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Peyssonnosides A-B, Unusual Diterpene Glycosides with a Sterically Encumbered Cyclopropane Motif: Structure Elucidation Using an Integrated Spectroscopic and Computational Workflow

Khatri Chhetri, Bhuwan and Lavoie, Serge and Sweeney-Jones, Anne Marie and Mojib, Nazia and Raghavan, Vijay and Gagaring, Kerstin and Dale, Brandon and McNamara, Case W. and Soapi, Katy M. and Quave, Cassandra L. and Polavarapu, Prasad L. and Kubanek, Julia (2019) Peyssonnosides A-B, Unusual Diterpene Glycosides with a Sterically Encumbered Cyclopropane Motif: Structure Elucidation Using an Integrated Spectroscopic and Computational Workflow. The Journal of Organic Chemistry . TBC. ISSN 0022-3263

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Abstract

Two sulfated diterpene glycosides featuring a highly substituted and sterically encumbered cyclopropane ring have been isolated from the marine red alga Peyssonnelia sp. Combination of a wide array of 2D NMR spectroscopic experiments, in a systematic structure elucidation workflow, revealed that peyssonnosides A–B (1–2) represent a new class of diterpene glycosides with a tetracyclo [7.5.0.01,10.05,9] tetradecane architecture. A salient feature of this workflow is the unique application of quantitative interproton distances obtained from the rotating frame Overhauser effect spectroscopy (ROESY) NMR experiment, wherein the β-d-glucose moiety of 1 was used as an internal probe to unequivocally determine the absolute configuration, which was also supported by optical rotatory dispersion (ORD). Peyssonnoside A (1) exhibited promising activity against liver stage Plasmodium berghei and moderate antimethicillin-resistant Staphylococcus aureus (MRSA) activity, with no cytotoxicity against human keratinocytes. Additionally, 1 showed strong growth inhibition of the marine fungus Dendryphiella salina indicating an antifungal ecological role in its natural environment. The high natural abundance and novel carbon skeleton of 1 suggests a rare terpene cyclase machinery, exemplifying the chemical diversity in this phylogenetically distinct marine red alga.

Item Type: Journal Article
Subjects: Q Science > QD Chemistry
Divisions: Faculty of Science, Technology and Environment (FSTE) > Institute of Applied Science
Depositing User: Fulori Nainoca
Date Deposited: 26 Jun 2019 13:49
Last Modified: 26 Jun 2019 13:49
URI: http://repository.usp.ac.fj/id/eprint/11623
UNSPECIFIED

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