) scavenging activity, hydrogen peroxide (H(2)O(2)), total antioxidant activity, ferric ions (Fe(3+)) and cupric ions (Cu(2+)) reducing ability, ferrous ions (Fe(2+)) chelating activity. L-adrenaline inhibited 74.2% lipid peroxidation of a linoleic acid emulsion at 30 microg/mL concentration. On the other hand, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), alpha-tocopherol and trolox displayed 83.3, 82.1, 68.1 and 81.3% inhibition on the peroxidation of linoleic acid emulsion at the same concentration, respectively. BHA, BHT, alpha-tocopherol and trolox were used as reference antioxidants and radical scavenger compounds. Moreover, this study will bring an innovation for further studies related to antioxidant properties of L-adrenaline. According to present study, L-adrenaline had effective in vitro antioxidant and radical scavenging activity.     

Screening of antiradical and antioxidant activity of monodesmosides and crude extract from Leontice smirnowii tuber.

Leontice smirnowii is a member of the Berberidaceae family. In the current study we investigated the possible antiradical and antioxidant activity of the monodesmosides (MLS) and crude extract (CELS) of Leontice smirnowii using different antioxidant tests: 1,1-diphenyl-2-picryl-hydrazyl (DPPH) free radical scavenging, scavenging of superoxide anion radical-generated non-enzymatic system, ferric thiocyanate (FTC) method, reducing power, hydrogen peroxide scavenging and metal chelating activities. Experiment revealed that MLS and CELS have an antioxidant effect concentration-dependently. Total antioxidant activity was performed according to FTC method. At the 30mug/ml concentration, the inhibition effects of MLS and CELS on peroxidation of linoleic acid emulsion were found to be 95.3% and 95.6%, respectively. On the other hand, percentage inhibition of butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), alpha-tocopherol and trolox were found to be 98.2%, 98.5%, 84.0% and 87.9% inhibition of peroxidation of linoleic acid emulsion, respectively, at the same concentration. In addition, MLS and CELS had effective DPPH radical scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, reducing power and metal chelating activities. Also, these various antioxidant activities were compared with BHA, BHT, alpha-tocopherol and trolox which were accepted as references antioxidants.     

Ramalin, a novel nontoxic antioxidant compound from the Antarctic lichen Ramalina terebrata

Ramalin (γ-glutamyl-N′-(2-hydroxyphenyl)hydrazide), a novel compound, was isolated from the methanol-water extract of the Antarctic lichen Ramalina terebrata by several chromatographic methods. The molecular structure of ramalin was determined by spectroscopic analysis. The experimental data showed that ramalin was five times more potent than commercial butylated hydroxyanisole (BHA) in scavenging 1-diphenyl-2-picryl-hydazil (DPPH) free radicals, 27 times more potent in scavenging 2,2′-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid free radicals (ABTS⁺) than the vitamin E analogue, trolox, and 2.5 times more potent than BHT in reducing Fe³⁺ to Fe²⁺ ions. Similarly, ramalin was 1.2 times more potent than ascorbic acid in scavenging superoxide radicals and 1.25 times more potent than commercial kojic acid in inhibiting tyrosinase enzyme activity, which ultimately leads to whitening of skin cells. Ramalin showed no or very little cytotoxicity in human keratinocyte and fibroblast cells at its antioxidant concentration. Furthermore, ramalin was assessed to determine its antioxidant activity in vivo. One microgram per milliliter ramalin significantly reduced the released nitric oxide (NO) and 0.125 μg/ml ramalin reduced the produced hydrogen peroxide (H₂O₂) in LPS (lipopolysaccharide)-stimulated murine macrophage Raw264.7 cells. Considering all the data together, ramalin can be a strong therapeutic candidate for controlling oxidative stress in cells.     

