Follistatin-344

A synthetic cyclic analog of alpha-melanocyte stimulating hormone (alpha-MSH) that non-selectively activates melanocortin receptors MC1R through MC5R. Melanotan II stimulates melanogenesis for skin tanning via MC1R, modulates sexual arousal through MC3R/MC4R in the hypothalamus, and reduces appetite through central MC4R activation. It is not FDA-approved and carries significant safety concerns.

IGF-1 LR3 is a synthetic analogue of insulin-like growth factor 1 with an N-terminal extension of 13 amino acids and a substitution of arginine for glutamic acid at position 3. These modifications reduce binding to IGF-binding proteins, resulting in an extended half-life and increased bioavailability compared to native IGF-1. The peptide promotes anabolic processes including muscle protein synthesis, glucose uptake, and cellular proliferation. IGF-1 LR3 is not approved for human use and is primarily available as a research reagent, though it is sometimes misused in athletic and bodybuilding contexts.

IGF-1 DES (1-3) is a truncated analogue of insulin-like growth factor 1 lacking the first three N-terminal amino acids (glycine-proline-glutamate). This structural modification prevents binding to IGF binding proteins in serum, resulting in a shorter half-life but significantly increased potency at the IGF-1 receptor compared to native IGF-1. The peptide is hypothesized to promote localized muscle hypertrophy and tissue repair through enhanced receptor activation in target tissues.

Mechano Growth Factor is a splice variant of the IGF-1 gene expressed in response to mechanical stress on muscle tissue. The peptide contains a unique C-terminal domain resulting from alternative splicing that distinguishes it from systemic IGF-1. MGF is proposed to act locally in skeletal muscle to activate satellite cells and promote muscle fiber repair and hypertrophy following mechanical loading or injury.