DIFFERENTIAL AGAR-DIFFUSION BIOASSAY FOR CYTOTOXIC SUBSTANCES

A differential agar‐diffusion bioassay for antitumor compounds was developed based on the cytocidal effects of the test compound on Eagle' KB cells, Earle' L cells, and L‐1210 cells in an agar medium. The three cell strains were grown in suspension culture in Waymouth' medium MB 752/1 supplemented with calf serum. Paper disks dipped in test solutions were applied to seeded agar plates and after 18‐hr. incubation the cytocidal effects were determined by flooding the surface with the vital stain, 2,6‐dichlorophenolindophenol. The diameters of the nonreduced zone around the paper disks were measured. The KB cells were sensitive to more compounds than the Earle' L cells or the L‐1210 cells in a survey of 30 compounds with demonstrated antitumor activity in vivo. The agar plates were also used for preparing bioautographs of paper chromatograms and thin‐layer chromatograms. Copyright © 1969 Wiley‐Liss, Inc., A Wiley Company