diketopiperazine ring

例句：

1. 1.The structure of this compound is a key to its biological activity.
   这种化合物的结构是其生物活性的关键。
2. 2. This compound has been shown to have anticancer properties.
   这种化合物已被证明具有抗癌症性质。
3. 3.The researchers found that the compound had a unique ring structure that made it effective against cancer cells.
   研究人员发现，这种化合物具有独特的环状结构，使其对癌细胞有效。