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Published April 18, 2023 | Published + Supplemental Material
Journal Article Open

Cryptic Chemical Variation in a Marine Red Alga as Revealed by Nontargeted Metabolomics


Many marine algae occupy habitats that are dark, deep, or encrusted on other organisms and hence are frequently overlooked by natural product chemists. However, exploration of less-studied organisms can lead to new opportunities for drug discovery. Genetic variation at the individual, species, genus, and population levels as well as environmental influences on gene expression enable expansion of the chemical repertoire associated with a taxonomic group, enabling natural product exploration using innovative analytical methods. A nontargeted LC-MS and ¹H NMR spectroscopy-based metabolomic study of 32 collections of representatives of the calcareous red algal genus Peyssonnelia from coral reef habitats in Fiji and the Solomon Islands revealed significant correlations between natural products' chemistry, phylogeny, and biomedically relevant biological activity. Hierarchical cluster analysis (HCA) of LC-MS data in conjunction with NMR profiling and MS/MS-based molecular networking revealed the presence of at least four distinct algal chemotypes within the genus Peyssonnelia. Two Fijian collections were prioritized for further analysis, leading to the isolation of three novel sulfated triterpene glycosides with a rearranged isomalabaricane carbon skeleton, guided by the metabolomic data. The discovery of peyssobaricanosides A–C (15–17) from two Fijian Peyssonnelia collections, but not from closely related specimens collected in the Solomon Islands that were otherwise chemically and phylogenetically very similar, alludes to population-level variation in secondary metabolite production. Our study reinforces the significance of exploring unusual ecological niches and showcases marine red algae as a chemically rich treasure trove.

Additional Information

© 2023 The Authors. Published by American Chemical Society. Attribution 4.0 International (CC BY 4.0). This research was funded by the International Cooperative Biodiversity Groups (ICBG) Grant U19-TW007401 from the National Institutes of Health to J.K. and K.S.; the National Institutes of Health, National Center for Complementary and Integrative Health R01AT011990 to C.L.Q. and J.K.; and funding from the Jones Center at Ichauway to L.M. We thank the governments of Fiji and the Solomon Islands for allowing us to perform research in their territorial waters; M.E. Hay and Hay and Kubanek lab members for performing field collections and taking photos; the Georgia Tech NMR Center and Systems Mass Spectrometry Centers for use of instrumentation and access to their expertise; A. Burns, J. Mathew-Valayil, G. Longo, and S. Engel for managing the collection and extract library at the Georgia Institute of Technology; K. Feussner for overseeing the collection library at the University of the South Pacific; C.W. McNamara at Calibr, a division of The Scripps Research Institute for malaria assays; and S. Lavoie at Université du Québec à Chicoutimi for valuable suggestions. The authors declare no competing financial interest.

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Published - ao3c00301.pdf

Supplemental Material - ao3c00301_si_001.pdf


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August 22, 2023
December 21, 2023