[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"detail-sidebar-cat-0-en-105":3,"doc-seo-462737-105":59,"doc-detail-462737-en":130},{"code":4,"msg":5,"data":6},0,"success",[7,13,18,23,28,33,38,43,48,51,55],{"id":8,"doc_module":4,"doc_module_name":9,"category_name":10,"show_sort_weight":11,"slug":12},1,"Document","Story & Novel",90,"story-novel",{"id":14,"doc_module":4,"doc_module_name":9,"category_name":15,"show_sort_weight":16,"slug":17},2,"Literature",80,"literature",{"id":19,"doc_module":4,"doc_module_name":9,"category_name":20,"show_sort_weight":21,"slug":22},4,"Exam",70,"exam",{"id":24,"doc_module":4,"doc_module_name":9,"category_name":25,"show_sort_weight":26,"slug":27},5,"Comic",60,"comic",{"id":29,"doc_module":4,"doc_module_name":9,"category_name":30,"show_sort_weight":31,"slug":32},6,"Technology",50,"technology",{"id":34,"doc_module":4,"doc_module_name":9,"category_name":35,"show_sort_weight":36,"slug":37},7,"Healthcare",40,"healthcare",{"id":39,"doc_module":4,"doc_module_name":9,"category_name":40,"show_sort_weight":41,"slug":42},8,"Research & Report",30,"research-report",{"id":44,"doc_module":4,"doc_module_name":9,"category_name":45,"show_sort_weight":46,"slug":47},9,"Religion & Spirituality",20,"religion-spirituality",{"id":46,"doc_module":4,"doc_module_name":9,"category_name":49,"show_sort_weight":46,"slug":50},"World Cup","world-cup",{"id":52,"doc_module":4,"doc_module_name":9,"category_name":53,"show_sort_weight":52,"slug":54},10,"Lifestyle","lifestyle",{"id":56,"doc_module":4,"doc_module_name":9,"category_name":57,"show_sort_weight":24,"slug":58},19,"General","general",{"code":4,"msg":60,"data":61},"ok",{"site_id":62,"language":63,"slug":64,"title":65,"keywords":66,"description":67,"schema_data":68,"social_meta":123,"head_meta":125,"extra_data":127,"updated_unix":129},105,"en","is-the-reindeer-lichen-cladonia-arbuscula-really-producing-isousnic-acid-a-chemotaxonomy-query","Is the Reindeer Lichen Cladonia arbuscula Really Producing Isousnic Acid? A Chemotaxonomy Query","","Isousnic acid (isoUA) has been reported in a small number of usnic acid (UA)-producing lichens using chemotaxonomic criteria, yet its isolation and detection in Cladonia arbuscula have not been independently reproduced. This study identifies Iceland-collected C. arbuscula s.l. via DNA barcoding (nrITS) and tests isoUA production using chromatographic workflows. Routine profiling failed, but isoUA was confirmed only after intensive flash chromatography and preparative UHPLC concentration, appearing at trace levels (~24 µg/g). A rapid UHPLC method was also developed to separate UA from isoUA, supporting integrative DNA- and chemistry-based lichen research.",{"@graph":69,"@context":122},[70,84,105],{"@type":71,"itemListElement":72},"BreadcrumbList",[73,77,79,82],{"item":74,"name":75,"@type":76,"position":8},"https://docshare.wps.com","Home","ListItem",{"item":78,"name":9,"@type":76,"position":14},"https://docshare.wps.com/document/",{"item":80,"name":40,"@type":76,"position":81},"https://docshare.wps.com/document/research-report/",3,{"item":83,"name":65,"@type":76,"position":19},"https://docshare.wps.com/document/is-the-reindeer-lichen-cladonia-arbuscula-really-producing-isousnic-acid-a-chemotaxonomy-query/462737/",{"url":83,"name":65,"@type":85,"image":86,"author":91,"headline":65,"publisher":94,"fileFormat":97,"inLanguage":63,"description":67,"dateModified":98,"datePublished":99,"encodingFormat":97,"isAccessibleForFree":100,"interactionStatistic":101},"DigitalDocument",{"url":87,"@type