Navegando por Autor "Silva, Adalberto M. da"
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Item Assessing the chemical composition and antimicrobial activity of essential oils from Brazilian plants—Eremanthus erythropappus (Asteraceae), Plectrantuns barbatus, and P. amboinicus (Lamiaceae)(Molecules, 2015-05-11) Santos, Nara O. dos; Mariane, Bruna; Lago, João Henrique G.; Sartorelli, Patricia; Rosa, Welton; Soares, Marisi G.; Silva, Adalberto M. da; Lorenzi, Harri; Vallim, Marcelo A.; Pascon, Renata C.The chemical composition and antimicrobial activity of essential oils obtained from three Brazilian plant species—leaves and branches of Eremanthus erythropappus (Asteraceae), leaves of Plectranthus barbatus, and leaves of P. amboinicus (Lamiaceae)—were determined. Analysis by GC/MS and determination of Kovats indexes both indicated δ-elemene (leaves—42.61% and branches—23.41%) as well as (−)-α-bisabolol (leaves—24.80% and stem bark—66.16%) as major constituents of E. erythropappus essential oils. The main components of leaves of P. barbatus were identified as (Z)-caryophyllene (17.98%), germacrene D (17.35%), and viridiflorol (14.13%); whereas those of leaves of P. amboinicus were characterized as p-cymene (12.01%), γ-terpinene (14.74%), carvacrol (37.70%), and (Z)-caryophyllene (14.07%). The antimicrobial activity against yeasts and bacteria was assessed in broth microdilution assays to determine the minimum inhibitory concentration (MIC) necessary to inhibit microbial growth. In addition, the crude oil of branches of E. erythropappus was subjected to chromatographic separation procedures to afford purified (−)-α-bisabolol. This compound displayed biological activity against pathogenic yeasts, thus suggesting that the antimicrobial effect observed with crude oils of E. erythropappus leaves and branches may be related to the occurrence of (−)-α-bisabolol as their main component. Our results showed that crude oils of Brazilian plants, specifically E. erythropappus, P. barbatus, and P. amboinicus and its components, could be used as a tool for the developing novel and more efficacious antimicrobial agents.Item Cu2O spheres as an efficient source of catalytic Cu(I) species for performing azide-alkyne click reactions(Tetrahedron Letters, 2017-02-08) Rodrigues, Thenner S.; Silva, Anderson G.M. da; Oliveira, Lucas C. de; Silva, Adalberto M. da; Teixeira, Róbson R.; Camargo, Pedro H.C.We report herein the high yield synthesis of Cu2O spheres displaying well-defined shapes and monodisperse sizes that could be employed as the source of highly catalytic active Cu(I) species towards click reactions between several of alkynes and azides to produce a variety of 1,2,3-triazoles under ligand-free and ambient conditions (in an open reactor). The utilization of Cu2O spheres enabled superior performance as compared to a conventional protocol in which CuSO4 is employed in combination with sodium ascorbate as the catalyst system. In addition, the compounds were obtained in synthetically useful yields, and seven of them have not been previously reported. We believe the results reported herein shed new insights into the optimization of activity and versatility of click reactions towards the synthesis of target molecules in environmentally friendly conditions.Item In vitro trypanocidal evaluation of pinane derivatives from essential oils of ripe fruits from Schinus terebinthifolius Raddi (Anacardiaceae)(Química Nova, 2012-11-23) Sartorelli, Patricia; Santana, Jefferson S.; Guadagnin, Rafael C.; Lago, João Henrique G.; Pinto, Érika G.; Tempone, André G.; Stefani, Hélio A.; Soares, Marisi G.; Silva, Adalberto M. daEssential oils of ripe fruits from Schinus terebinthifolius (Anacardiaceae), obtained using a pilot extractor and a Clevenger apparatus were chemically characterized. Due the high amount of (-)- α-pinene in both oils, this monoterpene was tested against the protozoan parasite Trypanosoma cruzi, showing a moderate potential (IC50 63.56 µg/mL) when compared to benznidazole (IC50 43.14 µg/mL). Otherwise, (-)- α-pinene oxide did not showed anti-trypanosomal activity (IC50 > 400 µg/mL) while (-)-pinane showed an IC50 of 56.50 µg/mL. The obtained results indicated that the epoxydation of α-pinene results to the loss of the anti-parasitic activity while its hydrogenation product, contributed slightly to the increased activity.