Chemical characterization of pine bark (Pinus pinaster Aiton subsp. atlantica), antioxidant properties and phenolic profile of its extracts

Introduction: Pine bark is an agroindustrial residue from the timber industry and represents a source of phenolic compounds. These compounds have several beneficial properties being antioxidants, antimicrobial, anti-inflammatory, cardiovascular, among others. Objetives: The aim of this work was to study the chemical composition of the bark from Pinus pinaster Aiton subsp. atlantica and the phenolic profile of its aqueous, ethanolic and hydroethanolic extracts. Methods: The moisture content, ash, protein, crude fat and carbohydrates were analysed. The bark was extracted with water, ethanol or a mixture of both in a Soxhlet apparatus and the extraction yield, total phenolic content (TPC), antioxidant activity and phenolic profile by RP-HPLC-UV, in the extracts with higher TPC, were determined. Results: The results obtained for chemical composition were: 63.43 of carbohydrates, 2.81 of crude fat, 1.60 of proteins and 1.75 of ash, calculated in % w/w of dry bark. The extraction yield was greater for the ethanolic and the hydroethanolic extracts (17.08 and 17.55% w/w dry bark, respectively). The TPC and antioxidant activity were higher in the hydroethanolic extract (73.48 mg GAE/g and 108.74 mg AAE/g dry bark, respectively). Regarding the phenolic profile of the hydroethanolic extract, gallic acid, taxifolin, ferulic acid and quercetin were identified at 280 nm, and catechin was identified in the ethanolic extract at 320 nm. Conclusion: P. pinaster Aiton subsp. atlantica bark is mainly constituted by carbohydrates and it is rich in hydroethanolic and ethanolic extractives, being that these have high antioxidant activity. The ethanolic extract presents higher catechin amount when compared to the hydroethanolic extract.