Abstract
Betulin, betulinic acid and lupeol are naturally occurring pentacyclic triterpenoids with significant medicinal values. Great amounts of triterpenoids are found in the bark of white birch (Betula platyphylla Suk.) trees, which can be affected by climatic factors along the geographical gradients. In this study, site-based data of triterpenoids’ (betulin, betulinic acid and lupeol) concentrations were determined in barks of white birch trees from 48 sites in Northeast China. Triterpenoid concentration in white birch tree barks did not change in response to any geographical gradients along latitudes, longitudes or elevations. Instead, concentrations of betulin and lupeol in birch tree barks increased with the increase of temperature and precipitation but declined with the increase of relative humidity. As a result, betulin concentration was higher in birch trees in the northeastern and southwestern parts of the study area, and lower in the central part of the study area in Northeast China. Although betulinic acid concentration did not change with climatic factors, its distribution pattern was similar to betulin concentration. Lupeol concentration was highest in the north-eastern part and along the southern and eastern boundaries in the study area. Our results can supply information for precondition of triterpenoids’ extraction for industrial production, which can be an available approach to solve the issue of bark waste processing of white birch.
Highlights
The white birch is widespread in the northern latitudes of the world and represents an abundant and currently under-utilized natural resource [1]
Lupeol concentration in barks of white birch trees was higher in the northeastern part of the study area and along the southern and eastern boundaries of the study area
Concentrations of triterpenoids in the barks of white birch trees did not change in response to any geographical gradients of latitude, longitude and elevation
Summary
The white birch is widespread in the northern latitudes of the world and represents an abundant and currently under-utilized natural resource [1]. Birch tree bark (BTB) is a kind of large-scale timber-processing waste and a source of valuable extractive components [2]. Triterpenoid is one of main extractive components from BTB which may account for up to 30% (weight percent) of the dry mass in exfoliated narrow foils. Triterpenoid compounds are abundant in natural sources and have a wide variety of pharmacological uses. Betulin is a component of cosmetic powders and other cosmetic products [5]. Betulin can be used to inhibit the Forests 2017, 8, 334; doi:10.3390/f8090334 www.mdpi.com/journal/forests
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