Characterization of Calea ternifolia and its Adulterant Chromolaena odorata Using Macro-Microscopy, HPTLC and UHPLC-UV-MS

Calea ternifolia Kunth (syn. C. zacatechichi Schltdl.), Asteraceae, commonly known in English as dream herb, bitter-grass, or Mexican Calea, is a medicinal plant native to Mexico and Central America. It has long been used in traditional folk medicine and is traded as a dietary supplement in the United States. However, this species is often misidentified and adulterated with other botanicals, such as Chromolaena odorata (L.) R.M.King & H.Rob., Asteraceae, or the 'non-bitter calea,' which contains carcinogenic pyrrolizidine alkaloids. Adverse reactions and toxicities associated with adulterated and misidentified herbal dietary supplements have been widely reported, warranting the need for authentication and quality control of botanical raw materials. Comprehensive research on the quality, authenticity, and safety of Calea ternifolia is still pending. The present study provides an orthogonal approach to differentiate the dream herb from non-bitter calea using three independent methodologies. Detailed morpho-anatomical and histochemical characterizations of Calea ternifolia and its adulterant C. odorata by bright-field light and scanning electron microscopy were established. The HPTLC fingerprints of the two species are easily distinguishable. More than 30 compounds representing quinic acid derivatives, flavonoids, flavonoid glycosides, and sesquiterpene lactones were identified in C. ternifolia samples using UHPLC-UV-MS analysis. In contrast, only six compounds were found in C. odorata and devoid of all the nineteen sesquiterpene lactones observed in C. ternifolia. The study results would aid in the authentication of botanical raw materials and quality control of Calea ternifolia-based products, as well as ensure that the finished products are free from their common adulterants.

Automated summary

This study provides an orthogonal approach to differentiate the dream herb from non-bitter calea using three independent methodologies. Detailed morpho-anatomical and histochemical characterizations of the two species were established, along with the identification of chemical compounds present. The study results would aid in authentication of botanical raw materials and quality control of Calea ternifolia-based products.