Mercedes Pérez Bonilla - Academia.edu (original) (raw)

Papers by Mercedes Pérez Bonilla

Research paper thumbnail of New Phocoenamicin and Maklamicin Analogues from Cultures of Three Marine-Derived Micromonospora Strains

Marine Drugs

Antimicrobial resistance can be considered a hidden global pandemic and research must be reinforc... more Antimicrobial resistance can be considered a hidden global pandemic and research must be reinforced for the discovery of new antibiotics. The spirotetronate class of polyketides, with more than 100 bioactive compounds described to date, has recently grown with the discovery of phocoenamicins, compounds displaying different antibiotic activities. Three marine Micromonospora strains (CA-214671, CA-214658 and CA-218877), identified as phocoenamicins producers, were chosen to scale up their production and LC/HRMS analyses proved that EtOAc extracts from their culture broths produce several structurally related compounds not disclosed before. Herein, we report the production, isolation and structural elucidation of two new phocoenamicins, phocoenamicins D and E (1–2), along with the known phocoenamicin, phocoenamicins B and C (3–5), as well as maklamicin (7) and maklamicin B (6), the latter being reported for the first time as a natural product. All the isolated compounds were tested aga...

Research paper thumbnail of Reference-Grade Genome and Large Linear Plasmid of Streptomyces rimosus: Pushing the Limits of Nanopore Sequencing

Microbiology spectrum, Apr 4, 2022

Streptomyces rimosus ATCC 10970 is the parental strain of industrial strains used for the commerc... more Streptomyces rimosus ATCC 10970 is the parental strain of industrial strains used for the commercial production of the important antibiotic oxytetracycline. As an actinobacterium with a large linear chromosome containing numerous long repeat regions, high GC content, and a single giant linear plasmid (GLP), these genomes are challenging to assemble. Here, we apply a hybrid sequencing approach relying on the combination of short-and long-read next-generation sequencing platforms and whole-genome restriction analysis by using pulsed-field gel electrophoresis (PFGE) to produce a high-quality reference genome for this biotechnologically important bacterium. By using PFGE to separate and isolate plasmid DNA from chromosomal DNA, we successfully sequenced the GLP using Nanopore data alone. Using this approach, we compared the sequence of GLP in the parent strain ATCC 10970 with those found in two semi-industrial progenitor strains, R6-500 and M4018. Sequencing of the GLP of these three S. rimosus strains shed light on several rearrangements accompanied by transposase genes, suggesting that transposases play an important role in plasmid and genome plasticity in S. rimosus. The polished annotation of secondary metabolite biosynthetic pathways compared to metabolite analysis in the ATCC 10970 strain also refined our knowledge of the secondary metabolite arsenal of these strains. The proposed methodology is highly applicable to a variety of sequencing projects, as evidenced by the reliable assemblies obtained. IMPORTANCE The genomes of Streptomyces species are difficult to assemble due to long repeats, extrachromosomal elements (giant linear plasmids [GLPs]), rearrangements, and high GC content. To improve the quality of the S. rimosus ATCC 10970 genome, producer of oxytetracycline, we validated the assembly of GLPs by applying a new approach to combine pulsed-field gel electrophoresis separation and GLP isolation and sequenced the isolated GLP with Oxford Nanopore technology. By examining the sequenced plasmids of ATCC 10970 and two industrial progenitor strains, R6-500 and M4018, we identified large GLP rearrangements. Analysis of the assembled plasmid sequences shed light on the role of transposases in genome plasticity of this species. The new Editor

Research paper thumbnail of Actividad antioxidante de plantas de distribución mediterránea. Aislamiento, identificación y aplicaciones de antioxidantes de madera de olivo

Las reacciones de oxidacion juegan un papel importante a nivel fisiologico, asi como en la indust... more Las reacciones de oxidacion juegan un papel importante a nivel fisiologico, asi como en la industria de la alimentacion y cosmetica, puesto que son las responsables del deterioro de los productos, aceleran el proceso de envejecimiento y provocan la aparicion de enfermedades degenerativas. Los antioxidantes, como su nombre indica, son sustancias que retrasan o evitan la oxidacion de otras sustancias, por lo que previenen el deterioro y actuan como mecanismo de proteccion de las biomoleculas. Actualmente existe un creciente interes en la sustitucion de antioxidantes sinteticos por los de origen natural, debido a la sospecha de que aquellos pueden ser carcinogenicos. Sin embargo, hasta ahora tan solo unas pocas plantas, como romero y salvia, parecen haber mostrado cierto grado de aplicacion. En este sentido, queda una interesante y util tarea por realizar, que es la de encontrar nuevas fuentes de antioxidantes naturales que puedan mejorar o complementar las ya existentes. Asi, se ha in...

