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.

Structure determination of maduralide: a new 24-membered ring macrolide glycoside produced by a marine bacterium (actinomycetales)

An extensive study of the secondary metabolites produced by the obligate marine actinomycete Salinispora tropica (strain CNB-392), the producing microbe of the potent proteasome inhibitor salinosporamide A (1), has led to the isolation of seven related gamma-lactams. The most important of these compounds were salinosporamide B (3), which is the deschloro-analogue of 1, and salinosporamide C (4), which is a decarboxylated pyrrole analogue. New SAR data for all eight compounds, derived from extensive testing against the human colon carcinoma HCT-116 and the 60-cell-line panel at the NCI, indicate that the chloroethyl moiety plays a major role in the enhanced activity of 1.

/pdf/new-cytotoxic-salinosporamides-from-the-marine-actinomycete-16foatimzp.pdf

New Cytotoxic Salinosporamides from the Marine Actinomycete Salinispora tropica.

Polyhaloketones from the red seaweed asparagopsis taxiformis

Four new bromotryptamine peptides, alternatamides A-D (1-4), have been isolated from the Atlantic bryozoan Amathia alternata. The structures of the alternatamides were assigned primarily on the basis of 2D NMR data. The absolute stereochemistry of the N-methylleucine amino acid was shown to be L (2'S) by hydrolysis and comparison with standards. The alternatamides show modest antibacterial activities against several Gram-positive bacteria.

Alternatamides A-D: new bromotryptamine peptide antibiotics from the Atlantic marine bryozoan Amathia alternata.

The chemical defense of the Caribbean octocoral Pseudopterogorgia americana was investigated using feeding assays performed in aquaria and in situ with a natural assemblage of predatory fishes. Using a bioassay-guided scheme, crude extracts, fractions and pure compounds were incorporated into palatable foods and tested. Only the secosterol fraction deterred fish feeding. Two secosterols were identified from the bioactive fraction by spectroscopic methods and comparison with literature data: 9,11-secogorgosterol (Compound 1) and 9,11-secodinosterol (Compound 2), both of which have been previously described from Pseudopterogorgia spp. Our results suggest that symbiont-produced gorgosterol and dinosterol are oxidized by the coral host to C-ring secosterols, which then provide a chemical defense to both coral and alga.

/pdf/antipredatory-secosterols-from-the-octocoral-1v5fqigj0d.pdf

William Fenical

Papers

Structure determination of maduralide: a new 24-membered ring macrolide glycoside produced by a marine bacterium (actinomycetales)

New Cytotoxic Salinosporamides from the Marine Actinomycete Salinispora tropica.

Polyhaloketones from the red seaweed asparagopsis taxiformis

Alternatamides A-D: new bromotryptamine peptide antibiotics from the Atlantic marine bryozoan Amathia alternata.

Antipredatory secosterols from the octocoral Pseudopterogorgia americana