Osmany Cuesta

• PhD
• Professor at Universidad Tecnica de Machala

Nemorosone is a bicyclic polyprenylated acylphloroglucinol derivative originally isolated from Clusia spp. and it can be obtained through chemical synthesis employing different synthetic strategies. Since its discovery, it has attracted great attention both from a biological and chemical viewpoint. In the present article, we attempted to review var...

El COVID-19 se ha convertido en un problema de salud pública a nivel mundial. El uso de los productos naturales y en particular de las plantas medicinales, resulta ser una herramienta terapéutica para el tratamiento de la enfermedad y su correspondiente sintomatología. La revisión que a continuación se presenta, luego de una búsqueda en bases de da...

The chemical composition and the antioxidant potential of Ecuadorian propolis samples (n = 19) collected in different provinces were investigated. HPLC-DAD-ESI/MSⁿ and GC-EI-MS analysis of the methanol extracts enabled us to define six types of Ecuadorian propolis based on their secondary metabolite composition. 68 compounds were identified, 59 of...

Aims: Propolis is a resinous substance accumulated by bees from resinous plants material, produced by different botanical processes. It has been used since ancient times for its therapeutic benefits. The chemical composition of propolis is mostly influenced by the geographic zone and also by botanic sources that the honey bee has used. In this sens...

The objective of the research was to define the best conditions for ultrasound-assisted extraction of H. sabdariffa L. calyces, and to obtain microencapsulated powders, by spray drying. The extracts were analyzed, considering as variables: extracting solvent (water and water/ethanol) and the temperature /extraction time ratio (25 °C/ 60 min and 60...

Resúmen: La investigación tuvo como objetivo definir las mejores condiciones de extracción asistida por ultrasonido de los cálices de H. sabdariffa L. y la obtención de polvos microencapsulados, mediante secado por aspersión. Los extractos fueron analizados, considerando como variables: disolvente (agua y agua/etanol) y la relación temperatura/tiem...

Tumor-associated macrophages (TAMs), primarily the M2 phenotype, are involved in the progression and metastasis of colorectal cancer (CRC). Cuban brown propolis (Cp) and its main component Nemorosone (Nem) displays an antiproliferative effect on different cancer cells, including CRC cell lines. However, whether Cp and Nem could exploit its effect o...

The majority of deaths related to colorectal cancer (CRC) are associated with the metastatic process. Alternative therapeutic strategies, such as traditional folk remedies, deserve attention for their potential ability to attenuate the invasiveness of CRC cells. The aim of this study is to investigate the biological activity of brown Cuban propolis...

Propolis is an attractive natural ingredient to design health products due to its pharmacological effects. Our chemical investigation of a polar extract of Nigerian propolis (NP) led the isolation and identification of five isoflavonoids (1-4, 6), one diarylpropane (5) and one prenylated flavanone (7) by the combination of chromatographic and spect...

Aims: In the tumor microenvironment, dysregulated immune cells could promote tumor progression, invasion and metastasis, by establishing a symbiotic relationship with cancer cells. A pivotal role is played by monocyte recruitment and induction of tumor-associated macrophages (TAMs), which provide immunosuppression and tumorigenesis. The effect of...

El objetivo de la investigación fue evaluar las propiedades químicas y biológicas de extractos acuosos e hidroalcohólicos del pseudotallo de Musa x paradisiaca L. La materia prima vegetal fue caracterizada mediante análisis físico-químicos. El estudio químico cualitativo de los extractos se realizó a través de un tamizaje fitoquímico, por cromatogr...

Propolis is a natural product obtained from bees, used since ancient times for its multiple pharmacological properties. Several evidences indicate that the antiproliferative effect of propolis against different cancer cell lines can be ascribed to its components. However, little is known about the possible use of this natural product in the treatme...

Background: Leishmaniasis is a complex protozoa disease caused by Leishmania genus (Trypanosomatidae family). Currently, there have been renewed interests worldwide in plants as pharmaceutical agents. In this study, the in vivo efficacy of Solanum spp. is assessed in an L. amazonensis BALB/c mice model for experimental cutaneous leishmaniasis. Meth...

