The Mechanism Study Of Short Peptide TD-34 For Enhancing Transdermal Insulin Delivery

Patients with oral insulin therapy is not effective,usually,the patient is treated by subcutaneous injection of the insulin,this treatment has the existence of higher risk,insulin percutaneous administration can reduce the pain of the patients in the treatment process.Biological macromolecule drugs like insulin because of its large molecular weight,hydrophilic are difficult to penetrate into the blood through the skin to achieve therapeutic effect,the traditional methods of promoting include the use of chemical penetration enhancers and some physical promotion methods such as iontophoresis and so on have the inevitable shortcomings,such as easy to cause irritation to the skin,the need for specialized equipment,expensive and so on.2006 Nature biotechnology published a research paper,the researchers discovered a peptide sequence?TD-1?through the in vivo phage display technology,this peptide can promote insulin through the skin into the body circulation through the physical blends,reduce diabetes rats blood sugar levels.TD-34 was screened on the basis of TD-1,and the effect of hypoglycemic effect after blending with insulin was better than that of TD-1.However,the mechanism of how TD-34 can promote insulin transdermal into the blood circulation has not yet clear.In this study,the interaction between TD-34 and insulin and the effect of TD-34 on the skin were studied in this paper.The results show that the blood glucose level can be continuously reduced in 8 hours by blending the novel cationic cyclone peptide TD-34?ACSSKKSKHCG,two cysteine-forming disulfide bonds?with insulin when applied on the abdominal skin of type?diabetic rats.It can reduce the blood sugar to the initial value of 26%,but administration of insulin alone or administration of TD-34 alone had no hypoglycemic effect,indicating that TD-34 is due to promote the transdermal insulin and thus played a hypoglycemic effect.TD-34 significantly promoted the penetration of FITC-labeled insulin into the stratum corneum,and the penetration of FITC-labeled TD-34 was mainly through the follicular pathway.Fluorescence spectra showed that TD-34 could interact with the hydrophobic residues of insulin in the solution.After adding TD-34,the Zeta potential of the insulin solution was significantly increased.The results of ATR-FTIR showed that TD-34 had no significant effect on the lipid domain of the skin.However,after 8 hours of treatment with TD-34 solution,the amide II peak of keratin was shifted to the lower wave number,indicating that TD-34 changed the the secondary structure of keratin,from the dense?-spiral to the more loose?-folding and random curl.The addition of TD-34 significantly increased the uptake of insulin for HaCaT cells.Addition of TD-34 did not improve the stability of insulin in the skin homogenate,nor did it improve the skin-media partition coefficient of insulin.Ultrafiltration was used to study the effect of TD-34 addition on the aggregation of insulin in solution.The results showed that TD-34 did not significantly change the aggregation state of insulin in solution.Skin irritation results showed no significant skin irritation after a week of continuous administration of TD-34.The cytotoxicity of TD-34 was studied by MTT assay.The results showed that the IC₅₀ value of TD-34 was about 7.6 mg/m L,which belonged to non-toxic compounds.