Caroline Junqueira Sartori

Chemical characterization of the bark of Eucalyptus urophylla hybrids in view of their valorization in biorefineries

Abstract Eucalyptus urophylla hybrids are important raw materials for the forest industry in Brazil, and large quantities of barks are available at mill site that may be used for added-value products. The chemical composition of barks of six commercial hybrids clones of E. urophylla×E. grandis, E. urophylla×E. Camaldulensis, and undisclosed E. urophylla hybrids was studied. The hybrids had similar composition, on average (data based on oven dry bark): 16% extractives, mainly corresponding to polar compounds that are soluble in ethanol and water, 19% lignin, 47% polysaccharides, 1% suberin, and 2% ash. The polysaccharides consists mainly of cellulose as indicated by 84% of total neutral monosaccharides in the acid hydrolysate and 10% xylose. The compositions of the lipophilic extracts was determined by GC-MS before and after alkaline hydrolysis. In all the barks, fatty acids, and triterpenes (namely: betulinic and ursolic acids) were the most abundant compounds followed by smaller amounts of sterols, long-chain aliphatic alcohols, phenolic acids, and acylglycerols. The ethanol-water bark extract had a high phenolic content: total phenolics ranged 211–551 mg gallic acid equivalents (GAE) g-1 of extract, tannins 76–184 mg catechin equivalents (CE) g-1 extract, and flavonoids 98–234 mg CE g-1 of extract. The antioxidant activity corresponds to 338 mg Trolox g-1 of extract. Development of high-value products is proposed through an integrated biorefinery approach including valorisation of extractives and targeting for cellulose-based applications.

Teores de fenóis totais e taninos nas cascas de angico-vermelho (Anadenanthera peregrina)

This study aimed to quantify total phenols and tannins in barks of Anadenanthera peregrina in different diameter classes and compare two methods of quantification of phenols. Barks of thirty-five trees, distributed in seven diameter classes, were collected. They were air-dried, ground and sieved; the material retained on 60 mesh sieve was used. Methanol:water (50%) solution was used for the extraction of phenols. Quantification of total phenols was performed by the modified Folin-Denis and Folin-Ciocalteau methods, while tannins were quantified by the radial diffusion method. No statistically significant differences were found between the phenol quantification methodologies. Increased contents of phenols and tannins were verified as the diameter of trees increased.

Teores de Fenóis Totais e Taninos nas Cascas de Angico-vermelho (Anadenanthera peregrina) / Content of Total Phenols and Tannins in Barks of Anadenanthera peregrina

This study aimed to quantify total phenols and tannins in barks of Anadenanthera peregrina in different diameter classes and compare two methods of quantification of phenols. Barks of thirty-five trees, distributed in seven diameter classes, were collected. They were air-dried, ground and sieved; the material retained on 60 mesh sieve was used. Methanol:water (50%) solution was used for the extraction of phenols. Quantification of total phenols was performed by the modified Folin-Denis and Folin-Ciocalteau methods, while tannins were quantified by the radial diffusion method. No statistically significant differences were found between the phenol quantification methodologies. Increased contents of phenols and tannins were verified as the diameter of trees increased.

Rendimento gravimétrico em taninos condensados nas cascas de Anadenanthera peregrina em diferentes classes diamétricas

O objetivo deste trabalho foi determinar o rendimento gravimetrico em taninos condensados nas cascas de Anadenanthera peregrina em diferentes classes diametricas. Coletaram-se amostras de cinquenta e nove arvores de Anadenanthera peregrina, a 1,30 m do solo (Diâmetro a altura do peito - DAP), distribuidas em sete classes diametricas. As cascas foram secas ao ar e trituradas em moinho de martelo. Foram realizadas amostragem composta para o preparo do extrato. A extracao foi feita em agua, na relacao 15:1 (v/p), adicionados 3% de sulfito de sodio (v/v) em banho-maria a 70oC por 4 horas. O material foi filtrado com emprego de coador de pano fino e concentrado em chapa de aquecimento a aproximadamente 150 g. Foi determinada a massa do extrato e retirados 10 g para a obtencao do teor de solidos e 20g para a para o indice de Stiasny. Os valores medios de teor de solidos totais, indice de Stiasny, teor de tanino condensado e teor de compostos nao tânicos foram de 11,34%; 75,79%; 12,76% e 4,07%, respectivamente. O teor de solidos, indice de Stiasny, teor de compostos nao tânicos tiveram diferencas significativas entre as classes diametricas. Ja para a producao de taninos condensados, o parâmetro classe diametrica nao influenciou.

Bark anatomy, chemical composition and ethanol-water extract composition of Anadenanthera peregrina and Anadenanthera colubrina

The bark of Anadenanthera peregrina (L.) Speg and Anadenanthera colubrina (Vell.) Brenan were characterized in relation to anatomical and chemical features. The barks were similar and included a thin conducting phloem, a largely dilated and sclerified non-conducting phloem, and a rhyridome with periderms with thin phellem interspersed by cortical tissues. Only small differences between species were observed that cannot be used alone for taxonomic purposes. The summative chemical composition of A. peregrina and A. colubrina was respectively: 8.2% and 7.7% ash; 28.8% and 29.3% extractives; 2.4% and 2.6% suberin; and 18.9% lignin. The monosaccharide composition showed the predominance of glucose (on average 82% of total neutral sugars) and of xylose (9%). The ethanol-water extracts of A. peregrina and A. colubrina barks included a high content of phenolics, respectively: total phenolics 583 and 682 mg GAE/g extract; 148 and 445 mg CE/g extract; tannins 587 and 98 mg CE/g extract. The antioxidant activity was 238 and 269 mg Trolox/g extract. The barks of the Anadenanthera species are a potential source of polar extractives that will represent an important valorization and therefore contribute to improve the overall economic potential and sustainability of A. peregrina and A. colubrina