Conformational Sampling in Computational Studies of Natural Products: Why Is It Important?

Conformational sampling is a vital component of a reliable computational chemistry investigation. With the aim of illustrating the importance of conformational sampling, and building awareness among new practitioners, we present a series of case studies that show how the quality and reliability of computational studies depend on undertaking a thorough conformer search. The examples are drawn from the most common types of research questions in natural products chemistry, but the fundamental principles apply more generally to computational studies of molecular structure and behavior in any field of chemistry.

Cryo-ultramicrotomy and Mass Spectrometry Imaging Analysis of Nudibranch Microstructures.

In this paper, we investigate the presence of latrunculin A in the outer rim of a nudibranch and show that by combining ultrathin cryosection methods with MALDI MSI we can achieve improved lateral ( and ) resolution and very high resolution in the dimension by virtue of the ultrathin 200 nm thin cryosections. We also demonstrate that a post ionization laser increases sensitivity. Recent advances in MALDI source design have improved the lateral resolution ( and ) and sensitivity during MSI.

Expanding the Repertoire of Spongian-16-One Derivatives in Australian Nudibranchs of the Genus and Evaluation of Their Anatomical Distribution.

Extracts of the mantle and viscera of the Indo-Pacific nudibranchs and sp. 1 afforded 11 new diterpenoids (-), all of which possess a tetracyclic spongian-16-one scaffold with extensive oxidation at C-6, C-7, C-11, C-12, C-13, and/or C-20. The structures and relative configuration were investigated by NMR experiments, while X-ray crystallography provided the absolute configuration of , including a 2' configuration for the 2-methylbutanoate substituent located at C-7.

Weapons or deterrents? Nudibranch molluscs use distinct ecological modes of chemical defence against predators.

Defensive chemicals are used by plants and animals to reduce the risk of predation through different mechanisms, including toxins that cause injury and harm (weapons) and unpalatable or odiferous compounds that prevent attacks (deterrents). However, whether effective defences are both toxins and deterrents, or work in just one modality is often unclear. In this study, our primary aim was to determine whether defensive compounds stored by nudibranch molluscs acted as weapons (in terms of being toxic), deterrents (in terms of being distasteful) or both.

The Validity of Brine Shrimp (Artemia Sp.) Toxicity Assays to Assess the Ecological Function of Marine Natural Products.

Many organisms employ toxic compounds for protection against predators. To understand the effectiveness of such compounds, chemoecological studies often use brine shrimp (Artemia spp.) as a model organism instead of more ecologically relevant species.