Pentadecapeptide

What "Pentadecapeptide" Means

A pentadecapeptide is simply any peptide that contains exactly 15 amino acid residues. The term is structural rather than functional — it describes a length, not a class of activity. Fifteen residues sits in an interesting window for drug development: long enough to fold into defined secondary structure and to present a recognizable binding surface to a receptor, but short enough to be synthesized routinely by solid-phase peptide synthesis and to cross tissue barriers more readily than full-length proteins.

In the peptide-research literature, "pentadecapeptide" is most often used as shorthand for research compounds designated by development code rather than by a final brand name. The two most cited examples in this space are BPC-157 (sometimes labeled as pentadecapeptide BPC 157) and PL-14736, an investigational gastrointestinal compound developed by Pliva.

BPC-157 as the Archetype

BPC-157, with the sequence GEPPPGKPADDAGLV, is the best-known pentadecapeptide in this library. It was derived in the early 1990s from a 62-residue parent protein isolated from human gastric juice, and its unusual stability in acidic conditions made it one of the first bioactive peptides seriously evaluated for oral administration. The preclinical literature on BPC-157 — over a hundred rodent studies on tendon, ligament, gut, and CNS repair — is dominated by a single research consortium, and independent replication has been slow. For a focused reference see our BPC-157 page, and for practical protocol context our dosage guide.

PL-14736 and the Inflammatory Bowel Program

PL-14736 is the development code assigned to a pentadecapeptide that entered Phase 2 clinical trials in the 2000s for inflammatory bowel disease. Its sequence overlaps substantially with BPC-157, and the program's sponsor studied it for ulcerative colitis. Published results were mixed and the program did not progress to Phase 3 under the PL-14736 designation. Much of the residual research-chemical market for "pentadecapeptide" traces back to this investigational compound — a reminder that a research code does not confer regulatory approval.

Why 15 Residues Recurs

The 15-residue window shows up repeatedly in peptide drug discovery for a few practical reasons:

• Synthesis economics. Solid-phase peptide synthesis scales nonlinearly — past 20 residues, both purity and cost become meaningful obstacles. Fifteen residues is still cleanly manufacturable at commercial scale.
• Stability. Short peptides are often rapidly degraded by serum peptidases; longer peptides are more prone to aggregation and immunogenicity. A 15-residue sequence with the right stabilizing motifs can split the difference.
• Receptor engagement. Many receptor binding pockets require a contiguous stretch of roughly 10 to 20 residues for adequate contact, which places the 15-residue range inside the sweet spot for mimicking larger protein loops.

Regulatory and Safety Landscape

"Pentadecapeptide" is not a regulatory category. Any given 15-residue peptide has its own FDA status, WADA position, and safety profile. In September 2023, the FDA placed BPC-157 on its Category 2 bulk drug substance list, restricting it from compounding — but that action applies only to that specific sequence. Other pentadecapeptides may face different regulatory treatment depending on their development history and safety data.

Safety considerations scale with the specific compound. Well-characterized pentadecapeptides with extensive preclinical data and at least Phase 2 clinical exposure (PL-14736, for example) have a meaningful safety signal to draw on. Novel pentadecapeptides sold through research-chemical channels do not, and buyers often cannot verify purity, identity, or endotoxin load in gray-market product.

Bottom Line

Treat "pentadecapeptide" as a description, not a therapy. The specific 15-residue sequence — where it came from, what clinical program generated it, and what independent data exists — is what matters for evaluating any given compound. See our peptide sourcing guide for context on how generic category labels can obscure meaningful differences between products.