Related Experiment Video
Updated: Dec 18, 2025
13:35
Structural Biology and Analytical Chemistry Approaches for Characterizing C-Glycoside Metabolic Enzymes in Human Gut Microbiota
Published on: May 23, 2025
782
Reassessing the structure of pyranonigrin
Gerhard Schlingmann1, Tohru Taniguchi, Haiyin He
1Department of Natural Products, Chemical and Screening Sciences, Wyeth Research, 401 North Middletown Road, Pearl River, New York 10965, USA. schling@wyeth.com
Journal of Natural Products
|July 3, 2007
Summary
Marine fungus Aspergillus niger produces secondary metabolites, including a corrected structure for pyranonigrin A. This study determined its absolute configuration using advanced computational and experimental methods.
Area of Science:
- Marine microbiology
- Natural product chemistry
- Fungal secondary metabolism
Background:
- Fermentation extracts from the marine fungus Aspergillus niger LL-LV3020 exhibited significant bioactivity.
- Chemical screening revealed the production of various secondary metabolites beyond citric acid.
Purpose of the Study:
- To isolate and elucidate the structure of a major secondary metabolite from Aspergillus niger LL-LV3020.
- To correct the previously reported structure of pyranonigrin A and determine its absolute configuration.
Main Methods:
- Isolation and structural elucidation of a UV-active compound.
- Spectroscopic analysis and comparison with existing literature.
- Determination of absolute configuration using electronic circular dichroism (ECD) and ab initio time-dependent density functional theory (TD-DFT) calculations.
Main Results:
- A compound, initially suspected to be pyranonigrin A, was isolated and structurally analyzed.
- The elucidated structure differed from the previously reported structure of pyranonigrin A.
- The absolute configuration was assigned as (7R)-3,7-dihydroxy-2-[(1E)-prop-1-enyl]-6,7-dihydropyrano[2,3-c]pyrrole-4,5-dione.
Conclusions:
- The study proposes a revised structure for pyranonigrin A.
- The absolute configuration of pyranonigrin A was definitively determined.
- This work contributes to the understanding of secondary metabolite diversity in marine fungi.
More Related Videos
Related Concept Videos
01:25Basicity of Heterocyclic Aromatic Amines
6.8K
Heterocyclic amines, where the N atom is a part of an alicyclic system, are similar in basicity to alkylamines. Interestingly, the heterocyclic amine having a nitrogen atom as part of an aromatic ring has much less basicity than its corresponding alicyclic counterpart. For this reason, as presented in Figure 1, piperidine (pKb = 2.8) is significantly more basic than pyridine (pKb = 8.8).
6.8K
01:19Structure of Amines
3.1K
The hybridized nitrogen atom in amines possesses a lone pair of electrons and is bound to three substituents with a bond angle of around 108°, which is less than the tetrahedral angle of 109.5°. However, the C–N–H bond angle is slightly larger at 112°, with a carbon–nitrogen bond length of 147 pm. This carbon–nitrogen bond length of of amines is longer than the carbon–oxygen bond of alcohols (143 pm) but shorter than alkanes’ carbon–carbon bond (154 pm). These aspects are...
3.1K
02:06Newman Projections
20.0K
Different notations are used to represent the three-dimensional structure of molecules on two-dimensional surfaces. One of the most commonly used representations is the dash-wedge formula. The dashed wedges, solid wedges, and the plane lines indicate the groups situated behind the plane, coming out of the plane, and in the plane, respectively.
The organic molecules rotate across the single bonds leading to numerous temporary three-dimensional structures of varying energy known as...
The organic molecules rotate across the single bonds leading to numerous temporary three-dimensional structures of varying energy known as...
20.0K
02:18Fischer Projections
15.9K
Learning to draw Fischer projections of molecules and understanding their relevance plays a crucial role in the visual depiction of organic molecules. A Fischer projection is a two-dimensional projection on a planar surface to simplify the three-dimensional wedge–dash representation of molecules. This is especially helpful in the case of molecules with multiple chiral centers that can be difficult to draw. Here, all the bonds of interest are represented as horizontal or vertical lines. While...
15.9K
02:05Prochirality
4.7K
The concept of prochirality leads to the nomenclature of the individual faces of a molecule and plays a crucial role in the enantioselective reaction. It is a concept where two or more achiral molecules react to produce chiral products. A typical process is the reaction of an achiral ketone to generate a chiral alcohol. Here, the achiral reactant reacts with an achiral reducing agent, sodium borohydride, to generate an equimolar mixture of the chiral enantiomers of the product. For example, an...
4.7K
01:29Protein Folding Quality Check in the RER
4.9K
ER is the primary site for the maturation and folding of soluble and transmembrane secretory proteins. The calnexin cycle is a specific chaperone system that folds and assesses the confirmation of N-glycosylated proteins before they can exit the ER lumen. The primary players of this quality check pipeline are the lectins, ER-resident chaperones, and a glucosyl transferase enzyme. In case the calnexin system in the lumen fails to salvage a misfolded protein, it is transported to the cytoplasm...
4.9K