Abstract

The amebicidal activity of traditional anitiamoebic drug (emetine, carbasone, diodoquin, chloroquine, atabrine, chloramphenicol and tertracycline) and newly appeared chemicals(niridazole, metronidazole and No. 8603 substance) were assayed by in vitro experiment using five strains of human originated E, histolytica. The variety of amebicidal activity of drugs by the strains were discussed. Ranges of amoebicidal activity of traditional antiamoebic drugs kept almost similar titers of previous reports at the concentration; 1:5,000 to 1:20,000 with emetine hydrochloride, 1:10.000 to 1:20,000 with carbarsone, 1:8,000 to 1:16,000 with diodoquin, 1:50,000 with chloroquine, 1:1,000 to 1: 4,000 with atabrine ,1:1,000 to 1:2,000 with chloramphencol and 1:5,000 to 1:8,000 with tetracycline. The newly appeared chemicals showed higher amebicidal titres at the concentration; 1:500,000 to 1:5,000,000 with niridazole, 1:50,000 to 1:100,000 with metronidazol and 1:100,000 to 1:500,000 with No.8603 substance. Emetine, chloramphenicol and No. 8603 substance showed amebicidal activities at lower concentration to intestine originated amebae (YS 14, YS 15 and NAMRU II strain) than to liver originated amebae (YS 24 and YS 25 strain ), while carbarsone, chloroquine and metronidazole showed the activity at higher concentrations. Diodoquin showed lower amebicidal titres to trophozoite borne amebae (NAMRU II, YS 24 and YS 25 strain) than to cyst borne amebae(YS 14 and YS 15 strain), but niridazole showed converse results. The concentration of atabrine for amebicidal activity was not constant according to strains of the amoeba, but tetracycline showed almost settled titers.