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Covering period: up to 2019Water-soluble natural products constitute a relevant group of secondary metabolites notably known for presenting potent biological activities. Examples are aminoglycosides, β-lactam antibiotics, saponins of both terrestrial and marine origin, and marine toxins. Although extensively investigated in the past, particularly during the golden age of antibiotics, hydrophilic fractions have been less scrutinized during the last few decades. This review addresses the possible reasons on why water-soluble metabolites are now under investigated and describes approaches and strategies for the isolation of these natural compounds. It presents examples of several classes of hydrosoluble natural products and how they have been isolated. Novel stationary phases and chromatography techniques are also reviewed, providing a perspective towards a renaissance in the investigation of water-soluble natural products.

Although swarming motility and biofilms are opposed collective behaviors, both contribute to bacterial survival and host colonization. Pseudovibrio bacteria have attracted attention because they are part of the microbiome of healthy marine sponges. Two-thirds of Pseudovibrio genomes contain a member of a nonribosomal peptide synthetase-polyketide synthase gene cluster family, which is also found sporadically in Pseudomonas pathogens of insects and plants. After developing reverse genetics for Pseudovibrio, we isolated heptapeptides with an ureido linkage and related nonadepsipeptides we termed pseudovibriamides A and B, respectively. A combination of genetics and imaging mass spectrometry experiments showed heptapetides were excreted, promoting motility and reducing biofilm formation. In contrast to lipopeptides widely known to affect motility/biofilms, pseudovibriamides are not surfactants. Our results expand current knowledge on metabolites mediating bacterial collective behavior.

Covering: 2017-2019Guanidine natural products isolated from microorganisms, marine invertebrates and terrestrial plants, amphibians and spiders, represented by non-ribosomal peptides, guanidine-bearing polyketides, alkaloids, terpenoids and shikimic acid derived, are the subject of this review. The topics include the discovery of new metabolites, total synthesis of natural guanidine compounds, biological activity and mechanism-of-action, biosynthesis and ecological functions.

We report a selective, mild, and efficient C-H functionalization of tryptophan and tryptophan-containing peptides with activated α-bromo-carbonyl compounds under visible-light irradiation. The protocol efficiency is outlined by the wide substrate scope and excellent tolerance of sensitive functional groups present in the amino acid side chains. The method can be successfully extended to access pharmaco-peptide conjugate scaffolds.

The isolation of pure organic compounds from biological sources, reaction media, or other complex molecular matrixes is the first step to overcome before further biological and chemical investigations. While the isolation of chemicals soluble in organic solvents is commonly accomplished, the isolation of water-soluble organic compounds is less often addressed. We present here a simple method for the isolation of water-soluble organic compounds, using adsorptive macroporous resins and reversed-phase chromatography.

Investigation of the marine sponge Agelas dispar MeOH fractions using feature-based molecular networking, dereplication, and isolation led to the discovery of new bromopyrrole-derived metabolites. An in-house library of bromopyrrole alkaloids previously isolated from A. dispar and Dictyonella sp. was utilized, along with the investigation of an MS/MS fragmentation of these compounds. Our strategy led to the isolation and identification of the disparamides A−C (1–3), with a novel carbon skeleton. Additionally, new dispyrins B–F (4–8) and nagelamides H2 and H3 (9 and 10) and known nagelamide H (11), citrinamine B (12), ageliferin (13), bromoageliferin (14), and dibromoageliferin (15) were also isolated and identified by analysis of spectroscopic data. Analysis of MS/MS fragmentation data and molecular networking analysis indicated the presence of hymenidin (16), oroidin (17), dispacamide (18), monobromodispacamide (19), keramadine (20), longamide B (21), methyl ester of longamide B (22), hanishin (23), methyl ester of 3-debromolongamide B (24), and 3-debromohanishin (25). Antibacterial activity of ageliferin (13), bromoageliferin (14), and dibromoageliferin (15) was evaluated against susceptible and multi-drug-resistant ESKAPE pathogenic bacteria Klabsiella pneumoniae, Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Acinetobacter baumannii, and Enterococcus faecalis. Dibromoageliferin (15) displayed the most potent antimicrobial activity against all tested susceptible and MDR strains. Compounds 13–15 presented no significant hemolytic activity up to 100 μM.

