Table 2.

Main plasma antioxidants.

Species	Concentration (μM)	References
Low molecular weight
Reduced thiols	12–20	[67,68,108,112]
Ascorbic acid	30–150	[114,115]
Uric acid	160–450	[114,115]
α and γ-tocopherola	15–40	[114,115]
Lycopenea	0.5–1.0	[114]
β-Carotenea	0.3–0.6	[114]
Ubiquinol 10a	0.1–1.0	[114]
Bilirubinb	5–20	[114]
High molecular weight
Albumin	527–783	[34,74]
Glutathione peroxidase 3c	0.5–0.8	[116]
Selenoprotein P	0.1	[117]
Thioredoxin	0.07–1 × 10−3	[118]
Thioredoxin reductase	3 × 10−4	[119]
Glutaredoxin	1.1 × 10−3	[120]

^aLipid-soluble antioxidants present in lipoproteins.

^bMainly bound to HSA.

^cIt is unknown if it is active due to the low concentration of its reductant substrates (GSH, Trx).