
Concetta ImperatoreUniversity of Naples Federico II | UNINA · Department of Pharmacy
Concetta Imperatore
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Publications (68)
The one- or two-electron reduction in quinone compounds gives rise to semiquinones and hydroquinones, respectively, which, in turn, can be oxidized back to quinones, generating a cyclic redox system with the production of reactive oxygen species (ROS). For these reasons, quinone derivatives participate in various biological processes in metabolic p...
Human 15‐lipoxygenase‐1 (15‐LOX‐1) is a key enzyme that possesses an important role in (neuro)inflammatory diseases. The pocket of the enzyme plays the role of a chiral catalyst, and therefore chirality could be an important component for the design of effective enzyme inhibitors. To advance our knowledge on this concept, we developed a library of...
Marine natural products constitute a great source of potential new antidiabetic drugs. The aim of this study was to evaluate the role of phosphoeleganin (PE), a polyketide purified from the Mediterranean ascidian Sidnyum elegans, and its derivatives PE/2 and PE/3 on insulin sensitivity in human hepatocellular carcinoma (HepG2) cells. In our experim...
Hydrogen sulfide (H2S) is a signaling molecule endogenously produced within mammals’ cells that plays an important role in inflammation, exerting anti-inflammatory effects. In this view, the research has shown a growing interest in identifying natural H2S donors. Herein, for the first time, the potential of marine extract as a source of H2S-releasi...
Background:
Type 2 diabetes mellitus (T2DM) is an ongoing, risky, and costly health problem that therefore always requires new treatment options. Moreover, although several drugs are available, only 36% of patients achieve glycaemic control, and patient adherence is a major obstacle. With monotherapy, T2DM and its comorbidities/complications often...
Type 2 diabetes mellitus (T2DM) is a complex disease characterized by impaired glucose homeostasis and serious long-term complications. First-line therapeutic options for T2DM treatment are monodrug therapies, often replaced by multidrug therapies to ensure that non-responding patients maintain target glycemia levels. The use of multitarget drugs i...
Diabetes mellitus (DM) represents a complex and multifactorial disease that causes metabolic disorders with acute and long-term serious complications. The onset of DM, with over 90% of cases of diabetes classified as type 2, implies several metabolic dysfunctions leading to consider DM a worldwide health problem. In this frame, protein tyrosine pho...
The chemical investigation of the Mediterranean ascidian Clavelina lepadiformis has led to the isolation of a new lepadin, named lepadin L, and two known metabolites belonging to the same family, lepadins A and B. The planar structure and relative configuration of the decahydroquinoline ring of lepadin L were established both by means of HR-ESIMS a...
An in-depth study on the inhibitory mechanism on protein tyrosine phosphatase 1B (PTP1B) and aldose reductase (AR) enzymes, including analysis of the insulin signalling pathway, of phosphoeleganin, a marine-derived phosphorylated polyketide, was achieved. Phosphoeleganin was demonstrated to inhibit both enzymes, acting respectively as a pure non-co...
Dear Colleagues,
Marine ascidians (tunicates) hold a central role in the natural-product-based drug-discovery processes. With the over one thousands of new compounds isolated in the last 30 years, ascidians have established themselves as a valuable and heterogeneous source of new chemical scaffolds and pharmaceutically potent molecules, including...
The synthesis of two 5′-end (4-dimethylamino)azobenzene conjugated G-quadruplex forming aptamers, the thrombin binding aptamer (TBA) and the HIV-1 integrase aptamer (T30695), was performed. Their structural behavior was investigated by means of UV, CD, fluorescence spectroscopy, and gel electrophoresis techniques in K+-containing buffers and water-...
Interactions of novel bi-dimensional nanomaterials and live matter such as bacteria and viruses represent an extremely hot topic due to the unique properties of the innovative nanomaterials, capable in some cases to exhibit bactericide and antiviral actions. The interactions between bacteria and viruses and two dimensional nanosheets are here inves...
Among the sub-phylum of Tunicate, ascidians represent the most abundant class of marine invertebrates, with 3000 species by heterogeneous habitat, that is, from shallow water to deep sea, already reported. The chemistry of these sessile filter-feeding organisms is an attractive reservoir of varied and peculiar bioactive compounds. Most secondary me...
Malaria is a life-threatening disease and, what is more, the resistance to available antimalarial drugs is a recurring problem. The resistance of Plasmodium falciparum malaria parasites to previous generations of medicines has undermined malaria control efforts and reversed gains in child survival. This paper describes a continuation of our ongoing...
