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Cryptic species account for the seemingly idiosyncratic secondary metabolism of Sarcophyton glaucum specimens collected in Palau

TitleCryptic species account for the seemingly idiosyncratic secondary metabolism of Sarcophyton glaucum specimens collected in Palau
Publication TypeJournal Article
Year of Publication2020
AuthorsMaloney K.N, Botts R.T, Davis T.S, Okada B.K, Maloney E.M, Leber C.A, Alvarado O., Brayton C., Caraballo-Rodriguez A.M, Chari J.V, Chicoine B., Crompton J.C, Davis S.R, Gromek S.M, Kurnianda V., Quach K., Samples R.M, Shieh V., Sultana C.M, Tanaka J., Dorrestein PC, Balunas M.J, McFadden C.S
Date Published2020/03
Type of ArticleArticle
ISBN Number0163-3864
Accession NumberWOS:000526306000016
Keywordsanthozoa; biodiversity; cembrane-type diterpenes; cembrene; derivatives; marine terpenes; octocorals coelenterata; Pharmacology & Pharmacy; Plant Sciences; red-sea; sinularia; soft coral

Sarcophyton glaucum is one of the most abundant and chemically studied soft corals with over 100 natural products reported in the literature, primarily cembrane diterpenoids. Yet, wide variation in the chemistry observed from S. glaucum over the past 50 years has led to its reputation as a capricious producer of bioactive metabolites. Recent molecular phylogenetic analysis revealed that S. glaucum is not a single species but a complex of at least seven genetically distinct species not distinguishable using traditional taxonomic criteria. We hypothesized that perceived intraspecific chemical variation observed in S. glaucum was actually due to differences between cryptic species (interspecific variation). To test this hypothesis, we collected Sarcophyton samples in Palau, performed molecular phylogenetic analysis, and prepared chemical profiles of sample extracts using gas chromatography-flame ionization detection. Both unsupervised (principal component analysis) and supervised (linear discriminant analysis) statistical analyses of these profiles revealed a strong relationship between cryptic species membership and chemical profiles. Liquid chromatography with tandem mass spectrometry-based analysis using feature-based molecular networking permitted identification of the chemical drivers of this difference between clades, including cembranoid diterpenes (2R,11R,12R)-isosarcophytoxide (5), (2S,11R,12R)-isosarcophytoxide (6), and isosarcophine (7). Our results suggest that early chemical studies of Sarcophyton may have unknowingly conflated different cryptic species of S. glaucum, leading to apparently idiosyncratic chemical variation.

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