Metabolomic study of soft corals from the Colombian Caribbean: PSYCHE and 1H-NMR comparative analysis.

Marine organisms have evolved to survive against predators in complex marine ecosystems via the production of chemical compounds. Soft corals (Cnidaria, Anthozoa, Octocorallia) are an important source of chemically diverse metabolites with a broad spectrum of biological activities. Herein, we perform a comparative study between high-resolution proton nuclear magnetic resonance (1H-NMR) and pure shift yielded by chirp excitation (PSYCHE) experiments to analyze the metabolic profile of 24 soft corals from the Colombian Caribbean to correlate chemical fingerprints with their cytotoxic activity against three cancer cell lines (human cervical carcinoma (SiHa), human prostatic carcinoma (PC3) and human lung adenocarcinoma (A549)). All data obtained were explored using multivariate analysis using principal components analysis (PCA) and orthogonal partial least squares (OPLS) analysis. The results did not show a significant correlation between clusters using 1H-NMR data in the PCA and OPLS-DA models and therefore did not provide conclusive evidence; on the other hand, a metabolomic analysis of PSYCHE data obtained under the same parameters revealed that when a decoupled experiment is performed, it was possible to establish a statistically valid correlation between the chemical composition of soft corals and their cytotoxic activity against the PC3 cancer cell line, where the asperdiol and plexaurolone markers were putatively identified and related to the cytotoxic activity presented by extracts of Plexaurella sp. and Plexaura kukenthali, respectively. These results increase the speed, effectiveness and reliability of analyses for the study of this type of complex matrices.

Metabolic Profiling of the Soft Coral Erythropodium caribaeorum (Alcyonacea: Anthothelidae) from the Colombian Caribbean Reveals Different Chemotypes.

The Caribbean soft coral Erythropodium caribaeorum is a rich source of erythrolides-chlorinated briarane diterpenoids. These compounds have an ecological role as feeding deterrents, with a wide variation in their composition depending on the location where the sample is collected. In Colombia, this soft coral can be found at different locations in the Caribbean Sea including Santa Marta, Islas del Rosario, and Providencia-three environmentally different coral reef areas in the south and southwest Caribbean Sea. In order to evaluate differences in erythrolide composition, the metabolic profiles of samples from each of these locations were analyzed by HPLC-MS. Principal component analysis showed changes in the diterpene composition according to the sample origin. Diterpenes from samples collected at each location were isolated to describe the three chemotypes. The chemotype from Santa Marta was highly diverse, with the new erythrolides W and X together with eight known erythrolides. The sample from Islas del Rosario showed a low diversity chemotype constituted by high amounts of erythrolide A and B. The chemotype from Providencia showed low chemical diversity with only two main compounds-erythrolide V and R. Evaluation of cytotoxic activity against the human cancer cell lines PC-3, MCF7, and A549 showed erythrolides A and B as the more active compounds with IC50 values in the range from 2.45 to 30 µM.

Aproximaciones experimentales para la evaluación de interacciones alelopáticas entre corales hermatípicos y cianobacterias marinas bentónicas en el Caribe Colombiano / Experimental approaches for the evaluation of allelopathic interactions between hermatypic corals and marine benthic cyanobacteria in the colombian caribbean

ABSTRACT Blooms of marine benthic cyanobacteria are recurrent in several locations at the Colombian Caribbean. In these events, cyanobacteria grow over the substrate and benthic organisms although their effect has not been fully assessed. This study evaluated interactions between cyanobacteria and hermatypic corals, in order to identify any deleterious effects that could be related to allelopathic mechanisms. Organic extracts from cyanobacteria collected in San Andres, Old Providence and Rosario islands were tested against embryos of the reef-building coral Orbicella annularis. The indirect effect of cyanobacterial extracts was also assessed by resuspending the extracts in seawater and monitoring polyp retraction and recovery of the coral Madracis mirabilis (=auretenra). Additionally, the effect of direct contact between cyanobacterial extracts and the coral Porites porites was assessed by incorporating cyanobacterial extracts into Phytagel™ gels and placed in direct contact with the coral. After 24, 48 and 72 h of exposure, chromatographic profiles of associated zooxanthellae was evaluated by HPLC. A deleterious effect on the zooxanthellae was evidenced by an increase in pheophytin, a degradation product from chlorophyll. The competitive abilities of algae and cyanobacteria should be considered as a constraint to reef restoration initiatives. Cyanobacteria have the ability to compete with corals due to their growth rates, defenses against herbivory and potentially allelopathic mechanisms.

