Antifungals of acromyrmex, allomerus, and tetraponera ant- and cultivarassociated bacteria

The central purpose of this thesis is to test the utility of ant-microbe associations for discovering antifungal compounds with novel molecular (sub-) structures. Novel antifungals displaying reduced adverse side-effects, increased water-solubilities, and/or strong fungicidal properties would be helpful in medical science for responding to the rising prevalence of human mycoses and for solving problems with adverse side-effects in currently used antifungal drugs. Host-symbiont systems may represent a source of bacterial species that, due to their co-evolved association with hosts, have evolved antifungals differing in their molecular structures from antifungals of well-explored environmentalsources. To test the suitability of ant-microbe symbioses for discovering novel antifungals, I characterise ectosymbiotic bacteria and antifungal metabolites in three ant-associated niches: Acromyrmex octospinosus worker ants, fungal cultivars of Allomerus decemarticulatus and A. octoarticulatus, and Tetraponera penzigi worker ants and their putative fungal cultivar. I find that the A. octospinosus and T. penzigi niches hosted multiple bioactive actinobacteria including Streptomyces, Pseudonocardia, Nocardiopsis, and Saccharopolyspora. A Streptomyces strain from the Acromyrmex octospinosus niche was shown to produce the structurally unmodified antifungals candicidin and antimycin, which is suggestive of bacterial recruitment from environmental sources. Antimycin consisted of two sets of six molecules varying in number of attached CH2 groups. Both sets differ in polarity and fragmentation pattern. Only one set of antimycins inhibited the growth of Candida albicans, and this set revealed tandem-LCMS analogies with an antimycin A1-A4 standard. A Pseudonocardia strain from the same A. octospinosus niche was found to produce a partially novel (to science) and potentially water-soluble nystatinlike antifungal, which is suggestive of host-symbiont coevolution. These findings indicate that the host ant is able to use multiple-drug therapy in the form of antifungal �cocktails� to tackle resistance evolution in fungal pathogens. Overall, this research demonstrates that ant-microbe associations provide new opportunities for finding abundant bioactive bacteria and novel antibiotics

Predicting charge density distribution of materials using a local-environment-based graph convolutional network

Electron charge density distribution of materials is one of the key quantities in computational materials science as theoretically it determines the ground state energy and practically it is used in many materials analyses. However, the scaling of density functional theory calculations with number of atoms limits the usage of charge-density-based calculations and analyses. Here we introduce a machine learning scheme with local-environment-based graphs and graph convolutional neural networks to predict charge density on grid-points from crystal structure. We show the accuracy of this scheme through a comparison of predicted charge densities as well as properties derived from the charge density, and the scaling is O(N). More importantly, the transferability is shown to be high with respect to different compositions and structures, which results from the explicit encoding of geometry

Organocatalyzed Assembly of Chlorinated Quaternary Stereogenic Centers

The catalytic asymmetric construction of chiral quaternary stereocenters is a continual area of research for organic chemists. In this sense, when a chlorine atom is introduced to a quaternary stereocenter, the synthetic difficulty of the resulting molecule increases along with its significance. This is true not only because of the intrinsic interest in such chlorinated molecules but also because they are highly valuable chiral building blocks in organic synthesis, as they can be converted into more complex molecules by a SN2 displacement reaction. Among the different strategies to create chlorinated quaternary stereogenic centers, organocatalysis has played a pivotal role over the past decade. In this review, a comprehensive analysis of such organocatalyzed transformations with a focus on the α-chlorination of carbonyl compounds is presented.Financial support from the University of Alicante (VIGROB-173) and the Spanish Ministerio de Economía y Competitividad (CTQ2015-66624-P) is acknowledged

Применение фитогормонов отечественного производства на цветочно-декоративных культурах в условиях Беларуси : методические рекомендации

В методических рекомендациях обобщается опыт применения фитогормонов отечественного производства на цветочно-декоративных культурах в условиях Беларуси и даны практические рекомендации на наиболее популярных из них. Методические рекомендации предназначены для цветоводов и озеленителей, а также для студентов биотехнологического факультета УО «ПолесГУ» специальностей 1-31 01 01 «Биология (по направлениям)» и 1-75 02 01 «Садово-парковое строительство» со специализацией «Ландшафтное проектирование»

Os impactos do REACH sobre a indústria cosmética brasileira

A Comissão Européia apresentou em 2003 a proposta do REACH (Registration, Evaluation, Authorization and Restriction of Chemical) como uma forma de proteção à saúde humana e ambiental, sendo implementado em 2007. Trata-se de um regulamento que visa à regular a fabricação e a comercialização de produtos químicos dentro da União Européia, atribuindo às indústrias dessas substâncias o ônus de avaliar os riscos decorrentes da utilização de seus produtos, no caso de sua produção ultrapassar a medida de uma tonelada por ano. A empresa que quiser manter a comercialização de seus produtos dentro da UE deverá registrá-los junto à Agência Européia de Produtos Químicos (ECHA). Além das indústrias químicas, esta nova política afeta também as empresas que utilizam determinadas substâncias químicas como matéria-prima de seus produtos. Como a química está presente em, praticamente, todos os produtos utilizados no dia-a-dia pela sociedade, a política do REACH representa um enorme impacto para o setor industrial como um todo. O setor de cosméticos, por estar em crescente expansão ao longo dos últimos anos, independentemente das crises econômicas pelas quais o mundo passa, foi escolhido como objeto de estudo. A seguir discutiremos como o regulamento REACH irá impactar a indústria brasileira de cosméticos