Introduction: Diabetes is at present the main cause of death from disease in Ecuador. The species Anacardium occidentale L. (cashew) has been used in folk medicine for diabetes control. This plant has been attributed pharmacological and nutritional properties, due to its content of metabolites of therapeutic importance. Objective: Evaluate the chem...

Three propolis samples were collected from different regions of Ecuador (Quito, Guayaquil and Cotacachi) and their methanolic extracts were prepared. Preliminary information supplied by TLC and NMR data, allowed us to define two main types of propolis: Cotacachi propoli sample (CPS), rich in flavonoids and Quito and Guayaquil samples (QPS and GPS)...

Oxidative stress resulting from iron and reactive oxygen species (ROS) homeostasis breakdown has been implicated in several diseases. Therefore, molecules capable of binding iron and/or scavenging ROS may be reasonable strategies for protecting cells. Rapanone is a naturally occurring hydroxyl-benzoquinone with a privileged chelating structure. In...

Introduction: Portulaca oleracea is used in folk medicine for pain and inflammation relief related on musculoskeletal diseases. However, there is little information on the chemical composition and pharmacological activity of the species in Ecuador. Objective: to evaluate the chemical composition of the aerial parts of Portulaca oleracea (purslane)...

In this study, an in vitro antileishmanial assessment of plant extracts from 12 genera and 46 species growing in Cuba belonging to Solanaceae family was performed. A total of 226 extracts were screened against promastigotes of Leishmania amazonensis, and cytotoxicity of active extracts [median inhibitory concentration (IC50) promastigotes <100 µg/m...

The dermal healing activity and acute toxicity of Croton lechleri latex were evaluated using Wistar rats. The observation period to determine the healing activity was 7 days (d) and 14 d for the toxicity. Samples for histological evaluations were prepared 7 d after incised wound. The identification of chemical compounds present in the latex was per...

The chemical composition and biological activity of a sample of yellow propolis from Mato Grosso do Sul, Brazil (EEP-Y MS), were investigated for the first time and compared with green, brown, and red types of Brazilian propolis and with a sample of yellow propolis from Cuba. Overall, EEP-Y MS had different qualitative chemical profiles, as well as...

The dermal healing activity and acute toxicity of Croton lechleri latex were evaluated using Wistar rats. The observation period to determine the healing activity was 7 days (d) and 14 d for the toxicity. Samples for histological evaluations were prepared 7 d after incised wound. The identification of chemical compounds present in the latex was per...

Introduction: malaria control mostly depends on an effective therapy. Many current antimalarials are of natural origin. Cuban flora species contain anti-Plasmodium metabolites. This study identifies Solanaceae extracts with promising antiplasmodial activity. Objective: to evaluate anti-Plasmodium berghei schizonticidal activity of 31 extracts of se...

The Calophyllum genus is well-known for its antimicrobial and cytotoxic activities, and therefore, we analyzed these biological activities for resins of Calophyllum antillanum and Calophyllum inophyllum growing in Cuba. C. antillanum resins showed a potent activity against Plasmodium falciparum (IC50 = 0.3 ± 0.1 µg/mL), while its cytotoxicity again...

Nemorosone (Nem) and guttiferone A (GutA) are acyl phloroglucinol derivatives (APD) that are present in different natural products. For both compounds anti-cancer and anti-microbial properties have been reported. In particular, an anti-leishmanial activity of both compounds was demonstrated. The aim of this study was to explore the possible role of...

Three main types of Cuban propolis directly related to their secondary metabolite composition have been identified: brown, red and yellow propolis; the former is majoritarian and is characterized by the presence of nemorosone. In this study, brown Cuban propolis extracts were found cytotoxic against HepG2 cells and primary rat hepatocytes, in close...

