HGH Frag 176–191 – Fragment Research Overview

HGH Frag 176–191 – Fragment Research Overview

Peptide Research Documentation · For Research Use Only

Peptide Research Documentation

HGH Frag 176-191 – Research Documentation Overview

Neutral, research-only summary for laboratories and qualified organizations investigating human growth hormone C-terminal fragments and lipolytic mechanisms.

For Research Use Only. Not for human or veterinary consumption. This document provides technical reference material for institutional and academic research purposes only. All research activities must comply with institutional protocols, ethics guidelines, and applicable regulatory frameworks.

At a Glance

HGH Frag 176-191, also known as Frag 176-191 or C-terminal fragment of human growth hormone, is a 16-amino acid peptide derived from the C-terminus of human growth hormone (hGH). This fragment (Tyr-Leu-Met-Thr-Gly-Gln-Arg-Leu-Lys-Glu-Asp-Glu-Glu-Asp-Asp-Asp) has been extensively studied in research models investigating fat metabolism, adipocyte lipolysis, and growth hormone-mediated metabolic regulation independent of insulin-like growth factor 1 (IGF-1) signaling.

Document Objectives

  • Characterize structural features and bioactive C-terminal domain properties
  • Establish protocols for handling and preservation
  • Document solubility, stability, and long-term storage methods
  • Summarize mechanistic models in lipolytic research
  • Reference relevant peer-reviewed investigations

Storage & Stability

Optimal Storage Conditions

HGH Frag 176-191 is typically supplied as a lyophilized powder with the following stability profile:

  • Primary storage: 2–8°C (refrigerated) in sealed, light-protected containers (amber or opaque vials); ideal for 18–24 months
  • Extended preservation: −20°C (standard freezer) for 24–36 months; −80°C (ultra-low freezer) for 3+ years
  • Temperature sensitivity: Avoid storage above 25°C; each 10°C elevation approximately halves shelf life
  • Recommended solvents: Sterile water for injection (WFI), 0.9% bacteriostatic saline with benzyl alcohol, or phosphate-buffered saline (PBS, pH 7.2–7.4)

Reconstitution & Post-Dissolution Stability

Upon reconstitution, HGH Frag 176-191 solutions remain stable for 7–14 days at 2–8°C in sterile, airtight containers. Freezing reconstituted solutions at −20°C can extend usability to 30–60 days; however, repeated thaw cycles increase aggregation risk. At room temperature (20–25°C), reconstituted solutions degrade noticeably within 24–48 hours. To preserve bioactivity, prepare fresh aliquots for in vitro assays whenever possible.

Tip: Record all dates and conditions of reconstitution. Include solvent composition, final concentration, and any additives (such as stabilizing agents) on every aliquot label. Monitor for visible particulates or discoloration, which may indicate degradation or contamination.

Handling & Aliquoting

Safe Laboratory Protocols

HGH Frag 176-191 is a research-grade peptide requiring standard laboratory precautions:

  • Personal protective equipment: Lab coat, nitrile gloves, and safety glasses; respiratory protection if handling large quantities of powder
  • Work environment: Well-ventilated laboratory or biosafety cabinet to minimize inhalation of peptide particulates
  • Aseptic technique: Use sterile pipettes, tubes, and syringes when preparing solutions; avoid generating aerosols during transfers
  • Weighing accuracy: Use calibrated analytical balances (typically <5 mg minimum) for precise dosing in research protocols

Aliquoting Strategy

Prepare smaller working aliquots (0.5–2 mg per vial) from bulk stock to reduce repeated handling and oxidative exposure. Under aseptic conditions, divide the compound into sterile, sealed vials. Label each with lot number, preparation date, concentration, and expiration. Store divided aliquots in dedicated, temperature-monitored freezers with backup power. Remove only the aliquot needed for immediate use; limit thawing cycles to preserve peptide integrity.

Tip: If preparing solutions with additives (glycerol, trehalose, or surfactants for stabilization), document the formulation precisely. Some stabilizers may interfere with downstream assays, so coordinate with bioanalytical teams before use.

Documentation Checklist

Rigorous record-keeping ensures regulatory alignment and research reproducibility. Maintain documentation of:

  • Procurement data: Supplier identity, lot/batch number, certificate of analysis (CoA), reported purity, peptide sequence confirmation, date of receipt
  • Storage logs: Temperature readings (manual or continuous automated monitoring), any deviations or alarms, humidity levels if tracked
  • Inventory tracking: Initial mass upon receipt, aliquot sizes prepared, dates of access or use, personnel identities, residual mass or disposal records
  • Reconstitution records: Date, time, solvent type, volume added, final concentration, sterile filtration details (if applicable), solution appearance
  • Stability observations: Visual inspection results, any discoloration, precipitation, or odor changes; comparison to reference standards if performed
  • Protocol approvals: IACUC approval letters (for animal studies), IRB documentation (if human-relevant data generated), institutional chemical safety clearance
  • Disposal documentation: Final disposition method (incineration, chemical treatment, licensed waste removal), dates, authorization by institutional safety officer

Note: Federal and institutional audits may review compound sourcing and handling records. Comprehensive documentation demonstrates compliance with Good Laboratory Practice (GLP) standards and research integrity principles.

