Freddy A. Ramos
National University of Colombia
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Featured researches published by Freddy A. Ramos.
Food and Chemical Toxicology | 2013
Maurilio da Silva Morrone; Adriano Martimbianco de Assis; Ricardo Fagundes da Rocha; Juciano Gasparotto; Andressa Córneo Gazola; Geison M. Costa; Silvana Maria Zucolotto; Leonardo Castellanos; Freddy A. Ramos; Eloir Paulo Schenkel; Flávio Henrique Reginatto; Daniel Pens Gelain; José Cláudio Fonseca Moreira
The leaf extracts of many species of genus Passiflora have been extensively investigated for their biological activities on several rat tissues, but mainly in the central nervous system and liver. They posses anxiolytic-like, sedative effects and antioxidant properties. Evidences suggest a key role of C-glycosylflavonoids in the biological activities of Passiflora extracts. Some species (such as P. manicata) of the genus are still poorly investigated for their chemical and biological activity. In this work, we aim to investigate both antioxidant and antiglycation properties of aqueous extract of P. manicata leaves (PMLE) in vitro and ex vivo models. Crude extract showed the C-glycosylflavonoid isovitexin as the major compound. Isoorientin and vitexin were also identified. In TRAP/TAR assay, PMLE showed a significant antioxidant activity. PMLE at concentrations of 10 and 100 μg mL⁻¹ significantly decreasing LDH leakage in rat liver slices. Antioxidant effect also was observed by decreased in oxidative damage markers in slices hence hydrogen peroxide was added as oxidative stress inductor. PMLE inhibited protein glycation at all concentrations tested. In summary, P. manicata aqueous leaf extract possess protective properties against reactive oxygen species and also protein glycation, and could be considered a new source of natural antioxidants.
Phytomedicine | 2014
J. Brango-Vanegas; Geison M. Costa; Caroline Flach Ortmann; Eloir Paulo Schenkel; Flávio Henrique Reginatto; Freddy A. Ramos; Catalina Arévalo-Ferro; Leonardo Castellanos
The Cecropia genus is widely distributed in Latin America including at least 60 species, and some of them are commonly used in traditional medicine for the treatment of several diseases. We used Cecropia pachystachya Trécul to search for quorum sensing (QS) inhibitors compounds and found that the aqueous extract of C. pachystachya leaves is a promising source of substances with this activity. Using as biosensor Chromobacterium violaceum ATCC 31532 and Escherichia coli pSB403, the compounds chlorogenic acid (2), isoorientin (3), orientin (4), isovitexin (6), vitexin (7), and rutin (9) were identified as QS inhibitors. None of these compounds inhibited the growth of neither the used biosensors nor the microorganisms Staphylococcus aureus ATCC 23591, Escherichia coli ATCC 25922 and Saccharomyces cerevisiae, used here as growth inhibition controls. Along with the rutin, here we presented for the first time the QS-inhibition potential of the C-glycosyl flavonoids. The prospective of this evidence lead to the use of these compounds as antipathogenic drugs or antifoulants.
Marine Drugs | 2014
Alonso Pardo-Vargas; Ingrid de Barcelos Oliveira; Paulo Roberto Soares Stephens; Claudio Cesar Cirne-Santos; Izabel Christina Nunes de Palmer Paixão; Freddy A. Ramos; Carlos Jiménez; Jaime Rodríguez; Jackson A. L. C. Resende; Valéria Laneuville Teixeira; Leonardo Castellanos
The marine brown alga Dictyota pfaffii from Atol das Rocas, in Northeast Brazil is a rich source of dolabellane diterpene, which has the potential to be used in future antiviral drugs by inhibiting reverse transcriptase (RT) of HIV-1. Reexamination of the minor diterpene constituents yielded three new dolabellane diterpenes, (1R*,2E,4R*,7S,10S*,11S*,12R*)10,18-diacetoxy-7-hydroxy-2,8(17)-dolabelladiene (1), (1R*,2E,4R*,7R*,10S*,11S*,12R*)10,18-diacetoxy-7-hydroxy-2,8(17)-dolabelladiene (2), (1R*,2E,4R*,8E,10S*,11S,12R*)10,18-diacetoxy-7-hydroxy-2,8-dolabelladiene (3), termed dolabelladienols A–C (1–3) respectively, in addition to the known dolabellane diterpenes (4–6). The elucidation of the compounds 1–3 was assigned by 1D and 2D NMR, MS, optical rotation and molecular modeling, along with the relative configuration of compound 4 and the absolute configuration of 5 by X-ray diffraction. The potent anti-HIV-1 activities displayed by compounds 1 and 2 (IC50 = 2.9 and 4.1 μM), which were more active than even the known dolabelladienetriol 4, and the low cytotoxic activity against MT-2 lymphocyte tumor cells indicated that these compounds are promising anti-HIV-1 agents.
