From root of Coptis trifolia Salisb., Ranunculaceae: Gross, Am. J. Pharm. 45[4], 193 (1873); Mollett, Christensen, J. Am. Pharm. Assoc. 23, 310 (1934); from C. teeta Wall.: Chatterjee et al., J. Indian Chem. Soc. 28, 97 (1951); from C. chinensis Wils.: Schramm, Tang, Pharmazie 14, 405 (1959).