Volume 91, Issue 2 - Special issue: Distinguished Women in Chemistry and Chemical Engineering

The emergence of multidrug-resistant bacteria has necessitated the urgent need for novel antibacterial agents. Antimicrobial peptides (AMPs), the host-defence molecules of most living organisms, have shown great promise as potential antibiotic candidates due to their multiple mechanisms of action which result in very low or negligible induction of resistance. However, the development of AMPs for clinical use has been limited by their potential toxicity to animal cells, low metabolic stability and high manufacturing cost. Extensive efforts have therefore been directed towards the development of enhanced variants of natural AMPs to overcome these aforementioned limitations. In this review, we present our efforts focused on development of efficient strategies to prepare several recently discovered AMPs including antitubercular peptides. The design and synthesis of more potent and stable AMP analogues with synthetic modifications made to the natural peptides containing glycosylated residues or disulfide bridges are described.

The overuse of antibiotics in the healthcare and agricultural industries has led to the worldwide spread of bacterial resistance. The recent emergence of multidrug resistant (MDR) bacteria has resulted in a call for the development of novel strategies to address this global issue. Research on a diverse range of antimicrobial peptides (AMPs) has shown promising activity against several resistant strains. Increased understanding of the mode of action of AMPs has shown similarity and complementarity to conventional antibiotics and the combination of both has led to synergistic effects in some cases. Combination therapy has been widely used to combat MDR bacterial infections and the recent focus on their application with AMPs may allow antibiotics to be effective against resistant bacterial strains. By conjugation of an antibiotic onto an AMP, a compound may be produced with possibly greater activity and with reduced side-effects and toxicity. The AMP in these conjugates may also act as a unique adjuvant for the antibiotic by disrupting the resistance mechanisms used by bacteria thus allowing the antibiotic to once again be effective. This mini-review outlines some of the current and past work in combining AMPs with conventional antibiotics as strategies to address bacterial resistance.

Inhibition of amyloid β peptide (Aβ) aggregation is an important goal due to the connection of this process with Alzheimer’s disease. Traditionally, inhibitors were developed with an aim to retard the overall macroscopic aggregation. However, recent advances imply that approaches based on mechanistic insights may be more powerful. In such approaches, the microscopic steps underlying the aggregation process are identified, and it is established which of these step(s) lead to neurotoxicity. Inhibitors are then derived to specifically target steps involved in toxicity. The Aβ aggregation process is composed of at minimum three microscopic steps: primary nucleation of monomers only, secondary nucleation of monomers on fibril surface, and elongation of fibrils by monomer addition. The vast majority of toxic species are generated from the secondary nucleation process: this may be a key process to inhibit in order to limit toxicity. Inhibition of primary nucleation, which delays the emergence of toxic species without affecting their total concentration, may also be effective. Inhibition of elongation may instead increase the toxicity over time. Here we briefly review findings regarding secondary nucleation of Aβ, its dominance over primary nucleation, and attempts to derive inhibitors that specifically target secondary nucleation with an aim to limit toxicity.

Metal ions are essential cofactors required by the proteome of organisms from any kingdom of life to correctly exert their functions. Dedicated cellular import, transport and homeostasis systems assure that the needed metal ion is correctly delivered and inserted into the target proteins and avoid the presence of free metal ions in the cell, preventing oxidative damaging. Among metal ions, in eukaryotic organisms copper and iron are required by proteins involved in absolutely essential functions, such as respiration, oxidative stress protection, catalysis, gene expression regulation. Copper and iron binding proteins are localized in essentially all cellular compartments. Copper is physiologically present mainly as individual metal ion. Iron can be present both as individual metal ion or as part of cofactors, such as hemes and iron-sulfur (Fe-S) clusters. Both metal ions are characterized by the ability to cycle between different oxidation states, which enable them to catalyze redox reactions and to participate in electron transfer processes. Here we describe in detail the main processes responsible for the trafficking of copper and iron sulfur clusters, with particular interest for the structural aspects of the maturation of copper and iron-sulfur-binding proteins.

The present review highlights our findings in the field of antitumor gold complexes bearing biologically relevant molecules, such as DNA-bases, amino acids or peptide derivatives. The results show that very active complexes are achieved with this sort of ligands in several cancer cells. In these compounds the gold center is bonded to these biological molecules mainly through a sulfur atom belonging to a cysteine moiety or to a thionicotinic moiety as result of the functionalization of the biological compounds, and additionally phosphines or N -heterocyclic carbenes are present as ancillary ligands. These robust compounds are stable in the biological media and can be transported to their targets without previous deactivation. The presence of these scaffolds represents a good approach to obtain complexes with improved biologically activity, better transport and biodistribution to cancer cells. Thioredoxin reductase (TrxR) has been shown as the main target for these complexes and in some cases, DNA interactions has been also observed.

Current topics in combustion chemistry include aspects of a changing fuel spectrum with a focus on reducing emissions and increasing efficiency. This article is intended to provide an overview of selected recent work in combustion chemistry, especially addressing reaction pathways from fuel decomposition to emissions. The role of the molecular fuel structure will be emphasized for the formation of certain regulated and unregulated species from individual fuels and their mixtures, exemplarily including fuel compounds such as alkanes, alkenes, ethers, alcohols, ketones, esters, and furan derivatives. Depending on the combustion conditions, different temperature regimes are important and can lead to different reaction classes. Laboratory reactors and flames are prime sources and targets from which such detailed chemical information can be obtained and verified with a number of advanced diagnostic techniques, often supported by theoretical work and simulation with combustion models developed to transfer relevant details of chemical mechanisms into practical applications. Regarding the need for cleaner combustion processes, some related background and perspectives will be provided regarding the context for future chemistry research in combustion energy science.