Bioorganic & Medicinal Chemistry Letters | 2011
Eduardo Reina; Carlos Puentes; Juan Rojas; Josué García; Freddy A. Ramos; Leonardo Castellanos; Marcela Aragón; Luis Fernando Ospina
The screen of 10 soft coral extracts collected from the Colombian Caribbean Sea in the TPA-induced ear edema model allowed us to identify Eunicea fusca extract among others as an interesting source of active compounds. The new diterpene, fuscoside E (1), along with the known fuscoside B (2), fuscol (3), (+)-germacrene D (4) and a mixture of six sterols (5-10), were isolated from this soft coral. Their structures were elucidated by 1D and 2D NMR spectroscopy techniques. Fuscoside E (1) absolute stereochemistry was determined by chiroptical methods. Fuscoside E (1) and B (2) showed strong anti-inflammatory in the above mentioned bioassay. Additionally, fuscoside E (1) and the sterol mixture (5-10) presented antifouling activity against bacterial strains involved in surface colonization.
Journal of Liquid Chromatography & Related Technologies | 2012
Geison M. Costa; Andressa Córneo Gazola; Fernanda A. Madóglio; Silvana Maria Zucolotto; Flávio Henrique Reginatto; Leonardo Castellanos; Freddy A. Ramos; Carmenza Duque; Eloir Paulo Schenkel
The species of Passiflora are widely used in folk medicine as mild sedatives and tranquilizers. P. alata and P. quadrangularis are distributed throughout South America, with widespread occurrence in Brazil and Colombia. Due to the difficulty in making a botanical distinction between these species, especially in the absence of flowers and fruits, the use of chemical markers for these plants offer an alternative method of identification. This work describes the isolation and identification of the major flavonoids and saponins from the leaves of P. alata and P. quadrangularis, as well as rapid and efficient HPLC-DAD methods for comparison of these compounds in both species. Vitexin derivatives are proposed as chemical markers in the identification of P. alata and P. quadrangularis and the detection of adulterations in raw material.
Journal of Chromatography B | 2015
Geison M. Costa; Paola Andrea Cárdenas; Andressa Córneo Gazola; Diana Marcela Aragón; Leonardo Castellanos; Flávio Henrique Reginatto; Freddy A. Ramos; Eloir Paulo Schenkel
In this study, we applied a gradient High-Speed Counter-Current Chromatography (HSCCC) method that allowed, by direct injection of an aqueous crude extract of the leaves of Passiflora bogotensis, the successful isolation of six flavonoids in a single run, with purity of each compound higher than 81%. This separation enabled the isolation of two new flavonoid glycosides, apigenin-6-C-α-l-rhamnopyranosyl-(1→2)-(6″-O-acetyl)-β-d-glucopyranoside (2) and luteolin-6-C-α-l-rhamnopyranosyl-(1→2)-(6″-O-acetyl)-β-d-glucopyranoside (4), and four known ones, isovitexin (1), isoorientin (3), isovitexin-2″-O-rhamnoside (5) and isoorientin-2″-O-rhamnoside (6). The structures of the isolated compounds were identified by HPLC-DAD, LC-MS, (1)H and (13)C NMR and comparison with literature data. The inhibitory activities of all of these compounds were evaluated in vitro on α-glucosidase from S. cerevisiae, and the IC50 was determinate. This is the first study concerning the chemical composition and biological activity of Passiflora bogotensis.
Phytochemistry | 2008
Freddy A. Ramos; Yoshihisa Takaishi; Yoshiki Kashiwada; Coralia Osorio; Carmenza Duque; Ricardo Acuña; Yoshinori Fujimoto
From a methanolic extract of the leaves of Croton stipuliformis, three ent-3,4-seco-labdanes (1-3) and an ent-labdane (4) together with the known compounds 6-hydroxynidorellol (5), maravuic acid, and sitosterol were isolated and identified from their spectroscopic data. The absolute stereochemistry of compound 4 was determined by application of Moshers method in the NMR tube.
