Determination of Antioxidant Activity of Different Extracts From Bark of Pinus spp. grown in Giresun (Turkey) Province – Phenolic analysis by RP-HPLC-DAD

Abstract

This study aimed to investigate the phenolic compounds, total phenolic content, and antioxidant activities of Pinus sylvestris L. var hamata Steven, Pinus pinaster Aiton subsp. pinaster, and Pinus pinea L. bark extracts prepared with hot water. The phenolic composition and total phenolic content (TPC) of extracts were determined by Reversed Phase-High Performance Liquid Chromatography-Diode Array Detector (RP-HPLC-DAD) and Folin–Ciocâlteu method, respectively. The antioxidant activity was determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH•) radical scavenging and ferric ion (III) reducing / antioxidant power (FRAP) assays. Besides, the highest total phenolic content was detected in P. pinea bark extract [984.46±4.08 μg mL-1 gallic acid equivalent (GAE) and 1163.33±4.04 μg mL-1 catechin equivalent (CE)] and the lowest result was detected in P. sylvestris bark extract (361.53±3.52 μg mL-1 GAE and 427.26±4.17 μg mL-1 CE). Among the tested materials, the most abundant phenolic compounds in P. pinea bark extract were catechin (3.586±0.114 mg g-1) and taxifolin (1.866±0.096 mg g-1). According to the antioxidant results, P. pinea bark extract exhibited remarkable antioxidant activity than standard BHT and Trolox [SC50: 1.64310±0.00003 µg mL-1 for DPPH and 1428.75±5.62 µM Trolox Equivalent Antioxidant Capacity (TEAC) for FRAP]. The obtained results indicated that pine bark extracts can be used as an easily obtainable natural source of antioxidants for the food and pharmaceutical industry.