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Antioxidant activity of various teas against free radicals
and LDL oxidation.
Tea is a widely consumed beverage throughout the world. We assessed the
antioxidant activity of six teas, including the aqueous extracts of green tea and
oolong tea (Camellia sinensis), tochu (Eucommia ulmoides), Gymnema
sylvestre, Japanese mugwort (Artemisia princeps), and barley (Hordeum
vulgare), against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals and LDL
oxidation, and examined the association of LDL oxidizability with the plasma
catechin levels in 10 healthy volunteers with a single dose of 5 g green tea
powder. In vitro, the inhibitory effects of DPPH radicals and LDL oxidation were
found to be strongest in the extract of green tea and weakest in that of barley.
After the ingestion of green tea powder, the lag time increased from basal 52.2
+/- 4.1 to 60.3 +/- 4.2 min at 1 h and 59.5 +/- 4.1 min at 2 h, and then returned to
the baseline lag time (51.9 +/- 1.4 at 4 h and 52.1 +/- 4.7 min at 6 h). Regarding
the plasma catechin levels, epigallocatechingallate and epicatechingallate
significantly increased from basal 3.7 +/- 1.3 and 0.8 +/- 0.8 ng/mL to 65.7 +/-
11.6 and 54.6 +/- 12.6 ng/mL at 1 h, and 74.4 +/- 18.6 and 49.4 +/- 7.1 ng/mL at
2 h, respectively. Green tea therefore showed the strongest antioxidant activity
among the six different teas, and the inhibitory effects of green tea on LDL
oxidation depended on the plasma catechin levels.
Ohmori R, Iwamoto T, Tago M, Takeo T, Unno T, Itakura H, Kondo K.
First Department of Internal Medicine, National Defense Medical College,
Tokorozawa, Saitama. rhirano@ndmc.ac.jp
and LDL oxidation.
Tea is a widely consumed beverage throughout the world. We assessed the
antioxidant activity of six teas, including the aqueous extracts of green tea and
oolong tea (Camellia sinensis), tochu (Eucommia ulmoides), Gymnema
sylvestre, Japanese mugwort (Artemisia princeps), and barley (Hordeum
vulgare), against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals and LDL
oxidation, and examined the association of LDL oxidizability with the plasma
catechin levels in 10 healthy volunteers with a single dose of 5 g green tea
powder. In vitro, the inhibitory effects of DPPH radicals and LDL oxidation were
found to be strongest in the extract of green tea and weakest in that of barley.
After the ingestion of green tea powder, the lag time increased from basal 52.2
+/- 4.1 to 60.3 +/- 4.2 min at 1 h and 59.5 +/- 4.1 min at 2 h, and then returned to
the baseline lag time (51.9 +/- 1.4 at 4 h and 52.1 +/- 4.7 min at 6 h). Regarding
the plasma catechin levels, epigallocatechingallate and epicatechingallate
significantly increased from basal 3.7 +/- 1.3 and 0.8 +/- 0.8 ng/mL to 65.7 +/-
11.6 and 54.6 +/- 12.6 ng/mL at 1 h, and 74.4 +/- 18.6 and 49.4 +/- 7.1 ng/mL at
2 h, respectively. Green tea therefore showed the strongest antioxidant activity
among the six different teas, and the inhibitory effects of green tea on LDL
oxidation depended on the plasma catechin levels.
Ohmori R, Iwamoto T, Tago M, Takeo T, Unno T, Itakura H, Kondo K.
First Department of Internal Medicine, National Defense Medical College,
Tokorozawa, Saitama. rhirano@ndmc.ac.jp
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