Brazoides A-D, New Alkaloids from Justicia gendarussa Burm. F. Species

Souza, Luciana G. S.; Almeida, Macia C. S. de; Lemos, Telma L. G.; Ribeiro, Paulo Riceli Vasconcelos; Canuto, Kirley Marques; Braz-Filho, Raimundo; Cistia, Catarina N. Del; Sant’Anna, Carlos Maurício R.; Barreto, Francisco Stefânio; Moraes, Manoel O. de

doi:10.21577/0103-5053.20160291

Cited by 10 publications

(15 citation statements)

References 8 publications

(11 reference statements)

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“…40,41 When compared with the corresponding results of the lithium and sodium clusters, 65 the mean dipole polarizabilities of the gold clusters are significantly smaller. It is mainly attributed to the scalar relativistic effects.…”

Section: (Hyper)polarizabilitiesmentioning

confidence: 99%

Structures, Stabilities, Reactivities, and (Hyper)Polarizabilities of Small Gold Clusters

Jorge¹,

Santos²

2017

J. Braz. Chem. Soc.

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At the Douglas-Kroll-Hess level, the B3PW91 hybrid functional along with relativistic all-electron basis sets are used to evaluate geometric parameters, binding energies, vertical ionization potentials and electron affinities, and HOMO-LUMO (highest occupied molecular orbital-lowest unoccupied molecular orbital) energy gaps of the small golden clusters (Au n , n ≤ 8).The so expected odd-even oscillations of the experimental ionization potentials and electron affinities are confirmed in this work and the Au 7 cluster is predicted to be the most reactive cluster. Using the optimized geometries, DKH2 static mean dipole polarizability and polarizability anisotropy are also computed. From n ≥ 2, the mean dipole polarizabilities per atom present an odd-even oscillatory characteristic, whereas the polarizability anisotropies increase with the cluster size. At the non-relativistic level, the second hyperpolarizabilities are calculated. It is the first time that hyperpolarizabilities of gold clusters are reported. Comparisons with theoretical results obtained previously for the copper and silver clusters at the same level of theory are made.Keywords: B3PW91 functional, all-electron basis sets, DKH2 calculations, gold clusters, (hyper)polarizabilities IntroductionAtomic cluster is formed by an assembling of a few or hundreds of atoms. It is necessary to understand how the cluster properties vary with the size, to clarify how they evolve in the direction of the bulk properties. Metal clusters have received special attention in the literature due to their unusual characteristics, properties, and applications to build new electronic devices.1 Theoretical 2-11 and experimental [12][13][14][15][16][17][18][19] studies about metal clusters have been carried out for about thirty three years. Among the metal clusters, there is an increasing interest [20][21][22][23][24][25][26][27][28][29][30][31][32] in the noble metals (Cu, Ag, and Au) because they can be considered as a connection between the alkali metals and the transition metals. We recall that their electronic configurations are nd 10 (n + 1)s 1 , with n = 3, 4, and 5, respectively to Cu, Ag and Au. It has been verified that in general the gold clusters and compounds present large relativistic effects when compared to those of the copper and silver ones. 33,34 We would like to cite the experiments about vertical ionization potentials and electron affinities performed by some research groups, 28,[35][36][37][38][39] where the results of all studied gold clusters surpass those of the copper and silver ones (see Figure 2 of Wesendrup et al.). 29 As a consequence of this finding, the properties and surfaces of the gold clusters will be differently affected. Thus, a study about the variation of such properties with the cluster size will be interesting. In this article, the vertical ionization potentials and electron affinities of gold clusters with up to 8 atoms as well as binding energies, highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) energ...

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Section: (Hyper)polarizabilitiesmentioning

confidence: 99%

Structures, Stabilities, Reactivities, and (Hyper)Polarizabilities of Small Gold Clusters

Jorge¹,

Santos²

2017

J. Braz. Chem. Soc.

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“…The formation and accumulation of these undesired intermediates should be avoided for the green production of AN. 40 Catalysts based on Pd are known to be capable of selectively hydrogenating nitro-compounds to their corresponding aniline, 41,42 thus it was investigated the catalytic performance of Pd/TTH by testing it as catalyst for NB reduction and the kinetics of its conversion to AN was accompanied through UV-Vis spectroscopy (Figure 6b).…”

Section: Catalytic Performance Of Pd/tth Towards Nitrobenzene Reductionmentioning

confidence: 99%

Human Hair as Adsorbent of Palladium(II) in Solution: A Precursor of Well-Dispersed Size-Controlled Pd Nanoparticles