Objective: to evaluate, preliminary, chemical composition of different extracts obtained from leaves of Cnidoscolus aconitifolius (Mill.) I. M. Johns, and antioxidant and hypoglycemic activity of water extract. Methods: phytochemical study to different extracts obtained by maceration in hexane, acetone and methanol was conducted by Gas chromatograp...

The Copey tree (Clusia rosea) has a large distribution in Cuba and its floral resin is a rich source of polyisoprenylated benzophenones. To determine the presence of these natural products, we carried out a study by HPLC of 21 propolis samples produced by honey bees (Apis mellifera) from different provinces of Cuba. Nemorosone resulted to be the mo...

Objective: To investigate the leishmanicidal effect of the Bixa orellana crude seed extract and its fractions against Leishmania amazonensis. Methods: Four main fractions (BO-A, BO-B, BO-C and BO-D) were obtained by exhaustion with solvent with increased polarity from the Bixa orellana crude seed extract and 28 sub-fractions. The antileishmanial ac...

Clusianone is a member of the polycyclic polyprenylated acylphloroglucinol family of natural products; its cytotoxic mechanism is unknown. Clusianone is a structural isomer of nemorosone, which is a mitochondrial uncoupler and a well-known cytotoxic anti-cancer agent; thus, we addressed clusianone action at the mitochondria and its potential cytoto...

Introduction: Previous studies have revealed genus Garcinia to be a rich source of secondary metabolites, namely xanthones, acylphloroglucinols and bioflavonoids. However, the chemical composition of Cuban species in this genus is almost unknown.

The genus Garcinia is a source of a large variety of organic compounds including biflavonoids, acylphloroglucinols and xanthones mainly, but few data are available about the chemical composition of Cuban species. The aim of this investigation was to identify the main constituents of G. bakeriana Urb., a rare Cuban endemic plant. A new biflavonoid,...

Brown propolis is the major type of propolis found in Cuba; its principal component is nemorosone, the major constituent of Clusia rosea floral resins. Nemorosone has received increasing attention due to its strong in vitro anti-cancer action. The citotoxicity of nemorosone in several human cancer cell lines has been reported and correlated to the...

Propolis is a resinous mixture of different plant exudates collected by honeybees. Currently, propolis is widely used as a food supplement and in folk medicine. We have evaluated 20 Cuban propolis extracts of different chemical types, brown (BCP), red and yellow (YCP), with respect to their in vitro antibacterial, antifungal and antiprotozoal prope...

Pyranochromanone acids isolated from Calophyllum species have shown a variety of biological potentialities including antioxidant, antiulcer, anticancer and anti-Helicobacter pylori activities. These compounds seem to be the main constituents of Cuban Calophyllum species together xanthones and biflavonoids. Recently, the pyranochromanone acids calop...

Reactive oxygen species (ROS) are important mediators in a number of neurodegenerative diseases and molecules capable of scavenging ROS may be a feasible strategy for protecting neuronal cells. We previously demonstrated a powerful iron-chelating action of Guttiferone-A (GA), a naturally occurring polyphenol, on oxidative stress injuries initiated...

Origin Osmany Cuesta-Rubio,1,2 Anna Lisa Piccinelli 2 Propolis is a resinous hive product that honey bees produce using parts of plants as buds, leaves, exudates or resins, and beeswax. Propolis has a pleasant aromatic smell and varies in color depending on its source and age. Its chemical composition is highly variable and depends greatly on the p...

Currently, a wide range of research involving natural products is focused on the discovery of new drugs in many different therapeutic areas. A great number of the synthetic compounds on the market were derived from natural products, especially plants. Nemorosone is the major constituent of the floral resin of Clusia rosea Jacq., Clusiaceae, and in...

Histone acetyltransferases (HATs) are a class of epigenetic enzymes crucial for chromatin restructuring and transcriptional regulation in eukaryotic cells, thus being a promising target for therapeutic development. Nonetheless, differently from histone deacetylases (HDACs) inhibitors, there is still paucity of small-molecule modulators of HAT activ...

