Novel Natural Oximes and Oxime Esters with a Vibralactone Backbone from the Basidiomycete Boreostereum vibrans

Abstract

A variety of novel natural products with significant bioactivities are produced by the basidiomycete Boreostereum vibrans. In the present study, we describe 16 novel natural oximes and oxime esters with a vibralactone backbone, vibralactoximes, which were isolated from the scale‐up fermentation broth of B. vibrans. Their structures were determined through extensive spectroscopic analyses. These compounds represent the first oxime esters from nature. The hypothetical biosynthetic pathway of these compounds was also proposed. Seven compounds exhibited significant pancreatic lipase inhibitory activity, while ten compounds exhibited cytotoxicities against five human cancer cell lines (HL‐60, SMMC‐7721, A‐549, MCF‐7, and SW480), with IC50 values comparable with those of cisplatin.

Heteroatom–Heteroatom Bond Formation in Natural Product Biosynthesis

“…135 Novel oxime-containing natural products continue to be isolated, including the stachylines from the sponge-derived fungus Stachylidium, brevioxime from Penicillium brevicompactum , Aspergillusol A from Aspergillus aculeatus, and vibralactoxime from the Basidiomycete Boreostereum vibrans . 136–139 The biosynthetic pathways generating this latter group of compounds have not yet been elucidated and will not be included in the review, but these metabolites may represent interesting targets for future studies. The organization of this section will follow Section 2.1, with each subsection grouped by the type of N- oxygenase.…”

Synthesis and Antifungal Activity of Novel 3-Caren-5-One Oxime Esters

“…On the other hand, oxime esters as an important class of bioactive compounds for agrochemical and pharmaceutical use were investigated extensively by chemists. It was reported that oxime esters exhibited insecticidal [ 16 , 17 ], herbicidal [ 18 ], antiviral [ 19 ], antitumor [ 20 , 21 , 22 ], and antibacterial activities [ 23 , 24 , 25 ]. For example, a series of 3-ethoxy-4-hydroxybenzaldehyde oxime esters were synthesized and evaluated for their in vitro antifungal activity against three pathogenic fungi and antibacterial activity against three bacterial strains, and the structure-activity relationship was also preliminarily summarized [ 26 ].…”

One‐Pot Transformation of Ketoximes into Optically Active Alcohols and Amines by Sequential Action of Laccases and Ketoreductases or ω‐Transaminases

“…The oxime function is ubiquitous in nature and can be found in the structure of innumerable natural and synthetic bioactive compounds as well as in several metabolic pathways, being modified by the action of enzymes . So for example, from bacterial origin the group of 2,2′‐bipyridyl‐containing natural products includes members bearing oximes such as pyrisulfoxins, caerulomycins and collismycins which display antibacterial, antifungal and cytotoxic activities, and fungi like basidiomycete Boreostereum vibrans produce vibralactoximes with significant cytotoxic activity . On the other hand, oximes are valuable synthetic precursors of ketones and aldehydes since those can be prepared from non‐carbonyl precursors.…”