Roberto Chang

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.

Chemical Analysis and Study of Phenolics, Antioxidant Activity, and Antibacterial Effect of the Wood and Bark of Maclura tinctoria (L.) D. Don ex Steud.

Maclura tinctoria (L.) D. Don ex Steud. has one of the highest qualities among the coefficients for Brazilian woods (up to 9.6) and resistance rates equivalent to Indian teak (Tectona grandis). In this study, the macromolecular constituents and total phenols compounds as well as the antioxidant and antibacterial activities of this wood were evaluated. Total phenols and proanthocyanidin levels were higher in wood when compared with bark levels. The antioxidant activity of wood extracts (IC50 = 18.7 μg/mL) was more effective than that of bark extracts (IC50 = 20.9 μg/mL). Wood and bark extracts revealed a high potential for inhibition of aerobic and anaerobic bacteria. The bark extracts were the most active (MIC from 20 to 60 μg/mL). Both antioxidant activity and high potential for bacteria inhibition turn these extracts promising for drug formulations, especially as antibacterial agent.

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.

Variação química no óleo essencial das folhas de seis indivíduos de Duguetia furfuracea (Annonaceae)

Duguetia furfuracea, Annonaceae, a pasture weed, is also used in folk medicine in several Brazilian states. Because of the significant difference in odor between two groups of this plant in a remnant patch of savanna in Campo Grande county, Mato Grosso do Sul, six samples were selected according to the odor intensity in the leaves (In-01, In-03, and In-05: pronounced odor; In-02, In-04, and In-06: weak odor or its absence). The leaves were collected and subjected to steam distillation for extraction of essential oils, which were analyzed by GC-MS. A good agreement was found between CG/MS results and olfactory evaluation of the samples: specimens exhibiting leaf scent had a high percentage of monoterpenes and some sesquiterpenes, as follows: In-01 (β-phellandrene, 42.2%; myrcene, 6.8%; α-phellandrene, 4.6%); In-03 (terpin-4-ol, 21.6%; sabinene, 17.3%; p-cymene, 5.6%); In-05 (sabinene, 25.1%; terpin-4-ol, 16.2%; p-cymene, 8.3%). Only sesquiterpenes were found in the specimens having weakly scented or scentless leaves (main constituent bicyclogermacrene: 21.4%, 24.0%, and 29.1%, respectively, for In-02, In-04 and In-06).

Chemical Composition, Cytotoxic and Antimicrobial Activity of Essential Oils from Cassia bakeriana Craib. against Aerobic and Anaerobic Oral Pathogens

The chemical composition of the essential oils from leaves, bark and wood of Cassia bakeriana Craib. was determined by gas chromatography (GC) and gas chromatography–mass spectrometry (GC-MS). Alcohols, aldehydes and fatty acids were the major components in leaf and bark oil, while wood essential oil was rich in fatty acids. Terpenes such as linalool, (E)-nerolidol and phytol were present in low concentrations. The antimicrobial activity against aerobic and anaerobic oral bacteria was evaluated using the microdilution method, as was the cell viability test carried out with Vero cells. The oils from leaves and bark showed high antimicrobial activity, with minimum inhibitory concentrations between 62.5 and 125 µg·mL−1 for most of the tested bacteria, including Streptococcusmutans, the main etiological agent of dental caries. Leaves oil displayed the lowest cytotoxic effect (EC50 of 153 µg·mL−1), while wood oil exhibited the highest toxicity to Vero cells. C. bakeriana oils are thus a source of biologically active compounds against aerobic and anaerobic oral microorganisms. This study is the first report on the chemical composition, antimicrobial activity and cytotoxicity of C.bakeriana.