The chemical analysis of the sponge Dysidea avara afforded the known sesquiterpene quinone avarone, along with its reduced form avarol. To further explore the role of the thiazinoquinone scaffold as an antiplasmodial, antileishmanial and antischistosomal agent, we converted the quinone avarone into the thiazinoquinone derivative thiazoavarone. The...
The identification of molecules whose biological activity can be properly modulated by light is a promising therapeutic approach aimed to improve drug selectivity and efficacy on the molecular target and to limit the side effects compared to traditional drugs. Recently, two photo-switchable diastereomeric benzodiazopyrrole derivatives 1RR and 1RS h...
Several marine natural linear prenylquinones/hydroquinones have been identified as anticancer and antimutagenic agents. Structure-activity relationship studies on natural compounds and their synthetic analogs demonstrated that these effects depend on the length of the prenyl side chain and on the type and position of the substituent groups in the q...
Schistosomiasis is the most significant neglected tropical parasitic disease caused by helminths in terms of morbidity and mortality caused by helminths. In this work we present the anti-schistosomal activity against Schistosoma mansoni of a rationally selected small set of thiazinoquinone derivatives, some of which previously found to be active ag...
A deep study of the metabolic content of the tunicate Polycarpa aurata, collected from Indonesian coast, afforded the isolation of two novel alkaloids, polyaurines A (1) and B (2), along with two new p-substituted benzoyl derivatives (3 and 4) and four known compounds (5–8). The structural elucidation of the new secondary metabolites was assigned b...
A small library of antiplasmodial methoxy-thiazinoquinones, rationally designed on the model of the previously identified hit 1, has been prepared by a simple and inexpensive procedure. The synthetic derivatives have been subjected to in vitro pharmacological screening, including antiplasmodial and toxicity assays. These studies afforded a new lead...
Covering: up to 2018
Even today, when planar structures of natural products can be determined with microgram samples, the configurational assignment continues to be a challenge. The relative and absolute configurations of natural products can be assigned by devising original approaches, relying on carefully acquired data on a case-by-case basis. In...
The electrochemical response of four natural cytotoxic thiazinoquinones isolated from the Aplidium species was studied using conventional solution-phase and solid-state techniques, based on the voltammetry of immobilized particles methodology. The interaction with O2 and electrochemically generated reactive oxygen species (ROS) was electrochemicall...
The full absolute configuration assignment of phosphoeleganin (1), a recently discovered marine-derived phosphorylated polyketide with protein tyrosine phosphatase 1B inhibitory activity, was achieved. It was based on the synthesis of model diasteroisomeric compounds of the C-8–C-12 segment portion of phosphoeleganin, chiral derivatization methods,...
A new sulfated sterol, phallusiasterol C (1), has been isolated from the Mediterranean ascidian Phallusia fumigata and its structure has been determined on the basis of extensive spectroscopic (mainly 2D NMR) analysis. The possible role in regulating the pregnane X receptor (PXR) activity of phallusiasterol C has been investigated; although the new...
A new phosphorylated polyketide, phosphoeleganin (1), has been isolated from the Mediterranean ascidian Sidnyum elegans. Its structure and configuration have been determined by extensive use of 2D NMR and microscale chemical degradation and/or derivatization. Phosphoeleganin (1) inhibited the protein tyrosine phosphatase 1B (PTP1B) activity.
In the search for new antimalarials, we used the quinone scaffold of marine secondary metabolites as a chemical starting point to synthesize new thiazinoquinone compounds. Most of synthetic derivatives have shown a significant pharmacological activity and some structural requirements, critical for both the antiplasmodial effect and cytotoxicity, ha...
The marine organisms, mainly invertebrates such as sponges and ascidians, are a rich source of varied natural alkaloids with unique chemical scaffolds and diverse bioactivities. From a medicinal chemistry perspective, the marine alkaloids' fascinating structures as well as their broad spectrum of pharmacological activity make them promising lead co...
The present review describes research on novel natural antitumor alkaloids isolated from marine invertebrates. The structure, origin, and confirmed cytotoxic activity of more than 130 novel alkaloids belonging to several structural families (indoles, pyrroles, pyrazines, quinolines, and pyridoacridines), together with some of their synthetic analog...
Purification of the apolar extracts of the marine ascidian Phallusia fumigata, afforded two new sulfated sterols, phallusiasterols A (1) and B (2). The structures of the new compounds have been elucidated using mass spectrometry and NMR experiments. The effects of phallusiasterols A and B as modulators of pregnane-X-receptor (PXR) have been investi...