Research paper thumbnail of Aislamiento de antioxidantes naturales de madera de olivo

Research paper thumbnail of Krisynomycins, Imipenem Potentiators against Methicillin-Resistant Staphylococcus aureus, Produced by Streptomyces canus

A reinvestigation of the acetone extract of the strain CA-091830 of Streptomyces canus, producer ... more A reinvestigation of the acetone extract of the strain CA-091830 of Streptomyces canus, producer of the imipenem potentiator krisynomycin, resulted in the isolation of two additional analogues, krisynomycins B (1) and C (2), with different chlorination patterns. Genome sequencing of the strain followed by detailed bioinformatics analysis led to the identification of the corresponding biosynthetic gene cluster (BGC) of this cyclic nonribosomal peptide family. The planar structure of the new molecules was determined using HRMS, ESI-qTOF-MS/MS, and 1D and 2D NMR data. Their absolute configuration was proposed using a combination of Marfey's and bioinformatic BGC analyses. The krisynomycins displayed weak to negligible antibiotic activity against methicillin-resistant Staphylococcus aureus (MRSA), which was significantly enhanced when tested in combination with sublethal concentrations of imipenem. The halogenation pattern plays a key role in the antimicrobial activity and imipenem-potentiating effects of the compounds, with molecules having a higher number of chlorine atoms potentiating the effect of imipenem at lower doses.

Research paper thumbnail of New hormonemate derivatives from the endophytic fungus Dothiora sp

Research paper thumbnail of Olive tree wood phenolic compounds with human platelet antiaggregant properties

Blood Cells, Molecules, and Diseases, 2009

Oleuropein and (+)-cycloolivil are natural polyphenolic compounds with a significant radical scav... more Oleuropein and (+)-cycloolivil are natural polyphenolic compounds with a significant radical scavenging activity present in olive tree. We have investigated the antiaggregant effects of oleuropein and (+)-cycloolivil isolated from an ethyl acetate extract of olive tree wood. Oleuropein and (+)-cycloolivil reduced the ability of thrombin to stimulate platelet aggregation. Both compounds reduced thrombin-evoked Ca(2+) release and entry to a similar extent to hydroxytyrosol. This effect was greater in platelets from patients with type 2 diabetes mellitus than in controls. Thrombin-, thapsigargin- and 2,5-di-(tert-butyl)-1,4-hydroquinone (TBHQ)-evoked protein tyrosine phosphorylation, which is involved in Ca(2+) signalling and platelet aggregation, is inhibited by oleuropein and (+)-cycloolivil. oleuropein and (+)-cycloolivil are natural oxygen radical scavengers that reduce thrombin-induced protein tyrosine phosphorylation, Ca(2+) signalling and platelet aggregation. These observations suggest that oleuropein and (+)-cycloolivil may prevent thrombotic complications associated to platelet hyperaggregability and be the base for the development of antiaggregant therapeutic strategies.

Research paper thumbnail of Multi-omics Study of Planobispora rosea, Producer of the Thiopeptide Antibiotic GE2270A

mSystems, 2021

Planobispora rosea is a genetically intractable bacterium used for the production of GE2270A on a... more Planobispora rosea is a genetically intractable bacterium used for the production of GE2270A on an industrial scale. GE2270A is a potent thiopeptide antibiotic currently used as a precursor for the synthesis of two compounds under clinical studies for the treatment of Clostridium difficile infection and acne.

Research paper thumbnail of {"__content__"=>"Zebrafish-Based Discovery of Antiseizure Compounds from the Red Sea: Pseurotin A and Azaspirofuran A.", "sub"=>{"__content__"=>"2"}}

ACS chemical neuroscience, Jan 19, 2018

In search for novel antiseizure drugs (ASDs), the European FP7-funded PharmaSea project used zebr... more In search for novel antiseizure drugs (ASDs), the European FP7-funded PharmaSea project used zebrafish embryos and larvae as a drug discovery platform to screen marine natural products to identify promising antiseizure hits in vivo for further development. Within the framework of this project, seven known heterospirocyclic γ-lactams, namely, pseurotin A, pseurotin A, pseurotin F1, 11- O-methylpseurotin A, pseurotin D, azaspirofuran A, and azaspirofuran B, were isolated from the bioactive marine fungus Aspergillus fumigatus, and their antiseizure activity was evaluated in the larval zebrafish pentylenetetrazole (PTZ) seizure model. Pseurotin A and azaspirofuran A were identified as antiseizure hits, while their close chemical analogues were inactive. Besides, electrophysiological analysis from the zebrafish midbrain demonstrated that pseurotin A and azaspirofuran A also ameliorate PTZ-induced epileptiform discharges. Next, to determine whether these findings translate to mammalians, ...

Research paper thumbnail of Phocoenamicins B and C, New Antibacterial Spirotetronates Isolated from a Marine Micromonospora sp

Marine drugs, Jan 16, 2018

Phocoenamicins B and C (and), together with the known spirotetronate phocoenamicin (), were isola... more Phocoenamicins B and C (and), together with the known spirotetronate phocoenamicin (), were isolated from cultures ofsp. The acetone extract from a culture of this strain, isolated from marine sediments collected in the Canary Islands, displayed activity against methicillin-resistant(MRSA),H37Ra and. Bioassay-guided fractionation of this extract using SP207ss column chromatography and preparative reversed-phased HPLC led to the isolation of the new compoundsandbelonging to the spirotetronate class of polyketides. Their structures were determined using a combination of HRMS, 1D and 2D NMR experiments and comparison with the spectra reported for phocoenamicin. Antibacterial activity tests of the pure compounds against these pathogens revealed minimal inhibitory concentration (MIC) values ranging from 4 to 64 µg/mL for MRSA, and 16 to 32 µg/mL forH37Ra, with no significant activity found againstand vancomycin-resistant(VRE) at concentrations below 128 µg/mL, and weak activity detected ...

