doi:10.1007/s12020-019-02055-z Capasso I, Esposito E, Pentimalli F, Montella M, Crispo A, Maurea N,
Melanotan 1, is typically injected or administered as an implant, and binds to the melanocortin receptors 1, 3, 4, and 5 (MC1R, MC3R, MC4R, MC5R), with a strong effect on MC1R, leading to increased melanin production and tanning in test subjects [2, 3, 4, 5, 6]
D-carnitine, the mirror image, is biologically inactive and potentially harmful, as it can competitively deplete L-carnitine stores
Denison HJ, Cooper C, Sayer AA, Robinson SM
This is the same receptor through which the natural hormone ghrelin-often referred to as the hunger hormone-exerts its effects