":88,"width":89,"height":90},"https://docshare.wps.com/thumbnails/is-the-reindeer-lichen-cladonia-arbuscula-really-producing-isousnic-acid-a-chemotaxonomy-query/462737.png","ImageObject",300,407,{"name":92,"@type":93},"Dipper","Person",{"url":74,"name":95,"@type":96},"DocShare","Organization","application/pdf","2026-10-05","2026-09-30",true,{"@type":102,"interactionType":103,"userInteractionCount":14},"InteractionCounter",{"@type":104},"ViewAction",{"@type":106,"mainEntity":107},"FAQPage",[108,114,118],{"name":109,"@type":110,"acceptedAnswer":111},"What is the main research question about isousnic acid in Cladonia arbuscula?","Question",{"text":112,"@type":113},"Whether Cladonia arbuscula s.l. truly produces isousnic acid (isoUA), given prior reports that have not been reproduced with clear evidence.","Answer",{"name":115,"@type":110,"acceptedAnswer":116},"How was the lichen specimen identified in this study?",{"text":117,"@type":113},"The specimen was identified using DNA barcoding based on the fungal nuclear ribosomal internal transcribed spacer (nrITS) barcode.",{"name":119,"@type":110,"acceptedAnswer":120},"Why was isoUA not detected in routine metabolite profiling?",{"text":121,"@type":113},"IsoUA was present only in trace quantities (~24 µg/g dry weight), which likely explains why it was not seen without rigorous chromatographic purification and concentration.","https://schema.org",{"og:url":83,"og:type":124,"og:title":65,"og:site_name":95,"og:description":67},"article",{"robots":126,"canonical":83},"index,follow",{"doc_id":128,"site_id":62},462737,1791184605,{"code":4,"msg":5,"data":131},{"doc_id":128,"user_id":132,"nickname":92,"user_avatar":133,"doc_module":4,"category_id":39,"category_name":40,"doc_title":65,"doc_description":67,"doc_content":134,"file_id":135,"file_url":136,"file_type":137,"file_size":138,"view_count":14,"is_deleted":4,"is_public":8,"is_downloadable":8,"audit_status":8,"page_count":52,"language":139,"language_code":63,"site_id":62,"html_lang":63,"table_of_contents":140,"faqs":141,"seo_title":142,"seo_description":67,"update_tm":143,"read_time":144},1374404997633,"https://ap-avatar.wpscdn.com/davatar_a8503ba1806abce46bf441b54a3ca4cd","Article  \nIs the Reindeer Lichen Cladonia arbuscula Really Producing Isousnic Acid? A Chemotaxonomy Query  \nDagmar Ísleifsdóttir 1, Maonian Xu 1, Maia Biwersi 1, Marie-Jeanne Leblanc 2, Starri Heiðmarsson 3, Snæbjörn Pálsson 4, John L. Sorensen 2, Elvar Örn Viktorsson 1 and Elín Soffía Ólafsdóttir 1, *  \n1 Faculty of Pharmaceutical Sciences, University of Iceland, Hofsvallagata 53, IS-107 Reykjavik, Iceland; [dai8@hi.is](dai8@hi.is) (D.Í .); [maonian@hi.is](maonian@hi.is) (M.X.); [mab130@hi.is](mab130@hi.is) (M.B.); [eov@hi.is](eov@hi.is) (E.Ö .V.)  \n2 Department of Chemistry, University of Manitoba, Winnipeg, MB R3T 2N2, Canada; [leblan38@myumanitoba.ca](leblan38@myumanitoba.ca) (M.-J.L.); [john.sorensen@umanitoba.ca](john.sorensen@umanitoba.ca) (J.L.S.)  \n3 Northwest Iceland Nature Research Centre, Aðalgata 2, IS-550 Sauðárkrókur, Iceland; [starri@nnv.is](starri@nnv.is)  \n[4](4 Faculty of Life and Environmental Sciences)[ Faculty of Life and Environmental Sciences](4 Faculty of Life and Environmental Sciences), [University of Iceland](University of Iceland), [Sturlugata 7](Sturlugata 7), [IS-102 Reykjavik](IS-102 Reykjavik), [Iceland](Iceland); [snaebj@hi.is](snaebj@hi.is)  \n* Correspondence: [elinsol@hi.is](elinsol@hi.is)  \nAbstract  \nIsousnic acid (isoUA) has been detected in a few usnic acid (UA)-producing lichens with chemotaxonomic values. IsoUA was first isolated from a specimen belonging to Cladoniaarbuscula s.l. (referred to as C. mitis in the publication) . However, the isolation and detection of isoUA in this Cladonia species have not been reproduced and confirmed with clear evidence. This study focused on C. arbuscula s.l. collected in Iceland and aimed to  \n(1) identify the lichen specimen using DNA barcoding and (2) investigate whether isoUA is produced using a series of chromatographic methods. The fungal nuclear ribosomal internal transcribed spacer (nrITS) barcode was sequenced, and the specimen was identified as C. arbuscula, following recent circumscription recommendations. Routine metabolite profiling did not detect isoUA, and it could only be identified after vigorous chromatographic purification and concentration steps using flash chromatography and preparative highperformance liquid chromatography. IsoUA was found in trace quantities (~24 µg/g dry weight), which likely explains its absence in routine metabolite profiling. A rapid ultrahigh-performance liquid chromatography (UHPLC) method using a pentafluorophenyl column was developed to separate UA and isoUA. Our study highlights the importance of an integrative approach combining DNA barcoding and detailed chromatographic analyses for lichen chemistry research.  \nKeywords: chemotaxonomy; Cladonia arbuscula; Cladonia mitis; DNA barcoding; isousnic acid; lichen; UHPLC  \nReceived: 25 November 2025  \nRevised: 18 December 2025  \nAccepted: 27 December 2025  \nPublished: 1 January 2026  \nCopyright: © 2026 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license.  \n1. Introduction  \nLichens are classic examples of successful microbial symbiosis, adapting to extreme environments and producing a wide range of unique, specialized metabolites [1–3] . These lichen-specific compounds, including depsides, depsidones, and dibenzofurans, serve diverse ecological functions, such as protection against UV radiation, herbivory, and allelopathy [4–7] . They also display significant biological potential, with reported antimicrobial, anti-inflammatory, cytotoxic, and antioxidant activities [3,8,9] . Lichen chemistry played an indispensable role in the early lichen taxonomy before the advent of DNA sequencing, with most morphological species found to be chemically uniform [10] . However, chemical  \nvariations can be found within a single lichen taxon, leading to controversy over whether chemical varieties should be treated as separate species or subspe","cbCaibJnN0h9WbsN","https://ap.wps.com/l/cbCaibJnN0h9WbsN","pdf",1841101,"English","# Abstract\n# Introduction","[{\"question\":\"What is the main research question about isousnic acid in Cladonia arbuscula?\",\"answer\":\"Whether Cladonia arbuscula s.l. truly produces isousnic acid (isoUA), given prior reports that have not been reproduced with clear evidence.\"},{\"question\":\"How was the lichen specimen identified in this study?\",\"answer\":\"The specimen was identified using DNA barcoding based on the fungal nuclear ribosomal internal transcribed spacer (nrITS) barcode.\"},{\"question\":\"Why was isoUA not detected in routine metabolite profiling?\",\"answer\":\"IsoUA was present only in trace quantities (~24 µg/g dry weight), which likely explains why it was not seen without rigorous chromatographic purification and concentration.\"}]","Is the Reindeer Lichen Cladonia arbuscula Really Producing Isousnic Acid? A Chemotaxonomy Query | PDF",1790765026,25]