Chemical investigation of the Mediterranean ascidian A. conicum resulted in the isolation of two new meroterpenes, the conithiaquinones A (1) and B (2), in addition to two previously reported chromenols (3 and 4) and conicaquinones (5 and 6). The structures of conithiaquinones A and B were determined by interpretation of spectroscopic data, and reg...
Meroterpenes are widely distributed among marine organisms; they are particularly abundant within brown algae, but other important sources include microorganisms and invertebrates. In the present review the structures and bioactivities of meroterpenes from marine invertebrates, mainly sponges and tunicates, are summarized. More than 300 molecules,...
Two new sulfoxide-containing metabolites, aplisulfamines A and B, have been isolated from an Aplidium sp. collected in the Bay of Naples. Their planar structure and geometry of a double bond were readily determined by using standard methods, mainly NMR spectroscopy. An original approach was used to assign the absolute configuration at the three con...
Chemical investigation of two species of marine ascidians, Aplidium elegans and Ciona edwardsii, collected in Mediterranean area, led to isolation of a series of alkyl sulfates (compounds 1–5) including three new molecules 1–3. Structures of the new metabolites have been elucidated by spectroscopic analysis. Based on previously reported cytotoxic a...
An exhaustive exploration into the metabolic content of the Mediterranean sponge Axinella-polypoides resulted in the isolation of the new betaine 5 and the new cyclonucleoside 8. The structures of the new metabolites were elucidated by spectroscopic methods assisted by computational methods. The analysis also provided evidence that the sponge does...
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About 300 alkaloid structures isolated from marine ascidians are discussed in term of their occurrence, structural type and reported pharmacological activity. Some major groups (e.g., the lamellarins and the ecteinascidins) are discussed in detail, highlighting their potential as therapeutic agents for the treatment of cancer or viral infections.
The new pigment "moraxanthin" was found in natural samples from a fish mortality site in the Inland Bays of Delaware, USA. Pure cultures of the species, tentatively named Chattonella cf. verruculosa, and natural samples contained this pigment as a dominant carotenoid. The pigment, obtained from a 10 L culture of C. cf. verruculosa, was isolated and...
Chemical analysis of the Mediterranean ascidian Polyandrocarpa zorritensis (Van Name 1931) resulted in the isolation of a series of molecules including two monoindole alkaloids, 3-indolylglyoxylic acid (3) and its methyl ester (4), 4-hydroxy-3-methoxyphenylglyoxylic acid methyl ester (1) and a new alkaloid we named zorrimidazolone (2). The structur...
Supplementary file (PDF, 424 KB) Description: Supplementary Information
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Chemical investigation of the Mediterranean ascidian Ciona edwardsii has been performed, leading to the isolation of two halogenated compounds: a new tyrosineiodinated derivative iodocionin (1) and the relevant brominated analogue (2), previously isolated from a Caribbean sponge. The structure of the new compound 1 has been assigned on the basis of...
Glycolipid analysis of the Caribbean sponge Amphimedon compressa has shown it to contain two novel glycosphingolipids, amphiceramide A (1a) and B (2a), which possess an unusual Δ6-phytosphingosine. The saccharide chain of amphiceramide A is composed of a β-glucose residue glycosylated at the 6-position by an N-acetyl-β-glucosamine and has never bee...
Reinvestigation of the glycosphingolipid composition of the marine sponge Spheciospongia vesparia revealed the presence of vesparioside B ( 2a), a new furanose-rich hexaglycosylated glycosphingolipid that is the most complex glycosphingolipid isolated from a marine sponge to date. The structure of the new compound was elucidated using extensive 2D...
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
The new diglycosylceramide terpioside (1a) has been isolated from the marine sponge Terpios sp. Terpioside is a diglycosylated glycosphingolipid which is the first example of a natural glycosphingolipid having an L-fucofuranose unit. The structure of terpioside was elucidated by extensive spectroscopic analysis, whereas chemical degradation was use...
Corrugoside (1a), a new immunostimulatory triglycosilated alpha-galactoglycosphingolipid, was isolated from the marine sponge Axinella corrugata, and its structure determined by spectral analysis and chemical degradation. Compound 1a activated murine NKT cells in vitro, with a potency of about 2 logs lower than that of alphaGalCer. Four stereoisome...
The sea star Oreaster reticulatus contains, along with the known ophidiacerebrosides C–E, nine new glycosphingolipids named oreacerebrosides A–I. Their structures were elucidated by a combination of spectroscopic methods and chemical degradation. All compounds contain a 4,8,10-triunsaturated sphingoid base. Oreacerebrosides A–C have a β-glucopyrano...
