Abstract I first heard about IUPAC in 1972 in undergraduate organic (nomenclature) lectures; I already knew about the Periodic Table from high school days, but I did not make the connection between this chemistry and the organisation named IUPAC until much later. In 1996, I became involved in planning for Australia to bid for a General Assembly (GA)/World Chemistry Congress (WCC); ultimately the bid was successful, and the meeting was held in my home city of Brisbane in July 2001. In the way, I learnt much about the various component parts of IUPAC while the Executive Secretary role, which I held for a trio of combined meetings including an Asian Chemistry Congress plus an Asian Federation of Medicinal Chemistry meeting, brought me into contact with the IUPAC leadership. I also interacted with Titular Members, many volunteers, as well as key movers and shakers within the chemistry field. And I got to know our wonderful current IUPAC staff members Fabienne Meyers and Enid Weatherwax.

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.

In addition to three known compounds (1–3), two new rearranged spongian diterpenes (4 and 5) with perhydroazulene and dioxabicyclooctane ring systems were isolated from the mantle and viscera of the Australian nudibranch Goniobranchus coi. The relative configuration of the major spiroepoxide 4 was explored by comparison with those of m-chloroperbenzoic acid oxidation products derived from dendrillolide A (1). Aldehydes 6 and 7 were identified as the ring-opened artefacts of the spiroepoxides 5 and 4 respectively, and yielded ketone 3 on storage. The relative configurations of lactols 8 and 9, isolated as an inseparable mixture of diastereomers, were deduced by molecular modelling and computational studies. Acetylation of the lactol mixture provided dendrillolide A (1), further confirming the structural assignments of 8 and 9. Dissection of animal tissue established that the norditerpenoid metabolites were present in both mantle and viscera tissues.

It is a great pleasure to introduce a collection of papers

In this paper, we investigate the presence of latrunculin A in the outer rim of a nudibranch Chromodoris kuiteri and show that by combining ultrathin cryosection methods with MALDI MSI we can achieve improved lateral (x and y) resolution and very high resolution in the z 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 (x and y) and sensitivity during MSI. Taken together, very high z resolution, from ultrathin sections, and improved lateral (x and y) resolution will allow for subcellular molecular imaging with the potential for subcellular 3D volume reconstruction.

Since antiquity, the sense of smell (olfaction) is considered as a distance sense, just like sight and hearing. Conversely, the sense of taste (gustation) is thought to operate by direct contact, similarly to touch. With the progress of natural sciences, information at molecular, anatomical, and neurobiological levels has also contributed to the taste-smell dichotomy, but much evidence inconsistent with a sharp differentiation of these two senses has emerged, especially when considering species other than humans. In spite of this, conflicting information has been interpreted so that it could conform to the traditional differentiation. As a result, a confirmation bias is currently affecting scientific research on chemosensory systems and is also hindering the development of a satisfactory narrative of the evolution of chemical communication across taxa. From this perspective, the chemosensory dichotomy loses its validity and usefulness. We thus propose the unification of all chemosensory modalities into a single sense, moving toward a synthetic, complex, and interconnected perspective on the gradual processes by which a vast variety of chemicals have become signals that are crucially important to communication among and within cells, organs, and organisms in a wide variety of environmental conditions.

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. Our secondary aim was to investigate the response of different taxa to these defensive compounds. To do this, we identified secondary metabolites in 30 species of nudibranch molluscs and investigated their deterrent properties using antifeedant assays with three taxa: rock pool shrimp, Palaemon serenus, and two fish species: triggerfish Rhinecanthus aculeatus and toadfish Tetractenos hamiltoni. We compared these results to toxicity assays using brine shrimp Artemia sp. and previously published toxicity data with a damselfish Chromis viridis. Overall, we found no clear relationship between palatability and toxicity, but instead classified defensive compounds into the following categories: Class I & II-highly unpalatable and highly toxic; Class I-weakly unpalatable and highly toxic; Class II-highly unpalatable but weakly toxic; WR (weak response)-weakly unpalatable and weakly toxic. We also found eight extracts from six species that did not display activity in any assays indicating they may have very limited chemical defensive mechanisms (NR, no response). We found that the different classes of secondary metabolites were similarly unpalatable to fish and shrimp, except extracts from Phyllidiidae nudibranchs (isonitriles) that were highly unpalatable to shrimp but weakly unpalatable to fish. Our results pave the way towards better understanding how animal chemical defences work against a variety of predators. We highlight the need to disentangle weapons and deterrents in future work on anti-predator defences to better understand the foraging decisions faced by predators, the resultant selection pressures imposed on prey and the evolution of different anti-predator strategies.

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. This is mostly because brine shrimp assays are simple and quick, but also due to the ethical implications associated with inducing harm to vertebrate predators in toxicity assays. In this study, we examined whether brine shrimp assays produce similar results to ichthyological toxicity assays with the aim of validating the use of brine shrimp as a preliminary screening tool. We extracted compounds from eight nudibranch molluscs including six species that we consider to signal their chemical defenses via warning coloration to visually hunting vertebrate predators. We tested the relative toxicity of these compounds against brine shrimp and a vertebrate potential predator, the blue-green damselfish (Chromis viridis). We found that extracts toxic to brine shrimp were also toxic to damselfish; however, extracts non-toxic to brine shrimp may still be toxic to damselfish. We also produced and tested mantle vs whole-body extracts for some nudibranch species, which exhibited similar toxicities in both assays except for the whole-body extract of Goniobranchus splendidus which was harmless to shrimp but toxic to fish, while the mantle extract was toxic to both. Overall, we argue that the brine shrimp assay can reasonably indicate the potential toxicity of a compound to fish, but additional experiments with more ecologically relevant predators are required if a no dose-response is observed against brine shrimp.

