Sweet Birch (Betula lenta) has several economic and medicinal uses. Very little is known about the chemical composition of B. lenta. In this study, the volatile compositions of the bark of B. lenta from authentic and commercial sources were assessed by gas chromatography-mass spectrometry (GC-MS) and gas chromatography-flame ionization detection (GC-FID). Overall, more than 60 compounds were identified in natural sweet birch EO obtained by hydro-distillation. The oil was dominated by methyl salicylate (93.24-99.84%). A good approach to distinguishing wintergreen and birch oils would be biomarker-based analysis. The biomarkers are selected based upon three main criteria: (1) the marker should be commercially unavailable or too expensive which renders the adulteration process very costly, (2) The marker should be detected consistently in all the tested authentic EO samples, and (3) A birch EO marker should be found exclusively in birch EO, not in wintergreen and vice versa. The minor components o-guaiacol, veratrole, 2-E-4-Z-decadienal, and 2-E-4-E-decadienal were identified as natural marker compounds for authentic sweet birch oil. Surprisingly, none of the tested 27 commercial samples contained any of the identified birch markers. The detection of wintergreen markers such as vitispirane and β-dehydroelsholtzia ketone, the synthetic marker dimethyl-2-hydroxyterephthalate, and ricenalidic acid lactone suggest the addition of wintergreen, synthetic methyl salicylate, and castor oil, respectively. This is the first report to identify birch biomarkers to the best of our knowledge.
Keywords: 2-E-4-E-decadienal; 2-E-4-Z-decadienal; Betula lenta; dimethyl 2-hydroxyterephthalate; essential oil; o-guaiacol; sweet birch; veratrole.