Amino Acids

, Volume 48, Issue 2, pp 535–547 | Cite as

In vitro and in vivo insulinotropic properties of the multifunctional frog skin peptide hymenochirin-1B: a structure–activity study

  • Bosede O. Owolabi
  • Opeolu O. Ojo
  • Dinesh K. Srinivasan
  • J. Michael Conlon
  • Peter R. Flatt
  • Yasser H. A. Abdel-WahabEmail author
Original Article


Hymenochirin-1b (Hym-1B; IKLSPETKDNLKKVLKGAIKGAIAVAKMV.NH2) is a cationic, α-helical amphibian host-defense peptide with antimicrobial, anticancer, and immunomodulatory properties. This study investigates the abilities of the peptide and nine analogues containing substitutions of Pro5, Glu6, and Asp9 by either l-lysine or d-lysine to stimulate insulin release in vitro using BRIN-BD11 clonal β cells or isolated mouse islets and in vivo using mice fed a high-fat diet to produce obesity and insulin resistance. Hym-1B produced a significant and concentration-dependent increase in the rate of insulin release from BRIN-BD11 cells without cytotoxicity at concentrations up to 1 µM with a threshold concentration of 1 nM. The threshold concentrations for the analogues were: [P5K], [E6K], [D9K], [P5K, E6K] and [E6K, D9k] 0.003 nM, [E6K, D9K] and [D9k] 0.01 nM, [P5K, D9K] 0.1 nM and [E6k] 0.3 nM. All peptides displayed cytotoxicity at concentrations ≥1 µM except the [P5K] and [D9k] analogues which were non-toxic at 3 µM. The potency and maximum rate of insulin release from mouse islets produced by the [P5K] peptide were significantly greater than produced by Hym-1B. Neither Hym-1B nor the [P5K] analogue at 1 µM concentration had an effect on membrane depolarization or intracellular Ca2+. The [P5K] analogue (1 µM) produced a significant increase in cAMP concentration in BRIN-BD11 cells and stimulated GLP-1 secretion from GLUTag cells. Down-regulation of the protein kinase A pathway by overnight incubation with forskolin completely abolished the insulin-releasing effects of [P5K]hym-1B. Intraperitoneal administration of the [P5K] and [D9k] analogues (75 nmol/kg body weight) to high-fat-fed mice with insulin resistance significantly enhanced glucose tolerance with a concomitant increase in insulin secretion. We conclude that [P5K]hym-1B and [D9k]hym-1B show potential for development into anti-diabetic agents.


Hymenochirin-1b Type 2 diabetes Amphibian skin peptide Insulin release 



Lactate dehydrogenase




Intracellular calcium concentration




Protein kinase C


Protein Kinase A


Glucagon-like peptide 1


Tumor necrosis factor α


Interleukin 17


Caerulein precursor fragment 6




Matrix-assisted laser desorption/ionization time of flight


Ethylene glycol tetraacetic acid


Cholecystokinin 8


4-(2-Hydroxyethyl)-1-piperazineethanesulfonic acid



This study was supported by the University of Ulster Research Strategy Funding and an award of a University Vice Chancellor Research Studentship to DKS. We thank Professor D. Drucker for access to GLUTag cells.

Compliance with ethical standards

Conflict of interest

No conflict of interest declared.


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Copyright information

© Springer-Verlag Wien 2015

Authors and Affiliations

  • Bosede O. Owolabi
    • 1
  • Opeolu O. Ojo
    • 1
    • 2
  • Dinesh K. Srinivasan
    • 1
  • J. Michael Conlon
    • 1
  • Peter R. Flatt
    • 1
  • Yasser H. A. Abdel-Wahab
    • 1
    Email author
  1. 1.SAAD Centre for Pharmacy and Diabetes, School of Biomedical SciencesUniversity of UlsterColeraineNorthern Ireland, UK
  2. 2.School of Health, Sport and BioscienceUniversity of East LondonStratfordUK

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