Impact of Different Storage Time on Antioxidant Activity of Organic Solvent Extracts of Pu-erh Teas
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Abstract:
The antioxidant activity of different organic solvent extracts of pu-erh teas (raw and ripened pu-erh which produced in different years) was evaluated by half-inhibitory concentration (IC50). Results showed that the IC50 value of raw teas to scavenge DPPH free radical and superoxide radical were 0.339 mg/mL, 0.074 mg/mL and 1.206 mg/mL, respectively. And the IC50 of ripe teas to the obove-mentioned radicals were 0.554 mg/mL, 0.164 mg/mL and 1.927 mg/mL, respectively. Raw teas had higher antioxidant activity than ripe ones. The extracts by different organic solvents showed different scavenging abilities to different free radicals, which depended on the content of tea polyphenol and flavonoids. The highest content of tea polyphenol in raw teas was extracted by ethyl acetate, ranged from 7.33% to 9.57% and the extract from butyl alcohol had the largest amount of flavonoids(7.08~10.99%). For the ripe tea, the highest contents of tea polyphenol and flavonoids were 3.62% to 5.73% and 4.75% to 5.83%, respectively, which were all extracted by butyl alcohol. In conclusion, the extracts by ethyl acetate and butyl alcohol had higher capacity of scavenging free radicals due to the higher content of hydroxyl; and the storage time of teas showed little effect on the antioxidant activity from different extracts.
