The vitamin A that we ingest is converted by a family of enzymes to something called retinoic acid.

我们摄入的维生素 A 被一系列酶转化为一种叫做视黄酸的物质。

Then there are chemical peels, which use compounds like salicylic acid or retinoic acid to perform what's basically a controlled injury to the top layer of skin, killing the top layer of cells.

此外还有化学换肤，用水杨酸或维生素A酸之类的化合物，有控制性地损伤表层皮肤 ，杀死表层皮肤细胞。