Mini-Reviews in Organic Chemistry - Volume 18, Issue 6, 2021

Nucleosides and their analogues have been in use for many years and have become essential for treating patients with viral infections. Many additional nucleoside drugs have been approved over the past decades. This strongly demonstrates how important these compounds are and the crucial role they play. Given that a significant amount of research and literature has been documented regarding nucleoside analogues, this review article mainly focuses on nucleosides and nucleoside analogues that have proven to play a significant role in the treatment of known viral infections. This article covers the names, structures, applications, toxicity, and mode of action of relevant nucleoside analogues.

Currently, there is a growing interest in the development of suitable methods for the preparation of eco-friendly and biocompatible materials in order to increase environmental protection and reduce human health risk. Therefore, this mini-review summarizes several studies involving lactides and lactones as monomers for the synthesis of biodegradable and biocompatible polymers via metal-catalyzed Ring-Opening Polymerization (ROP). Hence, synthetic approaches involving mono, bi and trinuclear metallic catalysts, with different catalytic activity, were reviewed. Complexes mostly based on metals such as Na, Mg, Al, Ti, Zn are considered. Generally, from ROP reactions, it has been found that conversion, stereoselectivity, number-average molar mass (Mn) and dispersity of the molar mass (Ð) of polymers are influenced by the type of monomer, the characteristics of the catalyst, the nature of the solvent, temperature and reaction time. Additionally, the polymer properties can also be controlled by varying the molar ratios between the monomer and the initiating system. Thus, this review may be found helpful for the scientific community and students involved in research in different areas of chemistry such as organic chemistry, inorganic chemistry, polymers chemistry, and materials science. The survey covers selected data published between 2017 and 2020; however, previous relevant reports were also studied.

This paper presents a short review of synthetic approaches aiming to synthesise (+)- Grandisol, the main constituent of grandlure, a pheromone mixture released by the boll weevil, which is proven to exhibit significant biological activity. (+)-Grandisol 1 is among the components of the male-produced pheromone of the boll weevil Anthonomuns grandis, an important pest of cotton crops in Mesoamerica (from the south USA to Argentina). As a result of its biological activity and unique structure, several synthetic approaches have been reported. The aim is to explore remarkable methodologies towards the synthesis of (+)-Grandisol 1. Several methodologies have been applied towards the synthesis of (+)-Grandisol 1, including classical methods for cyclobutane ring construction, which promoted substantial improvements to access this pheromone, as well as a better comprehension of its biological profile.

Tetrahydrocarbazoles (THC) is a privileged structural scaffold containing natural indole as the central moiety. This extraordinary skeleton features in a plethora of naturally occurring pharmacological compounds and alkaloids exhibiting a significant inhibitory activity such as antibacterial, protein kinase inhibitor, and tumor growth inhibitor, etc. Due to its versatile biological properties, it always gains considerable attention among the scientific community. The main objective of this review is to make a comprehensive reference work on the synthesis and biological properties of THCs, thus targeting a broad audience on the assessment of various catalysts along with their reaction condition, mechanism of action, and yield, which are categorized into three groups: 1) organocatalyzed reactions; 2) TfOH catalyzed reactions; 3) metal-catalyzed reactions and 4) miscellaneous.

Gelatin produced from fish processing by-product is the most potential alternative source of gelatin. They have biological activities, particularly antioxidant, antihypertensive, and reduce type 2 diabetic risk. This paper reviews the mechanisms of fish gelatin hydrolysates for those human diseases being discussed in recent studies. Based on the review, mostly, skin and bone are used as sources of fish-based gelatin in which about thirty percent comes from the weight of total fish. Some species have been analysed based on their bioactivities, including Tuna, Nile tilapia, Amur sturgeon, Pangasius catfish, Cod, Blacktip shark, Salmon, Halibut, and Tilapia fish. In short, the antioxidant mechanism of this fish-based gelatin is by scavenging and neutralizing the radicals. The antihypertensive mechanism is by inhibition of Angiotensin-Converting Enzyme (ACE) activity. Whilst the mechanism to reduce type 2 diabetes is by inhibiting dipeptidyl peptidase IV (DPP-IV) action.

