Butyrates , L- canitine and L-arginine

Dear Andy,
i know that l-carnitine and l-arginine are amino acids but how are they butyrates also???!!!
i tried to search the net but i only find vague results.

They're not butyrates. Butyrates are  fatty acids. Their mechanisms in thalassemia are not the same. Butyrates and hydroxyurea are used because they can stimulate the production of fetal hemoglobin.