Table 2.
Representative therapeutic peptides/proteins under research for oral delivery.
| Name | Structure/composition | Primary therapy | Ref. |
|---|---|---|---|
| EGFR targeted hybrid peptide | In a total of 32 amino acid residues and a molecular weight of 3774 Da | Highly selective activity toward EGFR-positive cancer cells | 5 |
| Vancomycin | A branched tricyclic glycopeptide | Infections by Gram-positive bacteria | 6 |
| Myrcludex B | A linear myristoylated peptide composed of 47 amino acids | Hepatitis B | 7 |
| hGH | A 191 amino acids protein | Adult growth hormone deficiency and children׳s growth disorders | 8 |
| Octreotide | An 8 amino acids synthetic analogue of somatostatin | Acromegaly, psoriasis and gastro–intestinal disorders | 9., 10. |
| Urokinase | A protein consisting of 411-amino acid residues | A thrombolytic agent | 11 |
| Rituxan | A whole antibody with a molecular weight of about 144 kDa | Non-Hodgkin׳s lymphoma, chronic lymphocytic leukemia | 11 |
| sCT | With a molecular weight of 3431 Da and composed of 32 amino acids | Paget׳s disease | 11., 12., 13., 14. |
| Polypeptide-k | Contained 9 out of 11 essential amino acids, among a total of 17 types, 168 amino acids | Antidiabetic | 15 |
| Dalargin | A model opioid peptide composed of 6 amino acids with a molecular weight of 725 Da | Immunoregulation | 16 |
| Elisidepsin | A synthetic marine-derived cyclic peptide | Antitumor | 17 |
| Cholera toxin | An oligomeric complex made up of six protein subunits with a molecular weight of 83 kDa | As a neuronal tracer | 18 |
| Ovalbumin | Consisted of 385 amino acids and has a relative molecular mass of 42.7 kDa | Used in proteomics and immunology | 18., 19., 20. |
| BSA | With a molecular weight of 66.5 kDa and composed of 607 amino acids | Often used as a blocker in immunohistochemistry | 21., 22., 23., 24., 25. |
| Lysozyme | With a molecular weight of 14 kDa and consisting of 130 amino acids | Diarrhea | 21., 26., 27. |
| SOD | A homodimer of molecular weight-33 kDa | Inflammatory bowel diseases | 28 |
| Antide | A decapeptide with an antagonist of GnRH | Endometriosis and uterine fibrosis | 29 |
| IAPP | A 37-residue peptide hormone | Obesity | 30 |
| Irisin | A peptide hormone composed of 111 amino acids | Obesity | 30 |
| SIINFEKL (OVA257-264) | A 8-amino-acid peptide | A specific antigenic peptide | 31 |
| Exendin-4 | A 39-amino-acid peptide | Type 2 diabetes | 32., 33., 34., 35., 36., 37., 38. |
| GLP-1 | A 30 amino acid long peptide hormone | Type 2 diabetes | 39., 40. |
| Insulin | A dimer of an A-chain and a B-chain composed of 51 amino acids and has a molecular weight of 5808 Da | Diabetes | 41., 42., 43., 44., 45., 46., 47., 48., 49., 50., 51., 52., 53., 54., 55. |
hGH, human growth hormone; IAPP，islet amyloid polypeptide; GLP-1, glucagon-like peptide-1; GnRH, gonadotropin hormone-releasing hormone; SOD, superoxide dismutase; BSA, albumin from bovine serum; sCT, salmon calcitonin; EGFR, epidermal growth factor receptor.