Extracts of the mantle and viscera of the Indo-Pacific nudibranchs Goniobranchus aureopurpureus and Goniobranchus sp. 1 afforded 11 new diterpenoids (1–11), 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 1, including a 2′S configuration for the 2-methylbutanoate substituent located at C-7. Dissection of animal tissue revealed that the mantle and viscera tissues differed in their metabolite composition with diterpenes 1–11 present in the mantle tissue of the two nudibranch species.

Seven oxygenated sesquiterpenes 1 to 7 each with a drimane framework were isolated from an organic extract of the nudibranch Ardeadoris rubroannulata collected from Eastern Australia. The structure of pu’ulenal 2 was revised by 1D NOESY, providing a 9Z configuration, while isopu’ulenal 3 has the 9 E configuration previously ascribed to pu’ulenal.

Abstract In a year marked by unprecedented challenges, IUPAC hosted the largest ever Global Women’s Breakfast (GWB2021) on 9 February 2021, bringing together more than 20,000 people around the world to celebrate the achievements of women scientists, to strengthen and expand professional networks, to inspire the next generations, and to challenge the status quo with respect to equality for women scientists in the workplace.

Seven oxygenated sesquiterpenes 1 to 7 each with a drimane framework were isolated from an organic extract of the nudibranch Ardeadoris rubroannulata collected from Eastern Australia. The structure of pu’ulenal 2 was revised by 1D NOESY, providing a 9Z configuration, while isopu’ulenal 3 has the 9 E configuration previously ascribed to pu’ulenal. Keywords , , sesquiterpene , terpenoid , NMR , x-ray crystallography , DFT , absolute configuration

Two new oxygenated terpenes (1 and 2) have been characterized from the Australian nudibranch Goniobranchus coi. Broadened 1H NMR signals, together with the absence of individual carbon NMR signals, complicated analysis of 5,9-epoxydendrillolide A (1); increasing the temperature to 323 K revealed the missing NMR signals. Low-temperature 1H NMR experiments provided an activation barrier of ∼15 kcal mol-1 and, together with DFT calculations, supported interconversion of a twist chair conformer with two different chair conformers. X-ray crystallographic analysis coupled with biosynthetic reasoning suggested a (5R, 8S, 9R, 13R, 14R, 15R, 16R) configuration. Ketone 2 demonstrated similar dynamic conformational processes to 1.

Abstract On February 12, 2019, women chemists from over 50 different countries shared breakfast. They were taking part in the international networking event Empowering Women in Chemistry, an activity to celebrate the centenary of IUPAC. Women have made enormous contributions to the advancement of chemistry over the last 100 years, including as winners of Nobel prizes and many other major international awards, but they rarely take time to celebrate these achievements.

INTRODUCTION:Lipids are a diverse group of macromolecules that occur in rice grains and are known to impact rice grain properties. Identifying the relationships between specific lipids and traits of quality is important to improve varietal selection for high quality rice.OBJECTIVES:Using untargeted lipidomics, this study aims to understand the role of lipids on different traits of quality by identifying the genotypic effect of lipids and their impact on traits of cooking and eating quality of a rice mapping population.METHODS:Lipids from milled rice grains of three sets of rice samples were screened by ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) in the positive ionisation mode. Lipid features were putatively identified using analytical standards and online databases. Multivariate statistics were carried out to identify the lipid profile of varieties across three experiments. Correlation analysis was carried out between lipid features and 12 quality traits across a rice mapping population that segregates for grain physical and texture-associated traits.RESULTS:Thousands of features in rice grain lipids were detected, and were grouped into six categories-fatty acyls, glycerolipids, glycerophospholipids, sphingolipids, sterol lipids and prenol lipids. A strong genotypic basis for the lipid profile was observed among the four varieties grown under five nitrogen treatments. Clear differentiation in lipid profiles between waxy and non-waxy rice was observed. Strong correlations were observed for putative lipids that form the amylose-lipid complex and with amylose content and viscosity parameters.CONCLUSIONS:This study demonstrates the strength of untargeted lipidomics in putatively determining features that differentiate varieties from each other, and reveals the role of specific lipids on the physical and textural quality of rice.

The sesquiterpene isonitrile, 9-isocyanoneoallopupukeanane 1, has been obtained from the Indo-Pacific nudibranch Phyllidiella pustulosa. The structure of 1, which was investigated by extensive NMR experiments, molecular modelling studies, and density functional calculations, has a different arrangement of the tricyclic ring system compared with other isonitrile metabolites isolated from nudibranchs or sponges. The viability of a biosynthetic pathway leading to 1, proposed to involve a series of carbocation rearrangements, is explored in a computational study. Isonitrile 1 exhibited micromolar antimalarial activity when screened against Plasmodium falciparum infected erythrocytes.

Oxygenated sesquiterpenes were isolated from the sponge Acanthodendrilla sp. 2510 and identified as caparrapi oxide (1) and the bioactive oxocene sesquiterpene, arenaran A (2). An extract of the nudibranch Chromodoris strigata, found feeding on the sponge, also contained 2. Also characterized from the sponge extract were three compounds 3–5 derived from the oxocene skeleton of arenaran A that possessed hydroperoxy functionality. The structure and stereochemistry of each compound was identified using 1D and 2D NMR spectroscopic and mass spectrometry techniques, in combination with X-ray crystallography and molecular modelling/computational studies. Isolation of the hydroperoxy products provided insight into the reactivity of the oxocene skeleton.