Estudo fitoquímico e alelopático do extrato de caule de sucupira-branca (Pterodon emarginatus)

Allelopathy is one of the natural phenomena little studied in the cerrado. It is the result of the release of substances capable of stimulating or inhibiting the growth of other plants. The objective of this work was to evaluate the allelophatic action of the white sucupira (Pterodon emarginatus) stem extract on the germination and development of coloniao grass (Panicum maximum) under germination, root and aerial part development of coloniao grass (Panicum maximum) root and aerial part. Germination assays carried out in Petri dishes confirmed that the methanolic (200 ppm) extract inhibited the growth of hypocotyl (75%), root (83%), and germination (30%) of coloniao grass. The greenhouse results obtained were: hypocotyl 83%, root 80% and germination 63%, but at a concentration of 400 ppm. Methanolic extract fractions did not reproduce the results cited above. The most active fraction (dichloromethane/chloroform) was analyzed by GC/MS. It contains mainly long-chain aliphatic compounds such as phytol (13.5%), oleic acid (12.8%), methyl linolelaidate (10.9%) and palmitic acid (6.9%); 1,2,4-trimethyl- and isopropenylbenzene (12.2%); two isomeric ketones (isopropenyl methyl and 3-penten-2-one) (7.3%) were also detected. Three unknown compounds were also important: one with a low molecular weight (98 Da, 13.5%) and two of high molecular weight (13.6%).

A new approach for quantifying furanodiene and curzerene: a case study on the essential oils of Eugenia uniflora L., Myrtaceae (pitangueira) leaves

The essential oil obtained from the leaves of Eugenia uniflora L., Myrtaceae, which grows in the Brazilian savannah, was studied by gas chromatography mass spectrometry (GC-MS). Furanodiene (1.2%) was thermally rearranged to curzerene (85.1%) to produce a combined content of 86.3%. GC analysis carried out under mild conditions (with a constant temperature of 100 oC) showed that the furanodiene concentration was three-fold greater than the curzerene concentration, i.e., the essential oil contained 64.7% furanodiene and 21.6% curzerene. Germacrene B also rearranged to γ-elemene and the concentration of both was 2.3%. Special care should be taken when conventional gas chromatography analysis is used for quantifying compounds that can rearrange at high temperatures.

Chemical Constituents and Evaluation of Antimicrobial and Cytotoxic Activities of Kielmeyera coriacea Mart. & Zucc. Essential Oils

Many essential oils (EOs) of different plant species possess interesting antimicrobial effects on buccal microorganisms and cytotoxic properties. EOs of Kielmeyera coriacea Mart. & Zucc. were analyzed by gas chromatography coupled to mass spectrometry (GC-MS). The EO from leaves is rich in sesquiterpenes hydrocarbons and oxygenated sesquiterpenes. The three major compounds identified were germacrene-D (24.2%), (E)-caryophyllene (15.5%), and bicyclogermacrene (11.6%). The inner bark EO is composed mainly of sesquiterpenes hydrocarbons and the major components are alpha-copaene (14.9%) and alpha-(E)-bergamotene (13.0%). The outer bark EO is composed mainly of oxygenated sesquiterpenes and long-chain alkanes, and the major components are alpha-eudesmol (4.2%) and nonacosane (5.8%). The wood EO is mainly composed of long-chain alkanes and fatty acids, and the major components are nonacosane (9.7%) and palmitic acid (16.2%). The inner bark EO showed the strongest antimicrobial activity against the anaerobic bacteria Prevotella nigrescens (minimum inhibitory concentration-MIC of 50 µg mL−1). The outer bark and wood EOs showed MICs of 100 µg mL−1 for all aerobic microorganisms tested. The EOs presented low toxicity to Vero cells. These results suggest that K. coriacea, a Brazilian plant, provide initial evidence of a new and alternative source of substances with medicinal interest.

Allelophatic action of Cecropia pachystachya extracts on the growth of guinea grass (Panicum maximum)

Cecropia pachystachya (embauba) is a tree of the Urticaceae family, typical of forest margins. It grows quickly and is abundant throughout Brazil. In this study, the allelophatic potential of the methanolic extracts from the bark, trunk and roots of Cecropia pachystachya cultivated in Uberaba, Minas Gerais, Brazil was analyzed through germination bioassays and growth measurements of the aerial part of Panicum maximum. The best effect was observed in the root extracts at 150 ppm concentration. The following main volatile constituents were identified by GC/MS: geranylacetone, lauric acid, palmitic acid, octadecanal and long chain alkenes in the bark; geranylacetone, farnesol, farnesylacetone, octadecanal, palmitic acid and long-chain alkenes in the root; and geranylacetone, palmitic acid and long-chain alkenes in the wood.