Natural Bridged Bicyclic Peptide Macrobiomolecules from and .

Bridged peptide macrobicycles (BPMs) from natural resources belong to types of compounds that are not investigated fully in terms of their formation, pharmacological potential, and stereo- chemical properties. This division of biologically active congeners with multiple circular rings has merits over other varieties of peptide molecules. BPMs form one of the most hopeful grounds for the establishment of drugs because of their close resemblance and biocompatibility with proteins, and these bio-actives are debated as feasible, realistic tools in diverse biomedical applications.

Towards the Synthesis of a Heterocyclic Analogue of Natural Cyclooligopeptide with Improved Bio-properties.

Aims: The present investigation is targeted towards the synthesis of a novel analogue of a natural peptide of marine origin.

Background: Marine sponges are enriched with bioactive secondary metabolites, especially circu-lar peptides. Heterocycles are established organic compounds with potential biological value.

Synthesis and Bioactivity of a Cyclopolypeptide from Caribbean Marine Sponge.

Synthesis of a natural proline-rich cyclopolypeptide - rolloamide A was carried out by coupling of tri- and tetrapeptide units Boc-Phe-Pro-Val-OMe and Boc-Pro-Leu-Pro-Ile-OMe after proper deprotection at carboxyl and amino terminals using carbodiimide chemistry in alkaline environment followed by cyclization of linear heptapeptide segment in the presence of base. The structure of synthesized peptide was confirmed by spectral techniques including FTIR, H NMR, C NMR, MS analyses. Newly synthesized peptide was subjected to biological screening against pathogenic microbes and earthworms.

Total Synthesis and Pharmacological Investigation of Cordyheptapeptide A.

The present investigation reports the synthesis of a phenylalanine-rich -methylated cyclopeptide, cordyheptapeptide A (), previously isolated from the insect pathogenic fungus sp. BCC 1788, accomplished through the coupling of -methylated tetrapeptide and tripeptide fragments followed by cyclization of the linear heptapeptide unit. Structure elucidation of the newly synthesized cyclopolypeptide was performed by means of FT-IR, ¹H-NMR, C-NMR, and fast atom bombardment mass spectrometry (FABMS), and screened for its antibacterial, antidermatophytic, and cytotoxic potential.

First Total Synthesis and Biological Screening of a Proline-Rich Cyclopeptide from a Caribbean Marine Sponge.

A natural heptacyclopeptide, stylissamide G (), previously isolated from the Bahamian marine sponge from the Caribbean Sea, was synthesized via coupling of the tetrapeptide l-phenylalanyl-l-prolyl-l-phenylalanyl-l-proline methyl ester with the tripeptide Boc-l-leucyl-l-isoleucyl-l-proline, followed by cyclization of the linear heptapeptide fragment. The structure of the synthesized cyclooligopeptide was confirmed using quantitative elemental analysis, FT-IR, ¹H NMR, C NMR and mass spectrometry. Results of pharmacological activity studies indicated that the newly synthesized cycloheptapeptide displayed good anthelmintic potential against , and at 2 mg/mL and in addition, potent antifungal activity against pathogenic and dermatophytes and at a concentration of 6 μg/mL.