In this paper we analyzed the antiprotozoal effects of eighteen Cuban propolis extracts (brown, red and yellow type) collected in different geographic areas, using Leishmania amazonensis (as a model of intracellular protozoa) and Trichomonas vaginalis (as a model of extracellular protozoa). All evaluated propolis extracts caused inhibitory effect o...

Chemical composition of propolis depends on the specificity of the local flora at the site of collection and thus on the geographic and climatic characteristics of this place. This paper describes a comparative analysis of Cuban red propolis (CRP), Brazilian red propolis (BRP), and Dalbergia ecastophyllum exudates (DEE) by high-performance liquid c...

Guttiferone-A (GA) is a natural occurring polyisoprenylated benzophenone with cytotoxic action in vitro and anti-tumor action in rodent models. We addressed a potential involvement of mitochondria in GA toxicity (1-25 μM) toward cancer cells by employing both hepatic carcinoma (HepG2) cells and succinate-energized mitochondria, isolated from rat li...

Guttiferone-A (GA) is a natural occurring polyisoprenylated benzophenone with several reported pharmacological actions. We have assessed the protective action of GA on iron-induced neuronal cell damage by employing the PC12 cell line and primary culture of rat cortical neurons (PCRCN). A strong protection by GA, assessed by the 2,3-bis(2-methoxy-4-...

Polyisoprenylated benzophenones have been isolated from plants, particularly in the Clusiaceae family, and their biological properties recently have received considerable attention from a pharmacological point of view. The aim of the study was to investigate the polyisoprenylated benzophenones, nemorosone and guttiferone A, for their antimicrobial...

Estrogen receptor (ER) antagonists have been widely used for breast cancer treatment; however, patients have increasingly shown resistance and sensitivity to the high toxicity of these drugs, and identification of novel targeted therapies is therefore required. To determine whether nemorosone, a polycyclic polyisoprenylated benzophenone isolated fr...

Estrogen receptor (ER) antagonists have been widely used for breast cancer treatment however, patients have increasingly shown resistance and sensitivity to the high toxicity of these drugs, and identification of novel targeted therapies is therefore required. To determine whether nemorosone, a polycyclic polyisoprenylated benzophenone isolated fro...

Nemorosone, a natural-occurring polycyclic polyprenylated acylphloroglucinol, has received increasing attention due to its strong in vitro anti-cancer action. Here, we have demonstrated the toxic effect of nemorosone (1-25 μM) on HepG2 cells by means of the MTT assay, as well as early mitochondrial membrane potential dissipation and ATP depletion i...

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Chemical investigation of a red-type Mexican propolis sample has led to the isolation of three new compounds, 1-(3',4'-dihydroxy-2'-methoxyphenyl)-3-(phenyl)propane (1), (Z)-1-(2'-methoxy-4',5'-dihydroxyphenyl)-2-(3-phenyl)propene (2) and 3-hydroxy-5,6-dimethoxyflavan (3), together with seven known flavanones, isoflavans, and pterocarpans. Structur...

Brown Cuban propolis (BCP) is the major type of propolis in Cuba; its chemical composition is exclusive and the principal component is nemorosone. In this study we investigated the antiproliferative activity of the ethanol extract of BCP on human breast cancer cell lines. The MTT assay showed a significant antiproliferative activity (P<0.005) of BC...

Nemorosone is a polycyclic polyisoprenylated benzophenone (PPBs) with strong cytotoxic activity. It is the major constituent of Clusia rosea floral resin and brown Cuban propolis. Other PPBs found in Cuban propolis are oxidized and cyclized derivatives of nemorosone. The instability of PPBs carrying an enolizable 1,3-diketone system has been sugges...

In the present study, the phenolic composition analysis of seven red varieties of propolis, collected in different regions of Cuba, was evaluated by gas chromatography/mass spectrometry (GC-MS). Seventeen compounds were identified in all samples by the interpretation of their mass spectra. This appears to be the first report on the GC-MS analysis o...

