Identification of α-Amylase and α-Glucosidase Inhibitors and Ligularoside A, a New Triterpenoid Saponin from Passiflora ligularis Juss (Sweet Granadilla) Leaves, by a Nuclear Magnetic Resonance-Based Metabolomic Study

Author accepted manuscript[Abstract] The leaves of Passiflora ligularis Juss (known as sweet granadilla for its edible fruits) are a crop byproduct that is discarded. With the aim of contributing to give value-added products from these crop by-side products to farmers of Colombian Andes, we carried out a 1H-NMR-metabolomics analysis of polar extracts from leaves collected in three locations and stored in two conditions in order to identify glucosyl-hydrolase inhibitors. Variations in the metabolic profile and the bioactivity among samples were analyzed by orthogonal partial least square discriminant analysis. Thus, 1H-NMR signals related to polyphenolic compounds, saponins, and amino acids were correlated with higher inhibitory activities. Moreover, a targeted NMR and HPLC–MS/MS analysis allowed the identification of 14 polyphenolic compounds and the structural characterization of a new triterpenoid saponin, ligularoside A. The measurements of IC50 values for α-amylase and α-glycosidase inhibitors allowed the identification of quercetin-3-O-β-glucoside, kaempferol-3-O-β-glucoside, and ligularoside A as the most active compounds. These results suggest that P. ligularis leaves are a source of glucosyl-hydrolase inhibitors and lay the foundation for exploring additional applications.This research was financially supported by the Colombia Department of Science, Technology and Innovation COLCIENCIAS through the project “Estudio de la actividad antidiabética de un extracto nanovehículizado de hojas de Passiflora ligularis (granadilla)” contract 836/2017. This work was also supported by grant RTI2018-093634-B-C22 (AEI/FEDER, EU) from the State Agency for Research (AEI) of Spain, co-funded by the FEDER Programme from the European Union, and BLUEBIOLAB (0474_BLUEBIOLAB_1_E), Programme INTERREG V A of Spain-Portugal (POCTEP)Colombia.Colciencias; 836/201

Structural Requirements for Ga3+ Coordination in Synthetic Analogues of the Siderophore Piscibactin Deduced by Chemical Synthesis and Density Functional Theory Calculations

Financiado para publicación en acceso aberto: Universidade da Coruña/CISUG[Abstract] Stereoselective total synthesis of several analogues of piscibactin (Pcb), the siderophore produced by different pathogenic Gram-negative bacteria, was performed. The acid-sensitive α-methylthiazoline moiety was replaced by a more stable thiazole ring, differing in the configuration of the OH group at the C-13 position. The ability of these Pcb analogues to form complexes with Ga3+ as a mimic of Fe3+ showed that the configuration of the hydroxyl group at C-13 as 13S is crucial for the chelation of Ga3+ to preserve the metal coordination, while the presence of a thiazole ring instead of the α-methylthiazoline moiety does not affect such coordination. A complete 1H and 13C NMR chemical shift assignment of the diastereoisomer mixtures around C9/C10 was done for diagnostic stereochemical disposition. Additionally, density functional theory calculations were performed not only for confirming the stereochemistry of the Ga3+ complex among the six possible diastereoisomers but also for deducing the ability of these to form octahedral coordination spheres with gallium. Finally, the lack of antimicrobial activity of Pcb and Pcb thiazole analogue Ga3+ complexes against Vibrio anguillarum agrees with one of the roles of siderophores in protecting pathogens from metal ion toxicity. The efficient metal coordination shown by this scaffold suggests its possible use as a starting point for the design of new chelating agents or vectors for the development of new antibacterials that exploit the “Trojan horse” strategy using the microbial iron uptake mechanisms. The results obtained will be of great help in the development of biotechnological applications for these types of compounds.This work was supported by grant PID2021-122732OB-C22/C21 from MCIN/AEI/10.13039/501100011033/FEDER “A way to make Europe” (AEI, Spanish State Agency for Research and FEDER Programme from the European Union). M.B. was supported by grant PID2019-103891RJ-100 from MCIN/AEI/10.13039/501100011033 (Spain). Work at the University of Santiago de Compostela and the University of A Coruña was also supported by grants ED431C 2022/23 and ED431C 2022/39, respectively, from Xunta de Galicia. L.A. thanks Xunta de Galicia (Spain) for a predoctoral fellowship. J.R. and C.J. acknowledge Xunta de Galicia and CESGA for the computational resources. Funding for open access charge: Universidade da Coruña/CISUGXunta de Galicia; ED431C 2022/23Xunta de Galicia; ED431C 2022/3

