Inhibition of Growth of a Green Flagellate by the Antihistamine, -dimethylaminoethyl (Benadryl).

Abstract

Beta-dimethylaminoethyl benzhydryl ether (Benadryl-HCl, Parke-Davis Co.) in concns. of 1.7 x 10-5 [image]. or greater, inhibits the growth of the green flagellate Chlorogonium tetragamum. The inhibition occurs only at pH values above 6.8. Similar inhibition is produced by 4,4-diphenyl-N, N-dimethyl-butyl-1-amine, a compound structurally related to Benadryl but much lower in antihistaminic activity. The inhibition is not reversed by the addition of histamine, thiamine, nicotinamide, Krebs cycle intermediates, yeast extract, or casein hydrolyzate to the medium.