Metabolomics analysis detected tambjamine alkaloids in aqueous and EtOAc extracts of the marine invertebrates Virididentula dentata, Tambja stegosauriformis, Tambja brasiliensis, and Roboastra ernsti. Among several tambjamines, the new amino acid derivatives tambjamines M-O (17-19) were identified by Marfey's advanced analysis, UPLC-MS/MS analyses, and total synthesis. The tambjamine diversity increased from the bryozoan V. dentata to its nudibranch predators T. stegosauriformis and T. brasiliensis and attained a higher diversity in R. ernsti, the nudibranch that preys upon T. stegosauriformis and T. brasiliensis. The total tambjamine content also increases among the trophic levels, probably due to biomagnification. Tambjamines A (1), C (3), and D (4) are the major metabolites in the tissues of V. dentata, T. stegosauriformis, T. brasiliensis, and R. ernsti and are likely the main chemical defenses of these marine invertebrates.

Herein reported are results of the chemical and biological investigation of red propolis collected at the Brazilian Northeast coastline. New propolones A-D (1-4), with a 3-{3-[(2-phenylbenzofuran-3-yl)methyl]phenyl}chromane skeleton; propolonones A-C (5-7), with a 3-[3-(3-benzylbenzofuran-2-yl)phenyl]chromane skeleton; and propolol A (8), with a 6-(3-benzylbenzofuran-2-yl)-3-phenylchromane skeleton, were isolated as constituents of Brazilian red propolis by cytotoxicity-guided assays and structurally identified by analysis of their spectroscopic data. Propolone B (2) and propolonone A (5) display significant cytotoxic activities against an ovarian cancer cell line expressing a multiple drug resistance phenotype when compared with doxorubicin.

Microbial strains isolated from extreme and understudied environments, such as caves, are still poorly investigated for the production of bioactive secondary metabolites. Investigation of the ethyl acetate extract from the growth medium produced by the soil-derived fungus Aspergillus sp. SDC28, isolated from a Brazilian cave, yielded two anthraquinones: versicolorin C (1) and versiconol (2). The complete assignment of nuclear magnetic resonance and mass spectroscopic data of 1 and 2 was performed for the first time. Moreover, the yet unreported absolute configuration of both compounds was unambiguously established by analysis of experimental and theoretical electronic circular dichroism data. Vibrational circular dichroism was also applied to confirm the absolute stereochemistry of 2. Compounds 1 and 2 showed cytotoxic activity against human ovarian cancer cells (OVCAR3).

Sponges are among the earliest lineages of metazoans, with first fossil records dated back to 890 million years ago. All sponge species present associations with microorganisms to some extension, which influence sponges' survival and adaptation. Sponge species can be divided into two categories, Low Microbial Abundance and High Microbial Abundance, depending on the abundance of the microbial community that they host. Monanchora arbuscula (a Low Microbial Abundance sponge species) and Xestospongia muta (a High Microbial Abundance sponge species) are sponges with widespread distribution in the Tropical Western Atlantic. Despite previous studies on the major features of these species, little is known whether M. arcuscula and X. muta prokaryotic communities are stable across vast geographic regions. We obtained a total of ~9.26 million 16S rRNA gene Illumina sequences for M. arbuscula samples collected at seven locations and for X. muta samples collected at three locations, corresponding to five ecoregions of the Caribbean and the Southwestern Atlantic (N = 105, 39 from M. arcuscula and 66 from X. muta). These samples reflected different ecological strategies for prokaryotic communities assembly, since the core prokaryotic communities of M. arbuscula are more heterotrophic and shared with different sources (corals, sponges, seawater, sediments), while X. muta has more significant photosynthetic prokaryotic communities, mainly outsourced from other sponges. Results of M. arbuscula and X. muta prokaryotic communities analysis demonstrate that both sponge species have core prokaryotic communities stable across a vast geographic area (8000 km), and the world's most notable coastal marine biogeographic filter, the Amazon River Mouth, in spite of the significant differences found among transient prokaryotic communities of both sponge species.