Antimicrobial Diterpene Alkaloids from an Agelas citrina Sponge Collected in the Yucatán Peninsula

[Abstract] Three new diterpene alkaloids, (+)-8-epiagelasine T (1), (+)-10-epiagelasine B (2), and (+)-12-hydroxyagelasidine C (3), along with three known compounds, (+)-ent-agelasine F (4), (+)-agelasine B (5), and (+)-agelasidine C (6), were isolated from the sponge Agelas citrina, collected on the coasts of the Yucatán Peninsula (Mexico). Their chemical structures were elucidated by 1D and 2D NMR spectroscopy, HRESIMS techniques, and a comparison with literature data. Although the synthesis of (+)-ent-agelasine F (4) has been previously reported, this is the first time that it was isolated as a natural product. The evaluation of the antimicrobial activity against the Gram-positive pathogens Staphylococcus aureus, Streptococcus pneumoniae, Enterococcus faecalis showed that all of them were active, with (+)-10-epiagelasine B (2) being the most active compound with an MIC in the range of 1–8 µg/mL. On the other hand, the Gram-negative pathogenes Acinetobacter baumannii, Pseudomonas aeruginosa, and Klebsiella pneumoniae were also evaluated, and only (+)-agelasine B (5) showed a moderate antibacterial activity with a MIC value of 16 μg/mL.This work was supported by grants RTI2018-093634-B-C22 from the State Agency for Research (AEI) of Spain, cofunded by the FEDER Programme from the European Union (MCIN/AEI/10.13039/501100011033/FEDER) and BLUEBIOLAB (0474_BLUEBIOLAB_1_E), Programme INTERREG V A of Spain-Portugal (POCTEP). This work was supported by Projects PI17/01482 and PI20/01212 awarded to AB, all within in the National Plan for Scientific Research, Development and Technological Innovation 2017–2020 and funded by the ISCIII—General Subdirection of Assessment and Promotion of the Research-European Regional Development Fund (FEDER) “A way of making Europe”. The work was also supported by CIBERINFEC (CIBER de Enfermedades Infecciosas). The study was also funded by project IN607D 2021/12 (GAIN-Agencia Gallega de Innovación—Consellería de Economía, Emprego e Industria) awarded to AB. The study was also funded by projects GRC2018/039 from Xunta de Galicia. Dawrin Pech-Puch received his postdoctoral fellowship from the National Council of Science and Technology (CONACYT) of Mexico. This work was supported by the Max Planck Society and the DFG (Gr1211/19-1)/CAPES 418729698 projectXunta de Galicia; IN607D 2021/12Xunta de Galicia; GRC2018/039Deutsche Forschungsgemeinschaft = German Research Foundation; Gr1211/19-1Brasil. Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); 41872969

Enabling parallel computing in CRASH

We present the new parallel version (pCRASH2) of the cosmological radiative transfer code CRASH2 for distributed memory supercomputing facilities. The code is based on a static domain decomposition strategy inspired by geometric dilution of photons in the optical thin case that ensures a favourable performance speed-up with increasing number of computational cores. Linear speed-up is ensured as long as the number of radiation sources is equal to the number of computational cores or larger. The propagation of rays is segmented and rays are only propagated through one sub-domain per time step to guarantee an optimal balance between communication and computation. We have extensively checked pCRASH2 with a standardised set of test cases to validate the parallelisation scheme. The parallel version of CRASH2 can easily handle the propagation of radiation from a large number of sources and is ready for the extension of the ionisation network to species other than hydrogen and helium.Comment: Accepted by Monthly Notices of the Royal Astronomical Society. 18 pages, 20 figure

Uncovering the Cyanobacterial Chemical Diversity: The Search for Novel Anticancer Compounds

