Total Synthesis and Stereochemical Assignment of Nostosin B

Abstract

Nostosins A and B were isolated from a hydrophilic extract of Nostoc sp. strain from Iran, which exhibits excellent trypsin inhibitory activity. Nostosin A was the most potent natural tripeptide aldehyde as trypsin inhibitor up to now. Both r- and s-2-hydroxy-4-(4-hydroxy-phenyl)butanoic acid (Hhpba) were prepared and incorporated into the total synthesis of nostosin B, respectively. Careful comparison of the NMR spectra and optical rotation data of synthetic nostosin B (1a and 1b) with the natural product led to the unambiguous identification of the r-configuration of the Hhpba fragment, which was further confirmed by co-injection with the authentic sample on HPLC using both reversed phase column and the chiral AD-RH column.

Algal Toxic Compounds and Their Aeroterrestrial, Airborne and other Extremophilic Producers with Attention to Soil and Plant Contamination: A Review

“…FSN from a paddy field in Golestan Province (Iran) [ 174 ]. These low molecular linear tripeptides, which are the smallest and most potent trypsin inhibitors, exist in six variants (Ns A-F) [ 59 , 174 , 175 ]. Although found only in Nostoc , Ns have some similarity in the effects with the linear CNPs aeruginosins (Aers, namely, Aer-GH553, Aer-EI461, Aer-298B) and spumigin (spumigin E in particular), known from other cyanoprokaryotes [ 59 , 174 ].…”

Toxic compounds produced by cyanobacteria belonging to several species of the order Nostocales: A review

“…Binding to the trypsin in active site of enzyme (Hirata et al, 2003;Liu et al, 2014;X. Wang et al, 2017) (Continues) (Richter et al, 2008; Welwitindolinone A (Continues) (Ishibashi, Moore, Patterson, Xu, & Clardy, 1986).…”