Free radicals

This thesis documents a research program in which Australian grown Danshen extracts and related bioactive compounds have been demonstrated to be effective in scavenging free radicals, namely ROS generation, in a cell free system and NADPH oxidase derived superoxide (O2-) generation in vascular tissue (rat aorta). Danshen extracts, both aqueous and ethanol, and their active compounds (Tanshinone IIA, Salvianolic Acid B and Danshensu) demonstrated anti-oxidant activity however findings exhibited stronger activity in a cell free system than in the aortic vascular tissue.

138p runthenight07 01-03-2023 11 3   Download

This project investigates the use of free radical initiators in the recycling of post consumer recycled high density polyethylene using reactive extrusion. Both molecular and rheological characterisation of recycled and reprocessed materials was carried out and this was followed by tensile testing of the modified materials to satisfy end use applications such as packaging and drainage piping.

154p runthenight07 01-03-2023 9 3   Download

Glyoxal is a key compound involved in glyoxal oxidase (GLOX)-dependent production of glyoxylate, oxalate and H2O2 by lignin-degrading basidiomycetes. In this paper, we report that glyoxal was produced from a metabolite of ligninolytic fungi, linoleic acid, by manganese peroxidase (MnP)-dependent lipid peroxidation. In the absence of the parent substrate of linoleic acid, the dialdehyde was oxidized by MnP and Mn(III) chelate to start free radical reactions with emission of chemiluminescence at 700– 710 nm. ...

9p system191 01-06-2013 70 7   Download

One-electron oxidation of six different c-type lysozymes from hen egg white, turkey egg white, human milk, horse milk, camel stomach and tortoise was studied by gamma-and pulse-radiolysis.In the first step, one tryptophan side chain is oxidized to indolyl free radical, which is produced quantitatively.As shown already, the indolyl radical subse-quently oxidizes a tyrosine side chain to the phenoxy radical in an intramolecular reaction.However this reaction is not total and its stoichiometry depends on the protein.Rate constants also vary between proteins, from 120Æs )1 to 1000Æs )1 at pH 7.

7p tumor12 20-04-2013 42 2   Download

ADP-ribosylation has been coupled to intracellular events associated with smooth muscle cell vasoreactivity, cytoskel-etal integrity and free radical damage. Additionally, there is evidence that ADP-ribosylation is required for smooth muscle cell proliferation. Our investigation employed selective inhibitors to establish thatmono-ADP-ribosylation and not poly(ADP-ribosyl)ation was necessary for the sti-mulationofDNAsynthesis bymitogens.

10p tumor12 20-04-2013 24 2   Download

Oxidative stress and imbalance between free radical generation and detoxi-fication may play a pivotal role in the pathogenesis of Leber’s hereditary optic neuropathy (LHON). Mitochondria, carrying the homoplasmic 11778⁄ND4, 3460⁄ND1 and 14484⁄ND6 mtDNA point mutations associ-ated with LHON, were used to generate osteosarcoma-derived cybrids. Enhanced mitochondrial production of reactive oxygen species has recently been demonstrated in these cybrids [Beretta S, Mattavelli L, Sala G, Trem-olizzo L, Schapira AHV, Martinuzzi A, Carelli V & Ferrarese C (2004) Brain127, 2183–2192]. ...

0p awards 05-04-2013 45 4   Download

Metformin (1,1-dimethylbiguanide) is an antihyperglycae-mic drug used to normalize glucose concentrations in type 2 diabetes. Furthermore, antioxidant benefits have been reported in diabetic patients treated with metformin. This work was aimed at studying the scavenging capacity of this drug against reactive oxygen species (ROS) like Æ OH and O Æ
2 -free radicals. ROS were produced by gamma radio-lysis of water. The irradiated solutions of metformin were analyzed by UV/visible absorption spectrophotometry.

8p awards 05-04-2013 62 1   Download

To test thioredoxin resistance to oxidizing free radicals, we have studied the one-electron oxidation of wild-type thio-redoxin and of two forms with the point mutations D30A and W35A, using azide radicals generated byc-ray or pulse radiolysis. The oxidation patterns of wild-type thioredoxin and D30A are similar. In these forms, Trp35 is the primary target and is
repaired by one-electron reduction; first by intramolecular electron transfer from tyrosine, and then fromother residues. Conversely, duringoxidationofW35A, Trp13 is poorly reactive.