The Caribbean sponge, Plakortis simplex, is known to contain a large array of secondary metabolites, including the antimalarial polyketide plakortin, several unusual
glycolipids, and some hopanoids, which closely resemble typical bacterial metabolites. The hypothesis that they could be products
of bacterial metabolism was tested by localizing speci...
Two families of unique glycolipids, clathrosides A-C (2a-4a) and isoclathrosides A-C (5a-7a) were isolated from the Caribbean sponge Agelas clathrodes. Clathrosides and isoclathrosides are glycosides of a very-long-chain alcohol derived from fatty acids, a new class of glycolipids that appears to be characteristic of marine sponges. The six compoun...
The marine sponge Spheciospongia vesparia produces vesparioside (1a), a diglycosylated glycosphingolipid which is the first example of a natural diglycosylceramide with a pentose sugar residue. The structure of vesparioside was mostly determined by extensive spectroscopic analysis but determination of the nature of the alkyl chains and elucidation...
Reinvestigation of the glycosphingolipid composition of the marine sponge Agelas clathrodes revealed the presence of a new tetraglycosylated alpha-galactoglycosphingolipid (1a), containing an unusual l-rhamnose unit in the sugar head. The structure of the new compound was elucidated using extensive 2D NMR studies. Because of the strong overlapping...
Ectyoceramide (1a), a unique monoglycosylceramide with a galactose in the furanose form, was isolated from Ectyoplasia ferox, and its structure was determined by NMR spectroscopy, multiple tandem mass spectrometry, and chemical degradation. Ectyoceramide is the first example of a monohexo-furanosylceramide and, more generally, the first natural gly...
Ectyoceramide (1a), a unique monoglycosylceramide with a galactose in the furanose form, was isolated from Ectyoplasia ferox, and its structure was determined by NMR spectroscopy, multiple tandem mass spectrometry, and chemical degradation. Ectyoceramide is the first example of a monohexofuranosylceramide and, more generally, the first natural glyc...
Sodium dithionite, which is known to cause dehalogenation of α-halo carbonyl compounds, also induces dehalogenation of protected 2-iodo-2-deoxyglycosides. Combined with the well-known iodonium-mediated haloalkoxylation, this reaction provides an easy, mild and highly stereoselective route for preparation of 2-deoxy-α-glycosides from glycals.
In addition to the previously reported crasserides (1a-m), marine sponges contain smaller amounts of the isomeric isocrasserides (3a-m). The structures of these new glycoglycerolipid analogues were determined by NMR analysis and chemical degradation. Crasserides and isocrasserides were present in all the species of marine sponges we analyzed and th...
A new and efficient approach to the total synthesis of 2′-deoxy-α-galactosyl glycosphingolipids was accomplished. Commercially available 3,4,6-tri-O-acetylgalactal was used as the chiral starting material for both the sugar and phytosphingosine building blocks required for the synthesis of 1-O-(2-deoxy-α-d-galactopyranosyl)-2-docosanoylamino-1,3,4-...
Plaxyloside, a glycolipid composed of a C35 linear polyisoprenoid alcohol aglycone and a linear carbohydrate chain made up of six β-xylopyranose units, has been isolated as its peracetate from the Caribbean sponge Plakortis simplex, and its structure determined on the basis of spectral and chemical data. Study of plaxyloside showed that: (a) carboh...
The application of the Wittig reaction to prepare chain-extended polyols starting from protected 2-deoxysugars has been investigated. The standard conditions cause alcohol elimination from the deoxysugar, leading to a diene. Triphenyl and tributyltin halides have been found to prevent alcohol elimination, so that the expected alkene is produced.
In addition to the previously reported bacteriohopanoids, the marine sponge Plakortis simplex was shown to contain large amounts of (32R,33S,34S)-32,35-anhydrobacteriohopanetetrol. The structure of this new bacteriohopanoid was determined by extensive NMR analysis, and further supports the hypothesized biosynthetic pathway to bacteriohopanoids. Alt...
Glycals can be converted into the corresponding 2-deoxysugars in good yields by treatment with N-iodosuccinimide in CH3CN–H2O 95:5 and removal of the iodide group using Na2S2O4 in DMF/H2O at room temperature. This method is easy to apply, sufficiently mild to allow the survival of acid-sensitive groups such as silyl and trityl ethers and less harmf...
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Large amounts of bacteriohopanoids have been isolated from the marine sponge Plakortis simplex. In addition to the common bacteriohopanetetrol, the new 12-methylbacteriohopanetetrol, with an unprecedented methylation at C-12, was isolated and characterized by an extensive NMR analysis. While bacteriohopanetetrol is most likely of dietary origin, th...