A potent, non-toxic insulin-releasing peptide isolated from an extract of the skin of the Asian frog, Hylarana guntheri (Anura:Ranidae)

Tigerinin-1R: a potent, non-toxic insulin-releasing peptide isolated from the skin of the Asian frog, Hoplobatrachus rugulosus

“…The origin and characteristics of these cells have been provided in detail previously [21]. The cells were pre‐incubated for 40 min at 37 °C in 1.0 ml Krebs–Ringer bicarbonate (KRB) buffer, pH 7.4 supplemented with either 5.6 or 16.7 mM glucose and 0.1% (w/v) bovine serum albumin [8]. Incubations with purified endogenous peptides (10 −12 − 3 × 10 −6 M; n = 8) were performed for 20 min at 37 °C using the same buffer.…”

“…Haemolytic activity was measured as previously described [8]. Peptides in the concentration range 16-500 μM were incubated with washed human erythrocytes (2 × 10 7 cells) from a healthy donor in Dulbecco's phosphate-buffered saline, pH 7.4 (100 μl) for 1 h at 37 • C. After centrifugation (12 000 g for 15 s), the absorbance at 450 nm of the supernatant was measured.…”

“…Such insulin‐releasing peptides have been identified in skin secretions and/or skin extracts from the species Hylarana güntheri [8], Lithobates catesbeianus [9], Lithobates palustris [10], Lithobates pipiens [11], Lithobates septentrionalis [12] and Pelophylax saharicus [13] belonging to the family Ranidae and from Hylomantis lemur [14] and Pseudis paradoxa [15] belonging to the family Hylidae. In addition, brevinin‐2GUb from H. güntheri [8], phylloseptin‐L2 from H. lemur [14] and brevinin‐2–related peptide (B2‐RP) from L. septentrionalis [12] have been shown to be active in vivo, increasing plasma insulin concentrations and improving glucose tolerance in mice. Structure–activity studies of synthetic replicates of peptides belonging to the temporin [16], pseudin‐2 [15] and B2‐RP [12] families have led to the design of analogues with increased insulin‐releasing potency.…”

Antimicrobial peptides from amphibians

“…Plylloseptin-L2 isolated from the skin secretion of Lemur leaf frog Hylomantis lemur has a significant effect on insulin release from the rat BRIN-BD11 clonal b cell line at a concentration of 3 nM and it does not cause cytolysis at a concentration of 3 mM (98). Brevinin-2GUb which belongs to the Brevinin-2 family can increase the release of insulin from BRIN-BD11 cells (139% of basal rate) at a concentration of 100 nM, whereas at a concentration of 3 mM the basal rate increased to 373% (99).…”

Insulinotropic Actions of the Frog Skin Host‐Defense Peptide Alyteserin‐2a: A Structure–Activity Study

“…]. In addition, tigerinin‐1R from Hoplobatrachus rugulosus , phylloseptin‐L2 from Hylomantis lemur (reclassified as Agalychnis lemur ) , brevinin‐2GUb from Hylarana guentheri , and brevinin‐2‐related peptide (B2RP) from Lithobates septentrionalis have been shown to be active in vivo, increasing plasma insulin concentrations and improving glucose tolerance in mice. These peptides represent promising candidates for development into therapeutically valuable agents for the treatment of patients with Type 2 diabetes.…”