RESUMEN Afloramientos de cianobacterias marinas bentónicas son recurrentes en varias localidades del Caribe colombiano. En estos eventos, las cianobacterias crecen sobre el sustrato y organismos bentónicos sin que su efecto se haya evaluado completamente. Este estudio evaluó interacciones entre cianobacterias y corales hermatípicos con el fin de identificar efectos perjudiciales que podrían estar relacionados con mecanismos alelopáticos. Extractos orgánicos de cianobacterias recolectadas en las islas de San Andrés, Providencia y las Islas del Rosario fueron evaluados contra embriones del coral hermatípico Orbicella annularis. También se evaluó el efecto indirecto de extractos de cianobacterias resuspendidos en agua de mar para determinar retracción de pólipos y recuperación del coral Madracis mirabilis (=auretenra). Adicionalmente, se evaluó el efecto del contacto directo de extractos de cianobacterias y el coral Porites porites mediante la incorporación de los extractos en geles de PhytagelTM dispuestos en contacto directo con el coral. Después de 24, 48 y 72 h de exposición, los perfiles cromatográficos de las zooxantelas asociadas al coral fueron evaluados por HPLC. Un efecto negativo sobre las zooxantelas se evidenció por el incremento en feofitina, producto de degradación de la clorofila. Las capacidades competitivas de algas y cianobacterias debieran considerarse como un factor que podría incidir negativamente en iniciativas de restauración arrecifal. Las cianobacterias tienen la capacidad de competir con corales debido a sus tasas de crecimiento, defensas contra herbivoría y potenciales mecanismos alelopáticos.

Comparative Analyses of Metabolomic Fingerprints and Cytotoxic Activities of Soft Corals from the Colombian Caribbean.

Soft corals (Cnidaria, Anthozoa, Octocorallia) are a diverse group of marine invertebrates that inhabit various marine environments in tropical and subtropical areas. Several species are recognized as prolific sources of compounds with a wide array of biological activities. Recent advances in analytical techniques, supported by robust statistical analyses, have allowed the analysis and characterization of the metabolome present in a single living organism. In this study, a liquid chromatography-high resolution mass spectrometry metabolomic approach was applied to analyze the metabolite composition of 28 soft corals present in the Caribbean coast of Colombia. Multivariate data analysis was used to correlate the chemical fingerprints of soft corals with their cytotoxic activity against tumor cell lines for anticancer purpose. Some diterpenoids were identified as specific markers to discriminate between cytotoxic and non-cytotoxic crude extracts of soft corals against tumor cell lines. In the models generated from the comparative analysis of PLS-DA for tumor lines, A549 and SiHa, the diterpene 13-keto-1,11-dolabell-3(E),7(E),12(18)-triene yielded a high score in the variable importance in projection. These results highlight the potential of metabolomic approaches towards the identification of cytotoxic agents against cancer of marine origin. This workflow can be useful in several studies, mainly those that are time consuming, such as traditional bioprospecting of marine natural products.

Screening of acetylcholinesterase inhibitors in marine organisms from the Caribbean Sea.

The acetylcholinesterase inhibitory activity of 89 organic extracts from marine organisms was evaluated through a TLC bioautography methodology. Extracts from soft corals (Eunicea and Plexaura) were the most active compared with extracts from sponges. The bioguided chemical study of the most active extract, obtained from Pseudoplexaura porosa, led to the isolation of a diterpene with spectroscopic properties consistent to those published to the cembrane Steylolide. However, further analysis by X-ray diffraction indicated that the compound was the 14-acetoxycrassine (1), correcting the structure reported to the Styelolide. Additionally, the acetylcholinesterase inhibitory activity of fourteen cembranoids (2-15) isolated from soft corals Eunicea knighti and Pseudoplexaura flagellosa was evaluated. Cembranoids 2, 3 and 4 were the most active compounds in the TLC bioassay. Then, the most promising cembranoids, 14-acetoxycrassine (1) and asperdiol (2), were tested quantitatively and they exhibited IC50 values of 1.40 ± 0.113 and 0.358 ± 0.130 µM, respectively.

