The Laurencia Paradox: An Endless Source of Chemodiversity

Abstract

Nature, the most prolific source of biological and chemical diversity, has provided mankind with treatments for health problems since ancient times and continues to be the most promising reservoir of bioactive chemicals for the development of modern drugs. In addition to the terrestrial organisms that still remain a promising source of new bioactive metabolites, the marine environment, covering approximately 70% of the Earth's surface and containing a largely unexplored biodiversity, offers an enormous resource for the discovery of novel compounds. According to the MarinLit database, more than 27,000 metabolites from marine macro- and microorganisms have been isolated to date providing material and key structures for the development of new products in the pharmaceutical, food, cosmeceutical, chemical, and agrochemical sectors. Algae, which thrive in the euphotic zone, were among the first marine organisms that were investigated as sources of food, nutritional supplements, soil fertilizers, and bioactive metabolites.Red algae of the genus Laurencia are accepted unanimously as one of the richest sources of new secondary metabolites. Their cosmopolitan distribution, along with the chemical variation influenced to a significant degree by environmental and genetic factors, have resulted in an endless parade of metabolites, often featuring multiple halogenation sites.The present contribution, covering the literature until August 2015, offers a comprehensive view of the chemical wealth and the taxonomic problems currently impeding chemical and biological investigations of the genus Laurencia. Since mollusks feeding on Laurencia are, in many cases, bioaccumulating, and utilize algal metabolites as chemical weaponry against natural enemies, metabolites of postulated dietary origin of sea hares that feed on Laurencia species are also included in the present review. Altogether, 1047 secondary metabolites, often featuring new carbocyclic skeletons, have been included.The chapter addresses: (1) the "Laurencia complex", the botanical description and the growth and population dynamics of the genus, as well as its chemical diversity and ecological relations; (2) the secondary metabolites, which are organized according to their chemical structures and are classified into sesquiterpenes, diterpenes, triterpenes, acetogenins, indoles, aromatic compounds, steroids, and miscellaneous compounds, as well as their sources of isolation which are depicted in tabulated form, and (3) the biological activity organized according to the biological target and the ecological functions of Laurencia metabolites.

Molecular networking prospection and characterization of terpenoids and C15-acetogenins in Brazilian seaweed extracts

“…Pachydictyol A (9). White powder; R f 0.29, silica gel 60 F 254 , Hex/AcOEt (98.5 : 1.5); 1 H NMR (CDCl 3 , 300 MHz) and 13 C NMR (CDCl 3 , 75 MHz) data were in agreement to the literature.…”

“…16 Many of these metabolites have been conrmed as presenting anticoagulant, antifouling, antimicrobial, antioxidant, herbivore-deterrent and cytotoxic activities. 9,10,[17][18][19][20] This study reports an exploratory MN analysis of fourteen algae extracts of algae collected mostly from Brazilian oceanic islands and the characterization of terpenoids and C 15 -acetogenins from some of the analyzed species.…”

Discrimination and Characterization of Two Mediterranean Species from theLaurenciaComplex (Rhodomelacea) Using anNMR‐Based Metabolomic Approach

“…The number of species among the genus Laurencia are subject to permanent revaluation as the taxonomy of the Laurencia complex has been revised several times, initially based on additional morphological criteria, and more recently based on molecular phylogenies . Plasticity of the morphological characteristics reported for certain species, including color adaptation, complicates species discrimination and has frequently led to erroneous species identification . Therefore, the use of DNA barcoding appears essential to reliably identify species and phylogenetic relationships.…”

“…[2] Plasticity of the morphological characteristics reported for certain species, including color adaptation, complicates species discrimination and has frequently led to erroneous species identification. [3] Therefore, the use of DNA barcoding appears essential to reliably identify species and phylogenetic relationships. Another approach only sporadically employed for marine organisms consists in identifying specific chemicals present in given species which are poorly distributed or totally absent from others.…”

A Synthetic Approach Toward a Brominated Oxocane Labdane Diterpenoid Isolated From Laurencia obtusa

“…1,2 In particular, red algae of Laurencia species are known to produce more than 700 compounds including a variety of frameworks along with halogenated compounds. [3][4][5][6] In 2003, Vagias et al isolated halogenated labdanes 1 and 2 from Laurencia obtusa obtained in the Ionian Sea of Greece, 7 which possess an 8-membered or 7-membered ether ring fused with a decalin core, a labile C-Br bond at C3, and an epoxide ring or a hydroxyl group encompassing seven asymmetric centers ( Figure 1). The absolute stereostructures of 1 and 2 are not yet determined.…”