Small cyclic agonists of iron regulatory hormone hepcidin

Abstract

Minihepcidins are in vitro and in vivo active mimetics of iron-regulatory hormone hepcidin. They contain various unusual amino acids including: N-substituted, β-homo-, and D-amino acids with their combination depending on particular minihepcidin. In the current study, we sought to limit the use of unusual/more expensive amino acids derivatives by peptide cyclisation. Novel cyclic mimetics of hepcidin were synthesized and tested in vitro and showed activity at low nanomolar concentration. Nonetheless, the most active cyclic compound (mHS17) is approximately ten times less active than the parental minihepcidin PR73. Collectively, our findings suggest that cyclisation is viable approach in the synthesis of hepcidin mimetics.

Lipid-conjugated Smac analogues

“…Obtained results (Figure 2F) indicated that both analogues are remarkably stable in experimental conditions (<31 h) and even after prolonged exposure (144h) both compounds were mainly intact (plasma stability: M11 =60.4±0.3% and D7 =80.1±0.5%). Notably, under the same experimental conditions unrelated control peptide, mHS1 72 was quickly degraded falling to less than 1% of initial content within 6 h.…”

“…Cholesterol was introduced in similar manner using cholesteryl chloroformate giving urethane type connectivity (see Scheme 2). Analogue M11 was synthesized using a previously described 1,1,3,3-tetramethylguanidine (TMG) driven alkylation of thiol(s) in organic solvents 71 that we adapted to peptides 72 . Notably, the same S-alkylation protocol was successfully employed in the synthesis of dimers D9-D16 .…”

Bridged Analogues for p53-Dependent Cancer Therapy Obtained by S-Alkylation

“…Stapling with 1,4-dibromobutane and 1,7-dibromoheptane: was performed in solution using modified Włostowski S-alkylation protocol (Wlostowski et al, 2010) that we adapted to peptides (Chua et al, 2015). Briefly, linear peptides were solubilized in anhydrous methanol (~0.5 mg/mL) containing, if necessary up 25% of DMSO.…”

“…These include hydrazone bridge (Cabezas and Satterthwait, 1999), oxime bridge (Haney et al, 2011), 1,4-disubstituted-[1,2,3]-triazole linkage (Holland-Nell and Meldal, 2011; Ingale and Dawson, 2011; Kawamoto et al, 2012; Lau et al, 2014c; Lau et al, 2014b; Lau et al, 2014a; Lau et al, 2015b; Scrima et al, 2010), metal chelation (Ghadiri and Choi, 1990; Ruan et al, 1990), disulfide bond formation (Almeida et al, 2012; Jackson et al, 1991; Leduc et al, 2003), lactam ring formation (Fujimoto et al, 2008; Geistlinger and Guy, 2001; Geistlinger and Guy, 2003; Houston, Jr. et al, 1995; Osapay and Taylor, 1992; Phelan et al, 1997) and S-alkylation based staples employing either α-haloacetamide alkylation of single cysteine (Brunel and Dawson, 2005; Cardoso et al, 2007; Galande et al, 2004; Woolley, 2005) or bridging two cysteines with bis-S-alkylating linker(s) (de Araujo et al, 2014; Jo et al, 2012; Muppidi et al, 2011b; Muppidi et al, 2011a; Muppidi et al, 2012; Spokoyny et al, 2013; Szewczuk et al, 1992; Timmerman et al, 2005; Wilkinson et al, 2007; Zhang et al, 2007; Zhang et al, 2008). Among these, the last seems to be most flexible approach as a wide range of inexpensive bis-thiol-reactive linkers is commercially available, including rigid aromatic derivatives (Chua et al, 2015; Jo et al, 2012; Muppidi et al, 2011b; Muppidi et al, 2011a; Muppidi et al, 2012; Timmerman et al, 2005; Zhang et al, 2007) and aliphatic counterparts (Byrne and Stites, 1995; Chua et al, 2015; Lindman et al, 2001; Wilkinson et al, 2007). In addition, the availability of various cysteine homologs: (L)Cys, (D)Cys, (L)homoCys, (D)homoCys, (L)Pen, and (D)Pen provides an additional option for “fine tuning” of pre-selected active derivatives.…”

Hepcidin: Homeostasis and Diseases Related to Iron Metabolism

“…Other experiments are being conducted with the aim of increasing the utility of the minihepcidin molecule by improving the ease of its synthesis, reducing costs, and improving its bioavailability [173,174]. …”