Stereoselective Shi-type epoxidation with 3-oxo-4,6-O-benzylidene pyranoside catalysts: unveiling the role of carbohydrate skeletons.

Asymmetric epoxidation represents a hot topic in organic synthesis. In recent years, organocatalysts based on sugar skeletons have been exploited in asymmetric epoxidation to achieve enantiomeric pure epoxides. In this work, two different endocyclic ketones derived from glucose and galactose protected with a 4,6-O-benzylidene group have been prepared and exploited for Shi-type epoxidation. The two carbohydrates show an opposite preferential stereoselective epoxidation on various olefins, affording the epoxides in high conversions and modest enantioselectivities. DFT calculations disclosed the reasons behind the inversion of selectivity achieved by the two catalysts, showing that a delicate balance between the catalyst conformation, its protecting groups, and the secondary interactions with the substrate govern the final observed results.

A New Glucosyl Flavone with Inhibitory Activity of Cancer Cell Viability and Other Bioactive Constituents from the Traditional Kurdish Plant Plantago loeflingii L.

A new glucosyl flavone, 5,7,2',5'-tetrahydroxyflavone 7-O-ß-d-glucopyranoside, named loeflingiin, together with apigenin 6-C-glucoside (isovitexin), coumarins citropten and isompinellin, triterpenoids betulin and betulinic acid, and a mixture of phytosterols ß-sitosterol, stigmasterol and campesterol were isolated for the first time from the leaves of wild Plantago loeflingii L. (Plantaginaceae) collected in the Iraqi Kurdistan region. The plant is used by local people to treat wounds and as a vulnerary remedy. The structures of isolated compounds were determined by spectroscopic analysis. The activities of isovitexin and loeflingiinon the viability of breast (MCF7), ovarian (BG-1), endometrial (Ishikawa), and mesothelioma (IST-MES1) human cancer cells and two normal cell lines were determined with an MTT assay. Notably, the new 7-O-glucosyl flavone showed effects higher than cisplatin against the Ishikawa and IST-MESI cell lines. The significant biological activities exhibited by all the compounds isolated from P. loeflingii provided scientific evidence to support the use of the plant in the Kurdish traditional medicine.

PPARα/γ-Targeting Amorfrutin Phytocannabinoids from Aerial Parts of Glycyrrhiza foetida.

An LC-MS/MS-guided analysis of the aerial parts of Glycyrrhiza foetida afforded new phenethyl (amorfrutin)- and alkyl (cannabis)-type phytocannabinoids (six and four compounds, respectively). The structural diversity of the new amorfrutins was complemented by the isolation of six known members and the synthesis of analogues modified on the aralkyl moiety. All of the compounds so obtained were assayed for agonist activity on PPARα and PPARγ nuclear receptors. Amorfrutin A (1) showed the highest agonist activity on PPARγ, amorfrutin H (7) selectively targeted PPARα, and amorfrutin E (4) behaved as a dual agonist, with the pentyl analogue of amorfrutin A (11) being inactive. Decarboxyamorfrutin A (2) was cytotoxic, and modifying its phenethyl moiety to a styryl or a phenylethynyl group retained this trait, suggesting an alternative biological scenario for these compounds. The putative binding modes of amorfrutins toward PPARα and PPARγ were obtained by a combined approach of molecular docking and molecular dynamics simulations, which provided insights on the structure-activity relationships of this class of compounds.

Δ8-THC Induces Up-Regulation of Glutamatergic Pathway Genes in Differentiated SH-SY5Y: A Transcriptomic Study.

Cannabinoids, natural or synthetic, have antidepressant, anxiolytic, anticonvulsant, and anti-psychotic properties. Cannabidiol (CBD) and delta-9-tetrahydrocannabinol (Δ9-THC) are the most studied cannabinoids, but recently, attention has turned towards minor cannabinoids. Delta-8-tetrahydrocannabinol (Δ8-THC), an isomer of Δ9-THC, is a compound for which, to date, there is no evidence of its role in the modulation of synaptic pathways. The aim of our work was to evaluate the effects of Δ8-THC on differentiated SH-SY5Y human neuroblastoma cells. Using next generation sequencing (NGS), we investigated whether Δ8-THC could modify the transcriptomic profile of genes involved in synapse functions. Our results showed that Δ8-THC upregulates the expression of genes involved in the glutamatergic pathway and inhibits gene expression at cholinergic synapses. Conversely, Δ8-THC did not modify the transcriptomic profile of genes involved in the GABAergic and dopaminergic pathways.

