Effects of phenanthrene on chemical composition and enzyme activity in fresh tea leaves

Phenanthrene pollution around roots of tea (Camellia Sinensis) seedlings and its effects on antioxidative enzymes and chemical composition in fresh tea leaves during 7 days of hydroponic culture were investigated. Phenanthrene concentration in the fresh tea leaves gradually increased over the 7 days. The activities of polyphenol oxidase (PPO) and superoxide dismutase (SOD) were promoted at the beginning of phenanthrene contamination and were suppressed from the fifth day, while peroxidase (POD) and catalase (CAT) followed an opposite trend. On the third day, the contents of water extract, amino acid and caffeine had peak values, and the protein content was the lowest. The contents of polyphenols and total sugar were increased on the first day and then began to decline. On the seventh day, all chemical components decreased, indicating that phenanthrene may reduce tea quality. Linear correlation analysis showed that the activities of PPO, POD and CAT and the content of polyphenols in the tea leaves correlated well with the concentration of phenanthrene in the tea leaves.