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Ferron S, Ismed F, Elyashberg ME, Buevich AV, Arifa N, Boustie J, Uriac P, Le Pogam P, Le Dévéhat F. CASE-DFT Structure Elucidation of Proton-Deficient Chlorodepsidones from the Indonesian Lichen Teloschistes flavicans and Structure Revision of Flavicansone. JOURNAL OF NATURAL PRODUCTS 2024. [PMID: 38780134 DOI: 10.1021/acs.jnatprod.4c00277] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2024]
Abstract
Biodiscovery efforts in Indonesia have aimed to explore the understudied chemical diversity of its rich lichen flora, seeking to find new products endowed with significant biological properties. The chemical screening of a Teloschistes flavicans extract led to selection of this species for further investigation. LC/MS and 1H NMR-based dereplication pinpointed six chlorodepsidones from the thallus of a sample of this lichen. This led to the streamlined isolation and the subsequent structure elucidation of the three new compounds norflavicansone 1, flavicansone 2, and isocaloploicin 3, along with the known chlorodepsidones 4-6, stictic acid 7, aurantiamide acetate 8, and parietin 9. The challenging structure elucidation of these proton-deficient metabolites benefited from a state-of-the-art workflow involving a synergistic combination of Computer-Assisted Structure Elucidation (CASE) and Density Functional Theory (DFT) calculations of the top-ranked candidates. This investigation also led to the revision of flavicansone's structure, previously described from this species. The three new molecules that are being reported here are remarkable in that they represent hybrid depsidones in which one of the aromatic rings is derived from orsellinic acid and the other is derived from β-orcinol, a rare structural feature for lichen depsidones.
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Affiliation(s)
- Solenn Ferron
- CNRS, ISCR (Institut des Sciences Chimiques de Rennes) - UMR 6226, Univ Rennes, 35000 Rennes, France
| | - Friardi Ismed
- The Laboratory of Natural Resource of Sumatra (LBS) and Faculty of Pharmacy, Andalas University, 26163 Padang, Indonesia
| | - Mikhail E Elyashberg
- Advanced Chemistry Development Inc. (ACD/Laboratories), 8 King Street, Toronto, ON M5C 1B5, Canada
| | - Alexei V Buevich
- Analytical Research and Development, Merck & Co., Inc., Rahway, New Jersey 07065, United States
| | - Nurwahidatul Arifa
- The Laboratory of Natural Resource of Sumatra (LBS) and Faculty of Pharmacy, Andalas University, 26163 Padang, Indonesia
- Program study of Pharmacy, Faculty of Sciences Medicine, Baiturrahmah University, 25586 Padang, Indonesia
| | - Joël Boustie
- CNRS, ISCR (Institut des Sciences Chimiques de Rennes) - UMR 6226, Univ Rennes, 35000 Rennes, France
| | - Philippe Uriac
- CNRS, ISCR (Institut des Sciences Chimiques de Rennes) - UMR 6226, Univ Rennes, 35000 Rennes, France
| | - Pierre Le Pogam
- Équipe "Chimie des Substances Naturelles" BioCIS, CNRS, Université Paris-Saclay, 17, Avenue des Sciences, 91400 Orsay, France
| | - Françoise Le Dévéhat
- CNRS, ISCR (Institut des Sciences Chimiques de Rennes) - UMR 6226, Univ Rennes, 35000 Rennes, France
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Egbert S, Hoffman JR, McMullin RT, Lendemer JC, Sorensen JL. Unraveling usnic acid: a comparison of biosynthetic gene clusters between two reindeer lichen (Cladonia rangiferina and C. uncialis). Fungal Biol 2022; 126:697-706. [PMID: 36517138 DOI: 10.1016/j.funbio.2022.08.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 08/09/2022] [Accepted: 08/15/2022] [Indexed: 01/07/2023]
Abstract
Lichenized fungi are known for their production of a diversity of secondary metabolites, many of which have broad biological and pharmacological applications. By far the most well-studied of these metabolites is usnic acid. While this metabolite has been well-known and researched for decades, the gene cluster responsible for its production was only recently identified from the species Cladonia uncialis. Usnic acid production varies considerably in the genus Cladonia, even among closely related taxa, and many species, such as C. rangiferina, have been inferred to be incapable of producing the metabolite based on analysis by thin-layer chromatography (TLC). We sequenced and examined the usnic acid biosynthetic gene clusters, or lack thereof, from four closely related Cladonia species (C. oricola, C. rangiferina, C. stygia, and C. subtenuis), and compare them against those of C. uncialis. We complement this comparison with tiered chemical profile analyses to confirm the presence or absence of usnic acid in select samples, using both HPLC and LC-MS. Despite long-standing reporting that C. rangiferina lacks the ability to produce usnic acid, we observed functional gene clusters from the species and detected usnic acid when extracts were examined by LC-MS. By contrast, C. stygia and C. oricola, have been previously described as lacking the ability to produce usnic acid, lacked the gene cluster entirely, and no usnic acid could be detected in C. oricola extracts via HPLC or LC-MS. This work suggests that chemical profiles attained through inexpensive and low-sensitivity methods like TLC may fail to detect low abundance metabolites that can be taxonomically informative. This study also bolsters understanding of the usnic acid gene cluster in lichens, revealing differences among domains of the polyketide synthase which may explain observed differences in expression. These results reinforce the need for comprehensive characterization of lichen secondary metabolite profiles with sensitive LC-MS methods.
