Peptides refer to biologically active molecules that contain at least two amino acids, interlinked by a peptide bond. Unlike large proteins, they are small in size and a typical chain will usually not go past 100 amino acids.
Since peptides are highly selective and also known to have relatively safe characteristics, their pharmacological profiles have always appealed to the research world. They are readily available in the human body where they play diverse biological roles.
For most applications, they mainly act as regulatory and signaling molecules in various physiological processes. Back in the day, the instability of peptides limited their use in the design and development of human drugs, but due to technological breakthroughs, the instability challenges have all been overcome, greatly increasing the broad application of peptides.