Natural Products with Heteroatom-Rich Ring Systems

Abstract

This review focuses on all known natural products that contain a "heteroatom-rich" ring system, specifically a five-, six- or seven-membered ring that contains three or more heteroatoms. The isolation and biological activity of these natural products is discussed, along with the biosynthetic processes that Nature employs to assemble these rare heterocyclic frameworks.

The Ascidian-Derived Metabolites with Antimicrobial Properties

“…Generally, natural products contain one or two heteroatoms like nitrogen and/or oxygen, sometimes more than two, whereas a sulfur atom is rarely found in metabolites of marine origin [25,26]. The ascidians belonging to the genus Lissoclinum (Didemnidae) are an exceptional source of unique chemical scaffolds, some of them endowed with antiviral activity as well as against mammalian cells [27,28].…”

Crystal structure of 7,8,15,16,17-pentathiadispiro[5.2.59.36]heptadecane

“…Cyclic polysulfides comprise a subgroup of pharmacologically interesting organosulfur compounds that -depending on constitution and conformation -have been shown to exert specific antibacterial, antifungal, allelopathic and cytotoxic activity (Davison & Sperry, 2017), as well as a plethora of H 2 Smediated effects relying on H 2 S formation (Szabo & Papapetropoulos, 2017). The benefits imparted by these compounds have led to the evolution of synthetic pathways in many natural products, as well as organoleptic detection mechanisms in organisms confronted by them, including the senses of smell and taste in humans.…”

“…Thus, volatile organic polysulfanes are among the most odorous compounds in natural products, including meat (Zhao et al, 2019), plants (Liang et al, 2017), and algae (Block et al, 2017). In fungi, 1,2,4-trithiolane, 1,2,4,6-tetrathiepane, and 1,2,3,4,5,6-hexathiepane have been found to contribute to the unique aroma of shiitake (Lentnius edodes), but it is 1,2,3,5,6-pentathiepane (lenthionine) that combines the most potent biological (antibacterial, antifungal, and anti-coagulative) and sensory activity (Davison & Sperry, 2017). Structural characterizations of this type of compounds are rather rare.…”

15N labeling and analysis of13C–15N and1H–15N couplings in studies of the structures and chemical transformations of nitrogen heterocycles

“…Nitrogen heterocycles are a ubiquitous class of organic compounds that include azirine, azetidine, azole, azine and azepine derivatives and their fused analogs. These structures are inherent in drug design [1][2][3][4][5][6][7] and natural compounds, 8,9 in catalysis for cross-coupling and asymmetric synthesis reactions, 10,11 in materials science as metal complexes with luminescent properties, [12][13][14] in ligands for the separation of lanthanides 15 and in high-density energy materials. 16,17 At rst glance, it seems that establishing the structure of poly-nitrogen-containing compounds can be achieved by general NMR methods suitable for carbon-containing compounds; however, this statement is not correct.…”