scholarly journals Ascorbate Free-Radical Reduction by Glyoxysomal Membranes

1990 ◽  
Vol 94 (2) ◽  
pp. 531-537 ◽  
Author(s):  
Mark l. Bowditch ◽  
Robert P. Donaldson
Keyword(s):  
Free Radical ◽  
Ascorbate Free Radical ◽  
Radical Reduction

ChemInform Abstract: SELECTIVITY IN THE FREE-RADICAL REDUCTION OF LACTONES WITH TRICHLOROSILANE

1974 ◽  
Vol 5 (47) ◽  
pp. no-no
Author(s):  
S. W. BALDWIN ◽  
R. J. DOLL ◽  
S. A. HAUT
Keyword(s):  
Free Radical ◽  
Radical Reduction

Rapid Free Radical Reduction in the Perfused Rat Liver

1994 ◽  
Vol 21 (3) ◽  
pp. 169-176 ◽  
Author(s):  
Kouichi Nakagawa ◽  
Shin-Ichi Ishida ◽  
Hidekatsu Yokoyama ◽  
Norio Mori ◽  
Shin-Ichi Niwa ◽  
...  
Keyword(s):  
Free Radical ◽  
Rat Liver ◽  
Perfused Rat Liver ◽  
Radical Reduction

Reduction of Folate and Dihydrofolate by Dithionite

1972 ◽  
Vol 50 (11) ◽  
pp. 1191-1198 ◽  
Author(s):  
M. Kawai ◽  
K. G. Scrimgeour
Keyword(s):  
Free Radical ◽  
Low Temperatures ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Kinetic Method ◽  
Sodium Dithionite ◽  
Nucleophilic Attack ◽  
Stopped Flow ◽  
Reduction Processes ◽  
Radical Reduction

Sodium dithionite reduces folate to 7,8-dihydrofolate at room temperature, but further reduction to the tetrahydro level can be obtained at elevated temperatures (11). Both folate and dihydrofolate form adducts with dithionite (presumably sulfinates), and these adducts appear to be intermediates in the reduction processes. The adduct of dihydrofolate is not converted to tetrahydrofolate at low temperatures, and is thus more amenable to examination. The mechanism of reduction of the folate compounds and of the nicotinamide ring by dithionite involves nucleophilic attack by the dithionite, not a free radical reduction as with p-nitrophenol. The rate of addition of bisulfite to folate and dihydrofolate has been measured by the stopped-flow kinetic method, and the nonenzymic and enzyme-catalyzed addition of nucleophiles to folate compounds is discussed.

scholarly journals Chilling Stress Protection in Cucumber: A Role for Antioxidants?

HortScience ◽  
1996 ◽  
Vol 31 (4) ◽  
pp. 645a-645
Author(s):  
David A. French ◽  
Kirk L. Parkin
Keyword(s):  
Ascorbic Acid ◽  
Free Radical ◽  
Tissue Damage ◽  
Chilling Stress ◽  
Storage Life ◽  
Ascorbate Free Radical ◽  
Stress Protection ◽  
Endogenous Antioxidants ◽  
Intermittent Warming

To examine the role of endogenous antioxidants in providing chilling stress protection, field-grown cucumber (Cucumis sativus L. cv. Eureka) fruit were stored in the dark and evaluated throughout storage. Storage treatments included continuous chilling (C) (5°C), continuous tempering (T) (12°C), intermittent warming (IW) (1 day at 12°C every 4 days) for 1, 2, 3, or 4 cycles, and preconditioning (PC) (12°C for 4 or 8 days) before chilling. Fruit exposed to in-field chilling (FC) were also stored under continuous chilling at 5°C. Samples were evaluated visually for tissue damage (lack of exudate, water-soaked appearance), and ascorbic acid (Asc) and reduced (GSH) and oxidized (GSSG) glutathione levels and glutathione reductase (GtR) and ascorbate free radical reductase (AFRR) activities were determined. Each 4 days of PC extended storage life by 7 days relative to C. FC or 1–2 IW cycles also extended storage life relative to C. With all treatments, Asc depletion preceded visual tissue damage, whereas GSH, GtR, and AFRR were not depleted before such damage. GSSG levels remained low throughout storage. GtR activity was elevated by FC and IW. AFRR activity was elevated by all treatments. Asc levels were elevated initially by all treatments, with this elevation lasting longer with PC and T. These results suggest that Asc levels decline during stress in the absence of an obvious lesion in the Asc regeneration scheme.

scholarly journals EVALUASI SEDIAAN MASKER ANTIOKSIDAN DARI EKSTRAK DAUN TEH HIJAU (CAMELLIA SINENSIS)

2019 ◽  
Vol 10 (2) ◽  
pp. 119-128
Author(s):  
Desi Nawangsari
Keyword(s):  
Antioxidant Activity ◽  
Free Radical ◽  
Green Tea ◽  
Camellia Sinensis ◽  
Ethanol Extract ◽  
Tea Leaves ◽  
Strong Activity ◽  
Reduction Activity ◽  
Radical Reduction ◽  
Green Tea Leaves