Made available in DSpace on 2022-04-29T08:35:35Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-11-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ) The genus Brachycephalus includes small species of aposematic anurans known as microendemic, occurring in the mountains of the Atlantic Forest. Brachycephalus ephippium, B. nodoterga and B. pernix have been reported to contain the neurotoxin tetrodotoxin in skin and viscera. The biological conservation of several Brachycephalus species is currently threatened by climate change, deforestation, and the pandemic caused by the fungus Batrachochytrium dendrobatidis (Bd). Despite the well-known importance of amphibians’ associated bacteria in the defensive role against pathogens, there is still a poor understanding of amphibian microbiome composition. The present study investigated the composition of B. pitanga microbial community and the presence of TTX in the host and in cultures of bacterial isolates, using a combination of metagenomics, bacterial culture isolation, mass spectrometry and metabolomic analyses. Results of culture-dependent and -independent analyses characterized the microbial communities associated with the skin and viscera of B. pitanga. Mass spectrometry analysis indicated the presence of TTX in host tissues, while bacterial production of TTX was not observed under the experimental conditions used in this investigation. This is the first report confirming the occurrence of TTX in B. pitanga. Instituto de Química de São Carlos Universidade de São Paulo, CP 780 Instituto de Biologia SAGE-COPPE Universidade Federal do Rio de Janeiro (UFRJ) Departamento de Tecnologia Bioquímico-Farmacêutica (FBT) Faculdade de Ciências Farmacêuticas Universidade de São Paulo Laboratório de Toxinologia Instituto de Biologia Universidade de Brasília Departamento de Biodiversidade e Centro de Aquicultura Instituto de Biociências Universidade Estadual Paulista (UNESP) Instituto D'Or de Pesquisa e Ensino (IDOR) Instituto de Ciências Biomédicas Universidade Federal do Rio de Janeiro (UFRJ) Departamento de Biodiversidade e Centro de Aquicultura Instituto de Biociências Universidade Estadual Paulista (UNESP) FAPESP: 2013/50228-8 FAPESP: 2013/50741-7 FAPESP: 2016/14375-4 FAPESP: 2016/21341-9 FAPESP: 2019/00447-1 FAPERJ: 202.488/2019

Made available in DSpace on 2019-10-04T12:39:55Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-08-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) National Institute of Science and Technology (INCT BioNat), Brazil National Institute of Science and Technology (INCT Areas Umidas), Brazil Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Centre for Scientific Computing (NCC/GridUNESP) of Sao Paulo State University (UNESP) Prenyl indole alkaloids constitute a diverse class of natural products with complex chemical structures and potent biological activities. Investigation of the growth medium EtOAc extract produced by the endophytic fungus Aspergillus terreus P63 collected from roots of the grass Axonopus leptostachyus, yielded the prenylated indole alkaloid, giluterrin, bearing an unprecedented carbon skeleton. The structure of giluterrin was established by analysis of spectroscopic data and HRMS. The absolute configuration of giluterrin was determined by combination of electronic and vibrational circular dichroism analyses. Giluterrin presented antiproliferative profile for prostate (PC-3) and kidney (786-0) cancer cell lines. Univ Sao Paulo, Inst Quim Sao Carlos, CP 780, BR-13560970 Sao Carlos, SP, Brazil Univ Fed Mato Grosso, Dept Quim, Inst Ciencias Exatas & Terra, BR-78060900 Cuiaba, MT, Brazil Univ Fed Mato Grosso, Dept Biol, Inst Ciencias Exatas & Nat, Campus Rondonopolis, BR-78735901 Rondonopolis, MT, Brazil Inst Fed Mato Grosso, BR-78721520 Rondonopolis, MT, Brazil Univ Fed Mato Grosso do Sul, Inst Quim, BR-79070900 Campo Grande, MS, Brazil Univ Fed Mato Grosso, Inst Biociencias, BR-78060900 Cuiaba, MT, Brazil Univ Estadual Paulista, Inst Quim, Nuleo Bioensaios Biossintese & Ecofisiol Prod Nat, Dept Quim Organ, BR-14800900 Araraquara, SP, Brazil Univ Fed Mato Grosso, Dept Enfermagem, Campus Rondonopolis, BR-78735901 Rondonopolis, MT, Brazil Univ Fed Sao Carlos, Dept Quim, BR-13565905 Sao Carlos, SP, Brazil Univ Estadual Campinas, Inst Biol, Dept Biol Func & Estrutural, BR-13083865 Campinas, SP, Brazil Univ Sao Francisco, Lab Pesquisa Biol Celular & Mol Tumores & Compost, BR-12916900 Braganca Paulista, SP, Brazil Univ Fed Sao Paulo, Inst Ciencia & Tecnol, BR-12231280 Sao Jose Dos Campos, SP, Brazil Univ Estadual Paulista, Inst Quim, Nuleo Bioensaios Biossintese & Ecofisiol Prod Nat, Dept Quim Organ, BR-14800900 Araraquara, SP, Brazil National Institute of Science and Technology (INCT BioNat), Brazil: 465637/2014-0 National Institute of Science and Technology (INCT Areas Umidas), Brazil: 421733/2017-9 FAPESP: 2013/50228-8 FAPESP: 2014/25222-9