Research paper thumbnail of Hormonemate Derivatives from Dothiora sp., an Endophytic Fungus

Journal of Natural Products, 2017

S1 Overlapped HSQC spectra of hormonemate B (2) and erythritol, showing the 'alditol' region. Blu... more S1 Overlapped HSQC spectra of hormonemate B (2) and erythritol, showing the 'alditol' region. Blue and red signals correspond to hormonemate B whereas green and pink are those of a standard of erythritol. S2 Overlapped HSQC spectra of hormonemate (5) and D-mannitol, showing the 'alditol' region. Blue and red signals correspond to hormonemate whereas green and pink are those of a standard of D-mannitol. S3 1 H-NMR (500 MHz, methanol-d4) spectrum of hormonemate A (1). S4 Zoom shot of the 1 H-NMR (500 MHz, methanol-d4) spectrum of hormonemate A (1). S5 13 C-NMR (125 MHz, methanol-d4) spectrum of hormonemate A (1). S6 HSQC (methanol-d4) spectrum of hormonemate A (1). S7 HMBC (methanol-d4) spectrum of hormonemate A (1). S8 COSY (methanol-d4) spectrum of hormonemate A (1). S9 1 H-NMR (500 MHz, methanol-d4) spectrum of hormonemate B (2). S10 Zoom shot of the 1 H-NMR (500 MHz, methanol-d4) spectrum of hormonemate B (2). S11 13 C-NMR (125 MHz, methanol-d4) spectrum of hormonemate B (2). S12 HSQC (methanol-d4) spectrum of hormonemate B (2). S13 HMBC (methanol-d4) spectrum of hormonemate B (2). S14 COSY (methanol-d4) spectrum of hormonemate B (2). S15 1 H-NMR (500 MHz, methanol-d4) spectrum of hormonemate C (3). S16 Zoom shot of the 1 H-NMR (500 MHz, methanol-d4) spectrum of hormonemate C (3). S17 13 C-NMR (125 MHz, methanol-d4) spectrum of hormonemate C (3). S18 HSQC (methanol-d4) spectrum of hormonemate C (3). S19 HMBC (methanol-d4) spectrum of hormonemate C (3). S20 COSY (methanol-d4) spectrum of hormonemate C (3). S21 1 H-NMR (500 MHz, methanol-d4) spectrum of hormonemate D (4). S22 Zoom shot of the 1 H-NMR (500 MHz, methanol-d4) spectrum of hormonemate D (4). S23 13 C-NMR (125 MHz, methanol-d4) spectrum of hormonemate D (4). S24 HSQC (methanol-d4) spectrum of hormonemate D (4). S25 HMBC (methanol-d4) spectrum of hormonemate D (4). S26 COSY (methanol-d4) spectrum of hormonemate D (4). S27 1 H-NMR (500 MHz, methanol-d4) spectrum of hormonemate (5). S28 Zoom shot of the 1 H-NMR (500 MHz, methanol-d4) spectrum of hormonemate (5). S29 13 C-NMR (125 MHz, methanol-d4) spectrum of hormonemate (5). S30 HSQC (methanol-d4) spectrum of hormonemate (5). S31 HMBC (methanol-d4) spectrum of hormonemate (5). S32 COSY (methanol-d4) spectrum of hormonemate (5). S33 1 H-NMR (500 MHz, methanol-d4) spectrum of hormonemate E (6). S34 Zoom shot of the 1 H-NMR (500 MHz, methanol-d4) spectrum of hormonemate E (6). S35 13 C-NMR (125 MHz, methanol-d4) spectrum of hormonemate E (6). S36 HSQC (methanol-d4) spectrum of hormonemate E (6). S37 HMBC (methanol-d4) spectrum of hormonemate E (6). S38 COSY (methanol-d4) spectrum of hormonemate E (6).

Research paper thumbnail of Acid hydrolysis as a strategy to increase the extraction of carbohydrates from macroalgae

20Th European Biomass Conference and Exhibition, 2012

Linear β-1,3 glucan chain with occasional β-1,6 linkages. Depending on the harvesting period, its... more Linear β-1,3 glucan chain with occasional β-1,6 linkages. Depending on the harvesting period, its concentration can attain up to 30%.

Research paper thumbnail of Multicomponent Analysis of the Differential Induction of Secondary Metabolite Profiles in Fungal Endophytes

Molecules, 2016

Small molecule histone deacetylase (HDAC) and DNA methyltransferase (DNMT) inhibitors are commonl... more Small molecule histone deacetylase (HDAC) and DNA methyltransferase (DNMT) inhibitors are commonly used to perturb the production of fungal metabolites leading to the induction of the expression of silent biosynthetic pathways. Several reports have described the variable effects observed in natural product profiles in fungi treated with HDAC and DNMT inhibitors, such as enhanced chemical diversity and/or the induction of new molecules previously unknown to be produced by the strain. Fungal endophytes are known to produce a wide variety of secondary metabolites (SMs) involved in their adaptation and survival within higher plants. The plant-microbe interaction may influence the expression of some biosynthetic pathways, otherwise cryptic in these fungi when grown in vitro. The aim of this study was to setup a systematic approach to evaluate and identify the possible effects of HDAC and DNMT inhibitors on the metabolic profiles of wild type fungal endophytes, including the chemical identification and characterization of the most significant SMs induced by these epigenetic modifiers.

