Antitumor activity in an extract of Thai rice seedlings

Abstract

Antitumor activity was found in an extract of Thai rice (RD-7) seedlings, which had potent cytotoxic effects on four (P388, HSOS-1, X63-Ag8 and Jurkat) out of seventeen transformed cell lines, but not on untransformed cell strains (YH-1, YH-3, KC-T1 and PAE). The activity was very weak, though significant, in dormant rice seeds, but it increased remarkably from 3 d to 7 d after inoculation, decreasing again in the later stages of growth. The activity was concentrated by salting out with ammonium sulfate and partially purified by column chromatographies of CM Sephadex (C-25) and Sephadex G-100. It was characterized as a protein-containing molecule with a molecular weight of 40 Kd which was resistant to freezing, heating, and pH 5.0 and 9.0 environments, and sensitive to trypsin digestion. The biological significance of this antitumor activity is discussed. © 1993.