During the postharvest period, citrus fruits can be affected by phytopathogens such as Penicillium digitatum, which causes green mold disease and is responsible for up to 90% of total citrus losses. Chemical fungicides are widely used to prevent green mold disease, leading to concerns about environmental and health risks., Penicillium digitatum is the most aggressive pathogen of citrus fruits. Tryptoquialanines are major indole alkaloids produced by P. digitatum. It is unknown if tryptoquialanines are involved in the damage of citrus fruits caused by P. digitatum. To investigate the pathogenic roles of tryptoquialanines, we initially asked if tryptoquialanines could affect the germination of Citrus sinensis seeds. Exposure of the citrus seeds to tryptoquialanine A resulted in a complete inhibition of germination and an altered metabolic response. Since this phytotoxic effect requires the extracellular export of tryptoquialanine A, we investigated the mechanisms of extracellular delivery of this alkaloid in P. digitatum. We detected extracellular vesicles (EVs) released by P. digitatum both in culture and during infection of citrus fruits. Compositional analysis of EVs produced during infection revealed the presence of a complex cargo, which included tryptoquialanines and the mycotoxin fungisporin. The EVs also presented phytotoxicity activity in vitro and caused damage to the tissues of citrus seeds. Through molecular networking, it was observed that the metabolites present in the P. digitatum EVs are produced in all of its possible hosts. Our results reveal a novel phytopathogenic role of P. digitatum EVs and tryptoquialanine A, implying that this alkaloid is exported in EVs during plant infection.

Penicillium digitatum is the most aggressive pathogen of citrus fruits. Tryptoquialanines are major indole alkaloids produced by P. digitatum. It is unknown if tryptoquialanines are involved in the damage of citrus fruits caused by P. digitatum. To investigate the pathogenic roles of tryptoquialanines, we initially asked if tryptoquialanines could affect the germination of Citrus sinensis seeds. Exposure of the citrus seeds to tryptoquialanine A resulted in a complete inhibition of germination and an altered metabolic response. Since this phytotoxic effect requires the extracellular export of tryptoquialanine A, we investigated the mechanisms of extracellular delivery of this alkaloid in P. digitatum. We detected extracellular vesicles (EVs) released by P. digitatum both in culture and during infection of citrus fruits. Compositional analysis of EVs produced during infection revealed the presence of a complex cargo, which included tryptoquialanines and the mycotoxin fungisporin. The EVs also presented phytotoxicity activity in vitro, and caused damage to the tissues of citrus seeds. Through molecular networking, it was observed that the metabolites present in the P. digitatum EVs are produced in all of its possible hosts. Our results reveal a novel phytopathogenic role of P. digitatum EVs and tryptoquialanine A, implying that this alkaloid is exported in EVs during plant infection.IMPORTANCEDuring the post-harvest period, citrus fruits can be affected by phytopathogens such as Penicillium digitatum, which causes the green mold disease and is responsible for up to 90 % of the total citrus losses. Chemical fungicides are widely used to prevent the green mold disease, leading to concerns about environmental and health risks. To develop safer alternatives to control phytopathogens, it is necessary to understand the molecular basis of infection during the host-pathogen interaction. In the P. digitatum model, the virulence strategies are poorly known. Here, we describe the production of phytotoxic extracellular vesicles (EVs) by P. digitatum during the infection of citrus fruits. We also characterized the secondary metabolites in the cargo of EVs and found in this set of molecules an inhibitor of seed germination. Since EVs and secondary metabolites have been related to virulence mechanisms in other host-pathogen interactions, our data are important for the comprehension of how P. digitatum causes damage to its primary hosts.