This article belongs to the Proceedings of The 7th Iberian Congress on Cyanotoxins/3rd Iberoamerican Congress on Cyanotoxins[Abstract] Cancer has a tremendous negative socio-economic impact on our society. Thus, the discovery of new and more effective anticancer drugs is of utmost importance. To address this societal challenge, the main goal of the CYANCAN project was the discovery of anticancer compounds from cyanobacteria. These photosynthetic bacteria are considered among the most promising groups capable of producing metabolites with pharmaceutical applications. A valuable and underexplored natural resource that can underpin the discovery of promising compounds can be found in the Blue Biotechnology and Ecotoxicology Culture Collection (LEGE-CC) at CIIMAR (Interdisciplinary Centre of Marine and Environmental Research), comprising more than 700 different cyanobacterial strains. Herein, we present the recent advances implemented for finding robust anticancer lead compounds from LEGE-CC cyanobacteria. For this purpose, we developed a natural product library. Sixty cyanobacterial strains, representative of LEGE-CC biodiversity, were chromatographed to yield 480 fractions that were tested for their cytotoxic activity against 2D and 3D models of human colon carcinoma (HCT 116). The conjugation of monolayer assays and 3D cancer spheroids led to the selection of 11 active fractions, of which the chemical space was studied using an untargeted metabolomics approach. The putative annotation and identification of several compounds led to the selection of two marine strains for compound isolation: Leptothoe sp. and Lusitaniella coriacea. The isolation of the compounds was guided through bioactivity assays and mass spectrometry. These molecules were purified from the crudes by employing several chromatography methods, and the chemical structures were determined by means of NMR (nuclear magnetic resonance) and MS/MS (tandem mass spectrometry) experiments. Thus, a novel macrolide-type compound was isolated from Leptothoe sp., which presented a highly cytotoxic activity against our cancer cell models. Its effects on cancer vascularization and metastasis were studied using the zebrafish model. Moreover, from L. coriacea, five unprecedented salicyl-capped thiazol(in)e NRPs-PKs (nonribosomal peptides-polyketides) compounds were isolated. These compounds showed the potential to act as reversers of P-glycoprotein efflux activity.CIIMAR strategic funds UIDB/04423/2020 and UIDP/04423/2020; CYANCAN PTDC/MED-QUI/30944/2017, co-financed by NORTE 2020, Portugal 2020, and the European Union through the ERDF. EMERTOX: EU Horizon 2020 R&I programme under the Marie Skłodowska-Curie grant agreement No 778,069. Ribeiro, T: FCT grant SFRH/BD/139131/2018. Castelo-Branco, R: FCT grant SFRH/BD/136367/2018Centro Interdisciplinar de Investigação Marinha e Ambiental (Porto); UIDB/04423/2020Portugal. Fundação para a Ciência e a Tecnologia; PTDC/MED-QUI/30944/2017Portugal. Fundação para a Ciência e a Tecnologia; SFRH/BD/139131/2018Portugal. Fundação para a Ciência e a Tecnologia; SFRH/BD/136367/201

Photography-based taxonomy is inadequate, unnecessary, and potentially harmful for biological sciences

The question whether taxonomic descriptions naming new animal species without type specimen(s) deposited in collections should be accepted for publication by scientific journals and allowed by the Code has already been discussed in Zootaxa (Dubois & Nemésio 2007; Donegan 2008, 2009; Nemésio 2009a–b; Dubois 2009; Gentile & Snell 2009; Minelli 2009; Cianferoni & Bartolozzi 2016; Amorim et al. 2016). This question was again raised in a letter supported by 35 signatories published in the journal Nature (Pape et al. 2016) on 15 September 2016. On 25 September 2016, the following rebuttal (strictly limited to 300 words as per the editorial rules of Nature) was submitted to Nature, which on 18 October 2016 refused to publish it. As we think this problem is a very important one for zoological taxonomy, this text is published here exactly as submitted to Nature, followed by the list of the 493 taxonomists and collection-based researchers who signed it in the short time span from 20 September to 6 October 2016

Connection of isolated stereoclusters by combining 13C-RCSA, RDC, and J-based configurational analyses and structural revision of a tetraprenyltoluquinol chromane meroterpenoid from Sargassum muticum

The seaweed Sargassum muticum, collected on the southern coast of Galicia, yielded a tetraprenyltoluquinol chromane meroditerpene compound known as 1b, whose structure is revised. The relative configuration of 1b was determined by J-based configurational methodology combined with an iJ/DP4 statistical analysis and further confirmed by measuring two anisotropic properties: carbon residual chemical shift anisotropies (13C-RCSAs) and one-bond 1H-13C residual dipolar couplings (1DCH-RDCs). The absolute configuration of 1b was deduced by ECD/OR/TD-DFT methods and established as 3R,7S,11R.Agencia Estatal de Investigación (AEI) de España | Ref. RTI2018-093634-B-C22Interreg España-Portugal | Ref. 0474_BLUEBIOLAB_1_EXunta de Galicia | Ref. GRC2018/039Xunta de Galicia | Ref. ED431E 2018/03Max Planck Society | Ref. CAPES 418729698SERB, New Delhi | Ref. ECR/2017/00181

