Variation of Chemical Composition of the Lipophilic Extracts from Yellow Birch (Betula alleghaniensis) Foliage

The occurrence of biologically active compounds identified for the first time in the lipophilic extracts of yellow birch (Betula alleghaniensis Britt.) foliage led to the quantification of the seasonal variation of their concentrations. Yellow birch foliage was collected from late June until late September 2003 in two different regions of Quebec. The extraction yields using hexane as a solvent were determined, and the extracts were analyzed by GC-MS to identify their molecular composition. In terms of both extraction yields and the concentration of the targeted molecules present in the extracts, mid-September has been determined as the best time to collect foliage samples. A total of 14 constituents were identified in these extracts. This is the first report of the presence of all of these constituents in yellow birch foliage and of some of them in the genus Betula. The most important compounds identified in yellow birch foliage extracts are triterpene squalene and aliphatic hydrocarbon tetracosan, aliphatic alcohol phytol, fatty acids hexadecanoic and octadecanoic, pentacyclic triterpenes alpha- and beta-amyrin, and phytosterol stigmast-5-en-3-ol.