The mycotoxin terrein is derived from the C10‐precursor 6‐hydroxymellein (6‐HM) via an oxidative ring contraction. Although the corresponding biosynthetic gene cluster (BGC) has been identified, details of the enzymatic oxidative transformations are lacking. Combining heterologous expression and in vitro studies we show that the flavin‐dependent monooxygenase (FMO) TerC catalyzes the initial oxidative decarboxylation of 6‐HM. The reactive intermediate is further hydroxylated by the second FMO TerD to yield a highly oxygenated aromatic species, but further reconstitution of the pathway was hampered. A related BGC was identified in the marine‐derived Roussoella sp. DLM33 and confirmed by heterologous expression. These studies demonstrate that the biosynthetic pathways of terrein and related (polychlorinated) congeners diverge after oxidative decarboxylation of the lactone precursor that is catalyzed by a conserved FMO and further indicate that early dehydration of the side chain is an essential step., Heterologous expression of two related biosynthetic gene clusters from Aspergillus terreus and Roussoella sp. DLM33 confirmed a conserved flavin‐dependent monooxygenase that initiates the oxidative decarboxylation of the key intermediate (dichloro‐) 6‐hydroxymellein. Further in vitro studies imply that both pathways diverge after this initial oxidation, whereas additional dehydration appears essential for downstream processing.

Collective behavior is a common feature of life. Although swarming motility and biofilms are opposed collective behaviors, both contribute to bacterial survival and host colonization. We have identified a link between motility/biofilms and a nonribosomal peptide synthetase-polyketide synthase gene cluster family (ppp) conserved in Pseudovibrio and Pseudomonas Proteobacteria known to interact with diverse eukaryotes. After developing reverse genetics for Pseudovibrio, we discovered two pseudovibriamide families, heptapeptides with a reversal in chain polarity via an ureido linkage 1-6 and related nonadepsipeptides 7-12. Imaging mass spectrometry showed that 1 was excreted whereas 7 was colony-associated. Deletion of pppA abolished production of 1-12 leading to reduced motility and increased biofilm production. pppD mutants that produced only 1-6 showed motility comparable to the wild-type and reduced biofilm formation, indicating that the excreted heptapeptides play a role in promoting motility. In contrast to lipopeptides widely known to affect swarming and biofilms, pseudovibriamides are not surfactants. Our results expand current knowledge on metabolites mediating bacterial collective behavior. Moreover, the establishment of reverse genetics will enable future exploration of the ecological and biotechnological potential of Pseudovibrio bacteria which have been proposed to contribute to marine sponge health.SignificanceBacteria contribute to health and disease of plants and animals. Specialized metabolites produced by bacteria are important in mediating their behavior and the colonization of their hosts. We have identified a conserved gene cluster family in Pseudovibrio and Pseudomonas bacteria known to colonize marine animals and terrestrial plants, respectively. Using Pseudovibrio as a model, we show the encoded metabolites, which we termed pseudovibriamides, promote motility and decrease biofilms. In contrast to lipopeptides widely known to affect motility/biofilms, pseudovibriamides are not surfactants, but instead are linear peptides with a reversal in chain polarity. The discovery of pseudovibriamides expands current knowledge of bacteria collective behavior. The establishment of reverse genetics will enable exploration of the ecological and biotechnological potential of Pseudovibrio bacteria.ClassificationBiological Sciences, Microbiology

