Tetrahydroxanthone dimers are fungal products, among which secalonic acid D () is one of the most studied compounds because of its potent biological activity. Because the biosynthetic gene cluster of has been previously identified, we sought to heterologously produce in by expressing the relevant biosynthetic genes. However, our initial attempt of the total biosynthesis of failed; instead, it produced four isomers of due to the activity of an endogenous enzyme of . Subsequent overexpression of the Baeyer-Villiger monooxygenase, AacuH, which competes with the endogenous enzyme, altered the product profile and successfully generated . Characterization of the key biosynthetic enzymes revealed the surprising substrate promiscuity of the dimerizing enzyme, AacuE, and indicated that efficient synthesis of requires highly selective preparation of the tetrahydroxanthone monomer, which is apparently controlled by AacuH. This study facilitates engineered biosynthesis of tetrahydroxanthone dimers both in a selective and divergent manner.
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http://dx.doi.org/10.1021/acs.jnatprod.1c00022 | DOI Listing |
J Nat Prod
February 2024
State Key Laboratory Cultivation Base for TCM Quality and Efficacy, School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, Jiangsu, People's Republic of China.
Xanthone-chromanone homo- or heterodimers are regarded as a novel class of topoisomerase (Topo) inhibitors; however, limited information about these compounds is currently available. Here, 14 new (-) and 6 known tetrahydroxanthone chromanone homo- and heterodimers (-) are reported as isolated from C-7-2-1. Their structures and absolute configurations were unambiguously demonstrated by a combination of spectroscopic data, single-crystal X-ray diffraction, modified Mosher's method, and electronic circular dichroism analyses.
View Article and Find Full Text PDFAn Acad Bras Cienc
July 2023
College of Food and Biological Engineering, Zhengzhou University of Light Industry, 136 Kexue Road, Zhengzhou 450001, China.
Front Microbiol
February 2023
Department of Nephrology, Zhongnan Hospital of Wuhan University, School of Pharmaceutical Sciences, Wuhan University, Wuhan, China.
Introduction: Dimeric natural products are widespread in plants and microorganisms, which usually have complex structures and exhibit greater bioactivities than their corresponding monomers. In this study, we report five new dimeric tetrahydroxanthones, aculeaxanthones A-E (), along with the homodimeric tetrahydroxanthone secalonic acid D (), chrysoxanthones B and C ( and ), and 4-4'-secalonic acid D (), from different fermentation batches of the title fungus.
Methods: A part of the culture was added to a total of 60 flasks containing 300 ml each of number II fungus liquid medium and culture 4 weeks in a static state at 28˚C.
Molecules
April 2022
School of Chemistry, Sun Yat-sen University, Guangzhou 510275, China.
Mangrove endophytic fungi represent significant and sustainable sources of novel metabolites with unique structures and excellent biological activities, attracting extensive chemical investigations. In this research, two novel heterodimeric tetrahydroxanthones, aflaxanthones A () and B (), dimerized via an unprecedented 7,7'-linkage, a sp-sp dimeric manner, were isolated from the mangrove endophytic fungus QQYZ. Their structures were elucidated through high resolution electrospray ionization mass spectroscopy (HRESIMS) and nuclear magnetic resonance (NMR) spectroscopy, the absolute configurations of them were determined by a single-crystal X-ray diffraction combined with calculated electronic circular dichroism (ECD) spectra and a 1D potential energy scan.
View Article and Find Full Text PDFOrg Lett
April 2022
School of Marine Sciences, Sun Yat-sen University, Guangzhou 510006, China.
Fungal cytochrome P450 enzymes have been shown to catalyze regio- and stereoselective oxidative intermolecular phenol coupling. However, an enzyme capable of catalyzing undirected - (C4-4') coupling has not been reported. Here, we revealed the biosynthetic gene cluster (BGC) of phomoxanthone A from the marine fungus sp.
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