Tuftsin is a tetrapeptide (Thr-Lys-Pro-Arg) that specifically binds monocytes, macrophages, and polymorphonuclear leukocytes and potentiates their natural killer activity against tumors and pathogens.

3α,12β-Dihydroxycholanoic acid 是一种胆汁酸，可以从健康人类尿标本分离出。

3-苯基丙酸甲酯是一种内源性代谢物。