Phospholipid fatty acids from Colombian Caribbean sea sponges

Five demosponges belonging to the order Axinellida: Axinella corrugata, Dragmacidon alvarezae, Dragmacidon reticulatum, Ptilocaulis walpersi, Myrmekioderma rea and one sponge belonging to the order Scopalinida: Scopalina ruetzleri were analyzed to assess their fatty acid composition in the phospholipid fraction. Additionally, the seasonal and intraspecific variation in fatty acids composition was assessed in M. rea and D. alvarezae. Fatty acid identification was conducted using an HRGC-MS with an ECL value of methyl ester derivatives, and analyzing their mass spectra. To confirm double bound location, N-acylpyrrolidide derivatives were used studying their mass spectra. In total, 83 fatty acids were identified with chain lengths ranging from C14 to C32. Interestingly, brominated fatty acids were identified, previously suggested for sponges. Polybranched fatty acids such as 4,8,12-trimethyltridecanoic acid (4,8,12-TMTD) and 3,7,11,15-tetramethylhexadecanoic (phytanic acid) were found, without a clear distribution pattern. A predominance of iso-acids (i-15:0 and i-17:0) on anteiso acids were observed. Some seasonal variations in fatty acid (FA) compositions for M. rea and D. alvarezae were observed. The hierarchical Clusters Analysis (HCA) showed that the FA composition was species-specific but not informative at the family or order level

