An Optimized Method for Extracting Oenothein B from Eucalyptus Leaves

Abstract

Eucalyptus is a fast-growing and high-yield tree species producing approximately one third of the timber of the world. Eucalyptus leaves are a by-product of timber with comparable biomass, and are largely unused. Eucalyptus leaves are rich in polyphenols, of which oenothein B is the most abundant. In this study, the authors developed an ultrasonic-based method for extracting oenothein B from Eucalyptus leaves. The ethanol concentration was proven to be a key determinant for the extraction efficiency and quality of oenothein B. Extracting with an ethanol concentration greater than 20% resulted in the altered chemical structure of oenothein B. The optimized conditions for Oenothein B extraction from Eucalyptus leaves used 10% ethanol and a 1 to 50 (g/mL) material to liquid ratio for 1 h under 40 kHz ultrasonic at a temperature of 87 °C. The highest extraction yield obtained was 12.4%. The oenothein B extract showed the capability of reactive oxygen scavenging. The accumulation pattern of oenothein B during the developmental processes of Eucalyptus leaves was detected using the developed method, and the rapid-accumulation period of oenothein B was determined, which will facilitate the utilization of Eucalyptus leaf resources.