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Affiliation(s)
- Susan Egbert
- Department of Chemistry, University of Manitoba, Winnipeg, Manitoba, R3T 2N2, Canada
| | - Jordan R Hoffman
- Department of Biology, Graduate Center, City University of New York, The New York, USA; Botanical Garden, 2900 Southern Blvd, Bronx, NY, 10458-5126, USA
| | - R Troy McMullin
- Research and Collections, Canadian Museum of Nature, PO Box 3443, Station D, Ottawa, Ontario, K1P 6P4, Canada
| | - James C Lendemer
- Botanical Garden, 2900 Southern Blvd, Bronx, NY, 10458-5126, USA.
| | - John L Sorensen
- Department of Chemistry, University of Manitoba, Winnipeg, Manitoba, R3T 2N2, Canada.
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A New Cryptic Lineage in Parmeliaceae (Ascomycota) with Pharmacological Properties. J Fungi (Basel) 2022; 8:jof8080826. [PMID: 36012814 PMCID: PMC9409757 DOI: 10.3390/jof8080826] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 08/01/2022] [Accepted: 08/03/2022] [Indexed: 11/17/2022] Open
Abstract
We used molecular data to address species delimitation in a species complex of the parmelioid genus Canoparmelia and compare the pharmacological properties of the two clades identified. We used HPLC_DAD_MS chromatography to identify and quantify the secondary substances and used a concatenated data set of three ribosomal markers to infer phylogenetic relationships. Some historical herbarium specimens were also examined. We found two groups that showed distinct pharmacological properties. The phylogenetic study supported the separation of these two groups as distinct lineages, which are here accepted as distinct species: Canoparmelia caroliniana occurring in temperate to tropical ecosystems of a variety of worldwide localities, including America, Macaronesia, south-west Europe and potentially East Africa, whereas the Kenyan populations represent the second group, for which we propose the new species C. kakamegaensis Garrido-Huéscar, Divakar & Kirika. This study highlights the importance of recognizing cryptic species using molecular data, since it can result in detecting lineages with pharmacological properties previously overlooked.
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Axenic culture and biosynthesis of secondary compounds in lichen symbiotic fungi, the Parmeliaceae. Symbiosis 2020. [DOI: 10.1007/s13199-020-00719-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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HPLC Fingerprint Analysis with the Antioxidant and Cytotoxic Activities of Selected Lichens Combined with the Chemometric Calculations. Molecules 2020; 25:molecules25184301. [PMID: 32961727 PMCID: PMC7571045 DOI: 10.3390/molecules25184301] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 09/18/2020] [Accepted: 09/18/2020] [Indexed: 10/26/2022] Open
Abstract
The aim of this study was to evaluate the ability of multivariate techniques to predict antioxidant and cytotoxic activity of the selected lichens from the chromatographic data. A simple and reproducible HPLC-DAD technique has been used to obtain the chromatographic fingerprint profiles. Reversed phase high performance liquid chromatography (RP-HPLC) linear gradient system with methanol, water and phosphoric acid (V) (pH 2.3) as the mobile phase was used (50 min). Principal Component Analysis (PCA) has been applied to the evaluation of the phytochemical similarity between studied samples, especially between the same species collected in various places of Poland (Cetraria islandica (L.) Ach., CI, Cladina mitis Sandst., CM, Hypogymnia physodes (L.) Nyl., HP). The ability to scavenge free radicals was evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) methods and the total phenolic content was determined by Folin-Ciocalteu (F-C) test. In the case of DPPH % of inhibition was higher for selected species (Pseudevernia furfuracea (L.) Zopf, H. physodes in comparison to the literature data. The FRAP test showed that the H. physodes extract had higher ability to scavenge free radical in comparison to Cladonia furcata (Huds.) Schrader and Evernia prunastri (L.) Ach., whereas P. furfuracea extract showed higher ability than C. islandica. The high content of phenolics in P. furfuracea and H. physodes confirms their high antioxidant activity. The cytotoxic activity of studied extracts was tested by cell culture method using the human HL-60 / MX2 acute CKL-22 (CRL-2257) promyelocytic leukemia tumor cell line. The lowest values of IC50 [µg∙mL-1] were obtained for: H. physodes (HP1)-99.4; C. digitate-122.6; H. physodes (HP)-136.5, C. subulata-142.6; C. mitis-180.2.