Δ8-THC Protects against Amyloid Beta Toxicity Modulating ER Stress In Vitro: A Transcriptomic Analysis.

Alzheimer's disease (AD) represents the most common form of dementia, characterized by amyloid ß (Aß) plaques and neurofibrillary tangles (NFTs). It is characterized by neuroinflammation, the accumulation of misfolded protein, ER stress and neuronal apoptosis. It is of main importance to find new therapeutic strategies because AD prevalence is increasing worldwide. Cannabinoids are arising as promising neuroprotective phytocompounds. In this study, we evaluated the neuroprotective potential of Δ8-THC pretreatment in an in vitro model of AD through transcriptomic analysis. We found that Δ8-THC pretreatment restored the loss of cell viability in retinoic acid-differentiated neuroblastoma SH-SY5Y cells treated with Aß1-42. Moreover, the transcriptomic analysis provided evidence that the enriched biological processes of gene ontology were related to ER functions and proteostasis. In particular, Aß1-42 upregulated genes involved in ER stress and unfolded protein response, leading to apoptosis as demonstrated by the increase in Bax and the decrease in Bcl-2 both at gene and protein expression levels. Moreover, genes involved in protein folding and degradation were also deregulated. On the contrary, Δ8-THC pretreatment reduced ER stress and, as a consequence, neuronal apoptosis. Then, the results demonstrated that Δ8-THC might represent a new neuroprotective agent in AD.

A Classic Photochemical Approach Inducing an Unexpected Rearrangement: Exploring the Photoreactivity of Pentacyclic Triterpenic Acids.

The discovery of new bioactivities is closely related to the generation of novel scaffolds, and in the past few years different strategies have been proposed to obtain unknown architectures from the manipulation of known compounds. In the present study, we exploited a vintage photochemical approach for the discovery of an unexpected pathway of reactivity related to Δ1-3-oxo-pentacyclic triterpenic acids gaining access to a new class of natural-unnatural 5(10→1)abeo-pentacyclic triterpenic acids.

Identification of a Novel Curcumin Derivative Influencing Notch Pathway and DNA Damage as a Potential Therapeutic Agent in T-ALL.

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematological malignancy considered curable by modern clinical management. Nevertheless, the prognosis for T-ALL high-risk cases or patients with relapsed and refractory disease is still dismal. Therefore, there is a keen interest in developing more efficient and less toxic therapeutic approaches. T-ALL pathogenesis is associated with Notch signaling alterations, making this pathway a highly promising target in the fight against T-ALL. Here, by exploring the anti-leukemic capacity of the natural polyphenol curcumin and its derivatives, we found that curcumin exposure impacts T-ALL cell line viability and decreases Notch signaling in a dose- and time-dependent fashion. However, our findings indicated that curcumin-mediated cell outcomes did not depend exclusively on Notch signaling inhibition, but might be mainly related to compound-induced DNA-damage-associated cell death. Furthermore, we identified a novel curcumin-based compound named CD2066, endowed with potentiated anti-proliferative activity in T-ALL compared to the parent molecule curcumin. At nanomolar concentrations, CD2066 antagonized Notch signaling, favored DNA damage, and acted synergistically with the CDK1 inhibitor Ro3306 in T-ALL cells, thus representing a promising novel candidate for developing therapeutic agents against Notch-dependent T-ALL.

Cannabinol: History, Syntheses, and Biological Profile of the Greatest "Minor" Cannabinoid.

Cannabis (Cannabis sativa L.) is an outstanding source of bioactive natural products, with more than 150 different phytocannabinoids isolated throughout the decades; however, studies of their bioactivity have historically concentrated on the so-called "big four" [∆9-THC (1a), CBD (2a), CBG (3a) and CBC (4a)]. Among the remaining products, which have traditionally been referred to as "minor cannabinoids", cannabinol (CBN, 5a) stands out for its important repercussions and implications on the global scientific landscape. Throughout this review, we will describe why CBN (5a) deserves a prominent place within the so-called "cannabinome", providing an overview on its history, the syntheses developed, and its bioactivity, highlighting its promising pharmacological potential and the significant impact that the study of its chemistry had on the development of new synthetic methodologies.

