1,720,997 research outputs found
Spice Space Race: a "Spicy" journey to the chemical galaxy of bioactive compounds
No full textThe research project of my PhD work focused on the biological potential of compounds isolated from spices, and aimed at integrating semisynthesis and total synthesis en route to the construction of series of improved analogues in terms of potency, stability and druggabilit
Trifluoromethyl Ketone Galactose Catalyst for Asymmetric Epoxidation: Experimental and Theoretical Model
No full textSince the introduction of the Shi catalyst, the organocatalytic epoxidation of olefins has become an area of continued research interest. To explore the possibility of enhancing the efficiency and stability of the catalyst, the synthesis of a galactose-derived trifluoromethyl ketone, and its use for stereoselective epoxidation reaction that exploits a transitory dioxirane as active species are herein reported. The trifluoromethyl ketone was built on the C6 of a protected d-galactopyranose. The organocatalyst was obtained smoothly in a few steps, and when utilized for stereoselective epoxidation exhibited excellent stability as no chemical alterations were observed during the reaction. The stereoselectivity, although sometimes moderate, appears surprisingly high considering the conformational freedom of the trifluoromethyl ketone moiety. DFT calculations were performed to investigate the interactions involved in regulating the observed selectivities. Moreover, a new mnemonic model has been developed to serve as a fast-predicting tool for epoxidation of new substrates
Triazole-curcuminoids: A new class of derivatives for 'tuning' curcumin bioactivities?
No full textCurcumin is a unique blend of pharmacophores responsible for the pleiotropy of this natural pigment. In the present study we have replaced the 1,3-dicarbonyl moiety with a 1,2,3-triazole ring to furnish a new class of triazole-curcuminoids as a possible strategy to generate new compounds with different potency and selectivity compared to curcumin. We obtained a proof-of-principle library of 28 compounds tested for their cytotoxicity (SY-SY5Y and HeLa cells) and for their ability to inhibit NF-κB. Furthermore, we also generated 1,3-dicarbonyl curcuminoids of selected click compounds. Triazole-curcuminoids lost their ability to be Michael's acceptors, yet maintained some of the features of the parent compounds and disclosed new ones. In particular, we found that some compounds were able to inhibit NF-κB without showing cytotoxicity, while others, unlike curcumin, activated NF-κB signalling. This validates the hypothesis that click libraries can be used to investigate the biological activities of curcumin as well as generate analogs with selected features
Synthetic approaches to cis-THC, a promising scaffold in medicinal chemistry
No full textThe chemistry of phytocannabinoids has witnessed renewed interest these last decades as a consequence of reduced restrictions, research on the endocannabinoid system and the development of approved therapeutic treatments based on cannabinoids. The medicinal cannabinoid market constitutes a prolific scenario in current medicine. Most studies, however, have focused on only two major components of Cannabis sativa L., namely, cannabidiol (CBD, 2) and (−)-Δ9-trans-tetrahydrocannabinol (Δ9-trans-THC, 6a), the latter being the main psychoactive compound of this plant. The cis-diastereoisomer of Δ9-trans-THC, Δ9-cis-THC, although also present in the same plant, has been less investigated in terms of biological, medicinal and synthetic perspectives. Interestingly, the cis-fused tetrahydrobenzo [c]chromene motif present in Δ9-cis-THC is embedded in many other natural products which also exhibit interesting biological activities such as anticancer, antifungal, and antiparasitic. This review discloses synthetic approaches that have been established towards the cis-fused tetrahydroisochromene system of Δ9-cis-THC.Fil: GURGONE, LUCIA. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; ArgentinaFil: la Venia, Agustina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; ArgentinaFil: Caprioglio, Diego. Universita del Piemonte Orientale; ItaliaFil: Riveira, Martín Jorge. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; Argentin
Cannabichromene (CBC) shows matrix-dependent thermal configurational stability
No full textThe optical purity of cannabichromene (CBC, 1a) is affected by the matrix in which it is generated by thermolysis from its native carboxylated form (cannabichromenic acid, CBCA, 1b). Thus, thermolysis at 130 °C in planta caused a marked decrease of the enantiomeric excess (ee), while, under the same conditions, only a modest decrease of optical purity was observed when thermolysis was carried out in extracto. To rationalize these puzzling observations, the kinetics of thermal (100 °C) racemization of enantiopure cannabichromene (1a) was evaluated by enantioselective ultrahigh performance liquid chromatography in solvents (decalin and isopropyl alcohol, neat and acidified with TFA) and surfaces (native and silanized borosilicate glass) of complementary polarity. Optical stability was more than halved in isopropanol compared to decalin (t1/2 50 h vs 135 h), but acidification had no effect on racemization. However, contact with a solid surface dramatically accelerated the process, with a t1/2 of only 6 h on both glass surfaces. The overall extent of racemization of enantiopure CBC (1a) was compared under conditions commonly used for decarboxylation (heating at 130 °C) between a decalin solution and a thin film on three different surfaces (native and silanized borosilicate glass and powdered blank cannabis biomass). In line with the kinetic data, a significant erosion of enantiopurity was observed on all solid surfaces compared to the solution. These observations suggest that discrepancies in the reported enantiomeric purity of natural CBC could be not only of biogenetic derivation but also be associated with the decarboxylation protocol of cannabichromenic acid (1b). These findings, while relevant for the exploitation of the bioactivity of natural CBC for human health, should also prompt the adoption of a standardized decarboxylation protocol for the studies on the configurational status of CBC (1a) in cannabis and, in general, of cannabinochromanoids in nature
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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