Mohangic Acids A–E, p-Aminoacetophenonic Acids from a Marine-Mudflat-Derived Streptomyces sp.

Abstract

Mohangic acids A-E (1-5) were isolated from a marine Streptomyces sp. collected from a mudflat in Buan, Republic of Korea. Comprehensive spectroscopic analysis revealed that the mohangic acids are new members of the p-aminoacetophenonic acid class. The relative and absolute configurations of the mohangic acids were determined by J-based configuration analysis and by the application of bidentate chiral NMR solvents followed by (13)C NMR analysis, chemical derivatization, and circular dichroism spectroscopy. Mohangic acid E (5), which is the first glycosylated compound in the p-aminoacetophenonic acid family, displayed significant quinone reductase induction activity.

Synthesis of the Proposed Structure of Mohangic Acid C

“…The molecular formula of the product was confirmed as C 28 H 39 NO 7 by ESI-TOF-MS. In the 1 H NMR spectrum, the triene moiety exhibited peaks (chemical shifts and J values) similar to those in the literature (see the Supporting Information), indicating that the Cu-mediated coupling reaction proceeded in the desired fashion. The geometries of the triene moiety were confirmed to be 4 E , 6 E , 8 E on the basis of the J values for H 4 –H 5 (15.0 Hz), H 6 –H 7 (15.0 Hz), and H 8 –H 9 (15.0 Hz).…”

“…In 2016, Oh et al reported the isolation of the mohangic acids ( 1–5 ), a series of natural products produced by Streptomyces from mudflats in Buan, Republic of Korea (Figure ). Because mohangic acid E ( 5 ) displays significant quinone reductase induction activity, this family of natural products is expected to serve as the lead compounds for new therapeutics. In addition to the biological profile, chemical structures of mohangic acids possess a p -aminoacetophenone moiety, contiguous stereocenters, and a triene, making them attractive synthetic targets.…”

Marine natural products

“…When all ve congeners were tested for cancer chemoprevention, using a quinone reductase (QR) assay at 20 mM, only mohangic acid E 6 displayed any activity (causing a 2.1-fold increase in QR activity compared to the control), suggesting the glucose moiety is important for QR activity in this chemotype. 16 Additional chemical investigations on the fermentation culture derived from a Streptomyces strain CNH189, 17 yielded the ansalactams B-D 7-9 along with the previously identied metabolite, ansalactam A. 17,18 Compounds 7-9 represent three new carbon skeletons and illustrate the plasticity within the ansamycin biosynthetic pathway.…”

Glycosylated Natural Products From Marine Microbes

“…Chemical analysis of these actinomycete strains using LC/MS identified a Streptomyces sp. SNM31 and led to a metabolite, mohangic acid E (103, Figure 7), which was the first glycosylated compound discovered in the paminoacetophenonic acid family and exhibited good quinonereductase induction activity at a concentration of 20 µM (Bae et al, 2016).…”