In this review, we examine ‘greener’ routes to nanoparticles of iron oxides, in the recent years; nanotechnology has emerged as a state-of-the-art and cutting edge technology with multifarious applications in a wide array of fields. Natural products or extracted from natural products, such as different plant extracts, have been used as reductants and as capping agents during synthesis. A very easy, efficient, and environment-friendly protocol was developed to synthesize green nanoparticles (NPs) with an aqueous extract of various plant, phenolic compounds extracted from plants play a major role as non-toxic reducing and capping agents for nanoparticles. Nanoparticles and their compounds are known to exert a strong inhibitory and microbial activity on bacteria, viruses, and fungi. In today's world, because of the epidemic of infectious diseases caused by different pathogenic bacteria and the development of antibiotic resistance, green synthesis, characterization, and application of nanoparticles (NPs) are becoming an important challenge in nanotechnology. Green synthesis of nanoparticles is made in large quantities worldwide for a wide range of applications. This technique is very safe and environmentally friendly.

New drugs introduced in the market each year, have privileged structures specifically for anticancer targets, of which quinoline-based analogues also play an important role. This review highlights quinoline and its derivatives, which have great potency against various cancer cells, including prostate cancer, breast cancer, colon cancer, pancreas cancer, and many more. This review describes the most preferred process-scale synthetic approaches of quinoline and its derivatives having a specific pharmacophore for anticancer targets. It also describes the undergoing development and recently approved drugs in tabular form. Quinoline moiety as a privileged structural pharmacophore has the most effective activity against different cancer cell lines like prostate cancer, breast cancer, stomach cancer, pancreas cancer, Colon cancer, CNS cancer, and renal cancer. It can be used as a lead compound for further research on anticancer drug discovery.

Benzoxazole compounds have an important and broad range of biological activities. The benzoxazole and its substituted derivatives possess antimicrobial, antitumor, anti-inflammatory, antihistaminic, anti-parasitic, herbicidal, anti-allergic, anti-helmintic, anti-tubercular, anticonvulsant, hypoglycaemic, HIV-1 reverse transcriptase inhibitor and insecticidal activities. It has also been shown to have a binding affinity to Aβ42 fibrils. Such complex biological uses of benzoxazole compounds have inspired new efforts to find new derivatives with improved biological activity and different applications in the pharmaceutical industry. Due to outstanding relevance of this structure, the purpose of this analysis is to highlight aspects published in recent years (2000-2020) on the chemistry and biological activity of benzoxazoles.

2-Imino-2H-chromene-3-carbo(thio)amides are considered versatile compounds because of their significance as building blocks in synthetic chemistry. In this review, we display all the available synthetic methods for 2-imino-2H-chromene-3-carbo(thio)amides as well as their reactions towards the different reagents. The presence of the imino and amide groups in these compounds makes C-4 the only reactive site of the pyran ring with a unique reactivity that could react with different reagents. The appropriate applications for the synthesis of condensed chromene derivatives and their relevancy are reported. The reactions of 2-imino-2H-chromene-3- carbo(thio)amides were divided into several categories depending on the used reagents in the reactions.

The process of melanogenesis that takes place in the melanocytes of the epidermis, leads to hyperpigmentation. The biosynthetic pathway for the production of melanin involves the enzyme tyrosinase that has been an attractive target for cosmaceutical research. Numerous synthetic, semisynthetic and natural, especially plant-based, inhibitors of tyrosinase have been reported in the literature. In plants, the secondary metabolites like flavonoids, chalcones, stilbenes, tannins, hydroquinone and kojic acid, etc., have been shown to possess anti-tyrosinase activity. In the current review, we have covered the progress in this sphere that would be useful for not only further mechanistic investigations but also for the optimization of the structure of the metabolites for improved activity and selectivity. Thus, the review presents a comprehensive report on tyrosinase inhibitors of plant origin reported in the extract form or as isolated compounds. A huge gap has been found between research and industry due to inconsistent pursual of potent plant-based extracts. There is a need to completely evaluate the extracts for structure optimization using molecular docking and evaluation of the safety in order to benefit the industry with non-toxic biological friendly products through in vivo and ex vivo optimization.