4-Guanidinobutyric acid is an L-arginine metabolite that has been used in the intestinal transport tranport studies.

H-Gly-Pro-OH is a dipeptide composed of glycine and proline and is an end product of collagen metabolism.

DL-Homocysteinethiolactone hydrochloride is a cysteine derivative that binds to and induces conformational changes in various plasma proteins slowing coagulation and inducing oxidative stress.?