Antioxidant and Anti-Inflammatory Properties of Lower-Polymerized Polyphenols in Oolong Tea

Figures & data

Table 1  Contents of total phenolics, total flavonoids, condensed tannin, and proanthocyanidins in oolong tea filtrates and fractionated tea extracts

Sample	Total Phenolic ^1	Total Flavonoids ^2	Condensed Tannin ^2	Proanthocyanidins ^3
OT	104.6 ± 0.5	11.9 ± 0.4	8.2 ± 1.3	6.7 ± 0.2
FT	128.8 ± 1.7	16.3 ± 0.3	14.1 ± 0.3	2.6 ± 0.3
^1mg gallic acid equivalent per gram of dry weight.
^2mg catechin equivalent per gram of dry weight.
^3mg cyanidin chloride equivalent per gram of dry weight.
Each value represents the mean ± SD of three independent experiments.

Table 2  Contents of gallic acid, caffeic acid, epicatechins (EC), and (-)-epigallocatechin gallate (ECGC) in TMT, MMT, and HMT

Sample*	Gallic Acid	Caffeic Acid	EC	EGCG
OT	1.3 ± 0.5	28.3 ± 5.9	2.2 ± 1.1	53.7 ± 3.6
FT	8.0 ± 1.7	69.1 ± 8.1	17.2 ± 2.0	37.2 ± 10.8
*Unit: mg/g extract.
Each value represents the mean ± SD of three independent experiments.

Table 3  2,2-diphenyl-1-picryhydrazyl- (DPPH-) radical-scavenging activity and antioxidant capacity of EGCG, OT, and FT

	DPPH radical-scavenging activity
Sample	IC50 (μg/mL)	TEAC (mmol/g)*
EGCG	17.9 ± 0.7^a	2.50 ± 0.09
OT	57.2 ± 6.0^c	2.41 ± 0.10
FT	41.2 ± 1.7^b	2.36 ± 0.09
*Trolox equivalent antioxidant capacity (TEAC).
Each value represents the mean ± SD of three independent experiments. The values with different letters are significantly different from each other at p < 0.05.

Figure 1 NO scavenging ability (a) and reducing power (b) of EGCG and the tea extracts. Each data point represents the mean ± SD of four independent experiments. For each data point, the means with different letters or symbol are significantly different from each other at p < 0.05.

Figure 2 Effect of EGCG and the tea extracts on NO production (a) and prostaglandin E₂ (PGE₂) synthesis (b) in lipopolysaccharide- (LPS-) activated RAW264.7 cells. Adherent RAW264.7 cells were incubated with medium containing LPS (0.1 μg/mL) alone (control), or with LPS and tea extract (500 μg/mL) or EGCG (100 μg/mL) for 16 h. Each lane represents the mean ± SD of three independent experiments. In each category, the means with different letters are significantly different from each other at p < 0.05.

Figure 3 Effect of EGCG and tea extracts on the expression of iNOS, and COX-2 in RAW264.7 cells (a). The relative density of the bands, which were assessed after Western blotting (b and c). Adherent RAW264.7 cells were incubated with medium containing LPS (0.1 μg/mL) alone (control), or with LPS and tea extract (500 μg/mL) or EGCG (100 μg/mL) for 16 h. The induction of NO synthase and cyclooxygenase-2 expression was determined by Western blotting. α-tubulin was used as a loading control. Each value represents the mean ± SD of three independent experiments. The values with different letters are significantly different from each other at p < 0.05. (Color figure available online.)

Figure 4 Effect of EGCG and tea extracts on the level of AA. RAW264.7 cells were incubated with only medium or medium containing EGCG (20 μg/mL) or tea extracts (400 μg/mL) for 16 h. Each value represents the mean ± SD of three independent experiments. The values with different letters are significantly different from each other at p < 0.05.