Here we report the X-ray crystal structure of nemorosone, a polyprenylated benzophenone derivative that presents biological activity and potential use as antimicrobial, cytotoxic and antioxidant drug. On the basis of crystallographic data, we carried out a theoretical investigation based on state-of-the-art density functional approaches. A remarkab...

Clusia minor fruits were investigated and three polyprenylated benzophenones were isolated using several chromatographic techniques. All the structures assigned (propolone D, hyperibone B and garcinielliptone I), including relative configuration, were elucidated by spectroscopic methods. These three benzophenones are reported for the first time in...

A new prenylated xanthone, pinetoxanthone (1), and two new pyranochromanones, pinetoric acid I (2) and pinetoric acid II (3), together with 10 known compounds, namely, the triterpenes friedelin and canophyllol, the xanthone macluraxanthone, the pyranochromanone derivatives calophyllic acid, isocalophyllic acid, calolongic acid, apetalic acid, and i...

RESUMEN Objetivos: aislar e identificar los componentes principales presentes en el extracto metanólico de la resina de la especie Calophyllum pinetorum Bisse. Métodos: la cromatografía líquida de alta resolución se utilizó para la separación de los compuestos. Para la caracterización estructural se emplearon las técnicas de resonancia magnética nu...

Analytical Thin Layer Chromatography (TLC) using Silica gel plates of GF254, hexane: ethyl acetate (7:3) as solvent system and, Ce(SO4)2/H2SO4 and vanillin/ H2SO4 as general developer, was carried out. The developed chromatographic procedure was validated, allowing the identification and differentiation of the three types of Cuban propolis. We anal...

Objectives: to isolate and identify the main components in the methanolic extract of the resin of the species Calophyllum pinetorum Bisse. Methods: high resolution liquid chromatography was used for the separation of the compounds. Magnetic resonance imaging and mass spectrometry were used for the structural characterization. Results: the separatio...

Sixty-five samples of propolis were collected from eleven regions of Cuba; methanolic extracts of propolis were prepared from all samples, and a classification method was developed using a combination of NMR, HPLC-PDA, and HPLC-ESI/MS techniques. The analysis of (1)H and (13)C NMR spectra and chromatographic profiles of all propolis extracts allowe...

Plants of the family Clusiaceae or Guttiferae, in articular those belonging to the genera Clusia, and Garcinia, produce a series of oxidized and polyisoprenylated benzophenone derivatives, some of which are structurally complex and biologically active. From a biogenetic point of view, these compounds may be considered as benzophenones in which the...

Chemical investigation of a red-type Cuban propolis sample has led to the isolation of 11 isoflavonoids (2 isoflavones, 3 isoflavans, and 6 pterocarpans), together with gallic acid, isoliquiritigenin, and (-)-liquiritigenin. Structural determination, including the absolute stereochemistry, was accomplished by spectroscopic analysis, particularly CD...

For the first time, the tautomeric pairs of clusianone and 7-epi-clusianone were isolated from the same source, Clusia torresii fruits. An extensive NMR spectroscopic study is described to establish 1H and 13C chemical shift assignments and the C-7 relative configuration of these epimers and to clarify contradictory NMR spectroscopic data previousl...

Two new compounds have been isolated from the leaves of Hypericum styphelioides. Their structures have been established on the basis of mass spectrometry and 2D NMR techniques as 1,3,5-trihydroxy-2-(2',2'-dimethyl-4'-isopropenyl)cyclopentanylxanthone (1) and 3,5-dihydroxybenzophenon-4-beta-d-glucoside (2). Known compounds 5-O-demethylpaxanthonin (3...

A tautomeric pair of new isoprenylated benzophenones, aristophenone A (1a) and B (1b), have been isolated from Garcinia aristata fruits. Their structures has been determined using high-field 2D NMR techniques.

Nemorosone, the major constituent of the floral resin of Clusia rosea was isolated after exhaustive chromatography. This compound was fully characterized as it is in the nature, without methylation as reported before. A keto-enol equilibrium was observed and both isomers were totally characterized by NMR spectroscopic techniques. The previously ann...