Curcumin-based-fluorescent probes targeting ALDH1A3 as a promising tool for glioblastoma precision surgery and early diagnosis.

Glioblastoma (GBM) is the most aggressive primary brain tumour for which both effective treatments and efficient tools for an early-stage diagnosis are lacking. Herein, we present curcumin-based fluorescent probes that are able to bind to aldehyde dehydrogenase 1A3 (ALDH1A3), an enzyme overexpressed in glioma stem cells (GSCs) and associated with stemness and invasiveness of GBM. Two compounds are selective versus ALDH1A3, without showing any appreciable interaction with other ALDH1A isoenzymes. Indeed, their fluorescent signal is detectable only in our positive controls in vitro and absent in cells that lack ALDH1A3. Remarkably, in vivo, our Probe selectively accumulate in glioblastoma cells, allowing the identification of the growing tumour mass. The significant specificity of our compounds is the necessary premise for their further development into glioblastoma cells detecting probes to be possibly used during neurosurgical operations.

Rotational constriction of curcuminoids impacts 5-lipoxygenase and mPGES-1 inhibition and evokes a lipid mediator class switch in macrophages.

Polypharmacological targeting of lipid mediator networks offers potential for efficient and safe anti-inflammatory therapy. Because of the diversity of its biological targets, curcumin (1a) has been viewed as a privileged structure for bioactivity or, alternatively, as a pan-assay interference (PAIN) compound. Curcumin has actually few high-affinity targets, the most remarkable ones being 5-lipoxygenase (5-LOX) and microsomal prostaglandin E2 synthase (mPGES)-1. These enzymes are critical for the production of pro-inflammatory leukotrienes and prostaglandin (PG)E2, and previous structure-activity-relationship studies in this area have focused on the enolized 1,3-diketone motif, the alkyl-linker and the aryl-moieties, neglecting the rotational state of curcumin, which can adopt twisted conformations in solution and at target sites. To explore how the conformation of curcuminoids impacts 5-LOX and mPGES-1 inhibition, we have synthesized rotationally constrained analogues of the natural product and its pyrazole analogue by alkylation of the linker and/or of the ortho aromatic position(s). These modifications strongly impacted 5-LOX and mPGES-1 inhibition and their systematic analysis led to the identification of potent and selective 5-LOX (3b, IC50 = 0.038 µM, 44.7-fold selectivity over mPGES-1) and mPGES-1 inhibitors (2f, IC50 = 0.11 µM, 4.6-fold selectivity over 5-LOX). Molecular docking experiments suggest that the C2-methylated pyrazolocurcuminoid 3b targets an allosteric binding site at the interface between catalytic and regulatory 5-LOX domain, while the o, o'-dimethylated desmethoxycurcumin 2f likely binds between two monomers of the trimeric mPGES-1 structure. Both compounds trigger a lipid mediator class switch from pro-inflammatory leukotrienes to PG and specialized pro-resolving lipid mediators in activated human macrophages.

Minor Phytocannabinoids: A Misleading Name but a Promising Opportunity for Biomedical Research.

Despite the very large number of phytocannabinoids isolated from Cannabis (Cannabis sativa L.), bioactivity studies have long remained focused on the so called "Big Four" [Δ9-THC (1), CBD (2), CBG (3) and CBC (4)] because of their earlier characterization and relatively easy availability via isolation and/or synthesis. Bioactivity information on the chemical space associated with the remaining part of the cannabinome, a set of ca 150 compounds traditionally referred to as "minor phytocannabinoids", is scarce and patchy, yet promising in terms of pharmacological potential. According to their advancement stage, we sorted the bioactivity data available on these compounds, better referred to as the "dark cannabinome", into categories: discovery (in vitro phenotypical and biochemical assays), preclinical (animal models), and clinical. Strategies to overcome the availability issues associated with minor phytocannabinoids are discussed, as well as the still unmet challenges facing their development as mainstream drugs.

Photochemistry of Cannabidiol (CBD) Revised. A Combined Preparative and Spectrometric Investigation.