Synthesis and Structure of Spirocyclic Tetraethers Derived from [1,1′-Binaphthalene]-2,2′-diol and Pentaerythritol

Molecular scaffolds that have well-defined geometries, are easy to synthesize and functionalize, and can hold attached sites of molecular recognition in suitable orientations are useful tools in various areas of science and technology. The utility of the tetraphenyl ether of pentaerythritol (4) as a scaffold in crystal engineering led us to study rigidified analogue SBINOX (5), the spirocyclic tetraether derived from pentaerythritol and [1,1′-binaphthalene]-2,2′-diol (BINOL). We have found that SBINOX (5) and derivatives can be prepared conveniently in acceptable yields and in stereoisomerically pure (S,S), (R,S), and (R,R) forms. X-ray crystallographic studies have revealed that the benzannulated 9-membered dioxonane rings in these structures adopt characteristic conformations of C1 symmetry. Intraannular C−H···O interactions help maintain the conformations of the individual rings, and the geometry of the spirocyclic SBINOX core is also controlled in part by distinctive short interannular C−H···O and C−H···π interactions. Despite the inherent flexibility of the dioxonane rings, derivatives of SBINOX (5) can be expected to orient peripheral substituents in preferred ways, making SBINOX a potentially useful scaffold for applications in drug discovery, crystal engineering, and other fields

Synthesis and Structure of Spirocyclic Tetraethers Derived from [1,1′-Binaphthalene]-2,2′-diol and Pentaerythritol

Molecular scaffolds that have well-defined geometries, are easy to synthesize and functionalize, and can hold attached sites of molecular recognition in suitable orientations are useful tools in various areas of science and technology. The utility of the tetraphenyl ether of pentaerythritol (4) as a scaffold in crystal engineering led us to study rigidified analogue SBINOX (5), the spirocyclic tetraether derived from pentaerythritol and [1,1′-binaphthalene]-2,2′-diol (BINOL). We have found that SBINOX (5) and derivatives can be prepared conveniently in acceptable yields and in stereoisomerically pure (S,S), (R,S), and (R,R) forms. X-ray crystallographic studies have revealed that the benzannulated 9-membered dioxonane rings in these structures adopt characteristic conformations of C1 symmetry. Intraannular C−H···O interactions help maintain the conformations of the individual rings, and the geometry of the spirocyclic SBINOX core is also controlled in part by distinctive short interannular C−H···O and C−H···π interactions. Despite the inherent flexibility of the dioxonane rings, derivatives of SBINOX (5) can be expected to orient peripheral substituents in preferred ways, making SBINOX a potentially useful scaffold for applications in drug discovery, crystal engineering, and other fields

Synthesis and Structure of Spirocyclic Tetraethers Derived from [1,1′-Binaphthalene]-2,2′-diol and Pentaerythritol

Molecular scaffolds that have well-defined geometries, are easy to synthesize and functionalize, and can hold attached sites of molecular recognition in suitable orientations are useful tools in various areas of science and technology. The utility of the tetraphenyl ether of pentaerythritol (4) as a scaffold in crystal engineering led us to study rigidified analogue SBINOX (5), the spirocyclic tetraether derived from pentaerythritol and [1,1′-binaphthalene]-2,2′-diol (BINOL). We have found that SBINOX (5) and derivatives can be prepared conveniently in acceptable yields and in stereoisomerically pure (S,S), (R,S), and (R,R) forms. X-ray crystallographic studies have revealed that the benzannulated 9-membered dioxonane rings in these structures adopt characteristic conformations of C1 symmetry. Intraannular C−H···O interactions help maintain the conformations of the individual rings, and the geometry of the spirocyclic SBINOX core is also controlled in part by distinctive short interannular C−H···O and C−H···π interactions. Despite the inherent flexibility of the dioxonane rings, derivatives of SBINOX (5) can be expected to orient peripheral substituents in preferred ways, making SBINOX a potentially useful scaffold for applications in drug discovery, crystal engineering, and other fields

Synthesis and Structure of Spirocyclic Tetraethers Derived from [1,1′-Binaphthalene]-2,2′-diol and Pentaerythritol

Molecular scaffolds that have well-defined geometries, are easy to synthesize and functionalize, and can hold attached sites of molecular recognition in suitable orientations are useful tools in various areas of science and technology. The utility of the tetraphenyl ether of pentaerythritol (4) as a scaffold in crystal engineering led us to study rigidified analogue SBINOX (5), the spirocyclic tetraether derived from pentaerythritol and [1,1′-binaphthalene]-2,2′-diol (BINOL). We have found that SBINOX (5) and derivatives can be prepared conveniently in acceptable yields and in stereoisomerically pure (S,S), (R,S), and (R,R) forms. X-ray crystallographic studies have revealed that the benzannulated 9-membered dioxonane rings in these structures adopt characteristic conformations of C1 symmetry. Intraannular C−H···O interactions help maintain the conformations of the individual rings, and the geometry of the spirocyclic SBINOX core is also controlled in part by distinctive short interannular C−H···O and C−H···π interactions. Despite the inherent flexibility of the dioxonane rings, derivatives of SBINOX (5) can be expected to orient peripheral substituents in preferred ways, making SBINOX a potentially useful scaffold for applications in drug discovery, crystal engineering, and other fields