Dolabellane diterpenes from the Caribbean soft corals Eunicea laciniata and Eunicea asperula and determination of their anti HSV-1 activity / Dolabellanos de los octocorales caribenos Eunicea laciniata y Eunicea asperula y determinación de su actividad anti VHS-1 / Dolabellanos dos octocorais caribenhos Eunicea laciniata e Eunicea asperula e determinação de sua atividade anti HSV-1

Abstract Dolabellane diterpenes have considerable antiviral activity, but most studies have been focused towards compounds isolated from Dictyota brown algae. Although soft corals are also a significant source of these diterpenes, their antiviral potential has not been studied in detail. With the aim of assessing the biological activity of marine sources, we evaluated the dolabellane content in the soft corals Eunicea laciniata and E. asperula collected in Santa Marta, Colombian Caribbean. Dolabellanes 1-6 were isolated from E. laciniata while compounds 2, 4 and 5 were isolated from E. asperula. All compounds were identified by NMR, GC-EIMS, optical rotation and comparison with previously reported dolabellanes. GC-EIMS analyses showed that dolabellatrienone (2) transforms into compounds 4 and 5 as oxidation products upon prolonged storage; however, those compounds were also naturally present in the extract of the studied organisms. Pure dolabellanes were tested in vitro in antiviral assays against HSV-1. Compound 6 inhibited virus replication in infected cells (73.7% of inhibition at 50 µM) without cytotoxic effect (CC50 = 95 9), showing similar activity to the positive control Acyclovir®. Thus, compound 6 is an interesting candidate for further studies of dolabellanes as antivirals.

Resumen Los dolabellanos son diterpenos con actividad antiviral, la mayor parte de los estudios se han realizado con compuestos aislados de algas pardas del genero Dictyota. Los corales blandos son también una importante fuente de dolabellanos, pero el potencial antiviral de estos ha sido muy poco estudiado. Se llevó a cabo el estudio químico de los dolabellanos presentes en los octocorales Eunicea laciniata y Eunicea asperula, recolectados en Santa Marta, Caribe colombiano. Los dolabellanos 1-6 fueron aislados del octocoral E. laciniata mientras que en E. asperula se encontraron los compuestos 2, 4 y 5. La elucidaci6n estructural se llev6 a cabo mediante RMN, espectrometría de masas, rotaci6n 6ptica y comparaci6n con reportes previos. El análisis por CG-EM evidenci6 que la dolabellatrienona (2) se puede transformar en los compuestos 4 y 5 como producto del almacenamiento prolongado, no obstante, tales compuestos también estuvieron presentes en los extractos de los organismos estudiados. El compuesto 6 inhibi6 la replicaci6n del VHS-1 (73,7% de inhibición en células infectadas a una concentraci6n de 50 µM) sin efecto citot6xico (CC50 = 959), mostrando una citotoxicidad similar al Aciclovir®, un control positivo, por lo cual es un candidato para la realizaci6n de estudios adicionales sobre el potencial antiviral de los dolabellanos.

Resumo Os dolabellanos são diterpenos que têm mostrado atividade antiviral, os estudos neste campo estão centrados nos compostos isolados de algas do gênero Dictyota. Os octocorais também são uma fonte importante de dolabellanos, mas não tem sido estudados. Foirealizado o estudo químico dos octocorais Eunicea laciniata e Eunicea asperula, coletados em Santa Marta, Caribe Colombiano. O estudo químico dos dois organismos permitiu o isolamento dos dolabellanos 1-6 de E. laciniata, enquanto que para E. aspérula foram identificados os compostos 2, 4 e 5. A elucidação estrutural foi realizada mediante RMN, espectrometria de massas, rotação óptica e comparação com os dados da literatura. A análise por GC-MS evidenciou que a dolabelatrienona (2) pode gerar os compostos 4 e 5 como produto de degradação, a partir de um armazenamento prolongado. No entanto, os compostos também estavam presentes nos extratos dos organismos estudados. O composto 6 mostrou uma citotoxicidade similar ao Aciclovir®, um controle positivo, numa porcentagem de inibição da replicação do HVS-1 (73,7% de inibição em células infectadas na concentração de 50 µM) sem efeito citotóxico (CC50 = 959), o quetorna esse composto um candidato para o desenvolvimento de antivirais.

