褪黑素的英文为什么不带black，好气啊

[img]http://img.nga.178.com/attachments/mon_201209/14/-47218_5052bc4cc6331.png[/img]建议向美国科普褪黑素的中文译名[img]http://img.nga.178.com/attachments/mon_201209/14/-47218_5052bc4cc6331.png[/img]