Albatredines A and B, a pair of epimers with unusual natural heterocyclic skeletons from edible mushroom Albatrellus confluens.

Shuaibing Zhang,Jianping Zuo,Zhenghui Li,Bin Wu,Tao Feng,Ying Huang,Heping Chen,Shijun He,Jikai Liu

doi:10.1039/c8ra04226h

Abstract

A chemical study of the common species Albatrellus confluens present in Yunnan province, southwest China led to the identification of a pair of epimers named albatredines A (1) and B (2). They feature a natural unprecedented 1,2,4-oxadiazolidin-5-one skeleton. The acyl substitution pattern and complete configurational assignments were deduced from the comparison between experimental and theoretical 13C NMR and ECD data, respectively. Bioassay results showed that compound 1 exhibited a weak immunosuppressive activity against the concanavalin A-induced T lymphocyte cell proliferation (IC50 2.99 μM).

Highlights

Nitrogen-containing heterocyclic scaffolds are basic and prevalent structural units of many drugs, such as Sovaldi, Abilify, and Nexium.[1]
Chemical investigations on the famous edible mushroom A. con uens were conducted, which resulted in the isolation of a pair of epimers, albatredines A (1) and B (2), bearing a previously undescribed natural heterocyclic scaffold
Immunosuppressive bioassay results suggested that the discovery of new types of heterocyclic compounds such as these from natural sources provides new possibilities to explore new immunosuppressants by the inhibition of T cell proliferation

Summary

Introduction

Nitrogen-containing heterocyclic scaffolds are basic and prevalent structural units of many drugs, such as Sovaldi, Abilify, and Nexium.[1] Nitrogen-containing compounds originating from mushrooms are a large group of diverse secondary metabolites[2,3] (characterized by various chiral structures with different bioactivities), such as enantiomers and epimers. Among the three possible substitution patterns, the most probable locations of the acyls are shown in Fig. 1 with 99.92% con dence (Table S20†).[14,15,16,17] the planar structure of 1 was determined to be a new natural N-. Albatredines A and B represent nor-peptides with unprecedented natural heterocyclic skeletons, which aroused our interest in their plausible biogenesis This pair of epimers might possibly be traced back to L-isoleucine since they possessed this common side chain.

Conclusions

Findings

Computational methods