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.

Diphenylguanidine (DPG) has been used as a primary and secondary accelerator in the vulcanization of rubber. Exposure to DPG may occur as a result of dermal contact during rubber manufacture or from contact with the finished products. DPG is poorly absorbed through skin. It can be found in latex gloves and other rubber products found in homes and offices. Diphenylguanidine is a standardized chemical allergen. It is used for diagnosis of contact allergy. It is a component of Carba Mix, used in the epicutaneous patch test, called T.R.U.E. TEST, approved by FDA in 1994. T.R.U.E. TEST is indicated for use as an aid in the diagnosis of allergic contact dermatitis in persons 18 years of age and older whose history suggests sensitivity to one or more of the 35 substances included on the T.R.U.E. TEST panels.