Unnatural Amino Acid: 4-Aminopyrazolonyl Amino Acid Comprising Tri-Peptides Forms Organogel With Co-Solvent (EtOAc:Hexane)

Amarnath Bollu; Prajnanandan Giri; Nihar Ranjan Dalabehera; Asmita Rani Asmi; Nagendra K Sharma

doi:10.3389/fchem.2022.821971

Unnatural Amino Acid: 4-Aminopyrazolonyl Amino Acid Comprising Tri-Peptides Forms Organogel With Co-Solvent (EtOAc:Hexane)

Front Chem. 2022 May 5:10:821971. doi: 10.3389/fchem.2022.821971. eCollection 2022.

Authors

Amarnath Bollu^{1

2}, Prajnanandan Giri^{1

2}, Nihar Ranjan Dalabehera^{1

2}, Asmita Rani Asmi^{1

2}, Nagendra K Sharma^{1

2}

Affiliations

¹ National Institute of Science Education and Research (NISER), Bhubaneswar, India.
² Homi Bhabha National Institute (HBNI), Mumbai, India.

Abstract

Ampyrone is an amino-functionalized heterocyclic pyrazolone derivative that possesses therapeutic values such as analgesic, anti-inflammatory, and antipyretics. The chemical structure of ampyrone exhibits excellent hydrogen bonding sites and is considered as the potential scaffold of supramolecular self-assembly. Recently, this molecule has been derived into unnatural amino acids such as aminopyrazolone amino acid and its peptides. This report describes that one of its amino acids, O-alkylated ampyrone, containing hybrid (α/β) peptides forms organogel after sonication at 50-55°C with 0.7-0.9% (w/v) in ethyl acetate: hexane (1:3). The formation/morphology of such organogels is studied by nuclear magnetic resonance Fourier-transform infrared (FT-IR), circular dichroism (CD), scanning electron microscope (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (Powder-XRD), and thermogravimetric analysis (TGA). Energy-minimized conformation of APA-peptides reveals the possibility of intermolecular hydrogen bonding. Hence, APA-peptides are promising peptidomimetics for the organogel-peptides.

Keywords: aminopyrazolonyl amino acid; ampyrone; hybrid-β-peptides; organogelation; unnatural amino acid.