PLOS ONE | 2017
Luz A. Betancur; Sandra J. Naranjo-Gaybor; Diana M. Vinchira-Villarraga; Nubia Moreno-Sarmiento; Luis A. Maldonado; Zulma Rocío Suárez-Moreno; Alejandro Acosta-González; Gillermo F. Padilla-Gonzalez; Mónica Puyana; Leonardo Castellanos; Freddy A. Ramos
Marine bacteria are considered as promising sources for the discovery of novel biologically active compounds. In this study, samples of sediment, invertebrate and algae were collected from the Providencia and Santa Catalina coral reef (Colombian Caribbean Sea) with the aim of isolating Actinobateria-like strain able to produce antimicrobial and quorum quenching compounds against pathogens. Several approaches were used to select actinobacterial isolates, obtaining 203 strains from all samples. According to their 16S rRNA gene sequencing, a total of 24 strains was classified within Actinobacteria represented by three genera: Streptomyces, Micromonospora, and Gordonia. In order to assess their metabolic profiles, the actinobacterial strains were grown in liquid cultures, and LC-MS-based analyses from ethyl acetate fractions were performed. Based on taxonomical classification, screening information of activity against phytopathogenic strains and quorum quenching activity, as well as metabolic profiling, six out of the 24 isolates were selected for follow-up with chemical isolation and structure identification analyses of putative metabolites involved in antimicrobial activities.
Zeitschrift für Naturforschung C | 2011
Jennyfer Mora-Cristancho; Catalina Arévalo-Ferro; Freddy A. Ramos; Edisson Tello; Carmenza Duque; Cintia Lhullier; Miriam Falkenberg; Eloir Paulo Schenkel
The growth inhibition of 12 native marine bacteria isolated from Aplysina sponge surfaces, the shell of a bivalve, and Phytagel™ immersed for 48 h in sea water were used as indicator of the antifouling activity of the extracts of 39 marine organisms (octocorals, sponges, algae, and zoanthid) collected in the Colombian Caribbean Sea and on the Brazilian coast (Santa Catarina). Gram-negative bacteria represented 75% of the isolates; identified strains belonged to Oceanobacillus iheyensis, Ochrobactrum pseudogrignonense, Vibrio campbellii, Vibrio harveyi, and Bacillus megaterium species and seven strains were classified at genus level by the 16S rRNA sequencing method. The extracts of the octocorals Pseudopterogorgia elisabethae, four Eunicea octocorals, and the sponges Topsentia ophiraphidites, Agelas citrina, Neopetrosia carbonaria, Monanchora arbuscula, Cliona tenuis, Iotrochota imminuta, and Ptilocaulis walpersii were the most active, thus suggesting those species as antifoulant producers. This is the first study of natural antifoulants from marine organisms collected on the Colombian and Brazilian coasts.
Bioorganic & Medicinal Chemistry Letters | 2014
Alonso Pardo-Vargas; Freddy A. Ramos; Claudio Cesar Cirne-Santos; Paulo Roberto Soares Stephens; Izabel Christina Nunes de Palmer Paixão; Valéria Laneuville Teixeira; Leonardo Castellanos
Research on dolabellane diterpenes of brown algae Dictyota spp. has shown that these diterpenoids have strong anti-HIV-1 activity, but there are not data about antiviral activity of dolabellane diterpenes isolated from octocorals, which are antipodes of those isolated from the brown algae. Dolabellanes 13-keto-1(R),11(S)-dolabella-3(E),7(E),12(18)-triene (1) and β-Araneosene (2) were isolated from the Caribbean octocoral Eunicea laciniata, and both showed low anti-HIV-1 activity and low toxicity. Since it was shown that oxygenated dolabellanes from algae have better anti-HIV-1 activity, in this work some derivatives of the main dolabellane of E. laciniata1 were obtained by epoxidation (3), epoxide opening (4), and allylic oxidation (5). The derivatives showed significant improvement in the anti-HIV-1potency (100-fold), being compounds 3 and 5 the most active ones. Their high antiviral activities, along with their low cytotoxicity, make them promissory antiviral compounds; and it is worth noting that the absolute configuration at the ring junction in the dolabellane skeleton does not seem to be determinant in the antiviral potency of these diterpeneoids.