Sérgio Antônio Lemos de Morais

Caracterizaçao dos taninos da aroeira-preta (Myracrodruon urundeuva)

This work presents a study on tannins from aroeira-preta (Myracrodruon urundeuva), based on acetone-water (AA) and methanol-water (MA) extracts, in which the contents of total phenols and proanthocyanidins were determined. The total phenols were determined by the Folin-Ciocalteau method and the modified Prussian Blue method. The contents obtained for AA were 19.1 and 24.7% and for MA, 20.2 and 22.8%, respectively by the Folin-Ciocalteau method and the modified Prussian Blue method. The proanthocyanidin contents were determined by the vanillin method, obtaining 2.7% in extract AA and 16.7% in extract MA. No evidence for the presence of antocyanidins and apigedinidins was found, but 3-deoxi-proantocyanidins of the luteolinidin type may be present in the extracts. Fisetin, gallic acid and ellagic acid were detected through high performance liquid chromatography (HPLC). These results show that Myracrodruon urundeuva wood contains a great amount of tannins, which can contribute to its natural durability.

Análise da madeira de Pinus oocarpa parte I: estudo dos constituintes macromoleculares e extrativos voláteis

The chemical composition of Pinus oocarpa wood cultivated in the Brazilian cerrado was established. The obtained results were: a-cellulose (59.05%), hemicelluloses A and B (21.22%), lignin (25.18%), dichloromethane extractives (2.78%), ethanol:toluene extractives (4.38%), hot water extractives (4.31%) and ash (1.26%). The cellulose content was high. This result opens perspectives for using Pinus oocarpa wood in pulp and paper industries. Most of the dichloromethane extractives were diterpenic, palmitic and oleic acids. The volatile composition, obtained by means of the Clevenger method followed by GC-MS analysis was constituted mainly by aromadendrene, ledane, hexadecanal and oleic acid.

Studies on polyphenols and lignin of Astronium urundeuva wood

), tambem num soxhlet. Do extrato resultante foi obtida a lignina demadeira moida (MWL). Nao considerando a MWL, a soma de todos os extratos alcancou 18,19%da madeira seca. O conteudo em lignina de Klason de A e o conteudo de grupos metoxila da MWLforam 23,84% e 19,00%, respectivamente. Outra amostra de A apresentou conteudos em polissa-carideos de dificil e facil hidrolise de 34,86% e 18,81%, respectivamente. Uma Segunda amostrade madeira moida foi submetida a uma extracao unica com metanol, a temperatura ambiente,fornecendo o extrato metanolico B (23,85% da madeira seca). Espectros de RMN do

Ligninas: métodos de obtenção e caracterização química

This review presents a short history of the study of the lignins. There are also various methods for isolation and quantification of functional groups in lignins by chemical and physical methods being presented.

Analysis of a Brazilian green propolis from Baccharis dracunculifolia by HPLC-APCI-MS and GC-MS

Os extratos em etanol e diclorometano de uma propolis verde de Baccharis dracunculifolia foram analisados por CLAE-ICPA-EM e CG-EM, respectivamente. A tecnica de CLAE-EM-ICPA, no modo positivo, forneceu uma completa e inequivoca composicao quimica da amostra de propolis verde. Ela serve como impressao digital para amostras diferentes de propolis. A composicao do extrato em etanol consistiu fundamentalmente de acido cinâmico e derivados, flavonoides, acido benzoico e alguns benzoatos, aromaticos nao hidroxilados, e acidos e esteres alifaticos, os quais sao normalmente ignorados na literatura porque nao absorvem luz UV. Os constituintes principais do extrato em diclorometano foram compostos prenilados, alcanos e terpenoides.

Um marcador químico de fácil detecção para a própolis de Alecrim-do-Campo (Baccharis dracunculifolia)

In the present work a volatile chemical marker (CM) for the Baccharis dracunculifolia (Bd) propolis is proposed, which is easily detectable by gas chromatography. It is the most abundant volatile compound in dichloromethane extracts of green propolis from this plant, but it appears also, in different concentrations, in dichloromethane extracts of brown, dark and red propolis from regions where Bd grows. The CM is present in significative concentration in the bud extract of Bd, in contrast to the leaf extract where its concentration is low. Propolis from regions without Bd does not contain the CM. This compound was recently isolated; it is the allyl 3-prenylcinnamate. Commercial samples of green propolis ethanol extract were analyzed and the first quality one (exportation standard) presented the highest concentration on CM. This finding makes easier the quality control of green propolis extracts sold at the market.

