Stereocontrolled synthesis and functionalization of cyclobutanes and cyclobutanones

In the last decade a certain number of new cyclobutane and cyclobutanone synthesis and functionalization protocols have been published. Organo- and biocatalyzed eco-friendly approaches to cyclobutane-containing molecules have been developed with interesting results. Also, successful new total synthesis of bioactive compounds and drugs have been recently reported where a four membered ring represented the key intermediate. Therefore, the rising interest in this field represents a great point of discussion for the scientific community, disclosing the synthetic potential of strained four membered ring carbocyclic compounds. Herein we report a critical survey on the literature concerning the enantiocontrolled synthesis and functionalization of cyclobutane derivatives, with particular attention to metal-free, low impact methodologies, published during the period 2000–2013

Isolamento ed analisi di molecole bioattive da estratti di <i>Pistacia Terebinthus L.</i> vegetante in Sardegna

Il genere Pistacia (Anacardiacee) include P. Terebinthus, piccolo albero a foglie decidue presente in Sardegna solo in una ristretta area calcarea della costa est, Cala Gonone (NU). Le specie del genere Pistacia hanno un largo uso in etnobotanica; venivano usati come antiinfiammatori, antibatterici, nel trattamento dell’eczema. Questo ci ha portato a pensare, anche in base alla letteratura presente, che nelle piante appartenenti a questo genere ci siano delle molecole particolarmente importanti dal punto di vista farmaceutico. Partendo dalle osservazioni di etnobotanica abbiamo voluto investigare la composizione chimica di questa specie con lo scopo di trovare, eventualmente, dei nuovi nutraceutici

Halogen and Hydrogen Bonding Benzothiophene Diol Derivatives: A Study Using ab initio Calculations and XRay Crystal Structure Measurements

The aim of this study is to describe and compare the supramolecular interactions, in the solid state, of chloro-, bromo-, and iodobenzothiophene diols. The compounds were obtained through organo-catalyzed reactions starting from 3-substituted halobenzothiophene carbaldehydes. Energies of the noncovalent interactions were obtained by density functional theory calculations. Bond distances and angles were found to be in accordance with those determined by X-ray structure analysis. anti-Bromobenzothiophene derivatives showed strong halogen ···p interactions between bromine and the heterocyclic phenyl ring, corresponding to an energy of 7.5 kcalmol1. syn- Bromo and syn-iodo derivatives appeared to be isostructural, showing X···O (carbonyl) interactions, p stacking, and formation of extended hydrogen bonding networks. In contrast, the chloro derivatives displayed no halogen bonding interaction

Synthesis of functionalized tryptamines by Brønsted acid catalysed cascade reactions

An original synthetic protocol has been developed for the preparation of highly functionalized tryptamines from 2-hydroxycyclobutanone and secondary arylamines via a solvent-free Brønsted acid catalysed two-step reaction sequence

4-(3-Nitrophenyl)thiazol-2-ylhydrazone derivatives as antioxidants and selective hMAO-B inhibitors: synthesis, biological activity and computational analysis

A new series of 4-(3-nitrophenyl)thiazol-2-ylhydrazone derivatives were designed, synthesised, and evaluated to assess their inhibitory effect on the human monoamine oxidase (hMAO) A and B isoforms. Different (un)substituted (hetero)aromatic substituents were linked to N1 of the hydrazone in order to establish robust structure–activity relationships. The results of the biological testing demonstrated that the presence of the hydrazothiazole nucleus bearing at C4 a phenyl ring functionalised at the meta position with a nitro group represents an important pharmacophoric feature to obtain selective and reversible human MAO-B inhibition for the treatment of neurodegenerative disorders. In addition, the most potent and selective MAO-B inhibitors were evaluated in silico as potential cholinesterase (AChE/BuChE) inhibitors and in vitro for antioxidant activities. The results obtained from molecular modelling studies provided insight into the multiple interactions and structural requirements for the reported MAO inhibitory properties

Atriplex mollis desf. Aerial parts: extraction procedures, secondary metabolites and color analysis

A method using high-performance liquid chromatography coupled with a photodiode array detector was proposed for the rapid characterization of different phenolic constituents from the extracts of Atriplex mollis aerial parts. Atriplex species are known for their multiple biological activities, but no information is available in the literature about A. mollis. With the aim to firstly characterize the main secondary metabolites of this plant, so as to orient better the biological evaluation, we applied three different extraction procedures and compared the chromatographic results. Microwave-assisted extraction gave the best yield and recovery of important compounds such as gallic acid, catechin, chlorogenic acid, p-OH benzoic acid, rutin, sinapinic acid, t-ferulic acid, naringenin and benzoic acid. These constituents belong to three important chemical classes: phenolic acids, flavonoids and monoterpenes. Color evaluation and analysis of chlorophylls (a and b) and carotenoids complete the preliminary profile of this plant. From these analyses, Atriplex mollis is a source of bioactive compounds (especially rutin, t-ferulic acid and gallic acid) and could be recommended as a plant of phyto-pharmaceutical relevance, opening new perspectives on this salt-tolerant plant

