7. An amino acid, C6H13N3O3, originally isolated from watermelon, that is produced as an intermediate in the conversion of ornithine to arginine during urea formation in the liver.

• 瓜氨酸一种氨基酸，C6H13N3O3，最初从西瓜中分离出来，在肝部的尿素形成过程中，其作为中介物将鸟氨酸转为精氨酸收藏指正