Batch-injection analysis with amperometric detection of the DPPH radical for evaluation of antioxidant capacity.

This work proposes the application of batch-injection analysis with amperometric detection to determine the antioxidant capacity of real samples based on the measurement of DPPH radical consumption. The efficient concentration or EC50 value corresponds to the concentration of sample or standard required to scavenge 50% DPPH radicals. For the accurate determination of EC50, samples were incubated with DPPH radical for 1h because many polyphenolic compounds typically found in plants and responsible for the antioxidant activity exhibit slow kinetics. The BIA system with amperometric detection using a glassy-carbon electrode presented high precision (RSD = 0.7%, n = 12), low detection limit (1 μmol L(-1)) and selective detection of DPPH (free of interferences from antioxidants). These contributed to low detection limits for the antioxidant (0.015 and 0.19 μmol L(-1) for gallic acid and butylated hydroxytoluene, respectively). Moreover, BIA methods show great promise for portable analysis because battery-powered instrumentation (electronic micropipette and potentiostats) is commercially available.

Biphenyl Type Lignin Model Compounds: Synthesis and 13C NMR Substituent Chemical Shift Additivity Rule

BiphenylType Lignin Model Compounds: Synthesis and C NMR Substituent Chemical Shift Additivity Rule By Mariza G. Drumond, Dorila PiloVeloso, Stela D. Santos Cota, Sergio A. Lemos de Morais, Evandro A. do Nascimento and Chen-Loung Chen 1 Departamento de Quimica, Institute de Cienias Exatas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil 2 Departamento de Quimica, Universidade Federal de Uberländia, Uberländia, Brazil 3 Department ofWood and Paper Science, North Carolina State University, Raleigh, N.C. 27695-8005, U.S. A.

Composition of the essential oil from the leaves of tree domestic varieties and one wild variety of the guava plant (Psidium guajava L., Myrtaceae)

The compositions of the essential oils from the leaves of three domestic varieties of the guava tree Psidium guajava L. (Paluma, Seculo XXI and Pedro Sato) and of one wild variety were compared. Essential oils were extracted by steam distillation, the components were identified by gas chromatography coupled to mass spectrometry GC-MS, and the apparent concentrations were determined by gas chromatography with a flame ionization detector. The results demonstrated that the three essential oils contained many common substances with a prevalence of 1,8-cineole, whereas the essential oil of the Paluma variety contained 1,8-cineole (42.68%) as the major constituent, as well as α-terpineol (38.68%). The principal components of the essential oil of the Seculo XXI variety were 1,8-cineole (18.83%), trans-caryophyllene (12.08%), and selin-11-en-4-αol (20.98%), while those of the Pedro Sato variety and of the wild plant were 1,8-cineole (17.68%) and (12.83%), caryophyllene oxide (9.34%) and (9.09%), and selin-11-en-4-α-ol (21.46%) and (22.19%), respectively.

Seasonal Variation of the Chemical Composition and Antimicrobial and Cytotoxic Activities of the Essential Oils from Inga laurina (Sw.) Willd.

The seasonal chemical composition of essential oils from Inga laurina was determined by GC/MS. In the stem bark’s essential oil extracted during the dry season, the presence of terpenoids (30.05%) stood out, and phytol (9.76%) was the major compound identified. For the stem bark oil obtained during the rainy season, in addition to terpenoids (26.63%), a large amount of fatty acids (46.84%) were identified, in particular palmitic acid (25.40%). Regarding the leaves’ essential oil obtained in the dry season, esters (42.35%) were the main components. The main ester present was (Z)-hex-3-enyl benzoate (10.15%) and the major compound of this oil was (Z)-hex-3-en-1-ol (14.23%). Terpenoids (33.84%), long-chain alkanes (27.04%) and fatty acids (21.72%) were the main components of the essential oil from leaves in the rainy season. Phytol (33.21%), nonacosane (21.95%) and palmitic acid (15.20%) were the major compounds identified. The antimicrobial activity against aerobic and anaerobic oral bacteria was evaluated by the microdilution broth method and cytotoxic activity was carried out with Vero cells. The essential oils from the rainy season showed a better inhibition of the bacterial growth with Minimal Inhibitory Concentrations (MIC) values of 25 or 50 µg·mL−1 for aerobic bacteria, and high selectivity against bacteria was observed. The large amount of fatty acids in rainy season oils may be related to the better inhibitory effects observed.