Benzo[b]tiophen-3-ol derivatives as effective inhibitors of human monoamine oxidase: design, synthesis, and biological activity

A series of benzo[b]thiophen-3-ols were synthesised and investigated as potential human monoamine oxidase (hMAO) inhibitors in vitro as well as ex vivo in rat cortex synaptosomes by means of evaluation of 3,4-dihydroxyphenylacetic acid/dopamine (DOPAC/DA) ratio and lactate dehydrogenase (LDH) activity. Most of these compounds possessed high selectivity for the MAO-B isoform and a discrete antioxidant and chelating potential. Molecular docking studies of all the compounds underscored potential binding site interactions suitable for MAO inhibition activity, and suggested structural requirements to further improve the activity of this scaffold by chemical modification of the aryl substituents. Starting from this heterocyclic nucleus, novel lead compounds for the treatment of neurodegenerative disease could be developed

Preparation of Cyclobutene Acetals and Tricyclic Oxetanes through Photochemical Tandem and Cascade Reactions

We describe a photochemical reaction using two starting materials, a cyclopent-2-enone and an alkene, which are transformed in a controlled manner via the initial [2+2]-photocycloaddition adducts into cyclobutene aldehydes (conveniently trapped as stable acetals) or unprecedented angular tricyclic 4:4:4 oxetane-containing skeletons. These compounds are formed through tandem or triple cascade photochemical reaction processes, respectively. Small libraries of each compound class were prepared, thus suggesting that this photochemistry approach opens new opportunities for synthesis design and for widening molecular diversity

SARS-CoV-2 Fusion Peptide Conjugated to a Tetravalent Dendrimer Selectively Inhibits Viral Infection

Fusion is a key event for enveloped viruses, through which viral and cell membranes come into close contact. This event is mediated by viral fusion proteins, which are divided into three structural and functional classes. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein belongs to class I fusion proteins, characterized by a trimer of helical hairpins and an internal fusion peptide (FP), which is exposed once fusion occurs. Many efforts have been directed at finding antivirals capable of interfering with the fusion mechanism, mainly by designing peptides on the two heptad-repeat regions present in class I viral fusion proteins. Here, we aimed to evaluate the anti-SARS-CoV-2 activity of the FP sequence conjugated to a tetravalent dendrimer through a classical organic nucleophilic substitution reaction (SN2) using a synthetic bromoacetylated peptide mimicking the FP and a branched scaffold of poly-L-Lysine functionalized with cysteine residues. We found that the FP peptide conjugated to the dendrimer, unlike the monomeric FP sequence, has virucidal activity by impairing the attachment of SARS-CoV-2 to cells. Furthermore, we found that the peptide dendrimer does not have the same effects on other coronaviruses, demonstrating that it is selective against SARS-CoV-2

Association between High Normal TSH Levels and Obesity in Women with Anti-Thyroid Autoantibodies (ATAs)

A positive correlation between Thyroid-Stimulating Hormone (TSH) and Body Mass Index (BMI) has been reported in many studies, but data on this topic remain controversial, especially when TSH values are in the normal range. Moreover, few studies have evaluated the co-existence of thyroid autoimmunity. This study investigated the role of thyroid autoimmunity in the interconnection between TSH, BMI, and waist circumference (WC) in euthyroid patients with overweight or obesity. We enrolled 902 patients (213 males; mean age +/- SD: 45 +/- 14 years; mean BMI +/- SD: 35.8 +/- 6.5 kg/m(2)), with normal serum TSH concentration; anti-thyroid autoantibodies (ATAs) were evaluated in 752 patients (186 males). Patients were divided into four BMI classes, based on WHO criteria, and the relationship between BMI, WC, and TSH was evaluated in the whole sample and compared to ATAs positivity, observed in 235 patients (44 males). No significant difference was found between TSH levels in the BMI classes. A statistically significant correlation between TSH and BMI was found only in ATAs-positive females (N = 191, Spearman rho: 0.149; p-value: 0.040). However, this finding was not confirmed when considering the WC. Our study shows a positive correlation only between TSH and BMI in obese women with positive ATAs, suggesting that in these patients, the high normal levels of TSH could be attributed to a mild thyroid failure with a possible worsening obesity-related effect, and both need a careful evaluation