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Maghembe R, Damian D, Makaranga A, Nyandoro SS, Lyantagaye SL, Kusari S, Hatti-Kaul R. Omics for Bioprospecting and Drug Discovery from Bacteria and Microalgae. Antibiotics (Basel) 2020; 9:antibiotics9050229. [PMID: 32375367 PMCID: PMC7277505 DOI: 10.3390/antibiotics9050229] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 04/10/2020] [Accepted: 04/29/2020] [Indexed: 12/20/2022] Open
Abstract
"Omics" represent a combinatorial approach to high-throughput analysis of biological entities for various purposes. It broadly encompasses genomics, transcriptomics, proteomics, lipidomics, and metabolomics. Bacteria and microalgae exhibit a wide range of genetic, biochemical and concomitantly, physiological variations owing to their exposure to biotic and abiotic dynamics in their ecosystem conditions. Consequently, optimal conditions for adequate growth and production of useful bacterial or microalgal metabolites are critically unpredictable. Traditional methods employ microbe isolation and 'blind'-culture optimization with numerous chemical analyses making the bioprospecting process laborious, strenuous, and costly. Advances in the next generation sequencing (NGS) technologies have offered a platform for the pan-genomic analysis of microbes from community and strain downstream to the gene level. Changing conditions in nature or laboratory accompany epigenetic modulation, variation in gene expression, and subsequent biochemical profiles defining an organism's inherent metabolic repertoire. Proteome and metabolome analysis could further our understanding of the molecular and biochemical attributes of the microbes under research. This review provides an overview of recent studies that have employed omics as a robust, broad-spectrum approach for screening bacteria and microalgae to exploit their potential as sources of drug leads by focusing on their genomes, secondary metabolite biosynthetic pathway genes, transcriptomes, and metabolomes. We also highlight how recent studies have combined molecular biology with analytical chemistry methods, which further underscore the need for advances in bioinformatics and chemoinformatics as vital instruments in the discovery of novel bacterial and microalgal strains as well as new drug leads.
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Affiliation(s)
- Reuben Maghembe
- Department of Molecular Biology and Biotechnology, College of Natural and Applied Sciences, University of Dar es Salaam, P.O. Box 25179, Dar es Salaam, Tanzania; (R.M.); (D.D.); (S.L.L.)
- Department of Biological and Marine Sciences, Marian University College, P.O. Box 47, Bagamoyo, Tanzania;
- Division of Biotechnology, Department of Chemistry, Center for Chemistry and Chemical Engineering, Lund University, Box 124, 22100 Lund, Sweden
| | - Donath Damian
- Department of Molecular Biology and Biotechnology, College of Natural and Applied Sciences, University of Dar es Salaam, P.O. Box 25179, Dar es Salaam, Tanzania; (R.M.); (D.D.); (S.L.L.)
| | - Abdalah Makaranga
- Department of Biological and Marine Sciences, Marian University College, P.O. Box 47, Bagamoyo, Tanzania;
- International Center for Genetic Engineering and Biotechnology (ICGEB), Omics of Algae Group, Aruna Asaf Ali Marg, New Delhi 110067, India
| | - Stephen Samwel Nyandoro
- Chemistry Department, College of Natural and Applied Sciences, University of Dar es Salaam, P.O. Box 35061, Dar es Salaam, Tanzania;
| | - Sylvester Leonard Lyantagaye
- Department of Molecular Biology and Biotechnology, College of Natural and Applied Sciences, University of Dar es Salaam, P.O. Box 25179, Dar es Salaam, Tanzania; (R.M.); (D.D.); (S.L.L.)
- Department of Biochemistry, Mbeya College of Health and Allied Sciences, University of Dar es Salaam, P.O. Box 608, Mbeya, Tanzania
| | - Souvik Kusari
- Institute of Environmental Research (INFU), Department of Chemistry and Chemical Biology, Technische Universität Dortmund, Otto-Hahn-Straße 6, 44221 Dortmund, Germany
- Correspondence: (S.K.); (R.H.-K.); Tel.: +49-2317554086 (S.K.); +46-462224840 (R.H.-K.)
| | - Rajni Hatti-Kaul
- Division of Biotechnology, Department of Chemistry, Center for Chemistry and Chemical Engineering, Lund University, Box 124, 22100 Lund, Sweden
- Correspondence: (S.K.); (R.H.-K.); Tel.: +49-2317554086 (S.K.); +46-462224840 (R.H.-K.)
