The Chemical Characteristics of Caucasian FIR ( <i>Abies nordmanniana</i> (Steven) Spach) Crown Gall Barks

ABSTRACT In this study, the chemical and thermal properties of tumorous (crown gall) and normal (healthy) root bark of five Abies nordmanniana (Steven) Spach trees were investigated. To this end, analyses were conducted on solubility fractions (cold water, hot water, acetone and 1% NaOH), basic structural components (holocellulose, α‐cellulose, hemicellulose, lignin and ash), total phenolic content, total flavonol and total flavonoid contents, as well as DPPH radical scavenging activity. The results demonstrated that all solubility values increased with gall formation. Tumour development was associated with decreases in cellulose and lignin contents, whereas hemicellulose and ash contents increased. These compositional changes were further supported by FTIR‐ATR (Fourier‐transform infrared spectroscopy with attenuated total reflectance) and TGA (thermogravimetric) analyses. In addition, total phenolic, flavonol and flavonoid contents were significantly lower in gall root bark compared with normal root bark, while the DPPH EC₅₀ value was higher, indicating reduced antioxidant capacity. These findings were corroborated by RS‐HPLC (Reversed‐phase high‐performance liquid chromatography) analysis, which revealed decreased concentrations of gallic acid, catechin, caffeic acid, vanillin and p‐coumaric acid in gall tissues.