Production of unusual dispiro metabolites in pestalotiopsis virgatula endophyte cultures: HPLC-SPE-NMR, electronic circular dichroism, and time-dependent Density-Functional Computation Study

Kesting, J. R. and Olsen, L. and Staerk, D. and Tejesvi, M. V. and Kini, K. R. and Prakash, H. S. and Jaroszewski, J. W. (2011) Production of unusual dispiro metabolites in pestalotiopsis virgatula endophyte cultures: HPLC-SPE-NMR, electronic circular dichroism, and time-dependent Density-Functional Computation Study. JOURNAL OF NATURAL PRODUCTS, 74 (10). pp. 2206-2215. ISSN 0163-3864

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Abstract

The endophytic fungus Pestalotiopsis virgatula, derived from the plant Terminalia chebula and previously found to produce a large excess of a single metabolite when grown in the minimal MID medium, was induced to produce a variety of unusual metabolites by growing in potato dextrose broth medium. Analysis of the fermentation medium extract was performed using an HPLC-PDA-MS-SPE-NMR hyphenated system, which led to the identification of a total of eight metabolites (1-8), six of which are new. Most of the metabolites are structurally related and are derivatives of benzoc]oxepin, rare among natural products. This includes dispiro derivatives 7 and 8 (pestalospiranes A and B), having a novel 1,9,11,18-tetraoxadispiro6.2.6.2]octadecane skeleton. Relative and absolute configurations of the latter were determined by a combination of NOESY spectroscopy and electronic circular dichroism spectroscopy supported by time-dependent density-functional theory calculations (B3LYP/TZVP level). This work demonstrates that a largely complete structure elucidation of numerous metabolites present in a raw fermentation medium extract can be performed by the HPLC-SPE-NMR technique using only a small amount of the extract, even with unstable metabolites that are difficult to isolate by traditional methods.

Item Type:	Article
Subjects:	B Life Science > Biotechnology
Divisions:	Department of > Biotechnology
Depositing User:	Users 23 not found.
Date Deposited:	14 Aug 2019 06:38
Last Modified:	14 Aug 2019 06:38
URI:	http://eprints.uni-mysore.ac.in/id/eprint/2384

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