Laurencia Species Research Articles

Morphological and Chemical Diversity within Japanese Laurencia Complex (Rhodomelaceae, Ceramiales, Rhodophyta).

Seaweeds of the red algal genus Laurencia are distributed worldwide in tropical, subtropical to temperate zones, growing in Japan from Hokkaido to Okinawa. Laurencia is highly difficult to classify morphologically because of a high degree of morphological variation within individual species. Nevertheless, Laurencia investigation is favored by organic chemists as it produces uniquely structured compounds. Halogenated secondary metabolites are considered to be used as chemical markers for chemical systematics (chemotaxonomy) of this troublesome genus. As a "weedy seaweed", Laurencia is not effectively utilized, yet it produces a variety of metabolites and thus, holds good potential for containing compounds with specific activity, especially in aspects of secondary metabolites. In this review, we reported significant morphological features to distinguish species in this genus, and the morphological features, habitat, distribution, and chemical composition that help discriminate Japanese Laurencia species.

New C15 Acetogenins from Two Species of Laurencia from the Aegean Sea.

The chemical diversity of the approximately 1,200 natural products isolated from red algae of the genus Laurencia, in combination with the wide range of their biological activities, have placed species of Laurencia in the spotlight of marine chemists’ attention for over 60 years. The chemical investigation of the organic (CH2Cl2/MeOH) extracts of Laurencia microcladia and Laurencia obtusa, both collected off the coasts of Tinos island in the Aegean Sea, resulted in the isolation of 32 secondary metabolites, including 23 C15 acetogenins (1–23), 7 sesquiterpenes (24–30) and 2 diterpenes (31 and 32). Among them, six new C15 acetogenins, namely 10-acetyl-sagonenyne (2), cis-sagonenyne (3), trans-thuwalenyne C (4), tinosallene A (11), tinosallene B (12) and obtusallene XI (17), were identified and their structures were elucidated by extensive analysis of their spectroscopic data. Compounds 1–3, 5–11, 13 and 15–32 were evaluated for their antibacterial activity against Staphylococcus aureus and Escherichia coli.

Codon Usage of Chloroplast Gene rbcL in Laurencia sensu lato (Rhodophyta) species

Recent advances in molecular biology make it possible to sequence not only genes or genomes, but also to understand codon dynamics. For the organelle genes of these organisms, a small set of preferred codons are used for encoding proteins. For the first time, this paper treats the divergence of synonymous codon usage and its bias in the rbcL gene within the Laurencia complex of red algae. We observed that the synonymous codon preference biases in rbcL are large and differ among species. A clear distinction in codon usage between genera is evident: the genera Dasya and Delesseria use a set that fluctuated between 53 and 58 codons. Whereas, in the genera Ceramium, Chondrophycus, Chlamydomonas, Chlorella, Laurencia s.s, Osmundea, and Palisada codon usage indicates a higher restriction fluctuating between 40 to 51 codons. Laurencia complex genera and other representative algae showed a defined composition pattern, with lower percentage values of NNC/G (7-24.9%). Dasya and Delesseria showed a selective pattern tendency because of high percentage values of NNC/G (54-55%). The estimated codon bias parameters were tested to infer systematic relationships and match suitable codons with the NNC / G codon percentages. Cluster analysis based on Codon Usage supports phylogenetic relationships between Chondrophycus, Palisada, Laurencia, Osmundea, and Yuzurua species.

Evaluation of Antifouling Potential and Ecotoxicity of Secondary Metabolites Derived from Red Algae of the Genus Laurencia.

Red algae of the genus Laurencia are known to biosynthesize and secrete an immense variety of secondary metabolites possessing a spectrum of biological activities against bacteria, invertebrates and mammalian cell lines. Following a rigorous cross-species screening process, herein we report the antifouling potential of 25 secondary metabolites derived from species of the genus Laurencia, as well as the thorough evaluation of the ecotoxicity of selected metabolites against non-target marine arthropods and vertebrate cell lines. A number of these secondary metabolites exhibited potent antifouling activity and performed well in all screening tests. Our results show that perforenol (9) possesses similar antifouling activity with that already described for bromosphaerol, which is used herein as a benchmark.

Synthesis, Characterization, and Reactivity of Complex Tricyclic Oxonium Ions, Proposed Intermediates in Natural Product Biosynthesis.