The importance of amino acids and biogenic amines is widely recognised in various fields, particularly in the fields of food science and nutrition. This mini-review contains a summary of my main research field that centres on aspects of Food Quality and Food Safety, with a particular emphasis on amino acids and biogenic amines. It also gives an overview of the recent developments on the related areas.

Hydrogen-bond (HB) patterns correspond to topologically distinct isomers of water clusters, and can be expressed by digraphs. The HB pattern is used to divide the configuration space of water cluster at a finite temperature. The populations of the HB patterns are transformed into the relative Helmholtz energies. The method is based on the combination of molecular simulation with graph theory. At a finite temperature it can be observed that other isomers than local minimum structures on the potential energy surface are highly populated. The dipole moment of a constituent molecule in a water cluster is enhanced depending on the local HB network around the water molecule. Rooted digraph is used to represent topologically distinct isomers of protonated water (PW) clusters. O–H bonds of PW clusters are classified into 10 topological types based on the combination of the local HB types of the contributing water molecules to the O–H bond. If the topological type is the same, vibrational frequencies of those O–H bonds of PW clusters are similar even in different isomers; i.e. vibrational frequency of O–H bond is transferable, and can be used as a vibrational spectral signature of PW clusters.

After an engagement in analytical chemistry during 50 years, I am looking back to my scientific carreer. To some extent it is based on my successful textbook in high-performance liquid chromatography. However, too much contemplation of one’s own contributions to science is boring, and it is necessary to look ahead to the future challenges in chemistry, namely to cope with the threats of climate change. And there is another topic which was and is most important in my life: mountain climbing. Its physical and maybe also mental top was to reach the summit of Mount Everest in May 2007.

There are multiple factors that contribute to the success of an industrial chemist. In addition to technical knowledge, business acumen and interprofessional skills are required for growth and advancement. The technical expertise that is developed through formal training cannot stagnate; continuous learning is required to remain relevant and drive innovation. Business acumen refers to understanding not only the company’s competitive advantage and financial picture but also the value proposition for your department and yourself. Interprofessional skills, the ability to communicate and work effectively with others, are critical since many industrial projects are multidisciplinary and cross-functional. Recommendations for development in all three areas are described.

For the last 12 years, I have had the pleasure and privilege to serve as the Director of the Swiss Federal Institute of Aquatic Science and Technology (Eawag) and as a professor at the Swiss Federal Institutes of Technology (ETH) Zurich and Lausanne (EPFL). My affiliations have afforded me a rare opportunity to observe the structure and governance of academic institutions and to reflect on my own experience in institutional leadership. I have attempted to place my experience in the context of the literature on leadership, particularly that relating to women and academia. On the basis of my experience and reading, I make some recommendations for women faculty, for women in positions of institutional leadership in academia, and for academic institutions. I am deeply convinced that greater participation by women (and members of other under-represented groups) in institutional leadership is needed if academia is to make a meaningful contribution to addressing the huge challenges that face humanity.

There are many greats in science history but relatively few women scientists that could be chosen as role models. This essay presents some from among contemporary contributors to chemistry, biochemistry, biology, physics, and astronomy. They had overcome barriers of discrimination, the difficulties of managing their time between research and family, and all have triumphed. They include some of the most famous, such as Isabella Karle, Christiane Nüsslein-Volhard, Anne McLaren, and Vera Rubin, and some less famous, including examples from Russia, India, and Turkey. Their presentation is based on personal encounters with them by the author; herself a scientist, wife, and mother.

I started my chemistry adventure while in high school, where I was the only female in a science and mathematics-oriented class. During our Junior year of high school, we were sent to the desert, close to the Red Sea in Israel to build roads. In the summers, we were in a Kibbutz on the border to help with the work needed. After work, we had time to discuss our future. Upon graduating from high school, I was drafted into the army, and in the evenings, started my college education and majored in chemistry. After finishing my term in the army, I continued my undergraduate studies in chemistry while raising my son. As I was conducting research on isotope effects, I realized that I wanted to make chemistry accessible to all. My tenet in life is that equal access to Science Education is a human right. I developed a method of teaching chemistry using art, music, dance, drama, and cultural backgrounds which attracted students at all educational levels to chemistry. I felt that as chemists, we have obligations to make the planet a better place for humankind. At this point, I became very active in working towards Scientific Freedom and Human Rights; helping chemists in the Soviet Union, China, Chile, Guatemala, and many other countries. The American Chemical Society established the Subcommittee on Scientific Freedom and Human Rights in 1986 and I chaired this committee for 26 years. At great risk to my personal safety, we succeeded in preventing executions, releasing prisoners of conscience from jail and bringing dissidents to freedom. This work led me to use chemistry as a bridge to peace in the Middle East by organizing Conferences which bring together chemists from 15 Middle East Countries with five Nobel Laureates. The Conferences allow the participants to collaborate on solutions to problems facing the Middle East and the World. The issues are; Air and Water Quality, Alternative Energy Sources, and Science Education at all Levels. Eight conferences were held and the ninth is scheduled for 2019. More than 600 Middle East scientists already participated in these conferences. Considering that most of the participants are professors or directors of science institutions who have access to thousands of students, the number of people in the network is in the thousands. Between the conferences, the cross-border collaborations are ongoing despite the grave situation in the Middle East. In these conferences, the participants succeed in overcoming the chasms of distrust and intolerance. They do not just form collaborations, but form friendships. Hopefully, we will manage to form a critical mass of scientists who will be able to start the chain reaction for peace in the Middle East. Commitment, perseverance, and many times, bravery, helped me to overcome the obstacles I encountered.