■ Abstract Apoptosis is a genetically programmed, morphologically distinct form of cell death that can be triggered by a variety of physiological and pathological stimuli. Studies performed over the past 10 years have demonstrated that proteases play critical roles in initiation and execution of this process. The caspases, a family of cysteine-dependent aspartate-directed proteases, are prominent among the death proteases. Caspases are synthesized as relatively inactive zymogens that become activated by scaffold-mediated transactivation or by cleavage via upstream proteases in an intracellular cascade. Regulation of caspase activation and activity occurs at several different levels: ( a) Zymogen gene transcription is regulated; ( b) antiapoptotic members of the Bcl-2 family and other cellular polypeptides block proximity-induced activation of certain procaspases; and ( c) certain cellular inhibitor of apoptosis proteins (cIAPs) can bind to and inhibit active caspases. Once activated, caspases cleave a variety of intracellular polypeptides, including major structural elements of the cytoplasm and nucleus, components of the DNA repair machinery, and a number of protein kinases. Collectively, these scissions disrupt survival pathways and disassemble important architectural components of the cell, contributing to the stereotypic morphological and biochemical changes that characterize apoptotic cell death.

Mammalian caspases: structure ,a ctivation ,s ubstrates, and functions during apoptosis

The normal biochemical reactions in our body, increased exposure to the environment, and higher levels of dietary xenobiotic's result in the generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS). The ROS and RNS create oxidative stress in different pathophysiological conditions. The reported chemical evidence suggests that dietary antioxidants help in disease prevention. The antioxidant compounds react in one-electron reactions with free radicals in vivo/in vitro and prevent oxidative damage. Therefore, it is very important to understand the reaction mechanism of antioxidants with the free radicals. This review elaborates the mechanism of action of the natural antioxidant compounds and assays for the evaluation of their antioxidant activities. The reaction mechanisms of the antioxidant assays are briefly discussed (165 references). Practical applications: understanding the reaction mechanisms can help in evaluating the antioxidant activity of various antioxidant compounds as well as in the development of novel antioxidants.

https://pubs.rsc.org/en/content/articlepdf/2015/RA/C4RA13315C

Free radicals, natural antioxidants, and their reaction mechanisms

Free radical generation is directly related with oxidation in foods and biological systems. Therefore, the search for methods to determine free radical scavenging is important. In this work are described the methods used for this purpose in both substrates as well as in specific cases of their application. The main methods comprise superoxide radicals scavenging (O2·-); hydrogen peroxide scavenging (H2O2); hypochlorous acid scavenging (HOCl); hydroxyl radical scavenging (HO.); peroxyl radical scavenging (ROO.), among them are the methods that use azo-compounds to generate peroxyl radicals, such as the ``TRAP'' method (Total Radical-Trapping Antioxidant Parameter) and the ``ORAC'' method (Oxygen-Radical Absorbance Capacity); the scavenging of radical cation 2,2-azinobis-(3-ethylbenzothiazoline-6-sulphonate) or the ABTS or the ``TEAC'' method (Trolox Equivalent Antioxidant Capacity); the scavenging of stable radical 2,2-diphenyl-1-picrylhydrazyl or DPPH . method and the scavenging of radical cation N,N-dime...

Review: Methods Used to Evaluate the Free Radical Scavenging Activity in Foods and Biological Systems:

Methodological aspects about in vitro evaluation of antioxidant properties.

Chemical composition, physical properties, and antioxidant activities of yam flours as affected by different drying methods

Dioscorin, the storage protein of yam (Dioscorea batatas Decne) tuber (which is different from dioscorine found in tubers of Dioscorea hirsuta), was purified to homogeneity after DE-52 ion exchange column according to the methods of Hou et al. (J. Agric. Food Chem. 1999, 47, 2168−2172). A single band of 32 kDa dioscorin was obtained on a sodium dodecyl sulfate−polyacrylamide gel electrophoresis gel with 2-mercaptoethanol treatment. This purified dioscorin was shown by spectrophotometric method to have scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical in a pH-dependent manner. There is a positive correlation between scavenging effects against DPPH (8−46%) and amounts of 32 kDa dioscorin (5.97−47.80 nmol) added in Tris-HCl buffer (pH 7.9), which are comparable to those of glutathione at the same concentrations. Using electron paramagnetic resonance (EPR) spectrometry for DPPH radical detection, it was found that the intensities of the EPR signal were decreased by 28.6 and 57 nmol of 3...

Antioxidant Activities of Dioscorin, the Storage Protein of Yam (Dioscorea batatas Decne) Tuber

The aim of this study is to examine possible antioxidant and antiproliferative activities of the different extracts from sweet potato (Ipomoea batatas (L.) Lam 'Tainong 57') organs. DPPH staining, total phenolic com- pounds and flavonoid content, DPPH radical, reducing power method, FTC method, and cell proliferation were all employed. In the DPPH staining, ethanol extract of vein had the highest radical-scavenging activity when it was diluted to 6.25 mg dry matter/mL. Among all the extracts, the highest amount of total phenolic and flavonoid com- pounds was found in the ethanol extract of vein. In the DPPH colorimetric method, it was found that ethanol extract of leaf had the highest radical-scavenging activity, followed by water extract of vein. In the reducing power activity assay, it was found that the water extract of leaf had the highest reducing power activity, followed by ethanol extract of vein. Like phenolic compounds, the highest FTC activity was found in the ethanol extract of vein. The antipro- liferative activities aof sweet potato were studied in vitro using human lymphoma NB4 cells, and the following re- sults were found: water extract of vein had the highest antiproliferative activity with an EC 50 of 449.6 ± 27.73 µg/mL, followed by water extract of storage root, water extract of leaf, ethanol extract of storage root, and ethanol extract of leaf. Although the ethanol extract of vein showed strong antioxidant activity, it had no antiproliferative activity under the experimental conditions tested.