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Gadea A, Fanuel M, Le Lamer AC, Boustie J, Rogniaux H, Charrier M, Lohézic-Le Devehat F. Mass Spectrometry Imaging of Specialized Metabolites for Predicting Lichen Fitness and Snail Foraging. PLANTS (BASEL, SWITZERLAND) 2020; 9:plants9010070. [PMID: 31935813 PMCID: PMC7020473 DOI: 10.3390/plants9010070] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2019] [Revised: 12/16/2019] [Accepted: 01/01/2020] [Indexed: 05/21/2023]
Abstract
Lichens are slow-growing organisms supposed to synthetize specialized metabolites to protect themselves against diverse grazers. As predicted by the optimal defense theory (ODT), lichens are expected to invest specialized metabolites in higher levels in reproductive tissues compared to thallus. We investigated whether Laser Desorption Ionization coupled to Mass Spectrometry Imaging (LDI-MSI) could be a relevant tool for chemical ecology issues such as ODT. In the present study, this method was applied to cross-sections of thalli and reproductive tissues of the lichen Pseudocyphellaria crocata. Spatial mapping revealed phenolic families of metabolites. A quantification of these metabolites was carried out in addition to spatial imaging. By this method, accumulation of specialized metabolites was observed in both reproductive parts (apothecia and soralia) of P. crocata, but their nature depended on the lichen organs: apothecia concentrated norstictic acid, tenuiorin, and pulvinic acid derivatives, whereas soralia mainly contained tenuiorin and pulvinic acid. Stictic acid, tenuiorin and calycin, tested in no-choices feeding experiments, were deterrent for N. hookeri while entire thalli were consumed by the snail. To improve better knowledge in relationships between grazed and grazing organisms, LDI-MSI appears to be a complementary tool in ecological studies.
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Affiliation(s)
- Alice Gadea
- Univ Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes)—UMR 6226, F-35000 Rennes, France; (A.G.); (J.B.)
- Univ Rennes, CNRS, ECOBIO (Ecosystèmes, biodiversité, évolution)—UMR 6553, F-35000 Rennes, France;
| | - Mathieu Fanuel
- INRA, UR1268 Biopolymers Interactions Assemblies, F-44316 Nantes, France; (M.F.); (H.R.)
| | | | - Joël Boustie
- Univ Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes)—UMR 6226, F-35000 Rennes, France; (A.G.); (J.B.)
| | - Hélène Rogniaux
- INRA, UR1268 Biopolymers Interactions Assemblies, F-44316 Nantes, France; (M.F.); (H.R.)
| | - Maryvonne Charrier
- Univ Rennes, CNRS, ECOBIO (Ecosystèmes, biodiversité, évolution)—UMR 6553, F-35000 Rennes, France;
| | - Françoise Lohézic-Le Devehat
- Univ Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes)—UMR 6226, F-35000 Rennes, France; (A.G.); (J.B.)
- Correspondence: ; Tel.: +33-223-230-540
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Gadea A, Charrier M, Fanuel M, Clerc P, Daugan C, Sauvager A, Rogniaux H, Boustie J, Le Lamer AC, Lohézic-Le Devehat F. Overcoming deterrent metabolites by gaining essential nutrients: A lichen/snail case study. PHYTOCHEMISTRY 2019; 164:86-93. [PMID: 31102999 DOI: 10.1016/j.phytochem.2019.04.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Revised: 04/19/2019] [Accepted: 04/27/2019] [Indexed: 06/09/2023]
Abstract
Specialised metabolites in lichens are generally considered repellent compounds by consumers. Nevertheless, if the only food available is lichens rich in specialised metabolites, lichenophages must implement strategies to overcome the toxicity of these metabolites. Thus, the balance between phagostimulant nutrients and deterrent metabolites could play a key role in feeding preferences. To further understand lichen-gastropod interactions, we studied the feeding behaviour and consumption in Notodiscus hookeri, the land snail native to sub-Antarctic islands. The lichen Usnea taylorii was used because of its simple chemistry, its richness in usnic acid (specialised metabolite) and arabitol (primary metabolite) and its presence in snail habitats. Choice tests in arenas with intact lichens versus acetone-rinsed lichens were carried out to study the influence of specialised metabolites on snail behaviour and feeding preference. Simultaneously, usnic acid and arabitol were quantified and located within the lichen thallus using HPLC-DAD-MS and in situ imaging by mass spectrometry to assess whether their spatial distribution explained preferential snail grazing. No-choice feeding experiments, with the pure metabolites embedded in an artificial diet, defined a gradual gustatory response, from strong repellence (usnic acid) to high appetence (D-arabitol). This case study demonstrates that the nutritional activity of N. hookeri is governed by the chemical quality of the food and primarily by nutrient availability (arabitol), despite the presence of deterrent metabolite (usnic acid).