Research paper thumbnail of Effect of Extraction Conditions on the Antioxidant Activity of Olive Wood Extracts

International Journal of Food Science, 2013

An investigation to optimize the extraction yield and the radical scavenging activity from the ag... more An investigation to optimize the extraction yield and the radical scavenging activity from the agricultural by-product olive tree wood (Olea europaeaL., cultivar Picual) using six different extraction protocols was carried out. Four olive wood samples from different geographical origin, and harvesting time have been used for comparison purposes. Among the fifty olive wood extracts obtained in this study, the most active ones were those prepared with ethyl acetate, either through direct extraction or by successive liquid-liquid partitioning procedures, the main components being the secoiridoids oleuropein and ligustroside. An acid hydrolysis pretreatment of olive wood samples before extractions did not improve the results. In the course of this study, two compounds were isolated from the ethanolic extracts of olive wood collected during the olives’ harvesting season and identified as (7′′R)-7′′-ethoxyoleuropein (1) and (7′′S)-7′′-ethoxyoleuropein (2).

Research paper thumbnail of 5-Hydroxy-2-methyl-3-oxo-6-(2,2,3-trimethyl-cyclopent-3-enyl)-hexanoic acid ethyl ester

Research paper thumbnail of (Z)-2-Methyl-3-(1-phenyl-ethylamino)-but-2-enoic acid ethyl ester

Research paper thumbnail of Isolation and identification of radical scavengers in olive tree (Olea europaea) wood

Journal of Chromatography A, 2006

Several extracts of Olea europaea wood (Picual olive cultivar) were obtained with solvents of dif... more Several extracts of Olea europaea wood (Picual olive cultivar) were obtained with solvents of different polarity and their antioxidant activities determined. The active compounds were detected in fractions of an ethyl acetate extract using HPLC with on-line radical scavenging detection. After applying different separation techniques, hydroxytyrosol, tyrosol, cycloolivil, 7-deoxyloganic acid, oleuropein and ligustroside were isolated and characterized. Hydroxytyrosol showed a higher activity than the natural antioxidant rosmarinic acid in scavenging the DPPH model radical. Cycloolivil and oleuropein showed stronger activities than the synthetic antioxidant BHT against the same radical. Ligustroside, tyrosol and 7-deoxyloganic acid showed little activity. The latter compound has not been previously identified in the genus Olea.

Research paper thumbnail of Radical-Scavenging Compounds from Olive Tree ( Olea europaea L.) Wood

Journal of Agricultural and Food Chemistry, 2014

The purpose of this study was to complete knowledge on the chemical composition and radical-scave... more The purpose of this study was to complete knowledge on the chemical composition and radical-scavenging activity of olive tree wood. Two new monoterpene glycosides, (-)-oleuropeic acid 6'-O-α-D-glucopyranosyl ester (6a) and (-)-perillic acid 1'-O-β-D-primeverosyl ester (8), together with the known compounds (-)-oleuropeic acid (1), (-)-olivil (2), the aldehydic form of oleuropein aglycone (3), (+)-1-hydroxypinoresinol 1-O-β-D-glucopyranoside (4), (-)-oleuropeic acid 1'-O-β-D-glucopyranosyl ester (5), (-)-oleuropeic acid 6'-O-β-D-glucopyranosyl ester (6b), and (-)-olivil 4-O-β-D-glucopyranoside (7) were isolated from an ethyl acetate extract. The radical scavengers found (2-4 and 7) were detected and isolated with the help of the online HPLC-DAD-DPPH/ABTS technique. Compounds 2-4 and 7 displayed a higher antioxidative effect against the free radical DPPH than the reference BHT and lower than hydroxytyrosol, whereas compounds 1, 5, 6a, 6b, and 8 showed no activity.

Research paper thumbnail of Isolation of antioxidative secoiridoids from olive wood (Olea europaea L.) guided by on-line HPLC–DAD–radical scavenging detection

Food Chemistry, 2011

Currently, there is an increasing interest in finding new sources of natural antioxidants to prov... more Currently, there is an increasing interest in finding new sources of natural antioxidants to provide safe antioxidant additives for the food industry. This is, in part, because some synthetic (artificial) antioxidants commonly used to preserve food, such as BHA and TBHQ, are ...

Research paper thumbnail of Preliminary assay on the radical scavenging activity of olive wood extracts

Fitoterapia, 2005

The dichloromethane and ethanol extracts of Olea europaea wood (picual olive cultivar) were scree... more The dichloromethane and ethanol extracts of Olea europaea wood (picual olive cultivar) were screened for antioxidant activity, determined by the DPPH free radical scavenging assay. The ethanol extract displayed potent antioxidant activity.

