Fragment 176-191, also known as HGH Fragment 176-191 or Somatotropin (176-191), is a synthetic 16-amino acid peptide corresponding to the C-terminal region of human growth hormone (hGH). With the molecular formula C78H125N23O23S2 and a molecular weight of 1815.13 g/mol, HGH Fragment 176-191 (CAS 66004-57-7) spans residues 176 through 191 of the full-length 191-amino acid hGH protein and contains an intramolecular region considered relevant to specific receptor-independent signalling pathways. Produced via solid-phase peptide synthesis, Fragment 176-191 is structurally distinct from intact growth hormone and does not activate the GH receptor.

HGH Fragment 176-191 has been investigated in preclinical metabolic research as an isolated C-terminal peptide fragment characterised in published studies for retaining specific biological characteristics independently of the full-length hGH protein. The observation that this fragment region does not engage the growth hormone receptor or modulate IGF-1 signalling has established it as a key reference compound in studies seeking to dissect the distinct functional domains of hGH. In vitro studies in adipocyte-based experimental preparations have examined Fragment 176-191’s interaction with lipid metabolism pathways, characterising lipolytic cascade activation and intracellular metabolic signalling associated with the C-terminal lipolytic domain of hGH in the absence of growth hormone receptor engagement [1]. Rodent model studies in obese mouse models have examined body composition changes following hGH C-terminal fragment administration, documenting fat oxidation and body composition parameters following repeated administration and investigating whether the metabolic activity of this GH domain can be characterised independently of the somatotropic effects of the intact protein [2], making Fragment 176-191 a key reference compound in C-terminal hGH domain metabolic research.

Fragment 176-191 is manufactured in a cGMP compliant laboratory to a guaranteed purity of 98% or above. Every batch is independently tested using HPLC and MS-UPLC analysis before dispatch. Vials are vacuum sealed and stored in a temperature controlled, monitored cold storage system. Certificates of Analysis are available on request.

Sold strictly for in vitro research purposes only. Not for human consumption. Intended for use by qualified researchers in laboratory settings only.

Editorial Team

Dr. Martina Rossi, PhD

Scientific Contributor and Reviewer

Reviewed and approved 14 June 2026

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