Reactive intermediates frequently play significant roles in the biosynthesis of numerous classes of natural products although the direct observation of these biosynthetically relevant species is rare. We present here direct evidence for the existence of complex, thermally unstable, tricyclic oxonium ions that have been postulated as key reactive intermediates in the biosynthesis of numerous halogenated natural products from Laurencia species. Evidence for their existence comes from full characterization of these oxonium ions by low-temperature NMR spectroscopy supported by density functional theory (DFT) calculations, coupled with the direct generation of 10 natural products on exposure of the oxonium ions to various nucleophiles.

Diversity and distribution of Laurencia sensu stricto (Rhodomelaceae, Rhodophyta) from the Mexican Pacific, including L. mutueae sp. nov.

SUMMARYThe alpha diversity of Laurencia sensu stricto, as well as the majority of the other algal groups along the Mexican Pacific, was underestimated because very few studies had incorporated the use of molecular markers in taxonomic studies, which would allow a more realistic estimation of diversity, incluing new records and new species. The records of Laurencia s.s. for the Eastern Pacific (California, USA to Chile) currently represent 23% of its richness worldwide. In this work, we proposed an updated census of the currently recognized species of Laurencia s.s. for the Mexican Pacific. This checklist reported the occurrence of 22 species that represent 16% of the 137 species worldly recorded. We further included taxonomic remarks, type localities, and a detailed distribution for each species. In addition, we proposed a new species for this region, Laurencia mutueae sp. nov., based on morphological observation as well as phylogenetic analyses. The distribution in the Mexican Pacific revealed that the highest records of species were for the sub‐temperate region, while the localities along the Mexican tropical Pacific were poorly recorded. The scarcity of floristic affinities between the eastern and the western and central parts of the North Pacific Ocean was hypothesized to be a consequence of a strong isolation and hard barriers, such as the water masses between these regions.

Laurencia longiramea sp. nov. for Brazil and an emendation of the generic delineation of Corynecladia (Ceramiales, Rhodophyta)

ABSTRACTStudies of the Laurencia complex based on phylogenetic and DNA barcoding analyses revealed a new species, Laurencia longiramea Cassano, G.N. Santos, J.M.C. Nunes, M.C. Oliveira & M.T. Fujii sp. nov., on the Brazilian coast. The rbcL phylogenetic analysis resolved L. longiramea as sister to Laurencia species from the North Atlantic (L. pyramidalis, L. viridis and L. obtusa) and the Caribbean Sea and Gulf of Mexico (L. intricata), with a divergence of 2.4%–3.7%. Using the DNA barcode COI-5P, L. longiramea was closest to L. pacifica from the United States, with a divergence of 4.2%. The new species has the typical features of the genus Laurencia and is characterised by: sparse branching, axes smaller than 1 mm diameter, often long branchlets, lenticular thickenings always present and abundant, and absence of cortical cells projected near branch apices. Morphologically, L. longiramea is similar to Laurencia filiformis. However, an rbcL sequence of L. filiformis from the type locality (Western Australia) confirmed that they are distinct species, with 4.3% divergence. Examination of Laurencia clavata from Brazil, deposited in the University of São Paulo (SPF) herbarium, were misidentified and corresponded to the new species, L. longiramea. In addition, the rbcL and COI-5P sequences of L. clavata from the type locality (Australia) did not join with L. longiramea. Laurencia clavata formed a well-supported clade with the two species of Coronaphycus. Priority supported the recognition of Corynecladia over Coronaphycus, requiring the new combinations Corynecladia elata (C.Agardh) comb. nov. and Corynecladia nova (Metti) comb. nov. Based on our results, Corynecladia clavata does not occur in the Brazilian marine flora.

THÀNH PHẦN VÀ HOẠT TÍNH KHÁNG KHUẨN CỦA CAO ETYL AXETAT CHIẾT TỪ 3 LOÀI RONG ĐỎ THUỘC CHI LAURENCIA

This paper is concerned with composition and antibacterial activities of ethyl acetate extracts from 3 species of Laurencia (Rhodophyta): Laurencia papillosa, Laurencia flexilis and Laurencia cartilaginea collected from the southern coasts of Vietnam. The results showed that ethyl acetate (EtOAc) extracts of these species displayed antibacterial activities against Salmonella typhimurium, Escherichia coli and Bacillus subtilis. The qualitative investigations revealed the presence of two sesquiterpene secondary metabolites Elatol and Palisadin A in EtOAc extracts from the three above- mentioned Laurencia species.

