The results of a single-crystal structure determination when in CIF format can now be validated routinely by automatic procedures. In this way, many errors in published papers can be avoided. The validation software generates a set of ALERTS detailing issues to be addressed by the experimenter, author, referee and publication journal. Validation was pioneered by the IUCr journal Acta Crystallographica Section C and is currently standard procedure for structures submitted for publication in all IUCr journals. The implementation of validation procedures by other journals is in progress. This paper describes the concepts of validation and the classes of checks that are carried out by the program PLATON as part of the IUCr checkCIF facility. PLATON validation can be run at any stage of the structure refinement, independent of the structure determination package used, and is recommended for use as a routine tool during or at least at the completion of every structure determination. Two examples are discussed where proper validation procedures could have avoided the publication of incorrect structures that had serious consequences for the chemistry involved.

/pdf/single-crystal-structure-validation-with-the-program-platon-2pdiuo25f2.pdf

Single-crystal structure validation with the program PLATON

Chemistry and biochemistry of 4-hydroxynonenal, malonaldehyde and related aldehydes.

https://pubs.rsc.org/en/content/articlepdf/2019/NP/C8NP00092A

Marine natural products.

Physiological and ecological constraints play key roles in the evolution of plant growth patterns, especially in relation to defenses against herbivores. Phenotypic and life history theories are unified within the growth-differentiation balance (GDB) framework, forming an integrated system of theories explaining and predicting patterns of plant defense and competitive interactions in ecological and evolutionary time. Plant activity at the cellular level can be classified as growth (cell division and enlargement) of differentiation (chemical and morphological changes leading to cell maturation and specialization). The GDB hypothesis of plant defense is premised upon a physiological trade-off between growth and differentiation processes. The trade-off between growth and defense exists because secondary metabolism and structural reinforcement are physiologically constrained in dividing and enlarging cells, and because they divert resources from the production of new leaf area. Hence the dilemma of plants: Th...

https://www.jstor.org/stable/pdfplus/2830650.pdf

The dilemma of plants: To grow or defend.

Advances in flavonoid research since 1992.

An uncommon ester, bis-p-hydroxybenzyl-2-isobutylmalate, habenariol, has been isolated, by bioassay-guided fractionation, from the organic extract of the freshwater orchid Habenaria repens. The structure of habenariol was determined by the interpretation of spectral data. Feeding bioassays showed that habenariol deters feeding by the common freshwater crayfish Procambarus clarkii. Habenariol is related to a bis-ester glycoside isolated from the non-aquatic orchid Galeola faberi.

Habenariol, a Freshwater Feeding Deterrent from the Aquatic Orchid Habenaria repens (Orchidaceae).

3,7,11-Trimethyl-13-oxabicyclo[8.3.0]trideca-2,6-diene-12-spiro-2' -(5',5'-dimethyltetrahydrofuran), asperketal B, C20H30O2, M(r) = 302.46, orthorhombic, P2(1)2(1)2(1), a = 10.064(1), b = 22.214(2), c = 8.330 (1) A, V = 1862.3 A3, Z = 4, Dx = 1.08 g cm-3, Cu K alpha, lambda = 1.54178 A, mu = 4.55 cm-1, F(000) = 664, T = 294 (1) K, R = 0.031, wR = 0.027 for 953 data. The backbone of the molecule is composed of a cyclodecadiene ring which is cis fused to a bicyclic ketal system. The relative configurations at C(1), C(10), C(11) and C(12) are 1S*, 10R*, 11R* and 12R*.

Structure of Asperketal B.

Ansalactams B—D exhibit weak antibacterial activity against methicillin-resistant S.aureus (MRSA).

Ansalactams B—D Illustrate Further Biosynthetic Plasticity within the Ansamycin Pathway.

Two metabolites, phomoxin and phomoxide, as well as the previously synthesized antibiotic eupenoxide, have been isolated from the fermentation broth of a marine-derived fungus of the genus Phoma (strain CNC-651). The new compounds are highly oxygenated polyketides of a new structural class. Phomoxin contains an unusual cyclic carbonate functionality that is rare among natural products. The structures of the new metabolites were assigned by spectroscopic methods that relied heavily on 2D NMR spectroscopic analysis.

A Cyclic Carbonate and Related Polyketides from a Marine-Derived Fungus of the Genus Phoma

altoough soil-derived bacteria, particularly those of the order Actinomycetales, are a well· studied resource for new antitumor-antibiotics, analogous comprehensive investigations of marine bacterial sources have not been u.ndertaken. In this paper, we describe preliminary studies of marine bacteria aimed at providing an overall assessment of the scope of marine microbial resources. An emphasis is placed upon developing new methods for the isolation and culture of salt-requiring microorganisms, and on developing the isolation of new compounds with potential in the treatment of infectious diseases and cancer. As the field of marine natural products chemistry matures and becomes even more effectively interfaced with drug development, new biological resources will need to be explored. A frontier in this regard are the microorganisms of the oceans which represent an immense resource, the scope of which remains to be fully understood. The term "microorganism" is all encompassing. It includes all organisms which require magnification for clear evaluation, and includes both unicellular organisms, filamentous fonns and multicellular organisms of small size. Further classifications are whether the organisms are phototrophic or chemotrophic (perform photosynthesis or chemical metabolism) or heterotrophic (require organic carbon sources) as a means of basic nutrition. Table 1 illustrates the diversity of microorganisms known from marine habitats. The variety is enormous, ranging from the primitive Archaebacteria to the Eucaryotes (algae, fungi, etc.). In the algae alone, there are at least 10 full plant Phyla known, with at least 100,000 species expected. In the other groups, the number of species can only be speculated. The large numbers of "microorganisms" in the world 's oceans indeed point to these organisms as a major resource for chemical and biomedical study. However, few marine microorganisms have been chemically-studied in detail. Problems in isolation and taxonomy, and in both small scale and mass scale cultivation have been formidable, thus far precluding comprehensive studies of these microbes. Troisième Symposium sur les substances naturelles d'interêt biologique de la région Pacifique-Asie -spirochetes (Order Spirochaetales) -gliding bacteria (Orders Cytophagales and Beggiatoales) Eucaryotes lower fungi (Class Phycomycetes) -fungi higher fungi Ascomycetes Deuteromycetes Basidiomycetes -microalgae -prolOzoa f1agellates amoebae cHiates Chemoheterotrophs Photoautotrophs -rods and cocci aerobic (Family Pseudomonadaceae) facultative (Family Vibrionaceae) anaerobic (sulfur-reducing bacteria) -endospore-forming rods and cocci -non spore-forming cocci (Family Micrococceae) -non spore-forming rods -actinomycetes (Order ActinomycetaIes) and related organisms Chemoheterotrophic Eubacteria

/pdf/antitumor-antibiotics-from-marine-microorganisms-2m58myipeh.pdf

William Fenical

Papers

Habenariol, a Freshwater Feeding Deterrent from the Aquatic Orchid Habenaria repens (Orchidaceae).

Structure of Asperketal B.

Ansalactams B—D Illustrate Further Biosynthetic Plasticity within the Ansamycin Pathway.

A Cyclic Carbonate and Related Polyketides from a Marine-Derived Fungus of the Genus Phoma

Antitumor-antibiotics from marine microorganisms