International audience; Enterococci are gram-positive, widespread nosocomial pathogens that in recent years have developed resistance to various commonly employed antibiotics. Since finding new infection-control agents based on secondary metabolites from organisms has proved successful for decades, natural products are potentially useful sources of compounds with activity against enterococci. Herein are reported the results of a natural product library screening based on a whole-cell assay against a gram-positive model organism, which led to the isolation of a series of anacardic acids identified by analysis of their spectroscopic data and by chemical derivatizations. Merulinic acid C was identified as the most active anacardic acid derivative obtained against antibiotic-resistant enterococci. Fluorescence microscopy analyses showed that merulinic acid C targets the bacterial membrane without affecting the peptidoglycan and causes rapid cellular ATP leakage from cells. Merulinic acid C was shown to be synergistic with gentamicin against Enterococcus faecium, indicating that this compound could inspire the development of new antibiotic combinations effective against drug-resistant pathogens.

A new method of screening was developed to generate 770 organic and water-soluble fractions from extracts of nine species of marine sponges, from the growth media of 18 species of marine-derived fungi, and from the growth media of 13 species of endophytic fungi. The screening results indicated that water-soluble fractions displayed significant bioactivity in cytotoxic, antibiotic, anti

Made available in DSpace on 2020-12-10T19:48:12Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-01-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) A new method of screening was developed to generate 770 organic and water-soluble fractions from extracts of nine species of marine sponges, from the growth media of 18 species of marine-derived fungi, and from the growth media of 13 species of endophytic fungi. The screening results indicated that water-soluble fractions displayed significant bioactivity in cytotoxic, antibiotic, anti-Leishmania, anti-Trypanosoma cruzi, and inhibition of proteasome assays. Purification of water-soluble fractions from the growth medium of Penicillium solitum IS1-A provided the new glutamic acid derivatives solitumine A (1), solitumine B (2), and solitumidines A-D (3-6). The structures of compounds 1-6 have been established by analysis of spectroscopic data, chemical derivatizations, and vibrational circular dichroism calculations. Although no biological activity could be observed for compounds 1-6, the new structures reported for 1-6 indicate that the investigation of water-soluble natural products represents a relevant strategy in finding new secondary metabolites. Univ Sao Paulo, Inst Quim Sao Carlos, CP 780, BR-13560970 Sao Carlos, SP, Brazil Univ Fed Sao Carlos, Dept Quim, BR-13565905 Sao Carlos, SP, Brazil Univ Estadual Paulista, Inst Biociencias, Dept Bioquim & Microbiol, Campus Rio Claro,Avenida 24-A,1515, Rio Claro, SP, Brazil Univ Fed Sao Paulo, Inst Ciencia & Tecnol, BR-12231280 Sao Jose Dos Campos, SP, Brazil Univ Franca, Nucleo Pesquisa Ciencia & Tecnol, Ave Dr Armando Salles Oliveira,201 Pq Univ, BR-14404600 Franca, SP, Brazil Univ Sao Paulo, Dept Ciencias Exatas, Escola Super Agr Luiz de Queiroz, Agron, Ave Padua Dias 11,CP 9, BR-13418900 Piracicaba, SP, Brazil Natl Ctr Res Energy & Mat, Brazilian Biosci Natl Lab, Giuseppe Maximo Scolfaro 10000, BR-13083970 Campinas, SP, Brazil Univ Estadual Campinas, Inst Biol, BR-13083862 Campinas, SP, Brazil Univ Estadual Paulista, Inst Biociencias, Dept Bioquim & Microbiol, Campus Rio Claro,Avenida 24-A,1515, Rio Claro, SP, Brazil FAPESP: 2013/50228-8 FAPESP: 2016/21341-9 FAPESP: 2017/06014-4 FAPESP: 2013/23153-7 FAPESP: 2016/16033-3

Studies of secondary metabolites (natural products) that cover their isolation, chemical synthesis and bioactivity investigation present myriad opportunities for discovery. For example, the isolation of novel secondary metabolites can inspire advances in chemical synthesis strategies to achieve their practical preparation for biological evaluation. In the process, chemical synthesis can also provide unambiguous structural characterization of the natural products. Although the isolation, chemical synthesis and bioactivity studies of natural products are mutually beneficial, they are often conducted independently. Here, we demonstrate the benefits of a collaborative study of the phomactins, diterpenoid fungal metabolites that serve as antagonists of the platelet activating factor receptor. Our isolation of novel phomactins has spurred the development of a bioinspired, unified approach that achieves the total syntheses of six congeners. We also demonstrate in vitro the beneficial effects of several phomactins in suppressing the rate of repopulation of tumour cells following gamma radiation therapy.