Marine Actinobacteria as a source of compounds for phytopathogen control: An integrative metabolic-profiling / bioactivity and taxonomical approach.

Marine bacteria are considered as promising sources for the discovery of novel biologically active compounds. In this study, samples of sediment, invertebrate and algae were collected from the Providencia and Santa Catalina coral reef (Colombian Caribbean Sea) with the aim of isolating Actinobateria-like strain able to produce antimicrobial and quorum quenching compounds against pathogens. Several approaches were used to select actinobacterial isolates, obtaining 203 strains from all samples. According to their 16S rRNA gene sequencing, a total of 24 strains was classified within Actinobacteria represented by three genera: Streptomyces, Micromonospora, and Gordonia. In order to assess their metabolic profiles, the actinobacterial strains were grown in liquid cultures, and LC-MS-based analyses from ethyl acetate fractions were performed. Based on taxonomical classification, screening information of activity against phytopathogenic strains and quorum quenching activity, as well as metabolic profiling, six out of the 24 isolates were selected for follow-up with chemical isolation and structure identification analyses of putative metabolites involved in antimicrobial activities.

Metabolite variability in Caribbean sponges of the genus Aplysina

Abstract Sponges of the genus Aplysina are among the most common benthic animals on reefs of the Caribbean, and display a wide diversity of morphologies and colors. Tissues of these sponges lack mineralized skeletal elements, but contain a dense spongin skeleton and an elaborate series of tyrosine-derived brominated alkaloid metabolites that function as chemical defenses against predatory fishes, but do not deter some molluscs. Among the earliest marine natural products to be isolated and identified, these metabolites remain the subject of intense interest for commercial applications because of their activities in various bioassays. In this study, crude organic extracts from 253 sponges from ten morphotypes among the species Aplysina archeri,Aplysina bathyphila,Aplysina cauliformis,Aplysina fistularis,Aplysina fulva,A. insularis, and Aplysina lacunosa were analyzed by liquid chromatography–mass spectrometry (LC–MS) to characterize the pattern of intra- and interspecific variabilities of the twelve major secondary metabolites present therein. Patterns across Aplysina species ranged from the presence of mostly a single compound, fistularin-3, in A. cauliformis, to a mixture of metabolites present in the other species. These patterns did not support the biotransformation hypothesis for conversion of large molecular weight molecules to smaller ones for the purpose of enhanced defense. Discriminant analyses of the metabolite data revealed strong taxonomic patterns that support a close relationship between A. fistularis,A. fulva and A. insularis, while two morphotypes of A. cauliformis (lilac creeping vs. brown erect) were very distinct. Two morphotypes of A. lacunosa, one with hard tissue consistency, the other soft and thought to belong to a separate genus (Suberea), had very similar chemical profiles. Of the twelve metabolites found among samples, variation in fistularin-3, dideoxyfistularin-3 and hydroxyaerothionin provided the most predictive influence in decreasing order. Except for one morphotype, weak relationships were found from within-morphotype analyses of metabolite concentrations as a function of geographic location (Florida, N Bahamas, S Bahamas) and depth (<10 m, 10–20 m, >20 m). Our data suggest that metabolite profiles are strongly influenced by sponge phenotype rather than by the diverse microbiome which many Aplysina species share.

Spatial scale of cyanobacterial blooms in Old Providence Island, Colombian Caribbean / Escala espacial de afloramientos de cianobacterias en la Isla de Old Providence, Caribe colombiano / Escala espacial de afloramentos de cianobacterias na ilha Oíd Providence, Caribe colombiano

Cyanobacterial blooms have increased in coastal waters worldwide, facilitated by excessive nutrient input and apparently global warming. They exert negative consequences in marine ecosystems, communities and habitats. Although reports of these events are frequent, their spatial extent and affected habitats are not completely recognized, hence restricting regional management actions. We examined the presence, spatial scale and cover of cyanobacterial blooms in different habitats of the reef systems off Old Providence Island, and identified the main bloom forming taxa. Cyanobacteria were registered in four different ecosystems, six geomorphological zones and nine habitats. Benthic cyanobacteria reached 18 to 72 % of the total cover in five habitats, particularly at the northwest, east and southeast portions of the island. These blooms consisted of complex consortia belonging to the genera Okeania, Lyngbya, Symploca, Phormidium, Oscillatoria or Spirulina. A bloom of planktonic cyanobacteria was dominated by Trichodesmium and developed on the fore reef of the island (NW), following heavy rains. These results suggest a potential new stressor for the island's reef complex. Future research should focus on the environmental factors that enable cyanobacterial blooms and their local impact on ecosystems and services.