New Metabolites Isolated from a Laurencia obtusa Population Collected in Corsica

The chemical investigation of an ethyl acetate extract (EtOAc) obtained from Laurencia obtusa, collected in Corsica, allowed for the identification of three new compounds (1, 2, and 4) and six known compounds. Compounds 1 to 4 were isolated and fully characterized by a detailed spectroscopic analysis. Compounds 1 and 2 are two C15-acetogenins sharing the same ring system: a tetrahydropyran linked by a methylene to a tetrahydrofuran ring. Compound 1 exhibits a bromoallene unit whereas compound 2 possesses an uncommon α-bromo-α,β-unsaturated aldehyde terminal unit. Compound 4 is the first diterpene exhibiting a 19(43)abeo-labdane skeleton isolated from a Laurencia species. Isolation of concinndiol (compound 3) together with compound 4 suggests a common biosynthetic origin. Additionally, five known compounds, namely sagonenyne, laurene, α-bromocuparene, microcladallene A, and β-snyderol were identified in chromatographic fractions by NMR analysis using a computerized method that was developed in our laboratory.

Bactericide, Antioxidant and Cytotoxic Activities from Marine Algae of Genus Laurencia Collected in Baja California Sur, Mexico

Abstract Background and Objective: Marine environment represents countless and diverse resource for new drugs to combat major diseases. Extracts from four Laurencia species ( L. johnstonii, L. pacifica, L. gardneri and L. papillosa) from Baja California Sur, Mexico were evaluated for their antioxidant, antibacterial and cytotoxic activity. Methodology: The antioxidants activity of Laurencia sp. were evaluated using the radical scavenging activity in three in vitro radicals: 1,1-Diphenyl-2-picrylhydrazyl (DPPH), 2,2'-Azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) and nitric oxide (NO). The antibacterial activity was evaluated by the broth microdilution method to determinate the Minimum Inhibitory Concentrations (MIC) against Staphylococcus aureus, Bacillus subtilis, Enterococcus faecalis, Micrococcus luteus, Pseudomonas aerugi nosa and Klebsiella pneumoniae . The cytotoxicity was analyzed on HeLa (cervix adenocarcinoma) and Vero (kidney epithelial) cells, using the reduction of tetrazolium salt WST-1. Results: The seaweed of genus Laurencia demonstrated an overall low activity, with half maximal effective concentration (EC50) values >1.5 mg mLG1. Laurencia pacifica showed the best biocide effects with MIC of 6.25 µg mLG1 against Gram positive bacterial and cytotoxic potential with half inhibitory concentration (IC50) <30 µg mLG1 against Vero and HeLa cells. Conclusion: Some Laurencia species have a great antibacterial and cytotoxic activity which could be considered for future studies.

Diversidad de especies y patrones biogeográficos de Laurencia sensu stricto (Rhodophyta) en el océano Atlántico

Recent morphological and phylogenetic studies of Laurencia in the Atlantic Ocean have modified our current knowledge of the group. Approximately 23% of the worldwide generic diversity has been recorded in this region. Goals. Update the checklist of the Laurencia species in the Atlantic and describe the distribution patterns within the genus. Methods. We obtained records of Laurencia species in the Atlantic from a review of the literature and distributional data were used to define areas of endemism through a PAE (Parsimony of Areas of Endemism) analysis. Results. We propose an updated checklist of the 30 currently recognized species of Laurencia in the Atlantic Ocean; this checklist also includes taxonomic synonyms, nomenclatural remarks, and a detailed distribution for each species. The distributional range for the genus in the Atlantic extends from Bermuda and Northern Europe in the North Atlantic to Brazil and South Africa in the South Atlantic. We were able to define four areas of endemism: Brazil with four endemic species, the Gulf of Guinea with four endemic species, the northeastern Atlantic with three endemic species, and South Africa with four endemic species; also documented was one secondary area (Macaronesian Islands) with the endemic species L. viridis. Moreover, 17 of the 30 species of the Atlantic are also distributed in the Indo-Pacific, of which five are amphi-Atlantic species. Conclusions. The patterns found are related to geological events that occurred in the past, a fact that allows us to formulate a vicariance hypothesis about these species biogeographic history. Therefore, future work that will document new species and the clarification of taxonomic problems will allow researchers to continue enriching this hypothesis.

Detection of a chemical cue from the host seaweed Laurencia dendroidea by the associated mollusc Aplysia brasiliana.