Research paper thumbnail of New Phocoenamicin and Maklamicin Analogues from Cultures of Three Marine-Derived Micromonospora Strains

Marine Drugs

Antimicrobial resistance can be considered a hidden global pandemic and research must be reinforc... more Antimicrobial resistance can be considered a hidden global pandemic and research must be reinforced for the discovery of new antibiotics. The spirotetronate class of polyketides, with more than 100 bioactive compounds described to date, has recently grown with the discovery of phocoenamicins, compounds displaying different antibiotic activities. Three marine Micromonospora strains (CA-214671, CA-214658 and CA-218877), identified as phocoenamicins producers, were chosen to scale up their production and LC/HRMS analyses proved that EtOAc extracts from their culture broths produce several structurally related compounds not disclosed before. Herein, we report the production, isolation and structural elucidation of two new phocoenamicins, phocoenamicins D and E (1–2), along with the known phocoenamicin, phocoenamicins B and C (3–5), as well as maklamicin (7) and maklamicin B (6), the latter being reported for the first time as a natural product. All the isolated compounds were tested aga...

Research paper thumbnail of Reference-Grade Genome and Large Linear Plasmid of Streptomyces rimosus: Pushing the Limits of Nanopore Sequencing

Microbiology spectrum, Apr 4, 2022

Streptomyces rimosus ATCC 10970 is the parental strain of industrial strains used for the commerc... more Streptomyces rimosus ATCC 10970 is the parental strain of industrial strains used for the commercial production of the important antibiotic oxytetracycline. As an actinobacterium with a large linear chromosome containing numerous long repeat regions, high GC content, and a single giant linear plasmid (GLP), these genomes are challenging to assemble. Here, we apply a hybrid sequencing approach relying on the combination of short-and long-read next-generation sequencing platforms and whole-genome restriction analysis by using pulsed-field gel electrophoresis (PFGE) to produce a high-quality reference genome for this biotechnologically important bacterium. By using PFGE to separate and isolate plasmid DNA from chromosomal DNA, we successfully sequenced the GLP using Nanopore data alone. Using this approach, we compared the sequence of GLP in the parent strain ATCC 10970 with those found in two semi-industrial progenitor strains, R6-500 and M4018. Sequencing of the GLP of these three S. rimosus strains shed light on several rearrangements accompanied by transposase genes, suggesting that transposases play an important role in plasmid and genome plasticity in S. rimosus. The polished annotation of secondary metabolite biosynthetic pathways compared to metabolite analysis in the ATCC 10970 strain also refined our knowledge of the secondary metabolite arsenal of these strains. The proposed methodology is highly applicable to a variety of sequencing projects, as evidenced by the reliable assemblies obtained. IMPORTANCE The genomes of Streptomyces species are difficult to assemble due to long repeats, extrachromosomal elements (giant linear plasmids [GLPs]), rearrangements, and high GC content. To improve the quality of the S. rimosus ATCC 10970 genome, producer of oxytetracycline, we validated the assembly of GLPs by applying a new approach to combine pulsed-field gel electrophoresis separation and GLP isolation and sequenced the isolated GLP with Oxford Nanopore technology. By examining the sequenced plasmids of ATCC 10970 and two industrial progenitor strains, R6-500 and M4018, we identified large GLP rearrangements. Analysis of the assembled plasmid sequences shed light on the role of transposases in genome plasticity of this species. The new Editor

Research paper thumbnail of Actividad antioxidante de plantas de distribución mediterránea. Aislamiento, identificación y aplicaciones de antioxidantes de madera de olivo

Las reacciones de oxidacion juegan un papel importante a nivel fisiologico, asi como en la indust... more Las reacciones de oxidacion juegan un papel importante a nivel fisiologico, asi como en la industria de la alimentacion y cosmetica, puesto que son las responsables del deterioro de los productos, aceleran el proceso de envejecimiento y provocan la aparicion de enfermedades degenerativas. Los antioxidantes, como su nombre indica, son sustancias que retrasan o evitan la oxidacion de otras sustancias, por lo que previenen el deterioro y actuan como mecanismo de proteccion de las biomoleculas. Actualmente existe un creciente interes en la sustitucion de antioxidantes sinteticos por los de origen natural, debido a la sospecha de que aquellos pueden ser carcinogenicos. Sin embargo, hasta ahora tan solo unas pocas plantas, como romero y salvia, parecen haber mostrado cierto grado de aplicacion. En este sentido, queda una interesante y util tarea por realizar, que es la de encontrar nuevas fuentes de antioxidantes naturales que puedan mejorar o complementar las ya existentes. Asi, se ha in...