7p awards 05-04-2013 38 4   Download

A number of drugs used in cancer chemotherapy induce oxidative stress by generation of oxygen free radicals (ROS) which might be an alternative mechanism for their cytotoxic effect via indu-cing apoptosis. In order to clarify the roles of antioxidants in chemotherapy, we investigated Quercetin (3,3’,4’,5,7-pentahyd-roxyflavone) and N-acetylcysteine (NAC) in different cell types treated with anticancer drugs. We studied cytotoxic activity of Topotecan alone and/or in combination with Quercetin in two human breast cancer cell lines, MCF-7 and MDA-MB-231. ...

7p inspiron33 26-03-2013 56 4   Download

Galloylated and nongalloylated catechin conjugates with cysteine deriva-tives have been synthesized and evaluated for their capacity to scavenge free radicals and to influence crucial functions (cell cycle, apoptosis) in HT29 colon carcinoma cells. We show that the nonphenolic part of the molecule modified the capacity of catechins to donate hydrogen atoms and to transfer electrons to free radicals.

12p inspiron33 26-03-2013 34 4   Download

Helicobacter pylorineutrophil-activating protein (HP-NAP) protects DNA from free radicals as a dodecamer through its ferroxidase activity without, however, directly binding to it. The retardation that was observed at pH 7.5 could be easily attributed to an iron effect, as it was revealed by experiments in the absence of HP-NAP.

16p media19 05-03-2013 50 3   Download

Pycnogenol  , which is extracted from the bark of French maritime pine, has been shown to have antioxidant and free radical scavenging activities. Thioredoxin reductase (TrxR), glutathione peroxidase (GPx) and glutathi-one reductase (GR) are three central redox enzymes that are active in endogenous defence against oxidative stress in the cell.

9p vinaphone15 27-02-2013 42 2   Download

Ig-like transcript 2 (ILT2) is a suppressive receptor that participates in the control of the autoimmune reactivity. This action is usually carried out in a proinflammatory microenvironment where there is a high production of free radicals and NO.

11p vinaphone15 25-02-2013 37 2   Download

Trà xanh rất có lợi đối với sức khỏe và sắc đẹp của chúng ta. Bài viết này sẽ chỉ ra rõ những lợi ích đó. Chất chống oxy hóa Trà xanh rất giàu chất chống oxy hóa, có tên gọi là catechin, chất catechin có tác dụng loại bỏ các Free Radical (gây ra hiện tượng máu đông, ung thư, bệnh tim mạch …). Ngoài ra, trà xanh còn có khả năng làm tăng nồng độ HDL cholesterol và làm giảm nồng độ LDL cholesterol....

4p uyendieu 06-12-2012 66 3   Download

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành y học dành cho các bạn tham khảo đề tài: Free radical scavenging activity and lipoxygenase inhibition of Mahonia aquifolium extract and isoquinoline alkaloids,,,

7p thulanh27 13-12-2011 61 2   Download

Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học Wertheim cung cấp cho các bạn kiến thức về ngành y đề tài: Beneficial effect of the oxygen free radical scavenger amifostine (WR-2721) on spinal cord ischemia/reperfusion injury in rabbits...

12p thulanh24 21-11-2011 56 3   Download

Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học quốc tế cung cấp cho các bạn kiến thức về ngành y đề tài: Free radical theory of autoimmunity

16p toshiba17 31-10-2011 43 2   Download

Các nhà khoa học của Trường Đại học California ở Los Angeles vừa lên danh sách những loại đồ uống có ích nhất cho sức khỏe. Việc đánh giá được dựa trên hàm lượng chất chống oxy hóa trong đồ uống. Chất chống oxy hóa là tên chung của các hợp chất bảo vệ tế bào khỏi các tác hại do phân tử mang tên free radicals (các gốc tự do) gây lão hóa. Free radicals có khả năng phá hủy các phân tử khác, thậm chí những tế bào trong cơ thể người. Loại phân tử này còn là...

4p nkt_bibo07 31-10-2011 76 5   Download

Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học 'Respiratory Research cung cấp cho các bạn kiến thức về ngành y đề tài: Role of free radicals in the pathogenesis of acute chest syndrome in sickle cell disease...

6p toshiba13 22-10-2011 42 5   Download

Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học General Psychiatry cung cấp cho các bạn kiến thức về ngành y đề tài: Combined antibiotic and free radical trap treatment is effective at combating Staphylococcus-aureus-induced septic arthritis...

5p thulanh12 12-10-2011 40 2   Download