• Stres oksidatif pada sistem biologis sering ditandai dengan beberapa parameter meliputi:

• (1) peningkatan formasi radikal bebas dan oksidan lainnya,

• (2) penurunan antioksidan, • (3) ketidakseimbangan reaksi redoks pada sel,

dan • (4) kerusakan oksidatif pada komponen-

komponen sel seperti lemak, protein, dan DNA (Powers dan Jackson, 2008: 1252).

Indikator Senyawa Stress oksidatif• (1) golongan oksidan meliputi Superoxide anions,

Hydroxyl radical, Hydrogen peroxide, dan Peroxynitrite, • (2) golongan antioksidan meliputi Glutathione,

Ascorbate, Alpha-tocopherol, dan Total antioxidant capacity,

• (3) golongan penyeimbang antioksidan/pro-oksidan meliputi GSH/GSSH ratio, Cysteine redox state, dan Thiol/disulfide state, serta

• (4) golongan produk oksidasi meliputi Protein carbonyls, Isoprostanes, Nitrotyrosine, 8-OH-dG, danMalondialdehyde (MDA).

• Oxidative stress is characterized by a decrease of endogenous antioxidant enzymes and by an increase of oxidation products of lipids, proteins, DNA and carbohydrates.

• I think at least you should measure the enzymes SOD, GPx, GR and oxidation products: MDA (lipid oxidation product), 8-hydroxyguanosine (DNA oxidation product), carbonyl groups (protein oxidation products). And finally, total antioxidant capacity.

• You could measure: lipid peroxidation, reduced glutathione, vit A, C, E in plasma and activities of superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx), glutathione reductase (GRx) and glutathione S transferase (GST) in red blood cells - That is what has been done in this paper: http://www.ncbi.nlm.nih.gov/pubmed/17668211

• Good luck!

• Malondialdehyde/TBARS• (in plasma/serum/erythrocytes)

• Protein carbonylation• (in plasma/serum)

• Oxidized LDL• (in plasma/serum)

• Uric acid• (in plasma/serum)

• Vitamin E (α-tocopherol)• (in plasma/serum)

• Vitamin C (ascorbic acid)• (in plasma/serum)

• Vitamin A (retinol)• (in plasma/serum)

• α-Carotene• (in plasma/serum)

• β-Carotene• (in plasma/serum)

• Total antioxidant capacity• (in plasma/serum)

• Superoxide dismutase• (in plasma/serum/erythrocytes)

• Glutathione peroxidase• (in plasma/serum/erythrocytes)

• Copper• (in plasma/serum)

• Ceruloplasmin (Cp)• (in plasma/serum)

• Cp oxidase activity– (in plasma/serum)

• Transferrin• (in plasma/serum)

• Glutathione reductase• (in erythrocytes)

• Catalase• (in erythrocytes)

• 8-hydroxyguanosine• (in lymphocytes)

• Plasma SH groups and FRAP and, surprisingly, TBAR's were significantly lower in free-living older subjects compared to younger subjects (P<0.001, P<0.001, P<0.01, respectively), but there was no significant differences in GSH levels.

• Lipid and protein oxidation were monitored by plasma define (TBAR's), and plasma thiol (SH) group,

• antioxidant defences assessed by erythrocyte Cu/Zn-superoxide dismutase (RBC Cu/Zn SOD) activity, ferric reducing antioxidant plasma (FRAP) assay and plasma total glutathione (GSH).

• we measured postprandial oxidative stress biomarkers after a high-fat meal. We used several markers as indicators of oxidative stress.

• In plasma you can measure malondialdehyde (MDA) as a marker of lipid peroxidation, H2O2 (using amplex red reagent methods), advanced oxidation end products (AOPP).

• You can also measure the antioxidant capacity of the blood through fairly simple techniques such as trolox equivalent antioxidant capactiy (TEAC).

• I think you can get away with measuring MDA, GSH, and protein oxidation. If you are measuring an acute oxidative stress you should see a decline in GSH and an increase in oxidized GSH (GSSG). If that's the case I think it's clear that there was an oxidative stress. I don't think there is one right answer.