Chemical cues from sessile hosts can attract mobile and associated organisms and they are also impotant to maintain associations and overall biodiversity, but the identity and molecular structures of these chemicals have been little explored in the marine environment. Secondary metabolites are recognized as possible chemical mediators in the association between species of Laurencia and Aplysia, but the identity of the compounds has not been established. Here, for the first time, we experimentally verify that the sesquiterpene (+)-elatol, a compound produced by the red seaweed Laurencia dendroidea, is a chemical cue attracting the associated sea hare Aplysia brasiliana. In addition to revealing the nature of the chemical mediation between these two species, we provide evidence of a chemical cue that allows young individuals of A. brasiliana to live in association with L. dendroidea. This study highlights the importance of chemical cues in Laurencia-Aplysia association.

Molecular systematics reveals increased diversity within the South African Laurencia complex (Rhodomelaceae, Rhodophyta).

Previous publications list ten species in the Laurencia complex from South Africa with all ascribed to the genus Laurencia sensu stricto. However, the diversity of the complex in South Africa has not yet been re-assessed following the numerous recent taxonomic changes. This study investigated the phylogenetic relationships and taxonomy of this group in South Africa using recent collections. Methods included molecular phylogenetic analyses of plastid rbcL gene sequences (a total of 146; including eleven outgroup taxa) using Maximum Likelihood and Bayesian Inference, and the examination of morphological and anatomical characters, including the number of corps en cerise when present. The seven genera of the Laurencia complex formed monophyletic clades with high posterior probabilities. Seventeen morphotypes were identified: 14 in the genus Laurencia sensu stricto, among which eight corresponded to Laurencia species currently recognized from South Africa and one each to species of Palisada, Chondrophycus, and Laurenciella. The six remaining morphotypes in Laurencia sensu stricto did not match any descriptions and are described here as five new species: Laurencia alfredensis sp. nov., Laurencia dichotoma sp. nov., Laurencia digitata sp. nov., Laurencia multiclavata sp. nov. and Laurencia sodwaniensis sp. nov. and a new variety: Laurencia pumila var. dehoopiensis var. nov. Laurencia stegengae nom. nov. is established to replace Laurencia peninsularis Stegenga, Bolton and Anderson nom. illeg. The diversity is likely greater, with six additional unidentified specimens found in this molecular investigation. These findings place South Africa alongside Australia in having one of the most diverse floras of this group in the world.

Cloning and Functional Characterization of Cycloartenol Synthase from the Red Seaweed Laurencia dendroidea.

The red seaweed Laurencia dendroidea belongs to the Rhodophyta, a phylum of eukaryotic algae that is widely distributed across the oceans and that constitute an important source of bioactive specialized metabolites. Laurencia species have been studied since 1950 and were found to contain a plethora of specialized metabolites, mainly halogenated sesquiterpenes, diterpenes and triterpenes that possess a broad spectrum of pharmacological and ecological activities. The first committed step in the biosynthesis of triterpenes is the cyclization of 2,3-oxidosqualene, an enzymatic reaction carried out by oxidosqualene cyclases (OSCs), giving rise to a broad range of different compounds, such as the sterol precursors cycloartenol and lanosterol, or triterpene precursors such as cucurbitadienol and β-amyrin. Here, we cloned and characterized the first OSC from a red seaweed. The OSC gene was identified through mining of a L. dendroidea transcriptome dataset and subsequently cloned and heterologously expressed in yeast for functional characterization, which indicated that the corresponding enzyme cyclizes 2,3-oxidosqualene to the sterol precursor cycloartenol. Accordingly, the gene was named L. dendroidea cycloartenol synthase (LdCAS). A phylogenetic analysis using OSCs genes from plants, fungi and algae revealed that LdCAS grouped together with OSCs from other red algae, suggesting that cycloartenol could be the common product of the OSC in red seaweeds. Furthermore, profiling of L. dendroidea revealed cholesterol as the major sterol accumulating in this species, implicating red seaweeds contain a ‘hybrid’ sterol synthesis pathway in which the phytosterol precursor cycloartenol is converted into the major animal sterol cholesterol.

Epimeric Face-Selective Oxidations and Diastereodivergent Transannular Oxonium Ion Formation Fragmentations: Computational Modeling and Total Syntheses of 12-Epoxyobtusallene IV, 12-Epoxyobtusallene II, Obtusallene X, Marilzabicycloallene C, and Marilzabicycloallene D.