Abstract Green tea (Camellia sinensis L.) has the main efficacy as an antioxidant and contains polyphenol compounds in green tea leaves with the main component of polyphenol fraction namely Epigallocatechin-3-gallate (EGCG) which has strong activity to prevent free radicals that cause premature aging. Research has been carried out on the formulation of maskantioxidant preparations containing green tea leaf extract. The study begins with testing the antioxidant activity of ethanol extract of green tea leaves with a free radical reduction method of 1,1-diphenyl-2-picrylhydrazyl using visible spectrophotometry. Testing of antioxidant activity showed that the ethanol extract of green tea leaves gave an IC50 value of 3.17µg / mL. Formulations of gel masks made were F0 (base without active substances), F1 (base + concentration of ethanol extract of green tea leaves for IC50 (0,000317%)), F2 (base + concentration of ethanol extract of green tea leaves for 50xIC50 (0, 0158%)), F3 (base + concentration of ethanol extract of green tea leaves for 100xIC50 (0.0317%)), F4 (base + concentration of ethanol extract of green tea leaves for IC50), F5 (base + concentration of ethanol extract of green tea leaves worth IC50), F6 (base + concentration of ethanol extract of green tea leaves for IC50. Evaluation of gel mask preparations include, organoleptic examination and homogeneity, pH, viscosity, dry time of preparation and testing of antioxidant stability. F2 provides better and higher free radical reduction activity than products on the market. F4, F5, F6 shows an increase in free radical reduction activity.   Keywords: Green tea leaves (Camellia sinensis L.), DPPh, IC50 gel mask.

scholarly journals UJI AKTIVITAS SEDIAAN MASKER ANTIOKSIDAN DARI EKSTRAK DAUN TEH HIJAU (CAMELLIA SINENSIS)

2019 ◽  
Vol 10 (2) ◽  
pp. 129-134
Author(s):  
Desi Nawangsari
Keyword(s):  
Antioxidant Activity ◽  
Free Radical ◽  
Green Tea ◽  
Camellia Sinensis ◽  
Ethanol Extract ◽  
Tea Leaves ◽  
Strong Activity ◽  
Reduction Activity ◽  
Radical Reduction ◽  
Green Tea Leaves

Abstract   Green tea (Camellia sinensis L.) has the main efficacy as an antioxidant and contains polyphenol compounds in green tea leaves with the main component of polyphenol fraction namely Epigallocatechin-3-gallate (EGCG) which has strong activity to prevent free radicals that cause premature aging. Research has been carried out on the formulation of maskantioxidant preparations containing green tea leaf extract. The study begins with testing the antioxidant activity of ethanol extract of green tea leaves with a free radical reduction method of 1,1-diphenyl-2-picrylhydrazyl using visible spectrophotometry. Testing of antioxidant activity showed that the ethanol extract of green tea leaves gave an IC50 value of 3.17µg / mL. Formulations of gel masks made were F0 (base without active substances), F1 (base + concentration of ethanol extract of green tea leaves for IC50 (0,000317%)), F2 (base + concentration of ethanol extract of green tea leaves for 50xIC50 (0, 0158%)), F3 (base + concentration of ethanol extract of green tea leaves for 100xIC50 (0.0317%)), F4 (base + concentration of ethanol extract of green tea leaves for IC50), F5 (base + concentration of ethanol extract of green tea leaves worth IC50), F6 (base + concentration of ethanol extract of green tea leaves for IC50. Evaluation of gel mask preparations include, organoleptic examination and homogeneity, pH, viscosity, dry time of preparation and testing of antioxidant stability. F2 provides better and higher free radical reduction activity than products on the market. F4, F5, F6 shows an increase in free radical reduction activity.   Keywords: Green tea leaves (Camellia sinensis L.), DPPh, IC50 gel mask.

scholarly journals The bioactive contents and antioxidant activity of honey bee nest extract of Apis dorsata Binghami from the North Sulawesi

Molekul ◽  
2019 ◽  
Vol 14 (2) ◽  
pp. 92
Author(s):  
Mokosuli Yermia Semuel ◽  
Eva Sherly Nonke Kaunang ◽  
Jacklin Stella Manopo
Keyword(s):  
Antioxidant Activity ◽  
Free Radical ◽  
Honey Bee ◽  
Ethanol Extract ◽  
Control Treatment ◽  
Apis Dorsata ◽  
Reduction Activity ◽  
North Sulawesi ◽  
Radical Reduction ◽  
Bioactive Content

Apis dorsata Binghami is a Sulawesi endemic honey bee. Apis dorsata Binghami cannot be bred, so it still lives wildlyin the forests of Sulawesi. However, Apis dorsata Binghami produces more honey, compared to all honey bee species. Furthermore, the diversity of plants as a source of nectar, pollen and plant resin, which is used in the formation of nests and honey is more, than all types of honey bees in the world. Ethnomedically, the Minahasa community has long used honeynest for degenerative diseases such as hyperlipidemia and cancer. Nevertheless, there have been no research reports on bioactive content and bioactivity of Apis dorsataBinghami nest extract.  This research wasaimed to determinethe bioactive content of honey bee nest and to obtain the inhibitory concentration 50 (IC50) antioxidant activity of honey bee nest extractofApis dorsata Binghami. Honey bee nest was obtained directly from the forest of Minahasa peninsula, North Sulawesi, Indonesia. Extraction of fresh honey bee nest was conductedusingmaceration method. Bioactive content analysis was carried out by the Harborne method, followed by analysis using UV Vis spectrophotometer and High performance liquid chromatography. IC50antioxidant activity of honey bee nest extract was obtained using DPPH free radical reduction method. The results showed that Apis dorsata Binghami honey bee nest extract containedalkaloids, flavonoids, saponins, tannins, steroids and triterpenoids. Identified flavonoids displayed the highest phytochemical content. Based on the results of HPLC and UV Vis spectrophotometer analysis, there were 20 flavonoid derivatives found in honey bee nest samples in Minahasa. Ethanol extract and n-hexane extract showed high free radical reduction activity compared to vitamin C as a control treatment. However, ethanol extract produced the highest DPPH free radical reduction activity.

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