Research paper thumbnail of Aislamiento de antioxidantes naturales de madera de olivo

Research paper thumbnail of Krisynomycins, Imipenem Potentiators against Methicillin-Resistant Staphylococcus aureus, Produced by Streptomyces canus

A reinvestigation of the acetone extract of the strain CA-091830 of Streptomyces canus, producer ... more A reinvestigation of the acetone extract of the strain CA-091830 of Streptomyces canus, producer of the imipenem potentiator krisynomycin, resulted in the isolation of two additional analogues, krisynomycins B (1) and C (2), with different chlorination patterns. Genome sequencing of the strain followed by detailed bioinformatics analysis led to the identification of the corresponding biosynthetic gene cluster (BGC) of this cyclic nonribosomal peptide family. The planar structure of the new molecules was determined using HRMS, ESI-qTOF-MS/MS, and 1D and 2D NMR data. Their absolute configuration was proposed using a combination of Marfey's and bioinformatic BGC analyses. The krisynomycins displayed weak to negligible antibiotic activity against methicillin-resistant Staphylococcus aureus (MRSA), which was significantly enhanced when tested in combination with sublethal concentrations of imipenem. The halogenation pattern plays a key role in the antimicrobial activity and imipenem-potentiating effects of the compounds, with molecules having a higher number of chlorine atoms potentiating the effect of imipenem at lower doses.

Research paper thumbnail of New hormonemate derivatives from the endophytic fungus Dothiora sp

Research paper thumbnail of Olive tree wood phenolic compounds with human platelet antiaggregant properties

Blood Cells, Molecules, and Diseases, 2009

Oleuropein and (+)-cycloolivil are natural polyphenolic compounds with a significant radical scav... more Oleuropein and (+)-cycloolivil are natural polyphenolic compounds with a significant radical scavenging activity present in olive tree. We have investigated the antiaggregant effects of oleuropein and (+)-cycloolivil isolated from an ethyl acetate extract of olive tree wood. Oleuropein and (+)-cycloolivil reduced the ability of thrombin to stimulate platelet aggregation. Both compounds reduced thrombin-evoked Ca(2+) release and entry to a similar extent to hydroxytyrosol. This effect was greater in platelets from patients with type 2 diabetes mellitus than in controls. Thrombin-, thapsigargin- and 2,5-di-(tert-butyl)-1,4-hydroquinone (TBHQ)-evoked protein tyrosine phosphorylation, which is involved in Ca(2+) signalling and platelet aggregation, is inhibited by oleuropein and (+)-cycloolivil. oleuropein and (+)-cycloolivil are natural oxygen radical scavengers that reduce thrombin-induced protein tyrosine phosphorylation, Ca(2+) signalling and platelet aggregation. These observations suggest that oleuropein and (+)-cycloolivil may prevent thrombotic complications associated to platelet hyperaggregability and be the base for the development of antiaggregant therapeutic strategies.

Research paper thumbnail of Multi-omics Study of Planobispora rosea, Producer of the Thiopeptide Antibiotic GE2270A

mSystems, 2021

Planobispora rosea is a genetically intractable bacterium used for the production of GE2270A on a... more Planobispora rosea is a genetically intractable bacterium used for the production of GE2270A on an industrial scale. GE2270A is a potent thiopeptide antibiotic currently used as a precursor for the synthesis of two compounds under clinical studies for the treatment of Clostridium difficile infection and acne.

Research paper thumbnail of {"__content__"=>"Zebrafish-Based Discovery of Antiseizure Compounds from the Red Sea: Pseurotin A and Azaspirofuran A.", "sub"=>{"__content__"=>"2"}}

ACS chemical neuroscience, Jan 19, 2018

In search for novel antiseizure drugs (ASDs), the European FP7-funded PharmaSea project used zebr... more In search for novel antiseizure drugs (ASDs), the European FP7-funded PharmaSea project used zebrafish embryos and larvae as a drug discovery platform to screen marine natural products to identify promising antiseizure hits in vivo for further development. Within the framework of this project, seven known heterospirocyclic γ-lactams, namely, pseurotin A, pseurotin A, pseurotin F1, 11- O-methylpseurotin A, pseurotin D, azaspirofuran A, and azaspirofuran B, were isolated from the bioactive marine fungus Aspergillus fumigatus, and their antiseizure activity was evaluated in the larval zebrafish pentylenetetrazole (PTZ) seizure model. Pseurotin A and azaspirofuran A were identified as antiseizure hits, while their close chemical analogues were inactive. Besides, electrophysiological analysis from the zebrafish midbrain demonstrated that pseurotin A and azaspirofuran A also ameliorate PTZ-induced epileptiform discharges. Next, to determine whether these findings translate to mammalians, ...

Research paper thumbnail of Phocoenamicins B and C, New Antibacterial Spirotetronates Isolated from a Marine Micromonospora sp

Marine drugs, Jan 16, 2018

Phocoenamicins B and C (and), together with the known spirotetronate phocoenamicin (), were isola... more Phocoenamicins B and C (and), together with the known spirotetronate phocoenamicin (), were isolated from cultures ofsp. The acetone extract from a culture of this strain, isolated from marine sediments collected in the Canary Islands, displayed activity against methicillin-resistant(MRSA),H37Ra and. Bioassay-guided fractionation of this extract using SP207ss column chromatography and preparative reversed-phased HPLC led to the isolation of the new compoundsandbelonging to the spirotetronate class of polyketides. Their structures were determined using a combination of HRMS, 1D and 2D NMR experiments and comparison with the spectra reported for phocoenamicin. Antibacterial activity tests of the pure compounds against these pathogens revealed minimal inhibitory concentration (MIC) values ranging from 4 to 64 µg/mL for MRSA, and 16 to 32 µg/mL forH37Ra, with no significant activity found againstand vancomycin-resistant(VRE) at concentrations below 128 µg/mL, and weak activity detected ...