The total syntheses of 12-epoxyobtusallene IV, 12-epoxyobtusallene II, obtusallene X, marilzabicycloallene C, and marilzabicycloallene D as halogenated C15-acetogenin 12-membered bicyclic and tricyclic ether bromoallene-containing marine metabolites from Laurencia species are described. Two enantiomerically pure C4-epimeric dioxabicyclo[8.2.1]tridecenes were synthesized by E-selective ring-closing metathesis where their absolute stereochemistry was previously set via catalytic asymmetric homoallylic epoxidation and elaborated via regioselective epoxide-ring opening and diastereoselective bromoetherification. Epimeric face-selective oxidation of their Δ12,13 olefins followed by bromoallene installation allowed access to the oppositely configured 12,13-epoxides of 12-epoxyobtusallene II and 12-epoxyobtusallene IV. Subsequent exploration of their putative biomimetic oxonium ion formation-fragmentations reactions revealed diastereodivergent pathways giving marilzabicycloallene C and obtusallene X, respectively. The original configurations of the substrates evidently control oxonium ion formation and their subsequent preferred mode of fragmentation by nucleophilic attack at C9 or C12. Quantum modeling of this stereoselectivity at the ωB97X-D/Def2-TZVPPD/SCRF = methanol level revealed that in addition to direction resulting from hydrogen bonding, the dipole moment of the ion-pair transition state is an important factor. Marilzabicycloallene D as a pentahalogenated 12-membered bicyclic ether bromoallene was synthesized by a face-selective chloronium ion initiated oxonium ion formation-fragmentation process followed by subsequent bromoallene installation.

The Laurencia Paradox: An Endless Source of Chemodiversity.

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.

Chloroplasts morphology investigation with diverse microscopy approaches and inter-specific variation in Laurencia species (Rhodophyta)

The present study described with different microscopy approaches chloroplasts lobes in Laurencia sensu latu (Rhodophyta) species and found inter-specific differences among them. Chloroplasts were investigated using confocal laser scanning microscopy (LSM), transmission electron microscopy (TEM) and high resolution scanning electron microscopy (HRSEM). Using and TEM and HRSEM images we distinguished chloroplasts with lobes than chloroplasts without lobes in Yuzurua poiteaui var. gemmifera (Harvey) M. J. Wynne and Laurencia dendroidea J. Agardh cortical cells. The LSM images showed chloroplasts lobes (CLs) with different morphologies, varying from thicker and longer undulated projections in Y. poiteaui var. and L. dendroidea to very small and thin tubules as in Laurencia translucida Fujii & Cordeiro-Marino. The diameter and length of CLs from Y. poiteaui var. and L. dendroidea were significantly higher than L. translucida CLs (p < 0.01). Based on LSM observations, we suggest that lobes morphology has a taxonomic validity only to characterize L. translucida species.

Extraction, Isolation, and Identification of Sesquiterpenes from Laurencia Species.

The knowledge about the chemical structure of the secondary metabolites and their relative abundances in algae is very important to several fields of basic and applied research in biology, chemistry, and many other disciplines. The attainment of such knowledge requires special attention to the origin of the organism in question and the methodology applied. Here, we present a protocol to obtain and identify some sesquiterpenes from Laurencia species based on traditional methodologies, such as flash and thin-layer chromatographies, nuclear magnetic resonance spectroscopy, and gas chromatography mass spectrometry. Red algae of the genus Laurencia are known to produce structurally diverse terpenes; most of them are halogenated compounds with important ecological functions and significant potential for the discovery of new biotechnological applications.

Laurencia laurahuertana sp. nov. (Rhodomelaceae, Rhodophyta): An epiphytic species from the Mexican Caribbean

SummaryLaurencia laurahuertana Mateo‐Cid, Mendoza‐González, Sentíes &amp; Díaz‐Larrea sp. nov. is described from Quintana Roo, Mexican Caribbean, on the basis of comparative morphology and ribulose bisphosphate carboxylase gene sequence analysis. It is distinguished from other Laurencia species by the small size of the sporophytes and dioecious gametophytes, the branching thalli, and its epiphytic habits. The phylogenetic analysis showed that the Mexican Caribbean sample, from Punta Herrero (Quintana Roo), formed a distinctive and well supported clade segregated from other species of Laurencia from Brazil and Mexico. The Mexican entity is morphologically and genetically distinct from other Laurencia species, warranting description as a new species.

Proof-of-principle direct double cyclisation of a linear C15-precursor to a dibrominated bicyclic medium-ring ether relevant to Laurencia species.

Bicyclic dibrominated C15 medium-ring ether hexahydrolaureoxanyne was produced directly from an acyclic model C15-epoxide when treated with NBS with water as the solvent.