Geo-climatic factors and soil properties affect phenolic compound synthesis and antioxidant activities in Betula platyphylla in Northeast China

Abstract

Phenolic compounds, one of the most important bioactive compounds, are susceptible to environmental factors. White birch (Betula platyphylla Suk.) is a major commercial tree species in Northeast China, and its bark is rich in phenolic compounds. We explored the influences of environmental factors on the concentrations of total phenols and total flavonoids, and individual phenolic compounds and DPPH (1, 1-diphenyl-2-picrylhydrazyl) free radical scavenging activity of B. platyphylla from seven producing areas in Northeast China were evaluated. The data analysis demonstrated that there were obvious differences in phenolic compound concentrations and bioactivities of the B. platyphylla bark extract from different locations. The concentrations of phenolic compounds, including total phenols, total flavonoids, hyperoside, and chlorogenic acid, were found to be higher in cold and dry high-latitude regions. The extracts of B. platyphylla bark had high antioxidant activities and were closely related to soil properties and geo-climate. Redundancy analysis revealed that soil moisture content produced a greater effect on phenolic compounds in B. platyphylla bark than other environmental factors. The total phenol and total flavonoid concentrations were negatively correlated with longitude, soil moisture content, and precipitation of wettest quarter, while they were significantly positively correlated with latitude. This study highlighted that geo-climatic factors, particularly soil moisture content, play a critical role in regulating the biosynthesis of phenolic compounds and their antioxidant activities, thereby enhancing the adaptation of B. platyphylla to its natural environment.