Antimicrobial and anti-proliferative meleagrin and oxaline are roquefortine C-derived alkaloids produced by fungi of the genus Penicillium. Tandem O-methylations complete the biosynthesis of oxaline from glandicoline B through meleagrin. Currently, little is known about the role of these methylation patterns in the bioactivity profile of meleagrin and oxaline. To establish the structural and mechanistic basis of methylation in these pathways, crystal structures were determined for two late-stage methyltransferases in the oxaline and meleagrin gene clusters from Penicillium oxalicum and Penicillium chrysogenum. The homologous enzymes OxaG and RoqN were shown to catalyze penultimate hydroxylamine O-methylation to generate meleagrin in vitro. Crystal structures of these enzymes in the presence of methyl donor S-adenosylmethionine revealed an open active site, which lacks an apparent base indicating that catalysis is driven by proximity effects. OxaC was shown to methylate meleagrin to form oxaline in vitro, the terminal pathway product. Crystal structures of OxaC in a pseudo-Michaelis complex containing sinefungin and meleagrin, and in a product complex containing S-adenosyl-homocysteine and oxaline, reveal key active site residues with His313 serving as a base that is activated by Glu369. These data provide structural insights into the enzymatic methylation of these alkaloids that include a rare hydroxylamine oxygen acceptor, and can be used to guide future efforts towards selective derivatization and structural diversification and establishing the role of methylation in bioactivity.

Mushroom alkaloids are of a considerable interest as a consequence of their unique secondary metabolites. This work describes the isolation and identification of brotasic acid methyl ester (1) from the fruiting bodies of the mushroom Auricularia sp. After isolation using a series of chromatographic steps, compound 1 was identified by analysis of spectroscopic data and has a novel carbon skeleton. The structure of 1 is related to the structure of the histone deacetylase inhibitor SAHA.

Marine sponges are a rich source of terpenoids with rearranged spongian carbon skeletons. Investigation of extracts from the sponge Darwinella cf. oxeata yielded four new rearranged diterpenoids, oxeatine (2) and oxeatamides H-J (3-5), as well as the known metabolites oxeatamide A (6), oxeatamide A methyl ester (7), and membranolide (1). Oxeatine (2) has a new heterocyclic skeleton, while oxeatamide J (5) has an N-methyl urea group included in a γ-lactam moiety. UPLC-QTOF analysis of the extract obtained from the mantle of the nudibranch Felimida grahami indicated the presence of 1 and 4.

Covering: 2015 and 2016The chemistry and biology of natural guanidines isolated from microbial culture media, from marine invertebrates, as well as from terrestrial plants and animals, are reviewed. Emphasis is directed to the biosynthesis, total synthesis, ecological roles as well as on the evolution of guanidines isolated from natural sources.

Chemical investigation of the aqueous fraction of the ethanol extract from the Brazilian endemic marine sponge Clathria (Clathria) nicoleae Vieira de Barros, Santos & Pinheiro, 2013, Microcionidae, sampled from a 55 m deep rhodolith bed at the Amazon River mouth, led to the isolation of a new hexapeptide, clathriamide (1). HP-20 resin was used to capture compound 1 from the aqueous fraction, which was purified by additional chromatographic steps. The absolute configuration of the amino acids of 1 was determined by advanced Marfey’s analysis using 5-fluoro-2,4-dinitrophenyl-Nα-l-tryptophanamide. The amino acid derivatives analyzed by ultra-performance liquid chromatography coupled to a mass spectrometry using a C8 column enabled a good chromatographic resolution of l-Ile and l-allo-Ile, previously unfeasible using C18 column. Keywords: Porifera, Peptide, Advanced marfey’s analysis, Rhodolith bed, Aqueous extract