Inhibitory Effect of Oolong Tea on the Oxidative State of Low Density Lipoprotein (LDL)

Hiroshi Kurihara; Harukazu Fukami; Yoshiko Toyoda; Norihiko Kageyama; Nobuo Tsuruoka; Hiroshi Shibata; Yoshinobu Kiso; Takaharu Tanaka

doi:10.1248/bpb.26.739

Notes

Inhibitory Effect of Oolong Tea on the Oxidative State of Low Density Lipoprotein (LDL)

Hiroshi Kurihara, Harukazu Fukami, Yoshiko Toyoda, Norihiko Kageyama, Nobuo Tsuruoka, Hiroshi Shibata, Yoshinobu Kiso, Takaharu Tanaka

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Keywords: oolong tea, antioxidant, low density lipoprotein (LDL), lag time, electron spin resonance (ESR)

JOURNAL FREE ACCESS

2003 Volume 26 Issue 5 Pages 739-742

DOI https://doi.org/10.1248/bpb.26.739

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Abstract

In the present study, we investigated the anti-oxidant activity of oolong tea in an oxidation model using human low-density lipoprotein (LDL). Oolong tea suppressed the oxidation of LDL induced by 2-2′-azobis 4-methoxy-2,4-dimethyvaleronitrile (V70) in a dose-dependent manner, that is, it prolonged the lag time to 114.3%, 138% and 199.9% as compared with the control group at 0.5 μg/ml, 1.0 μg/ml, and 2.5 μg/ml, respectively. We also determined the scavenging effect of oolong tea on active oxygen radicals using the electron spin resonance (ESR) technique with 5,5-dimethyl-1-pyrroline N-oxide (DMPO) as a spin trapping agent. The intensity of the ESR signals for the DMPO–OOH adduct formed by the hypoxanthine/xanthine oxidase reaction system with DMPO decreased in the presence of oolong tea. The IC₅₀ of oolong tea was 19.9 μg/ml. These findings suggested that oolong tea has beneficial effects on health related to its anti-oxidative action.

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