Research paper thumbnail of Hormonemate Derivatives from Dothiora sp., an Endophytic Fungus

Journal of Natural Products, 2017

S1 Overlapped HSQC spectra of hormonemate B (2) and erythritol, showing the 'alditol' region. Blu... more S1 Overlapped HSQC spectra of hormonemate B (2) and erythritol, showing the 'alditol' region. Blue and red signals correspond to hormonemate B whereas green and pink are those of a standard of erythritol. S2 Overlapped HSQC spectra of hormonemate (5) and D-mannitol, showing the 'alditol' region. Blue and red signals correspond to hormonemate whereas green and pink are those of a standard of D-mannitol. S3 1 H-NMR (500 MHz, methanol-d4) spectrum of hormonemate A (1). S4 Zoom shot of the 1 H-NMR (500 MHz, methanol-d4) spectrum of hormonemate A (1). S5 13 C-NMR (125 MHz, methanol-d4) spectrum of hormonemate A (1). S6 HSQC (methanol-d4) spectrum of hormonemate A (1). S7 HMBC (methanol-d4) spectrum of hormonemate A (1). S8 COSY (methanol-d4) spectrum of hormonemate A (1). S9 1 H-NMR (500 MHz, methanol-d4) spectrum of hormonemate B (2). S10 Zoom shot of the 1 H-NMR (500 MHz, methanol-d4) spectrum of hormonemate B (2). S11 13 C-NMR (125 MHz, methanol-d4) spectrum of hormonemate B (2). S12 HSQC (methanol-d4) spectrum of hormonemate B (2). S13 HMBC (methanol-d4) spectrum of hormonemate B (2). S14 COSY (methanol-d4) spectrum of hormonemate B (2). S15 1 H-NMR (500 MHz, methanol-d4) spectrum of hormonemate C (3). S16 Zoom shot of the 1 H-NMR (500 MHz, methanol-d4) spectrum of hormonemate C (3). S17 13 C-NMR (125 MHz, methanol-d4) spectrum of hormonemate C (3). S18 HSQC (methanol-d4) spectrum of hormonemate C (3). S19 HMBC (methanol-d4) spectrum of hormonemate C (3). S20 COSY (methanol-d4) spectrum of hormonemate C (3). S21 1 H-NMR (500 MHz, methanol-d4) spectrum of hormonemate D (4). S22 Zoom shot of the 1 H-NMR (500 MHz, methanol-d4) spectrum of hormonemate D (4). S23 13 C-NMR (125 MHz, methanol-d4) spectrum of hormonemate D (4). S24 HSQC (methanol-d4) spectrum of hormonemate D (4). S25 HMBC (methanol-d4) spectrum of hormonemate D (4). S26 COSY (methanol-d4) spectrum of hormonemate D (4). S27 1 H-NMR (500 MHz, methanol-d4) spectrum of hormonemate (5). S28 Zoom shot of the 1 H-NMR (500 MHz, methanol-d4) spectrum of hormonemate (5). S29 13 C-NMR (125 MHz, methanol-d4) spectrum of hormonemate (5). S30 HSQC (methanol-d4) spectrum of hormonemate (5). S31 HMBC (methanol-d4) spectrum of hormonemate (5). S32 COSY (methanol-d4) spectrum of hormonemate (5). S33 1 H-NMR (500 MHz, methanol-d4) spectrum of hormonemate E (6). S34 Zoom shot of the 1 H-NMR (500 MHz, methanol-d4) spectrum of hormonemate E (6). S35 13 C-NMR (125 MHz, methanol-d4) spectrum of hormonemate E (6). S36 HSQC (methanol-d4) spectrum of hormonemate E (6). S37 HMBC (methanol-d4) spectrum of hormonemate E (6). S38 COSY (methanol-d4) spectrum of hormonemate E (6).

Research paper thumbnail of Acid hydrolysis as a strategy to increase the extraction of carbohydrates from macroalgae

20Th European Biomass Conference and Exhibition, 2012

Linear β-1,3 glucan chain with occasional β-1,6 linkages. Depending on the harvesting period, its... more Linear β-1,3 glucan chain with occasional β-1,6 linkages. Depending on the harvesting period, its concentration can attain up to 30%.

Research paper thumbnail of Multicomponent Analysis of the Differential Induction of Secondary Metabolite Profiles in Fungal Endophytes

Molecules, 2016

Small molecule histone deacetylase (HDAC) and DNA methyltransferase (DNMT) inhibitors are commonl... more Small molecule histone deacetylase (HDAC) and DNA methyltransferase (DNMT) inhibitors are commonly used to perturb the production of fungal metabolites leading to the induction of the expression of silent biosynthetic pathways. Several reports have described the variable effects observed in natural product profiles in fungi treated with HDAC and DNMT inhibitors, such as enhanced chemical diversity and/or the induction of new molecules previously unknown to be produced by the strain. Fungal endophytes are known to produce a wide variety of secondary metabolites (SMs) involved in their adaptation and survival within higher plants. The plant-microbe interaction may influence the expression of some biosynthetic pathways, otherwise cryptic in these fungi when grown in vitro. The aim of this study was to setup a systematic approach to evaluate and identify the possible effects of HDAC and DNMT inhibitors on the metabolic profiles of wild type fungal endophytes, including the chemical identification and characterization of the most significant SMs induced by these epigenetic modifiers.