Passiflora

<i>2.3. Bioprospecting studies of Passiflora species related to QQ activity</i> <p> Having completed the metabolic profiling of the studied <i>Passiflora</i> species, the next step was to relate those profiles with the biological activity observed for the extracts in order to identify the compounds responsible for such an activity (Wu et al., 2015). The selected bioactivity was quorum sensing inhibitory activity (QSI activity) because the search of anti-pathogenic compounds seemed to be a better strategy than the search for antibiotics, in terms of reducing the damage in the host, without generating induced resistance in the pathogen. Several small molecules including <i>C</i> -glycoside flavonoids, vanillin, 3-indolyacetonitrile, among others have been reported to be quorum sensing inhibitors (Grandclément et al., 2016), (Brango-Vanegas et al., 2014).</p> <p> The MeOH/H 2 O extracts of <i>Passiflora</i> species were tested for the inhibition of violacein production using <i>Chromobacterium violaceum</i> ATCC 31532 as a biosensor (supporting info table 4). Results showed that <i>P. uribei</i>, <i>P. lehmannii</i> and <i>P. cumbalensis</i> exerted a strong activity (inhibition halo> 40 mm) (Fig. 17 supporting information) while other <i>Passiflora</i> samples showed less or no activity at all. The complete results are summarized in Supp. Table 4.</p> <p> The metabolites that had been detected by 1 H-NMR were correlated with the bioactivity (QSI) by applying the orthogonal projection to latent structures (OPLS-DA), using the coded QSI activity (20 mm-inhibition zone was coded as 1;> 30 mm of inhibition zone was coded as 3) as the Y-variable. Separation of the active groups is observed in the OPLS-DA score plot (R 2 = 0.425 and Q 2 = 0.302, pareto scaling), with the active groups on the negative side along OPLS1 (Fig. 7A). <i>Passiflora cumbalensis</i> clustered as a well-defined active group, while the other species did not show a clear clustering tendency. Three active groups were identified along the OPLS2 axis, one being on the negative side for <i>P. lehmannii</i> and <i>P. uribei,</i> one on the positive side for <i>P. cumbalensis</i> and a third one for the other species spread out in the middle of the plot, suggesting that the active compounds for these three groups were different.</p> <p> Using two <i>S-plots</i>, one excluding <i>P. lehmanii</i> samples (Fig. 7B) and the other excluding <i>P. cumbalensis</i> samples (Fig. 7C) it was possible to identify the active compounds. The variables important for the projection (VIPs) were selected, and the chemical shifts responsible for the QSI activity were highlighted. These highlighted chemical shifts were found to correspond mostly to the glycosylated flavonoids because the signals could be assigned to aromatic protons such as those of the A and B rings from flavonoids as well as signals for sugar moieties, including those of the anomeric protons close to 5 ppm (Tables 5 and 6, Supporting info).</p> <p> The quality and robustness of the OPLS-DA model was validated by a permutation test (n = 100). The Q 2 intercept value was −0.504 (below 0.05), showing that the original model was statistically effective (Fig. 18 Supporting info). The model was validated by calculating the area under the receiver operating characteristic (ROC) curve. The value of the area under the curve (AUC) was 0.9565 providing added confidence to the model (Fig. 18B supporting info).</p> <p> Pure compounds <b>1</b> and <b>2</b> were tested for their QS inhibition against <i>C. violaceum</i> at five concentrations in the range of 50 μM–400 μM in a 96 well-plate. The QS inhibition of compound <b>1</b> and compound <b>2</b> was detected at concentrations of 100 μg/mL (0.13 mM) and 300 μg/mL (0.47 mM) respectively. In order to establish whether the observed inhibition was due solely to QS inhibition and not to growth inhibition, samples were submitted to a growth inhibition test (Fig. 19 supporting information). Results of the assays showed not only the absence of growth inhibition but an increase in bacterial cell densities, indicating that the flavonoids likely inhibited cell communication.</p> <p> A second model, <i>Burkholderia glumae</i>, a well-known phytopathogen that causes rice grain rot and wilt in various field crops was also used to evaluate QSI (Compant et al., 2008). In <i>B. glumae</i>, the production of toxoflavin (a bright yellow pigment) is known to be one of the major virulence factors (Jeong et al., 2003; J. Kim et al., 2004). The biosynthesis of toxoflavin is controlled by ToxR, a LysR-type transcriptional regulator and this toxin also activates the expression of the <i>tox</i> operons (J. Kim et al., 2004). For this reason, the search for compounds that are able to inhibit toxoflavin production is an important target for the control of this phytopathogen. Two strains were chosen to determine the toxoflavin inhibitory activity of extracts and pure compounds. <i>Burkholderia glumae</i> COK 71, is a biosensor strain, that is highly specific for toxoflavin based on β- galactosidase activity on X gal substrate that produces a blue pigment, and the <i>B. glumae</i> ATCC 33617 strain as a toxoflavin producer. In this test, the levels of the blue pigment are used to determine toxoflavin inhibitory activity (Choi et al., 2013). Our results indicated that toxoflavin productions was inhibited by concentrations of 6.76 μM and 7.87 μM of compounds <b>1</b> and <b>2,</b> respectively, while the positive control, 2- <i>n</i> -propyl-9-hydroxy-4H-pyrid [1,2-a] pyrimidin-4-one was active at 80 μM, showing the potential of these flavonoids to control toxin production by the phytopathogen, <i>B. glumae</i> (Fig. 20, supporting information).</p> <p> The presence of flavonoids in plant extracts has been previously related to their QS inhibition activity. Phytochemical screening of <i>Centella asiatica</i> has revealed that flavonoids can disrupt AHL-mediated QS-controlled systems in <i>C. violaceum</i> and <i>P. aeruginosa</i> while major constituents such as the triterpene, asiatic acid, did not show an anti-QS activity (Vasavi et al., 2016). Concentrations of 100 μg/mL of quercetin and kaempferol have been reported to exhibit anti-QS activity against <i>C. violaceum</i> and <i>P. aeruginosa</i> PAO 1. The anti-QS activity of <i>Psidium guajava</i> leaf extract has been determined with a biosensor bioassay using <i>Chromobacterium violaceum</i> CV 026, and quercetin and quercetin 3- <i>O</i> -arabinoside were identified as the QQ compounds in the extract, against <i>C. violaceum</i> 12,472, at concentrations of 50 and 100 μg/mL, respectively (Vasavi et al., 2014). Similarly, Paczkowski et al. studied the QS inhibition mechanism of flavonoids, establishing that they are inhibitors of the QS transcriptional regulator LasR and that they specifically inhibit quorum sensing via antagonism with the transcriptional regulator LasR/RhlR. Further structure-activity relationship analyses suggest that the presence of two hydroxyl moieties in the flavone A-ring backbone are essential for potent inhibition of LasR/RhlR. Biochemical analyses also revealed that flavonoids function non-competitively to prevent LasR/RhlR DNA-binding. The administration of the flavonoids to <i>P. aeruginosa</i> was found to alter transcription of the quorum-sensing controlled target promoters and suppress virulence factor production, confirming their potential as antimicrobials which do not function by traditional bactericidal or bacteriostatic mechanisms (Paczkowski et al., 2017).</p>Published as part of <i>Castellanos, Leonardo, Naranjo-Gaybor, Sandra Judith, Forero, Abel M., Morales, Gustavo, Wilson, Erica Georgina, Ramos, Freddy A. & Choi, Young Hae, 2020, Metabolic fingerprinting of banana passion fruits and its correlation with quorum quenching activity, pp. 1-13 in Phytochemistry (112272) (112272) 172</i> on pages 8-9, DOI: 10.1016/j.phytochem.2020.112272, <a href="http://zenodo.org/record/8294125">http://zenodo.org/record/8294125</a&gt

Efecto de las catecolaminas sobre las células del sistema inmune expuestas a la cocaína - posibilidad de un receptor para la cocaína en las células

IP 1115-05-020-9