Cannabis is a plant with an astonishing ability to biosynthesize cannabinoids, and more than 100 molecules belonging to this class have been isolated. Among them in recent years cannabidiol (CBD) has received the interest of pharmacology as the major nonpsychotropic cannabinoid with many potential clinical applications. Although the reactivity of CBD has been widely investigated, only little attention has been given to the possible photodegradation of this cannabinoid, and the data available in the literature are outdated and, in some cases, conflicting. The aim of the present work is providing a characterization of the photochemical behavior of CBD in organic solvents, through a detailed GC-MS analyses, isolation, and NMR characterization of the photoproducts obtained.

Cannabinoquinones: Synthesis and Biological Profile.

Neutral cannabinoids are oxidatively unstable and are converted into quinone derivatives by atmospheric- and/or chemical oxidative dearomatization. The study of cannabinoquinones has long been plagued by their lability toward additional oxidative degradation, but full substitution of the quinone ring, as well as the introduction of steric hindrance on the alkyl substituent, have provided sufficient stability for a systematic investigation of their bioactivity and for further clinical development. These studies culminated in the discovery of the aminocannabinoquinone VCE-004.8 (5), a compound under phase 2 clinical development with orphan drug status by EMA and FDA for the management of scleroderma. The synthesis and rich chemistry of these compounds will be described, summarizing their biological profile and clinical potential.

EHP-101 alleviates angiotensin II-induced fibrosis and inflammation in mice.

Some cannabinoids showed anti-inflammatory and antifibrotic activities. EHP-101 is an oral lipidic formulation of the novel non-psychotropic cannabidiol aminoquinone VCE-004.8, which showed antifibrotic activity in murine models of systemic sclerosis induced by bleomycin. We herein examined the effect of EHP-101 on cardiac and other organ fibrosis in a mouse model induced by Angiotensin II. VCE-004.8 inhibited TGFß- and Ang II-induced myofibroblast differentiation in cardiac fibroblasts detected by α-SMA expression. VCE-004.8 also inhibited Ang II-induced ERK 1 + 2 phosphorylation, NFAT activation and mRNA expression of IL1ß, IL6, Col1A2 and CCL2 in cardiac fibroblasts. Mice infused with Ang II resulted in collagen accumulation in left ventricle, aortic, dermal, renal and pulmonary tissues; oral administration of EHP-101, Ajulemic acid and Losartan improved these phenotypes. In myocardial tissue, Ang II induced infiltration of T cells and macrophages together with the accumulation of collagen and Tenascin C; those were all reduced by either EHP-101 or Losartan treatment. Cardiac tissue RNA-Seq analyses revealed a similar transcriptomic signature for both treatments for inflammatory and fibrotic pathways. However, the gene set enrichment analysis comparing data from EHP-101 vs Losartan showed specific hallmarks modified only by EHP-101. Specifically, EHP-101 inhibited the expression of genes such as CDK1, TOP2A and MKi67 that are regulated to the E2 factor family of transcription factors. This study suggests that the oral administration of EHP-101 prevents and inhibits cardiac inflammation and fibrosis. Furthermore, EHP-101 inhibits renal, pulmonary and dermal fibrosis. EHP-101 could offer new opportunities in the treatment of cardiac fibrosis and other fibrotic diseases.

The Combined Effect of Branching and Elongation on the Bioactivity Profile of Phytocannabinoids. Part I: Thermo-TRPs.

The affinity of cannabinoids for their CB1 and CB2 metabotropic receptors is dramatically affected by a combination of α-branching and elongation of their alkyl substituent, a maneuver exemplified by the n-pentyl -> α,α-dimethylheptyl (DMH) swap. The effect of this change on other cannabinoid end-points is still unknown, an observation surprising since thermo-TRPs are targeted by phytocannabinoids with often sub-micromolar affinity. To fill this gap, the α,α-dimethylheptyl analogues of the five major phytocannabinoids [CBD (1a), Δ8-THC (6a), CBG (7a), CBC (8a) and CBN (9a)] were prepared by total synthesis, and their activity on thermo-TRPs (TRPV1-4, TRPM8, and TRPA1) was compared with that of one of their natural analogues. Surprisingly, the DMH chain promoted a shift in the selectivity toward TRPA1, a target involved in pain and inflammatory diseases, in all investigated compounds. A comparative study of the putative binding modes at TRPA1 between DMH-CBC (8b), the most active compound within the series, and CBC (8a) was carried out by molecular docking, allowing the rationalization of their activity in terms of structure-activity relationships. Taken together, these observations qualify DMH-CBC (8b) as a non-covalent TRPA1-selective cannabinoid lead that is worthy of additional investigation as an analgesic and anti-inflammatory agent.

