The environmentally amiable route to carbon-heteroatom bond formation, described by Sharpless as ‘click chemistry’, has become known as a fast, efficient, and reliable approach to the synthesis of novel compounds with desired functionalities. Readily available starting materials must be used in this methodology and they should be essentially inert to most biological and organic conditions, including water and molecular oxygen. In this review, we cover reactions included in this label such as cycloadditions, nucleophilic ring-opening reactions of strained cycles, and amide synthesis, as well as their applications in organic synthesis, molecular biology, macromolecular chemistry and materials science.

Hydroxytyrosol is a phenol found predominantly in the olive tree (Olea europea). It shows a broad spectrum of beneficial effects such as cancer chemoprevention by inducing apoptosis, cardioprotection and anti-atherogenic activity, skin photoprotection and anti-inflammatory activity. These biological properties are based on scavenging of reactive oxygen species by hydroxytyrosol, being more active than antioxidant vitamins and synthetic antioxidants. Its biological activities and beneficial effects on human health has stimulated the development of new methods of extraction and purification from olive mill wastewater, from table olive processing, or from leaves. Different procedures for the chemical and enzymatic synthesis of hydroxytyrosol have been developed from tyrosol, from 3,4-dihydroxyphenylacetic acid and its methyl ester, and from oleuropein. Some hydroxytyrosol acyl derivatives have been prepared by chemical and chemoenzimatic methods in order to increase both stability and solubility in lipophilic preparations. Mechanistic experiments on hydroxytyrosol oxidation and isolation of species formed by oxidation are also reported.

Drug resistance remains the major cause of cancer treatment failure especially at the late stage of the disease. However, based on their versatile chemistry, metal and metalloid compounds offer the possibility to design fine-tuned drugs to circumvent and even specifically target drug-resistant cancer cells. Based on the paramount importance of platinum drugs in the clinics, two main areas of drug resistance reversal strategies exist: overcoming resistance to platinum drugs as well as multidrug resistance based on ABC efflux pumps. The current review provides an overview of both aspects of drug design and discusses the open questions in the field. The areas of drug resistance covered in this article involve: 1) Altered expression of proteins involved in metal uptake, efflux or intracellular distribution, 2) Enhanced drug efflux via ABC transporters, 3) Altered metabolism in drug-resistant cancer cells, 4) Altered thiol or redox homeostasis, 5) Altered DNA damage recognition and enhanced DNA damage repair, 6) Impaired induction of apoptosis and 7) Altered interaction with the immune system. This review represents the first collection of metal (including platinum, ruthenium, iridium, gold, and copper) and metalloid drugs (e.g. arsenic and selenium) which demonstrated drug resistance reversal activity. A special focus is on compounds characterized by collateral sensitivity of ABC transporter-overexpressing cancer cells. Through this approach, we wish to draw the attention to open research questions in the field. Future investigations are warranted to obtain more insights into the mechanisms of action of the most potent compounds which target specific modalities of drug resistance.

Insecticides have a pivotal role in our lives, not only for crop protection in agriculture, but also to avoid the spreading of harmful pests causing human diseases such as malaria. Due to economic and medical reasons, the design of effective agents that control these pests is quite an important task in agrochemical science and in the industrial sector. Nevertheless, the non-restricted use of highly toxic insecticides for several decades has provoked negative effects in the environment and the poisoning of non-targeted species. For these reasons, the development of selective and harmless insecticides is needed. A short overview of some of the recent advances in the chemistry of insecticides is presented, with a highlight of their greenness compared with classical insecticides. Synthesis, mode of action and environmental profile of pyrethroids, neonicotinoids, and insect growth regulators will be described. Furthermore, the use of biological insecticides such as spinosyns, azadirachtin, and Bacillus thuringiensis as green alternatives for synthetic insecticides will also be reviewed.