A comparison of the toxicity and metabolism of phenol and chlorinated phenols by Lemna gibba, with special reference to 2,4,5-trichlorophenol

The toxicity of a series of chlorinated phenols, from phenol to pentachlorophenol, was determined using frond reproduction in aseptically grown Lemna gibba. The toxicities of the phenols tended to increase as the number of chlorine substituents on the phenol ring increased. The plants metabolized each of the phenols in the same manner producing metabolites that were more polar than their parent compounds. The metabolite for 2,4,5-trichlorophenol was isolated and identified by nuclear magnetic resonance spectroscopy and chemical ionization mass spectroscopy. The structural identity was confirmed by comparison with synthetic material as 2,4,5-trichlorophenyl-beta-D-glucopyranoside. These results, together with previously published results, suggest that conjugation with D-glucose is a stereotypic response of duckweed to challenge by phenol and chlorinated phenols.