Los afloramientos de cianobacterias han incrementado en las zonas costeras de todo el mundo, favorecidos por el exceso de nutrientes y el aparente calentamiento global. Éstos tienen consecuencias negativas sobre los ecosistemas, comunidades y hábitats marinos. Aunque los reportes de estos eventos son frecuentes, la extensión y los hábitats afectados aún no han sido completamente caracterizados, lo cual limita las acciones de manejo. En este estudio examinamos la presencia, escala espacial y cobertura de afloramientos de cianobacterias en diferentes hábitats del complejo arrecifal de la isla de Old Providence, e identificamos los principales taxa que generan afloramientos. Las cianobacterias fueron registradas en cuatro ecosistemas, seis zonas geomorfológicas y nueve hábitats. Las cianobacterias bentónicas cubrieron entre el 18 y el 72 % del sustrato en cinco hábitats, particularmente en el noroeste, este y parte sur de la isla. Tales afloramientos estuvieron conformados por consorcios complejos pertenecientes a los géneros Okeania, Lyngbya, Symploca, Phormidium, Oscillatoria o Spirulina. El afloramiento de cianobacterias planctónicas estuvo dominado por Trichodesmium y se desarrolló en la terraza prearrecifal (NO), tras un periodo de fuertes lluvias. Los resultados sugieren un nuevo estresor potencial para el complejo arrecifal de la isla. La investigación futura debería concentrarse en los factores ambientales que facilitan los afloramientos de cianobacterias y en el impacto local sobre los ecosistemas y sus servicios.

Os afloramentos de cianobactérias tém aumentado em aguas costeiras de todo o mundo, devido á entrada de nutrientes excessivos e também aparentemente ao aquecimento global. Estes afloramentos exercem efeitos negativos nos ecossistemas, comunidades e habitats marinhos. Embora os relatónos destes eventos sejam frequentes na literatura, a extensao e os hábitats atingidos nao sao completamente conhecidos, o que implica a restricao das acoes de gestao. Neste estudo analisamos a presenta, escala espacial e cobertura dos afloramentos de cianobactérias em diferentes habitats marinhos do complexo recifal da ilha Old Providence, e identificamos as principais taxas que geram afloramentos. As cianobactérias foram registradas em quatro ecossistemas, seis zonas geomorfológicas e nove hábitats. Durante os afloramentos bentónicos, as cianobactérias atingiram entre 18 a 72 % da cobertura total em cinco habitats, particularmente no noroeste, este e sudeste da ilha. Tais afloramentos sao consorcios complexos pertencentes aos géneros Okeania, Lyngbya, Symploca, Phormidium, Oscillatoria e Spirulina. O afloramiento de cianobactérias planctónicas foi dominado por Trichodesmium e se desenvolveu no terrado prearrecifal da porc.ao noroeste da ilha, depois de chuva intensa. Os resultados sugerem um novo "estressor" potencial para o complexo recifal da ilha. As investigacoes futuras devem se concentrar nos fatores ambientais que facilitam o afloramiento e no seu impacto local nos ecossistemas e servicos.

Almiramide D, cytotoxic peptide from the marine cyanobacterium Oscillatoria nigroviridis.

Marine benthic cyanobacteria are widely known as a source of toxic and potentially useful compounds.These microorganisms have been studied from many Caribbean locations, which recently include locations in the Colombian Caribbean Sea. In the present study, six lipopeptides named almiramides D to H, together with the known almiramide B are identified from a mat characterized as Oscillatoria nigroviridis collected at the Island of Providence (Colombia, S.W. Caribbean Sea). The most abundant compounds, almiramides B and D were characterized by NMR and HRESIMS, while the structures of the minor compounds almiramides E to H were proposed by the analysis of their HRESIMS and MS2 spectra. Almiramides B and D were tested against six human cell lines including a gingival fibroblast cell line and five human tumor cell lines (A549, MDA-MB231, MCF-7, HeLa and PC3) showing a strong but not selective toxicity.