Novel antioxidant bromophenols with acetylcholinesterase,butyrylcholinesterase and carbonic anhydrase inhibitory actions

In this study, a series of novel bromophenols were synthesized from benzoic acids and methoxylated bromophenols. The synthesized compounds were evaluated by using different bioanalytical antioxidant assays including 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS⁺) radical scavenging assays. Also, reducing power of novel bromophenols were evaluated by Cu²⁺-Cu⁺ reducing, Fe³⁺-Fe²⁺ reducing and [Fe³⁺-(TPTZ)₂]³⁺-[Fe²⁺-(TPTZ)₂]₂+ reducing and ferrous ions (Fe²⁺) chelating abilities. The compounds demonstrate powerful antioxidant activities when compared to standard antioxidant molecules of α-tocopherol, trolox, butylated hydroxyanisole (BHA), and butylated hydroxytoluene (BHT). Also in the last part of this studies novel bromophenols were tested against some metabolic enzymes including acetylcholinesterase (AChE), butyrylcholinesterase (BChE) enzymes and carbonic anhydrase I, and II (hCA I and hCA II) isoenzymes. The newly synthesized bromophenols showed Ki values in a range of 6.78 ± 0.68 to 126.07 ± 35.6 nM against hCA I, 4.32 ± 0.23 to 72.25 ± 12.94 nM against hCA II, 4.60 ± 1.15 to 38.13 ± 5.91 nM against AChE and 7.36 ± 1.31 to 29.38 ± 3.68 nM against BChE.     

Measurement of antioxidant ability of melatonin and serotonin by the DMPD and CUPRAC methods as trolox equivalent

Melatonin (N-acetyl-5-methoxytryptamine) is the chief secretory product of the pineal gland and synthesized enzymatically from serotonin (5-hydroxytryptamine). These indoleamine derivatives play an important role in the prevention of oxidative damage. In the present study, DMPD radical scavenging and cupric ion (Cu²⁺) reducing ability of melatonin and serotonin as trolox equivalent antioxidant activity (TEAC) was investigated. Melatonin and serotonin demonstrated 73.5 and 127.4 μg/mL trolox equivalent DMPD^√+ scavenging activity at the concentration of 100 μg/mL. Also, at the same concentration, melatonin and serotonin showed 14.41 and 116.09 μg/mL trolox equivalent cupric ion (Cu²⁺) reducing ability. These results showed that melatonin and serotonin had marked DMPD^√+ radical scavenging and cupric ions (Cu²⁺) reducing ability. Especially, serotonin had higher DMPD radical scavenging and cupric ions (Cu²⁺) reducing activity than melatonin because of its phenolic group.     

Antioxidant and free radical scavenging properties of N-acetylcysteine amide (NACA) and comparison with N-acetylcysteine (NAC)

The antioxidant potential of N-acetylcysteine amide (NACA), also known as AD4, was assessed by employing different in vitro assays. These included reducing power, free radical scavenging capacities, peroxidation inhibiting activity through linoleic acid emulsion system and metal chelating capacity, as compared to NAC and three widely used antioxidants, α-tocopherol, ascorbic acid and butylated hydroxytoluene (BHT). Of the antioxidant properties that were investigated, NACA was shown to possess higher 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) radical scavenging ability and reducing power than NAC, at all the concentrations, whereas the scavenging ability of H₂O₂ differed with concentration. While NACA had greater H₂O₂ scavenging capacity at the highest concentration, NAC was better than NACA at lower concentrations. NAC and NACA had a 60% and 55% higher ability to prevent β-carotene bleaching, respectively, as compared to control. The chelating activity of NACA was more than 50% that of the metal chelating capacity of EDTA and four and nine times that of BHT and α-tocopherol, respectively. When compared to NACA and NAC; α-tocopherol had higher DPPH scavenging abilities and BHT and α-tocopherol had better β-carotene bleaching power. These findings provide evidence that the novel antioxidant, NACA, has indeed enhanced the antioxidant properties of NAC.     

