The bark of Stryphnodendron rotundifolium as a source of phenolic extracts with antioxidant properties

Abstract

The objective of this study was to evaluate the anatomical and chemical components of the bark of Stryphnodendron rotundifolium, a tree species from the Brazilian Cerrado, aiming to provide information that values its use as a source of polyphenols and natural antioxidants for various industry sectors. Anatomy and bark histochemistry were analyzed, as well as the summative chemical composition (extractive, lignin, suberin, ash and polysaccharide) and quantitative elemental analysis of bark. The bark extracts were quantified for phenolic composition and antioxidant activity. The results indicated that the bark is formed by conducting phloem, nonconducting phloem and rhytidome composed of two or more successive periderms. The average chemical composition of the bark was 50.2% total extractives, 28.2% total lignin, 1.3% suberin, 1.9 ash and 18.4% polysaccharides. The ethanol–water extract had a high content of flavonoids and condensed tannins, with 232.1 and 501.3 mg EC g−1 extract, respectively. The bark extract showed strong antioxidant activity, reaching 89.4% inhibition of DPPH free radicals, superior to the commercial antioxidant BHT, which inhibited 76.4% at the same concentration. These results show that S. rotundifolium bark is a potential natural source of phenolic compounds and antioxidants and can be used for medicinal purposes and to compose various products such as wood adhesives, cosmetics and foams. The extraction of these compounds will represent an important valorization of bark from this species and, therefore, contribute to economic and environmental valorization of the Cerrado.