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.

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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.

A new manumycin-type natural product named pacificamide (1) and its candidate biosynthetic gene cluster (pac) were discovered from the marine actinobacterium Salinispora pacifica CNT-855. The structure of the compound was determined using NMR, electronic circular dichroism, and bioinformatic predictions. The pac gene cluster is unique to S. pacifica and found in only two of the 119 Salinispora genomes analyzed across nine species. Comparative analyses of biosynthetic gene clusters encoding the production of related manumycin-type compounds revealed genetic differences in accordance with the unique pacificamide structure. Further queries of manumycin-type gene clusters from public databases revealed their limited distribution across the phylum Actinobacteria and orphan diversity that suggests additional products remain to be discovered in this compound class. Production of the known metabolite triacsin D is also reported for the first time from the genus Salinispora. This study adds two classes of compounds to the natural product collective isolated from the genus Salinispora, which has proven to be a useful model for natural product research.

Structure and Candidate Biosynthetic Gene Cluster of a Manumycin-Type Metabolite from Salinispora pacifica.

Actinopolymorphols E and F, pyrazine alkaloids from a marine sediment-derived bacterium Streptomyces sp

A novel family of cyclic polyene natural products isolated from marine actinomycete strain CNQ140 is provided. This novel strain of actinomycetes was obtained from a previously unstudied population of marine actinomycetes that reside in sediments off La Jolla, Calif. Compounds derived from strain CNQ140 have been characterized as having a cyclic polyene-polyol structure; a molecular weight from about 996 to about 1010 in the core ring structure; and at least 58 carbons and at least 14 oxygens. The invention compounds have antitumor and/or anti-microbial activity.

Polyol macrolide antitumor-antibiotics from the marine actinomycete strain CNQ140

During an investigation of the base-induced transformation of secoisopimarene 1 to gibberellin analog 2, an unexpected solvent-specific cyclization occurred generating a bicyclo[3.2.1]spirodiketone of an unexpected structure class. The structure of this interesting reaction product has been fully defined using comprehensive 2D NMR methods.

An Unexpected Spirodiketone Obtained During Seco-Isopimarene Cyclization

Polycarpine dihydrochloride ( 1 ),a new cytotoxic dimeric disulfide alkaloid, and four related compounds ( 2–5 ) have been isolated from extracts of the ascidian Polycarpa clavata (Hartman, 1919) collected in Western Australia. The structure of the new alkaloid was determined on the basis of comprehensive spectral studies and by interconversion to its free base and several degradation products. On silica chromatography, 1 was converted to the corresponding unstable free base ( 2 ) which decomposed, via cleavage of the disulfide bridge, into monomeric derivatives. Polycarpine dihydrochloride is cytotoxic against the human colon tumor cell line HCT-116 at 0.9 μg/ml.

William Fenical

Papers

Structure and Candidate Biosynthetic Gene Cluster of a Manumycin-Type Metabolite from Salinispora pacifica.

Actinopolymorphols E and F, pyrazine alkaloids from a marine sediment-derived bacterium Streptomyces sp

Polyol macrolide antitumor-antibiotics from the marine actinomycete strain CNQ140

An Unexpected Spirodiketone Obtained During Seco-Isopimarene Cyclization

Polycarpine Dihydrochloride: A Cytotoxic Dimeric Disulfide Alkaloid from the Indian Ocean Ascidian Polycarpa clavata.