Goralatide

Ac-SDKP is one of the better-studied endogenous regulatory peptides, but the human clinical record is narrow. Its chemoprotection story peaked in the 1990s under the names Goralatide and Seraspenide, with a couple of small phase I-II trials showing it was safe and gave modest protection of blood counts alongside cytotoxic drugs; it never advanced to a marketed product. The much larger and more active body of work is preclinical: dozens of animal and cell studies show it lowers collagen deposition and inflammation in heart, kidney, lung and liver, largely by damping TGF-beta1 signaling.

A useful anchoring fact is that ACE inhibitor drugs raise circulating Ac-SDKP several-fold, because the N-domain of ACE is the enzyme that normally destroys it; so some of the antifibrotic benefit people already get from ACE inhibitors may run partly through this peptide. The practical read: real endogenous molecule, genuinely interesting biology, well tolerated in the small human exposures on record, but no established human dosing for the antifibrotic uses and essentially no modern clinical program behind it.

In the small human trials run under the Seraspenide and Goralatide names it was described as devoid of toxicity and well tolerated at the doses used with chemotherapy. That is reassuring but thin: those cohorts were small, short, and oncology-specific, so there is no long-term human safety data, no data in healthy long-term users, and nothing establishing a safe dose for the antifibrotic or anti-aging uses people discuss today.

Two mechanistic cautions worth stating plainly: because it restrains stem-cell cycling, and because it can promote angiogenesis, its net effect in a setting of active cancer is not something to assume is benign. Anyone on ACE inhibitors already has elevated endogenous levels, and no one has characterized what stacking exogenous peptide on top does. As with any research peptide, sourcing, purity and sterility of injectable material are real risks separate from the molecule itself. It is not an approved drug for any indication.

Ac-SDKP was isolated and structurally identified by Lenfant and colleagues in 1989 as an inhibitor of pluripotent hematopoietic stem cell proliferation purified from bone marrow. Through the early-to-mid 1990s it was developed as a chemoprotective agent under the names Seraspenide and Goralatide, with the idea that parking stem cells in quiescence before cytotoxic therapy would spare the marrow; phase I-II trials in patients on cytarabine and ifosfamide showed safety and some protection of peripheral counts, and animal work paired it with GM-CSF or G-CSF to speed count recovery.

The oncology program did not reach approval. Meanwhile a separate line of research, spurred by the discovery that ACE is its degrading enzyme, reframed Ac-SDKP as an endogenous antifibrotic and anti-inflammatory mediator; from the early 2000s onward most publications focus on heart, kidney, lung and liver fibrosis models rather than hematology.

Among researchers it is regarded as a legitimate, well-characterized endogenous peptide with a clear enzymatic origin (thymosin beta-4) and a clear clearance route (ACE N-domain), which is more than can be said for many peptides in this space. Its antifibrotic literature is taken seriously as mechanism, though almost all of it is preclinical. In the research-chemical and peptide-user community it gets far less attention than BPC-157, TB-500 or the racetams, partly because it has no consumer hype cycle behind it and partly because it is short-lived and awkward to dose. When it is discussed, it usually rides on its link to thymosin beta-4 and to ACE-inhibitor biology. There is no credible marketing claiming proven human antifibrotic benefit, and honest sources keep the preclinical caveat front and center.