Δ9-cis-Tetrahydrocannabinol: Natural Occurrence, Chirality, and Pharmacology.

The cis-stereoisomers of Δ9-THC [(-)-3 and (+)-3] were identified and quantified in a series of low-THC-containing varieties of Cannabis sativa registered in Europe as fiber hemp and in research accessions of cannabis. While Δ9-cis-THC (3) occurs in cannabis fiber hemp in the concentration range of (-)-Δ9-trans-THC [(-)-1], it was undetectable in a sample of high-THC-containing medicinal cannabis. Natural Δ9-cis-THC (3) is scalemic (ca. 80-90% enantiomeric purity), and the absolute configuration of the major enantiomer was established as 6aS,10aR [(-)-3] by chiral chromatographic comparison with a sample available by asymmetric synthesis. The major enantiomer, (-)-Δ9-cis-THC [(-)-3], was characterized as a partial cannabinoid agonist in vitro and elicited a full tetrad response in mice at 50 mg/kg doses. The current legal discrimination between narcotic and non-narcotic cannabis varieties centers on the contents of "Δ9-THC and isomers" and needs therefore revision, or at least a more specific wording, to account for the presence of Δ9-cis-THCs [(+)-3 and (-)-3] in cannabis fiber hemp varieties.

Biomimetic Approaches to the Synthesis of Natural Disesquiterpenoids: An Update.

Natural disesquiterpenoids represent a small group of secondary metabolites characterized by complex molecular scaffolds and interesting pharmacological profiles. In the last decade, more than 400 new disesquiterpenoids have been discovered and fully characterized, pointing out once more the "magic touch" of nature in the design of new compounds. The perfect blend of complex and unique architectures and biological activity has made sesquiterpene dimers an attractive and challenging synthetic target, inspiring organic chemists to find new and biomimetic approaches to replicate the efficiency and the selectivity of natural processes under laboratory conditions. In this work, we present a review covering the literature from 2010 to 2020 reporting all the efforts made in the total synthesis of complex natural disesquiterpenoids.

The SNAP-tag technology revised: an effective chemo-enzymatic approach by using a universal azide-based substrate.

SNAP-tag ® is a powerful technology for the labelling of protein/enzymes by using benzyl-guanine (BG) derivatives as substrates. Although commercially available or ad hoc produced, their synthesis and purification are necessary, increasing time and costs. To address this limitation, here we suggest a revision of this methodology, by performing a chemo-enzymatic approach, by using a BG-substrate containing an azide group appropriately distanced by a spacer from the benzyl ring. The SNAP-tag ® and its relative thermostable version (SsOGT-H5 ) proved to be very active on this substrate. The stability of these tags upon enzymatic reaction makes possible the exposition to the solvent of the azide-moiety linked to the catalytic cysteine, compatible for the subsequent conjugation with DBCO-derivatives by azide-alkyne Huisgen cycloaddition. Our studies propose a strengthening and an improvement in terms of biotechnological applications for this self-labelling protein-tag.

Isomeric O-methyl cannabidiolquinones with dual BACH1/NRF2 activity.

Oxidative stress and inflammation in the brain are two key hallmarks of neurodegenerative diseases (NDs) such as Alzheimer's, Parkinson's, Huntington's and multiple sclerosis. The axis NRF2-BACH1 has anti-inflammatory and anti-oxidant properties that could be exploited pharmacologically to obtain neuroprotective effects. Activation of NRF2 or inhibition of BACH1 are, individually, promising therapeutic approaches for NDs. Compounds with dual activity as NRF2 activators and BACH1 inhibitors, could therefore potentially provide a more robust antioxidant and anti-inflammatory effects, with an overall better neuroprotective outcome. The phytocannabinoid cannabidiol (CBD) inhibits BACH1 but lacks significant NRF2 activating properties. Based on this scaffold, we have developed a novel CBD derivative that is highly effective at both inhibiting BACH1 and activating NRF2. This new CBD derivative provides neuroprotection in cell models of relevance to Huntington's disease, setting the basis for further developments in vivo.