Evaluation of antioxidant activity of <Emphasis Type="Italic">Melothria maderaspatana in vitro</Emphasis>

In this study, an aqueous extract of leaves from Melothria maderaspatana was tested for in vitro antioxidant activity. Free radical scavenging assays, such as hydroxyl radical, hydrogen peroxide, superoxide anion radical and 2,2-diphenyl-1-picryl hydrazyl (DPPH), 2,2’-azinobis-(3-ethyl-enzothiazoline-6-sulfonic acid) (ABTS) radical scavenging, and reducing power assay, were studied. The extract effectively scavenged hydroxyl radical, hydrogen peroxide and superoxide anion radicals. It also scavenged DPPH and ABTS radicals. Furthermore, it was found to have reducing power. All concentrations of leaf extract exhibited free radical scavenging and antioxidant power, and the preventive effects were in a dose-dependent manner. The antioxidant activities of the above were compared to standard antioxidants such as butylated hydroxytoluene (BHT), ascorbic acid, and α-tocopherol. The results obtained in the present study indicate that the M. maderaspatana extract could be considered a potential source of natural antioxidant.     

Antioxidant and acetylcholinesterase inhibition properties of novel bromophenol derivatives

In this study, series of novel bromophenol derivatives were synthesized and investigated for their antioxidant and AChE inhibition properties. Novel brominated diarylmethanones were obtained from the acylation reactions of benzoic acids with substituted benzenes. One of the bromodiarylmethanone was synthesized from the bromination of diarylmethanone with molecular bromine. All diarylmethanones were converted into their bromophenol derivatives with BBr₃. The antioxidant activities of all synthesized compounds were elucidated by using various bioanalytical assays. Radical scavenging activities of compounds 10–24 were evaluated by means of DPPH and ABTS⁺ scavenging activities. In addition, reducing ability of 10–24 were determined by Fe³⁺, Cu²⁺, and [Fe³⁺-(TPTZ)₂]³ reducing activities. α-Tocopherol, trolox, BHA, and BHT were used as positive antioxidant and radical scavenger molecules. On the other hand, IC₅₀ values were calculated for DPPH, ABTS⁺ scavenging, and AChE inhibition effects of novel compounds. The results obtained from the current studies clearly show that novel bromophenol derivatives 20–24 have considerable antioxidant, antiradical, and AChE inhibition effects.     

Investigation of biological activities of various 1,2,3-triazole compounds: Their effects on cholinesterase enzymes,determination of antioxidant capacity and antimicrobial activity

1,2,3-triazoles are pharmaceutically significant compounds that have attracted recent interest from medicinal chemists because of their important biological activities. Addressed herein, some 1,2,3-triazoles were synthesized to investigate the inhibitory activities against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes, antioxidant capacity, and antimicrobial effect. The antioxidant profile of 1,2,3-triazoles determined by varied bioanalytical antioxidant methods, including 2,2′-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS^.+), 1,1-diphenyl-2-picrylhydrazil (DPPH·), cupric ion (Cu²⁺) and ferric ion (Fe³⁺) ascorbic acid, butylated hydroxyanisole (BHA), and butylated hydroxytoluene (BHT) were used as the standard compounds. In addition, the antibacterial and antifungal activities of these compounds were investigated against seven bacteria and three fungal species using the hollow agar method. As a result of these studies, it was determined that compound 4 showed the best antimicrobial activity and antioxidant activity close to the standards. Inhibitory effects and kinetic studies of these molecules on cholinesterase enzymes were performed. According to the results obtained, compound 4 showed stronger AChE inhibition and compound 3 stronger BChE inhibition compared to other compounds. In kinetic studies, it was found that AChE showed noncompetitive inhibition by compound 4, and BChE showed competitive inhibition by compound 3.     

Synthesis of dimeric phenol derivatives and determination of in vitro antioxidant and radical scavenging activities

In this study, di(2,6-dimethylphenol) (Di-DMP), di(2,6-diisopropylphenol) (Di-DIP, dipropofol) and di(2,6-di-t-butylphenol) (Di-DTP) were synthesized by the reaction of monomeric phenol derivatives with catalytic CuCl(OH). TMEDA and Na₂S₂O₄. Their antioxidant capacity and radical scavenging activity were examined using different in vitro methodologies such as 1,1-diphenyl-2-picryl-hydrazyl (DPPH·) free radical scavenging, 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging activity, total antioxidant activity by ferric thiocyanate, total reducing power by potassium ferricyanide reduction method, superoxide anion radical scavenging, hydrogen peroxide scavenging and ferrous ions chelating activities.