Metabolism of phenyl-3 H-indoles by cell suspension of Acer pseudoplatanus L. and their phytotoxicity

Phenyl-3H-indoles inhibited growth of Acer pseudoplatanus cells but were not toxic in vivo. Experiments were conducted to find out why the compounds gave a toxic response in cell suspension but not a phytotoxic response in whole plants. The behaviour of two phenyl-3H-indoles, (2-(4-chlorophenyl)-3,3-dimethyl-5-fluoro-3H-indole and 2-(4-chlorophenyl)-3,3-dimethyl-5-carboxy-3H-indole), was investigated in cell suspensions. Absorption and metabolism by cells were rapid. The major metabolite was identified as a polar conjugate of 2-(3-hydroxy-4-chlorophenyl)-3,3-dimethyl-5-fluoro-3H-indole. This metabolite did not inhibit cell growth. Different phenyl 3H-indole analogues with the hydroxylation site blocked were synthesised to determine if metabolism was involved in the disappearance of activity in vivo. The results indicated that this was not the case and thus the absence of phytotoxicity must be related to another factor.