Abstract
Barks of Tachigali guianensis and Tachigali glauca, from the Brazilian Amazon rainforest, were studied regarding anatomy and chemical composition. The barks were similar, with a narrow rhytidome, a ring of sclerified cells below the periderm, a widely dilated and sclerified nonconducting phloem, septate crystal strands, and extensive phenolic deposits in cells. Differences between the species were mainly in the sclerenchyma. Proportions of cell types in the T. guianensis and T. glauca barks were, respectively: 27.8% and 28.3% axial parenchyma, 15.6% and 15.1% sieve tube elements, 11.6% and 13.4% radial parenchyma, 15.6% and 8.7% sclereids, and 30.5% and 34.5% fibers. Chemical analysis showed that the T. guianensis and T. glauca barks included, respectively: 18.0% and 15.3% extractives, 1.8% and 1.0% suberin, 26.8% and 27.9% lignin, and 3.5% and 4.5% ash. The predominant polysaccharides were glucose (72.8% and 82.8% of total neutral sugars) and xylose (17.9% and 11.6%). Ethanol-water extracts were high in phenolics (total phenolics of 441.0 mg gallic acid equivalents (GAE) / g extract and 641.7 mg GAE / g extract), with moderate antioxidant activities (IC50 values of 7.3 µg extract / mL and 5.6 µg extract / mL). Tachigali guianensis bark and, particularly, T. glauca bark may be sources of phenolic compounds.
Highlights
Tree barks are a potential feedstock for the production of added-value products, including chemical compounds with interesting reactive functionalities and biochemical properties, such as antioxidant and biological activities, which may be applied in several industrial sectors (Jansone et al 2017)
Anatomical and chemical characterization has been presented for barks of temperate species, such as Quercus cerris (Şen et al 2010, 2011), Betula pendula (Miranda et al 2013; Ferreira et al 2017), Eucalyptus globulus (Neiva et al 2018a; Gominho et al 2020), Eucalyptus spp
The T. guianensis and T. glauca barks were low in suberin, which is consistent with the small proportion of phellem cells found in the rhytidome in both species and their being thin-walled
Summary
Tree barks are a potential feedstock for the production of added-value products, including chemical compounds with interesting reactive functionalities and biochemical properties, such as antioxidant and biological activities, which may be applied in several industrial sectors (Jansone et al 2017). Proportions of cell types in the T. guianensis and T. glauca barks were, respectively: 27.8% and 28.3% axial parenchyma, 15.6% and Chemical analysis showed that the T. guianensis and T. glauca barks included, respectively: 18.0% and 15.3% extractives, 1.8% and 1.0% suberin, 26.8% and 27.9%
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