Heterocyclic compounds hold a special place among pharmaceutically important natural and synthetic materials. The remarkable ability of heterocyclic nuclei to serve both as biomimetics and reactive pharmacophores has largely contributed to their unique value as traditional key elements of numerous drugs. In both lead identification and lead optimization processes there is an acute need for new organic small molecules. Traditional methods of organic synthesis are orders of magnitude too slow to satisfy the demand for these compounds. The fields of combinatorial and automated medicinal chemistry have been developed to meet the increasing requirement of new compounds for drug discovery, within these fields, speed is of the essence. The efficiency of microwave flash-heating chemistry in dramatically reducing reaction times (reduced from days and hours to minutes and seconds) has recently been proven in several different fields of organic chemistry. We believe that the time saved by using focused microwaves is potentially important in traditional organic synthesis but could be of even greater importance in high-speed combinatorial and medicinal chemistry. In this review, it is impossible to cover all significant developments in the area of microwave-assisted organic synthesis (MAOS). Rather, outlines the basic principles behind the technology and summarizes the areas in which microwave technology has made an impact, to date. Specific attention is given to application of microwave irradiation in liquid systems, and in the solid state as well of several representative biologically interesting nuclei. In addition we report some of the most recently disclosed applications in combinatorial chemistry.

The interest in the microwave assisted organic synthesis has been growing during the recent years. It results from an increasing knowledge of fundamentals of the dielectric heating theory, availability of an equipment designed especially for the laboratory use as well as the discovery of the special techniques of the microwave syntheses. The efficiency of microwave flash-heating chemistry in dramatically reducing reaction times (reduced from days and hours to minutes and seconds) has recently been proven in several different fields of organic chemistry and this aspect is of great importance in high-speed combinatorial and medicinal chemistry. In this contribution, the current state of the art is summarized providing examples of the most recent applications in the field of microwave assisted synthesis of biologically active compounds both in heterocyclic and in peptide and peptidomimetic optimization.

Hydrogen sulfide (H₂S) is a ubiquitous gaseous signaling molecule that has an important role in many physiological and pathological processes in mammalian tissues, with the same importance as two others endogenous gasotransmitters such as NO (nitric oxide) and CO (carbon monoxide). Endogenous H₂S is involved in a broad gamut of processes in mammalian tissues including inflammation, vascular tone, hypertension, gastric mucosal integrity, neuromodulation, and defense mechanisms against viral infections as well as SARS-CoV-2 infection. These results suggest that the modulation of H₂S levels has a potential therapeutic value. Consequently, synthetic H₂S-releasing agents represent not only important research tools, but also potent therapeutic agents. This review has been designed in order to summarize the currently available H₂S donors; furthermore, herein we discuss their preparation, the H₂S-releasing mechanisms, and their -biological applications.

Hydrogen sulfide (H₂S) is an endogenous gasotransmitter recently emerged as an important regulatory mediator of numerous human cell functions in health and in disease. In fact, much evidence has suggested that hydrogen sulfide plays a significant role in many physio-pathological processes, such as inflammation, oxidation, neurophysiology, ion channels regulation, cardiovascular protection, endocrine regulation, and tumor progression. Considering the plethora of physiological effects of this gasotransmitter, the protective role of H₂S donors in different disease models has been extensively studied. Based on the growing interest in H₂S-releasing compounds and their importance as tools for biological and pharmacological studies, this review is an exploration of currently available H₂S donors, classifying them by the H₂S-releasing-triggered mechanism and highlighting those potentially useful as promising drugs in the treatment of cardiovascular diseases.

The present research has been focused on the evaluation of seasonal changes in mass concentrations and compositions of heavy metals in Particular Matters (PM)₁₀ collected from a typical urban-industrial site in Acerra, a city located in an area called “triangle of death”. No significant (p < 0.05) seasonal variation was evidenced for the PM₁₀ concentration, but in all the seasons (except for autumn) exceedances of daily concentrations (50 μg m⁻³) were observed. Airborne PM was analyzed for these heavy metals: Al, As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sb, V and Zn, which represented about 8% of the PM₁₀ concentrations. None of the metals classified by IARC as carcinogenic in humans (group 1) exceeded on average the annual EU’s and Italy’s limit. For the mentioned heavy metals the enrichment factors (EnFs) were analyzed and highlighted high enrichment for Cd, Sb, Pb, As, Cu and Zn. Principal component analysis (PCA) for the heavy metals in PM₁₀ identified oil combustion, vehicle and industrial emissions as major sources. To assess the health risk related to the inhalation to airborne PM₁₀ metals, we applied the Cancer Risk (CR) and Target Hazard Quotient (THQ). The results showed that the CR was similar for a child and an adult, while the THQ proved to be higher for a child than for an adult. The low PM metals risk in the urban industrial site was in agreement with the ongoing lowering trend of metals in Italy and Europe.