Synthetic, in a peptide catalogue, almost always means made by solid-phase peptide synthesis (SPPS): the chain is assembled chemically, one residue at a time, anchored to an insoluble resin bead, then cleaved and purified. It is the production route for essentially every research peptide below about 50 residues, including BPC-157, semaglutide, ipamorelin and the nootropic peptides.
Why synthetic production matters in peptide research
Three properties follow from the chemistry. Control is complete — non-natural residues such as Aib, D-amino acids, acetyl caps and PEG conjugates can be installed at defined positions, which biological expression cannot do. Reproducibility is high, because the same protocol yields the same molecule without the biological variability of a cell culture. And no host-derived contaminants are present, so bacterial endotoxin is not an intrinsic concern in the way it is for recombinant material.
The characteristic impurities are instead chemical: deletion sequences from incomplete couplings, truncated chains, incompletely removed protecting groups, and residual TFA from cleavage. Those are what a certificate of analysis and its HPLC trace exist to quantify.