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.

Zygosporamide ( 1 ), a new cyclic pentadepsipeptide, was isolated from the seawater-based fermentation broth of a marine-derived fungus identified as Zygosporium masonii . The structure of 1 , which is composed of α-hydroxyleucic acid and both d - and l -amino acids, was determined by combined spectral and chemical methods. Despite a simple structure, zygosporamide illustrated significant cytotoxicity in the NCI’s 60 cell line panel (median GI 50  = 9.1 μM), with highly enhanced selectivity against the CNS cancer cell line SF-268 (GI 50  = 6.5 nM) and the renal cancer cell line RXF 393 (GI 50  ⩽ 5.0 nM).

Zygosporamide, a Cytotoxic Cyclic Depsipeptide from the Marine‐Derived Fungus Zygosporium masonii

The bioactive natural product seriniquinone was discovered as a potential melanoma drug, which was produced by the as-yet-undescribed marine bacterium of the rare genus Serinicoccus. As part of a long-term research program aimed at the discovery of new agents for the treatment of cancer, seriniquinone revealed remarkable in vitro activity against a diversity of cancer cell lines in the US National Cancer Institute 60-cell line screening. Target deconvolution studies defined the seriniquinones as a new class of melanoma-selective agents that act in part by targeting dermcidin (DCD). The targeted DCD peptide has been recently examined and defined as a “pro-survival peptide” in cancer cells. While DCD was first isolated from human skin and thought to be only an antimicrobial peptide, currently DCD has been also identified as a peptide associated with the survival of cancer cells, through what is believed to be a disulfide-based conjugation with proteins that would normally induce apoptosis. However, the significantly enhanced potency of seriniquinone was of particular interest against the melanoma cell lines assessed in the NCI 60-cell line panel. This observed selectivity provided a driving force that resulted in a multidimensional program for the discovery of a usable drug with a new anticancer target and, therefore, a novel mode of action. Here, we provided an overview of the discovery and development efforts to date.

https://www.mdpi.com/1660-3397/20/5/301/pdf?version=1652246139

Preclinical Development of Seriniquinones as Selective Dermcidin Modulators for the Treatment of Melanoma

Summary Cyclodidemnamide ( 1 ), a new cyclic heptapeptide, has been isolated from the marine ascidian Didemnum molle collected in the Philippine Islands. The structure of the new, weakly cytotoxic, heptapeptide was unambiguously assigned using comprehensive NMR analysis in combination with hydrolysis and chiral GC-MS analysis of its component amino acids. Computer analysis of 1 led to assignment of a solution conformation that fully rationalized the nOe correlations and shielding effects observed by 1 H NMR.

Cyclodidemnamide: A New Cyclic Heptapeptide from the Marine Ascidian Didemnum molle

The ocean contains a host of macroscopic life in a great microbial soup. Unlike the terrestrial environment, an aqueous environment provides perpetual propinquity and blurs spatial distinctions. Marine organisms are under a persistent threat of infection by resident pathogenic microbes including bacteria, and in response they have engineered complex organic compounds with antibacterial activity from a diverse set of biological precursors. The diluting effect of the ocean drives the construction of potent molecules that are stable to harsh salty conditions. Members of each class of metabolite—ribosomal and non-ribosomal peptides, alkaloids, polyketides, and terpenes—have been shown to exhibit antibacterial activity. The sophistication and diversity of these metabolites points to the ingenuity and flexibility of biosynthetic processes in Nature. Compared with their terrestrial counterparts, antibacterial marine natural products have received much less attention. Thus, a concerted effort to discover new antibacterials from marine sources has the potential to contribute significantly to the treatment of the ever increasing drug-resistant infectious diseases.

William Fenical

Papers

Zygosporamide, a Cytotoxic Cyclic Depsipeptide from the Marine‐Derived Fungus Zygosporium masonii

Preclinical Development of Seriniquinones as Selective Dermcidin Modulators for the Treatment of Melanoma

Cyclodidemnamide: A New Cyclic Heptapeptide from the Marine Ascidian Didemnum molle

Antibacterials from the Sea

Chondriol, ein halogeniertes acetylen aus algen der spezies chondria oppositiclada