/pdf/antioxidant-and-antiproliferative-activities-of-sweet-potato-3geh8b6md7.pdf

Antioxidant and antiproliferative activities of sweet potato (Ipomoea batatas (L.) Lam 'Tainong 57') constituents

This study aimed to investigate possible antioxidant activity of various extracts of Phellinus merrillii (PM). The explored items include: ABTS free radical scavenging assay, determination of total phenolics contents (TPC), ferric reducing antioxidant power assay (FRAP), rapid screening of antioxidant by dot-blot DPPH (1, 1-diphenyl-2-picrylhydrazyl) staining, DPPH radical-scavenging activities and reducing power measurement. In the ABTS free radical scavenging assay, the n-BuOH fraction displayed the highest total antioxidant activity (17.13 ± 0.04 mM). In the determination of total phenolics contents (TPC) and ferric reducing antioxidant power assay (FRAP), the EtOAc fraction had the highest phenolics contents (46.21±0.02 mM) and reducing antioxidant power (19.09±0.03 mM). In the rapid screening of antioxidant by dotblot DPPH staining, the n-BuOH fraction showed the highest strong dot-blot staining. In the reducing power measurement, the crude extract had the highest reducing power at 2 mg/ml concentration. In the DPPH radical-scavenging activities, the EtOAc fraction had the highest antioxidant activity (IC50=0.66±0.01 mg/ml). As regard the correlation coefficients among ABTS assay, FRAP assay, and total phenolics contents, it can be seen that correlation coefficients in each case were significant. Among all extracts, the highest amountof total phenolics contents were found in the EtOAc fractiont. It is suggested that the PM might ontribute its antioxidant activities on EtOAc and n-BuOH fraction. In high-performance liquid chromatography tandem mass (LC/MS/MS) analysis for hispolon, the daughter ion scanned chromatograms of PM was established. Both hispolon and PM showed similar daughter ion spectrum at the retention time of 4.7 min and had more lobes in m/z 219 and m/z 135. This indicated that PM did contain the active ingredient hispolon. Both the IC50 of DPPH radical scavenging activity for hispolon and BHT were 42.4±2.9 and 81.2 ± 3.2 μM, respectively. These findings mean that hispolon was most important in antiradical activities. It was suggested that hispolon might contribute to its antioxidant activities in PM.

Antioxidant and Free Radical Scavenging Activities of Phellinus merrillii Extracts

Trypsin inhibitors (TIs), root storage proteins, were purified from sweet potato (Ipomoea batatas[L.] Lam cv. Tainong 57) roots by trypsin affinity column according to the methods of Hou and Lin (Plant Sci. 1997, 126, 11-19 and Plant Sci. 1997, 128, 151-158). A single band of 33 kDa TI was obtained by preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) gels. This purified 33 kDa TI had scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical. There was positive correlation between scavenging effects against DPPH (2 to 22%) and amounts of 33 kDa TI (1.92 to 46 pmol). The scavenging activities of 33 kDa TI against DPPH were calculated from linear regression to be about one-third of those of glutathione between 5 and 80 pmol. Using electron paramagnetic resonance (EPR) spectrometry for hydroxyl radical detection, it was found that 33 kDa TI could capture hydroxyl radical, and the intensities of EPR signal were significantly decreased from 1.5 to 6 pmol of 33 kDa TI compared to those of the controls. It is suggested that 33 kDa TI, one of the sweet potato root storage proteins, may play a role as an antioxidant in roots and may be beneficial to health when it is consumed.

Antioxidant activities of trypsin inhibitor, a 33 KDa root storage protein of sweet potato (Ipomoea batatas (L.) Lam cv. Tainong 57).

The aim of this study was to examine possible antioxidant and antiproliferative activities of 95% ethanol or water extract from water spinach (Ipomoea aquatica Forsk) organs DPPH staining, total phenolic compounds, total flavonoid content, DPPH radical, reducing power method, FTC method, and inhibition of cancer cell prolifera- tion were employed Ethanol extract of stem demonstrated a positive effect in DPPH staining when it was diluted to 625 mg dry matter/mL while all other fractions showed no effect at the same dilution This fraction also had the highest content of the total phenolic compounds, as well as the highest reducing power and FTC activity Ethanol extract of leaf had the highest amount of flavonoids Using DPPH colorimetric method, it was found that ethanol extract of stem had the highest radical-scavenging activity, followed by ethanol extract of leaf The antiproliferative activities of water spinach extracts were studied in vitro using human lymphoma NB4 cells, and the following results were found: water extract of stem had the highest antiproliferative activity with an EC 50 of 66140 ± 336 µg dry matter/mL, followed by ethanol extract of stem and ethanol extract of leaf The water extract of leaf had the lowest antiproliferative activity (EC 50 >1000 µg dry matter/mL) under the experimental conditions

/pdf/antioxidant-and-antiproliferative-activities-of-water-n9udiwmg4l.pdf

Yaw-Huei Lin

Papers

Antioxidant Activities of Dioscorin, the Storage Protein of Yam (Dioscorea batatas Decne) Tuber

Antioxidant and antiproliferative activities of sweet potato (Ipomoea batatas (L.) Lam 'Tainong 57') constituents

Antioxidant and Free Radical Scavenging Activities of Phellinus merrillii Extracts

Antioxidant activities of trypsin inhibitor, a 33 KDa root storage protein of sweet potato (Ipomoea batatas (L.) Lam cv. Tainong 57).

Antioxidant and antiproliferative activities of water spinach (Ipomoea aquatica Forsk) constituents