Geographical origin traceability of mulberry leaves using stable hydrogen, oxygen, and carbon isotope ratios

Geographical discrimination of mulberry leaves is very important for their efficacy and quality as a traditional Chinese medicine. Stable hydrogen, oxygen, and carbon isotope ratios were measured in 292 mulberry leaves collected at 2 growth stages in 2 seasons from 8 regions of China. A stepwise linear discriminant analysis (LDA) approach were proposed to combine with stable isotope technology to tracing the origin of mulberry leaves. The results showed that leaves sampled in autumn were extremely depleted in ²H and ¹⁸O and slightly enriched in ¹³C compared with leaves sampled in summer, correlated with the effect of season, transpiration and photorespiration on stable isotopes. δ²H and δ¹⁸O of the leaves were enriched during the growth process. The overall discrimination accuracy of the autumn tender model was 81%, demonstrating that analysis of δ²H, δ¹⁸O, and δ¹³C is a promising technique for tracing the geographical origin of mulberry leaves, although season, growth stage and number of samples affect the accuracy of discrimination.