Possible ecological role of pseudopterosins G and P-U and seco-pseudopterosins J and K from the gorgonian Pseudopterogorgia elisabethae from Providencia Island (SW Caribbean) in regulating microbial surface communities.

The gorgonian Pseudopterogorgia elisabethae collected at Providencia Island (Colombia) has an unfouled surface, free of obvious algal and invertebrate growth. This gorgonian produces significant amounts of the glycosilated diterpenes pseudopterosins and seco-pseudopterosins (Ps and seco-Ps). Our previous experiments have shown activity of these compounds against eukaryotic (human cancer cell lines and Candida albicans) and prokaryotic cells (Staphylococcus aureus and Enterococcus faecalis). However, the potential role of pseudopterosins on the regulation of the fouling process is still under study. We evaluated the activity of these compounds against bacteria isolated from heavily fouled marine surfaces as an indicator of antifouling activity. Additionally, we assessed their activity against bacteria isolated from P. elisabethae to determine whether potentially they play a role in preventing surface bacterial colonization, thus impairing presumptively the establishment of further successional stages of fouling communities. Results showed that Ps and seco-Ps seem to modulate bacterial growth (controlling Gram-positive bacterial growth and inducing Gram-negative bacterial associations). We thus hypothesized that Ps and seco-Ps may play a role in controlling microbial fouling communities on the surface of this gorgonian. By using bTEFAP and FISH we showed that the most abundant bacteria present in the microbial communities associated with P. elisabethae are Gram-negative bacteria, with Proteobacteria and Gammaproteobacteria the most representative. To evaluate whether Ps and seco-Ps have a direct effect on the structure of the bacterial community associated with P. elisabethae, we tested these compounds against culturable bacteria associated with the surface of P. elisabethae, finding remarkable selectivity against Gram-positive bacteria. The evidence presented here suggests that Ps and seco-Ps might have a role in the selection of organisms associated with the gorgonian surface and in the regulation of the associated bacterial community composition.

Pseudopterosin content variability of the purple sea whip Pseudopterogorgia elisabethae at the islands of San Andres and Providencia (SW Caribbean).

To determine pseudopterosin composition and concentration in colonies of Pseudopterogorgia elisabethae from the islands of San Andres and Providencia, we collected fragments of individual colonies at various sites and depth ranges around the islands. Chromatographic profiles of the polar fraction, particularly those obtained by HPLC-MS analyses, allowed us to recognize two different chemotypes. Chemotype 1 characterized samples from Providencia whereas chemotype 2 characterized samples from San Andres. A complex pseudopterosin mixture (compounds 1-13) characterized chemotype 1. These compounds were isolated by a combination of chromatographic methods and identified by spectroscopic methods (MS, UV, 1H, and 13C NMR). We identified the known pseudopterosins G and K and seco-pseudopterosin A. We also isolated and identified seven new compounds, pseudopterosins P-V, isomers of known pseudopterosins. Pseudopterosins G and K were found at concentrations ranging between 1 and 3% of the animal dry mass. Pseudopterosins Q and U were the major compounds reaching up to 6% of the animal dry mass at some locations. Major metabolites in chemotype 2 had a molecular weight and fragmentation pattern different from that observed in the pseudopterosins, as determined by HPLC-MS. Total pseudopterosin concentration in this chemotype was below 3% dry mass at all sites. Total pseudopterosin concentration was significantly higher in chemotype 1, with concentrations ranging between 4 and 20% dry mass. At most locations on Providencia, however, total pseudopterosin concentration ranged between 11 and 15% dry mass. Concentrations exceed reports from other locations in the Caribbean. Furthermore, pseudopterosin composition in our samples is quite different from those in specimens of P. elisabethae from the Bahamas and Bermuda. Pseudopterosins G, K, and P-V are characteristic of P. elisabethae colonies from the island of Providencia, while pseudopterosins A-D are characteristic of colonies of P. elisabethae from the Bahamas islands, and pseudopterosins E-L have been isolated from P. elisabethae from the Bahamas and Bermuda. The overall morphology of P. elisabethae can be variable, and chemical differences are not correlated to specific morphs. We confirmed the species identity of each colony by morphological and sclerite analysis and found no significant differences in sclerite dimensions among different colonies and chemotypes.