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Affiliation(s)
- Alice Gadea
- Univ Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes), UMR 6226, F-35000 Rennes, France; Univ Rennes, CNRS, ECOBIO (Ecosystèmes, Biodiversité, évolution), UMR 6553, F-35000 Rennes, France
| | - Maryvonne Charrier
- Univ Rennes, CNRS, ECOBIO (Ecosystèmes, Biodiversité, évolution), UMR 6553, F-35000 Rennes, France
| | - Mathieu Fanuel
- INRA, UR1268 Biopolymers Interactions Assemblies, F-44316 Nantes, France
| | - Philippe Clerc
- Conservatoire et Jardin Botanique, Département de la culture et du sport, chemin de l'impératrice 1, 1292, Chambésy, Switzerland
| | - Corentin Daugan
- Univ Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes), UMR 6226, F-35000 Rennes, France
| | - Aurélie Sauvager
- Univ Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes), UMR 6226, F-35000 Rennes, France
| | - Hélène Rogniaux
- INRA, UR1268 Biopolymers Interactions Assemblies, F-44316 Nantes, France
| | - Joël Boustie
- Univ Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes), UMR 6226, F-35000 Rennes, France
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Chollet-Krugler M, Nguyen TTT, Sauvager A, Thüs H, Boustie J. Mycosporine-Like Amino Acids (MAAs) in Time-Series of Lichen Specimens from Natural History Collections. Molecules 2019; 24:E1070. [PMID: 30893758 PMCID: PMC6471344 DOI: 10.3390/molecules24061070] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Revised: 03/14/2019] [Accepted: 03/16/2019] [Indexed: 01/15/2023] Open
Abstract
Mycosporine-like amino acids (MAAs) were quantified in fresh and preserved material of the chlorolichen Dermatocarpon luridum var. luridum (Verrucariaceae/Ascomycota). The analyzed samples represented a time-series of over 150 years. An HPLC coupled with a diode array detector (HPLC-DAD) in hydrophilic interaction liquid chromatography (HILIC) mode method was developed and validated for the quantitative determination of MAAs. We found evidence for substance specific differences in the quality of preservation of two MAAs (mycosporine glutamicol, mycosporine glutaminol) in Natural History Collections. We found no change in average mycosporine glutamicol concentrations over time. Mycosporine glutaminol concentrations instead decreased rapidly with no trace of this substance detectable in collections older than nine years. Our data predict that a screening for MAAs in organism samples from Natural History Collections can deliver results that are comparable to those obtained from fresh collections only for some MAAs (e.g., mycosporine glutamicol). For other MAAs, misleading, biased, or even false negative results will occur as a result of the storage sensitivity of substances such as mycosporine glutaminol. Our study demonstrates the value of pilot studies with time-series based on model taxa with a rich representation in the Natural History Collections.
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Affiliation(s)
- Marylène Chollet-Krugler
- CNRS, ISCR (Institut des Sciences Chimiques de Rennes)-UMR 6226, Univ Rennes, F-35000 Rennes, France.
| | - Thi Thu Tram Nguyen
- CNRS, ISCR (Institut des Sciences Chimiques de Rennes)-UMR 6226, Univ Rennes, F-35000 Rennes, France.
- Department of Chemistry, Faculty of Science, Can Tho University of Medicine and Pharmacy, 179 Nguyen Van Cu Street, An Khanh, Ninh Kieu, Can Tho, 902495 Vietnam.
| | - Aurelie Sauvager
- CNRS, ISCR (Institut des Sciences Chimiques de Rennes)-UMR 6226, Univ Rennes, F-35000 Rennes, France.
| | - Holger Thüs
- State Museum of Natural History Stuttgart, Rosenstein 1, 70191 Stuttgart, Germany.
- The Natural History Museum London, Cromwell Rd, Kensington, London SW7 5BD, UK.
| | - Joël Boustie
- CNRS, ISCR (Institut des Sciences Chimiques de Rennes)-UMR 6226, Univ Rennes, F-35000 Rennes, France.
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