Narceine methyl ester and narceine are potent alkaloids which were isolated from Corydalis longipes were found effective in vitro at very low concentration, i.e., 100~500 ppm against spore germination of some test plant pathogenic fungi (Alternaria solani, A. tagetica, Cercospora abelmoschi, Curvularia maculans, Erysiphe cichoracearum, E. pisi, Fusarium udum, Helminthosporium oryzae, H. penniseti, Ustilago cynodontis). George Bell Frankforter was the first person to isolate narceine (in 1893) during his Ph.D. research for August Hofmann at the University of Berlin. Narceine has a weak morphine-like action, but is not much used in medicine. It may be administered in a pill, as a mild hypnotic and to allay cough; it is less depressant than morphine and does not constipate. Ethylnarceine is a narcotic, analgesic, and antitussive.

Ethylhydrocupreine Hydrochloride (optochin) is a reagent used in the alteration in bacterial morphology, it is now used in cell culture techniques for the presumptive identification of Streptococcus pneumoniae, which is optochin-sensitive, from other alpha-hemolytic streptococci such as viridans streptococci, which are resistant. However, a single standardized procedure does not exist. Optochin is included neither in the current EUCAST breakpoint tables nor in the CLSI performance standards for antimicrobial susceptibility testing.