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Small Molecule Ghrelin Mimics Derived From MK-677 Show Potent GH-Releasing Activity

RPEP-006902001Palucki, B L; Feighner, S D; Pong, S; McKee, K K; Hreniuk, D L; Tan, C; Howard, A D; Van der Ploeg, L H; Patchett, A A; Nargund, R P
In VitroPreliminary evidence
The takeaway

Spiro(indoline-piperidine) compounds designed to mimic ghrelin's active core showed potent binding and functional activation of the GH secretagogue receptor, advancing small-molecule ghrelin drug development.

Peptide to pill

Small molecules successfully mimicked ghrelin's receptor activation — translating a peptide hormone into drug-like compounds for potential oral delivery

What the researchers found

Spiro(indoline-piperidine) small molecules mimicking ghrelin's N-terminal active core showed potent GHS-R binding and functional calcium signaling activation, validating small-molecule ghrelin mimicry.

Why it matters

Translating a peptide hormone into a stable, oral small molecule drug is one of pharmacology's greatest challenges. These compounds demonstrate it's achievable for ghrelin.

How the study worked

In-vitro study. Series of spiro(indoline-piperidine) compounds synthesized and tested in GHS-R binding assays and intracellular calcium flux functional assays.

What this study cannot tell us

In-vitro data only. Oral bioavailability and in-vivo efficacy not demonstrated for all compounds. Selectivity profile incomplete.

How to read the evidence

Preliminary in-vitro evidence with binding and functional assay data for a novel chemical series.

When this study was published

Published in 2001. Small-molecule ghrelin mimetics continue to be developed for GH deficiency, cachexia, and gastroparesis.

The bigger picture

Converting peptide hormones into oral small-molecule drugs opens therapeutic applications that peptides alone cannot reach. These ghrelin mimics represent ongoing progress toward oral GH and appetite therapies.

Questions still open

  • Which compound has the best in-vivo oral bioavailability?
  • Do these maintain ghrelin's appetite-stimulating properties?
  • Can selectivity between GH release and appetite be engineered?

Common questions

Can a pill mimic ghrelin?
Yes. These small molecules activate ghrelin's receptor just like the natural hormone does. Unlike ghrelin (which would be destroyed if swallowed), these drug-like molecules could potentially be taken as pills.
What would a ghrelin pill be used for?
Potential uses include treating GH deficiency, stimulating appetite in cachexia (muscle wasting from cancer/HIV), and improving gastroparesis (slow stomach emptying). Multiple applications target ghrelin's diverse effects.

Read the original research

Spiro(indoline-3,4'-piperidine) growth hormone secretagogues as ghrelin mimetics.

Bioorganic & medicinal chemistry letters, 11(14), 1955-7

View on PubMed ↗

Citation

Palucki, B L; Feighner, S D; Pong, S; McKee, K K; Hreniuk, D L; Tan, C; Howard, A D; Van der Ploeg, L H; Patchett, A A; Nargund, R P. (2001). Spiro(indoline-3,4'-piperidine) growth hormone secretagogues as ghrelin mimetics.. Bioorganic & medicinal chemistry letters, 11(14), 1955-7.