Synthesis and biological properties of insulin-deoxycholic acid chemical conjugates.
Bile acids have been considered very useful in the preparation of new pharmaceuticals, and more recently in the preparation of peptide and protein drugs because of their natural chemical and biological properties. In this study, we modified recombinant human insulin by covalently attaching deoxycholic acid (DOCA) derivatives in order to synthesize orally active insulin analogues. DOCA derivatives, namely succinimido deoxycholate and succinimido bisdeoxycholyl-L-lysine were prepared and site specifically conjugated at Lys(B29) of insulin. The resultant insulin conjugates, [N(B29)-deoxycholyl] insulin (Ins-DOCA) and [N(B29)-bisdeoxycholyl-L-lysil] insulin (Ins-bisDOCA), were studied for their chemical, structural, and biological properties. Their chemical properties were determined by HPLC, MALDI-TOF mass spectroscopy, and dynamic light scattering. Lipophilicity and self-aggregation behavior of insulin conjugates were enhanced with increasing number of labeled bile acid. The far-ultraviolet region of circular dichroism spectra showed no significant change of the tertiary structure of insulin in aqueous solution due to conjugation. Competitive insulin binding assay with HepG2 cells revealed that monosubstituted insulin conjugates still retained high binding affinity to the insulin receptor. When the insulin conjugates were intravenously administered (0.33 IU/kg) to streptozotocin (STZ)-induced diabetic rats, the conjugates showed sustained biological activity for a longer period with the similar lowest blood glucose level (glucose nadir), compared to native insulin. In further studies, the resulting new insulin conjugates will be investigated for their oral efficiency as a long-acting insulin formulation for the treatment of diabetic patients.
Lee
Seulki
S
Department of Materials Science and Engineering, Gwangju Institute of Science and Technology, Buk-gu, Gwangju 500-712, Korea.
Kim
Kwangmeyung
K
Kumar
Tadiparthi Suresh
TS
Lee
Jisook
J
Kim
Sang Kyoon
SK
Lee
Dong Yun
DY
Lee
Yong-kyu
YK
Byun
Youngro
Y
D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D045744:Cell Line, Tumor; D002851:Chromatography, High Pressure Liquid; D002942:Circular Dichroism; D003840:Deoxycholic Acid / Q000737:chemistry*; D006801:Humans; D007003:Hypoglycemia / Q000503:physiopathology; D007328:Insulin / Q000138:chemical synthesis* / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D008297:Male; D015394:Molecular Structure; D051381:Rats; D017207:Rats, Sprague-Dawley; D011972:Receptor, Insulin / Q000378:metabolism
D001786:Blood Glucose; D007328:Insulin; D003840:Deoxycholic Acid; D011972:Receptor, Insulin