Mendonça¹,

Silva²,

Nascimento³

et al. 2018

J. Braz. Chem. Soc.

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This work describes, for the first time, the preparation of palladium nanoparticles supported in thermally-treated human hair. Human hair showed to be an efficient adsorbent of Pd 2+ in aqueous media, reaching nearly 100% of adsorption from a 100 ppm solution. The thermal treatment of hair containing Pd 2+ at 200 °C under nitrogen atmosphere led to the formation of an N, S-containing material presenting 0.5 wt.% of palladium. The material was extensively characterized by elemental analysis (CHN and inductively coupled plasma optical emission spectroscopy (ICP OES)), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) and Raman spectroscopies, and by thermogravimetry (TG), thermogravimetry coupled to mass spectrometry (TG-MS), scanning electron miscroscopy (SEM), transmission electron microscopy (TEM) and dispersive X-ray spectroscopy (EDS) analyses. It was possible to observe that the surface structure of hair was preserved during thermal treatment, presenting palladium nanoparticles with particle sizes of approximately 4 nm. This material was used as heterogeneous catalyst in a preliminary application in nitrobenzene reduction to aniline in aqueous medium using sodium borohydride.

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“…8 Four new alkaloids {brazoides A, B, C (3), and D (12)} were isolated from leaves of JG and tested against three human cancer cell lines (glioblastoma, prostate, and colon), but unfortunately, none exhibited activity. 9 Also reported for JG leaves is 1,5-dideoxy-3-C-{[(5-hydroxy-2-{[(5-oxotetrahydro-2-furanyl) carbonyl] amino} benzyl) oxy] carbonyl} pentitol (9). 10,11 Justidrusamide A (13), B (14), C (11), D (10), E (6), 12,13 6,8-di-C-α-L-arabinocylapigenin {gendarusin A (16)}, and 6-C-α-L-arabinocyl-8-C-β-arabinocylapigenin {gendarusin B (17)} were identified in ethanolic leaf extracts of JG originating from Indonesia, 6,13 and apigenin and its glycoside vitexin were isolated from leaves of JG from India.…”

mentioning

confidence: 99%

“…JG leaves, [9][10][11][12][13]22 and metabolite 9 in the roots, stems, and leaves. 11 The molecular ions of 4, 7, and 8 were almost identical (< 5 ppm) to those of 6, 10, and 11, respectively, 10,12,13 but their chemical structures were not identical ( Table 2).…”

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confidence: 99%

“…This might be due to the differences in the ESI method and/ or the different origin of the JG crude drug; brazoides A and B were previously detected using positive ESI mode. 9 Compound 5 was a carbamate pesticide, which is listed in the Shimadzu Pesticide MRM Library. 19 Thus the JG leaves had probably been contaminated with this pesticide, which was also found in JG fresh leaves from Gempol, but not in those from Surabaya.…”

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confidence: 99%

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Phytochemicals of Gandarusa (Justicia gendarussa) and Its Preparations

Ratih

Imawati

Nugroho

et al. 2019

Natural Product Communications

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Thirty-five metabolites of Justicia gendarussa (JG) leaves and its preparations were identified using LC-HR-MS/MS. Although alkaloids were detected in the leaves they were not identified in JG preparations using Smart Formula 3D software. This showed that an acidified extraction process used at the first stage of the purification procedure is able to remove the toxic alkaloids from the crude drug. The LC-MS/MS analyses showed that the main components of JG preparations were fatty acids and apigenin glycosides; it seemed that the fatty acids can be used for enhancing the dissolution of the polar glycosides. T-test calculation using Profile Analysis software showed that the acidified crude drugs, extract, granules of JG, and gendarussa capsules showed very similar LC-MS/MS profiles, which means that the biochemical components of JG are relatively stable during processing. Due to the lack of quality markers for these JG preparations, the application of metabolite profiling is recommended as the QC tool for commercial production by the pharmaceutical industry.

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Brazoides A-D, New Alkaloids from Justicia gendarussa Burm. F. Species

Cited by 10 publications

References 8 publications

Structures, Stabilities, Reactivities, and (Hyper)Polarizabilities of Small Gold Clusters

Structures, Stabilities, Reactivities, and (Hyper)Polarizabilities of Small Gold Clusters

Human Hair as Adsorbent of Palladium(II) in Solution: A Precursor of Well-Dispersed Size-Controlled Pd Nanoparticles

Phytochemicals of Gandarusa (Justicia gendarussa) and Its Preparations

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