Research paper thumbnail of Effect of Extraction Conditions on the Antioxidant Activity of Olive Wood Extracts

International Journal of Food Science, 2013

An investigation to optimize the extraction yield and the radical scavenging activity from the ag... more An investigation to optimize the extraction yield and the radical scavenging activity from the agricultural by-product olive tree wood (Olea europaeaL., cultivar Picual) using six different extraction protocols was carried out. Four olive wood samples from different geographical origin, and harvesting time have been used for comparison purposes. Among the fifty olive wood extracts obtained in this study, the most active ones were those prepared with ethyl acetate, either through direct extraction or by successive liquid-liquid partitioning procedures, the main components being the secoiridoids oleuropein and ligustroside. An acid hydrolysis pretreatment of olive wood samples before extractions did not improve the results. In the course of this study, two compounds were isolated from the ethanolic extracts of olive wood collected during the olives’ harvesting season and identified as (7′′R)-7′′-ethoxyoleuropein (1) and (7′′S)-7′′-ethoxyoleuropein (2).

Research paper thumbnail of 5-Hydroxy-2-methyl-3-oxo-6-(2,2,3-trimethyl-cyclopent-3-enyl)-hexanoic acid ethyl ester

Research paper thumbnail of (Z)-2-Methyl-3-(1-phenyl-ethylamino)-but-2-enoic acid ethyl ester

Research paper thumbnail of Isolation and identification of radical scavengers in olive tree (Olea europaea) wood

Journal of Chromatography A, 2006

Several extracts of Olea europaea wood (Picual olive cultivar) were obtained with solvents of dif... more Several extracts of Olea europaea wood (Picual olive cultivar) were obtained with solvents of different polarity and their antioxidant activities determined. The active compounds were detected in fractions of an ethyl acetate extract using HPLC with on-line radical scavenging detection. After applying different separation techniques, hydroxytyrosol, tyrosol, cycloolivil, 7-deoxyloganic acid, oleuropein and ligustroside were isolated and characterized. Hydroxytyrosol showed a higher activity than the natural antioxidant rosmarinic acid in scavenging the DPPH model radical. Cycloolivil and oleuropein showed stronger activities than the synthetic antioxidant BHT against the same radical. Ligustroside, tyrosol and 7-deoxyloganic acid showed little activity. The latter compound has not been previously identified in the genus Olea.

Research paper thumbnail of Radical-Scavenging Compounds from Olive Tree ( Olea europaea L.) Wood

Journal of Agricultural and Food Chemistry, 2014

The purpose of this study was to complete knowledge on the chemical composition and radical-scave... more The purpose of this study was to complete knowledge on the chemical composition and radical-scavenging activity of olive tree wood. Two new monoterpene glycosides, (-)-oleuropeic acid 6'-O-α-D-glucopyranosyl ester (6a) and (-)-perillic acid 1'-O-β-D-primeverosyl ester (8), together with the known compounds (-)-oleuropeic acid (1), (-)-olivil (2), the aldehydic form of oleuropein aglycone (3), (+)-1-hydroxypinoresinol 1-O-β-D-glucopyranoside (4), (-)-oleuropeic acid 1'-O-β-D-glucopyranosyl ester (5), (-)-oleuropeic acid 6'-O-β-D-glucopyranosyl ester (6b), and (-)-olivil 4-O-β-D-glucopyranoside (7) were isolated from an ethyl acetate extract. The radical scavengers found (2-4 and 7) were detected and isolated with the help of the online HPLC-DAD-DPPH/ABTS technique. Compounds 2-4 and 7 displayed a higher antioxidative effect against the free radical DPPH than the reference BHT and lower than hydroxytyrosol, whereas compounds 1, 5, 6a, 6b, and 8 showed no activity.

Research paper thumbnail of Isolation of antioxidative secoiridoids from olive wood (Olea europaea L.) guided by on-line HPLC–DAD–radical scavenging detection

Food Chemistry, 2011

Currently, there is an increasing interest in finding new sources of natural antioxidants to prov... more Currently, there is an increasing interest in finding new sources of natural antioxidants to provide safe antioxidant additives for the food industry. This is, in part, because some synthetic (artificial) antioxidants commonly used to preserve food, such as BHA and TBHQ, are ...

Research paper thumbnail of Preliminary assay on the radical scavenging activity of olive wood extracts

Fitoterapia, 2005

The dichloromethane and ethanol extracts of Olea europaea wood (picual olive cultivar) were scree... more The dichloromethane and ethanol extracts of Olea europaea wood (picual olive cultivar) were screened for antioxidant activity, determined by the DPPH free radical scavenging assay. The ethanol extract displayed potent antioxidant activity.