Chemical and pharmaceutical evaluation of roasted Ephedra herba and elucidation of the health hazards caused by white smoke generated during processing

In traditional Chinese medicine and traditional Japanese medicine (Kampo medicine), crude drugs are processed to obtain different efficacy, potentially improving the efficacy from the same sample or reducing its adverse effects. Honey-roasted Ephedra herba (EH) and roasted EH are often processed to reduce its sweating inducing effects and enhance its antitussive effects. We attempted to standardize roasted EH based on changes in ephedrine alkaloid content by optimizing the heating temperature and roasting color using a spectrophotometer. Additionally, the volatile oil content of the standardized roasted EH as well as its inhibition of adipose differentiation and change in thermogenesis-related gene expression were assessed using mouse preadipocytes and rat brown adipocytes. As the processing temperature increased, the contents of (1R, 2S)-(−)-ephedrine, (1S, 2S)-(+)-pseudoephedrine, (1R, 2S)-(−)-N-methylephedrine, (1R, 2S)-(−)-norephedrine, and (1S, 2S)-(+)-norpseudoephedrine decreased, with significant decreases recorded at temperatures > 250 °C for the five alkaloids. L* and b* decreased with increasing temperature, whereas a* increased. C* \(\left( {C* \, = \sqrt {\left( {a*} \right)^{2} + (b*)^{2} } } \right)\) of 22.28 (processing temperature: 280 °C), which was linked to 20% and 40% reductions in total ephedrine alkaloid and phenylpropanolamine ((1R, 2S)-(−)-norephedrine + (1S, 2S)-(+)-norpseudoephedrine) content, respectively, was similar to the characteristics of roasted EH used in Japan. Conversely, heat processing significantly increased the levels of volatile oils, including p-cymene, limonene, dehydro-p-cymene, β-terpineol, γ-terpinene, α-terpinolene, benzoic acid, and benzaldehyde. Moreover, EH had significantly reduced lipid droplet accumulation compared with negative control and roasted EH (both, P < 0.001). These changes were accompanied by decreased expression of, peroxisome proliferator-activated receptor gamma genne (Pparg), ligand-activated nuclear receptor, which is implicated to regulate fat-specific gene expression and activate adipocyte differentiation. EH, roasted EH (280 °C and 300 °C), ephedrine, and norephedrine significantly increased the expression of Ucp1 in rat brown adipocytes. However, no significant difference was observed between EH and roasted EH. We determined how heat processing of EH alters its alkaloid content and pharmacological effects. In addition, we found that the white smoke produced when EH is roasted in pharmacies poses health risks, as it contains ephedrine alkaloids and compounds such as furfural and furfuryl alcohol.

Graphical abstract