Example Non-Clinical Models

In Vitro Adipocyte Studies

HGH Frag 176-191 is extensively employed in cultured 3T3-L1 preadipocytes and primary human adipocytes to investigate lipolytic mechanisms independent of the growth hormone receptor (GHR) and IGF-1 signaling. Researchers measure glycerol release (spectrophotometric assay of glycerol-3-phosphate dehydrogenase activity), free fatty acid mobilization (fluorescence-based FFA quantification), and expression of lipolytic enzymes (hormone-sensitive lipase, adipose triglyceride lipase). Typical dose ranges are 10−8 to 10−6 M. Temporal studies often track lipid depletion over 24–72 hours of incubation.

Rodent Obesity Models

In vivo studies have employed high-fat diet-induced obese mice and rats, as well as genetic obesity models (ob/ob, db/db), to assess the fragment’s effects on body composition, adipose tissue mass, and serum lipid profiles. Administration routes (intraperitoneally, intramuscularly, or subcutaneously) influence kinetics and tissue distribution. Outcome measures include body weight tracking, MRI-derived adipose volume, histological examination of adipocyte morphology, and metabolic cage data (oxygen consumption, CO2 production).

Lipid Metabolism & Gene Expression

qPCR and RNA-seq analyses have characterized expression profiles of lipid metabolism genes in response to HGH Frag 176-191, including upregulation of hormone-sensitive lipase (HSL), adipose triglyceride lipase (ATGL), and carnitine palmitoyltransferase 1 (CPT1). Western blot analysis quantifies phosphorylated versus total HSL and other lipolytic enzymes. Mitochondrial function studies (Seahorse assays) measure oxidative capacity and ATP synthesis in adipocytes exposed to the fragment.

Note: All animal studies must obtain IACUC approval prior to initiation and comply with the Guide for the Care and Use of Laboratory Animals and AVMA Guidelines on Euthanasia.

Compliance & Risk Notes

Regulatory Classification

HGH Frag 176-191 is not approved for human therapeutic use by the FDA, EMA, or equivalent regulatory agencies worldwide. It is explicitly prohibited for human consumption, veterinary use, or clinical application. Under DSHEA and analogous international regulations, marketing this fragment as a dietary supplement, weight-loss agent, or therapeutic is unlawful. The FDA has issued public warnings regarding illicit marketing of peptide fragments as performance-enhancing or body-composition-altering compounds.

Risk Mitigation Procedures

Organizations conducting research with HGH Frag 176-191 must: obtain institutional approval via IACUC (if animal models) or equivalent oversight committees, restrict access to qualified scientific personnel, implement secure storage with access logs, establish procedures for safe destruction of unused material, and maintain comprehensive audit trails. Any deviation from approved research protocols or sale/distribution for non-research purposes constitutes violation of applicable law.

Quality Verification Upon Receipt

Validate product identity and purity immediately upon receipt via high-performance liquid chromatography (HPLC), liquid chromatography-mass spectrometry (LC-MS), or amino acid analysis. Cross-reference supplier documentation against published peer-reviewed characterization. Water content (Karl Fischer titration) should be <5%; bacterial endotoxin (LAL assay) <1 EU/mg; microbial limits per USP <61> <62>.

Disclaimer: This document is for institutional compliance reference only. Organizations bear full responsibility for ensuring all use conforms to applicable local, state, federal, and international law. Unauthorized possession, distribution, or use of HGH Frag 176-191 outside approved research contexts may violate criminal statutes and international pharmaceutical regulations.

References & Evidence Snapshot

Key Literature

Mechanistic Overview

The C-terminal fragment 176-191 of hGH stimulates lipolysis in adipose tissue through a receptor distinct from the classical growth hormone receptor (GHR). The mechanism involves activation of adipocyte hormone-sensitive lipase (HSL) and adipose triglyceride lipase (ATGL), leading to triglyceride hydrolysis and mobilization of free fatty acids. Unlike full-length hGH, the fragment does not activate IGF-1 signaling or elicit insulin antagonism, making it a valuable tool for studying growth hormone’s direct metabolic effects independent of endocrine (IGF-1) pathways.

Bioanalytical Characterization

Research-grade HGH Frag 176-191 typically achieves ≥95% purity by HPLC with identity confirmation via mass spectrometry (MALDI-TOF or LC-MS yielding m/z consistent with 2040.1 ± 0.5 Da for the 16-peptide sequence). Amino acid analysis confirms expected composition. Potency assays measure dose-dependent glycerol release in 3T3-L1 adipocytes, with EC50 values typically in the micromolar range (1–10 μM). Stability studies demonstrate preservation of lipolytic activity under documented storage conditions.

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Disclaimer: This content is for research documentation purposes only. Not for human consumption or therapeutic application.

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