Abstract: An object of the present invention is to provide a novel antitumor agent by evaluating the antitumor effect obtained by a mixture of polylactic acids which is produced by polymerizing lactides in the presence of certain amine compound. The present invention provides an antitumor agent which comprises a mixture of linear and cyclic lactic acid oligomers represented by the following formula (1) or (2): wherein m represents an integer of 1 to 30, and n represents an integer of 1 to 30, which is produced by polymerizing lactides in the presence of a compound represented by the following formula (3): Me—N(R1)(R2)??(3) wherein Me represents an alkali metal, and each of R1 and R2 independently represents an aliphatic group or aromatic group.

Abstract: An object of the present invention is to provide a novel antitumor agent by evaluating the antitumor effect which is expressed by a mixture of polylactic acids which contains cyclic polylactic acids as main component. The present invention provides an antitumor agent which comprises a mixture of polylactic acids which contains cyclic polylactic acids having a condensation degree ranging from 3 to 20 as main component.

Abstract: The object of the present invention is to provide an agent for preventing the implantation of cancer cells and/or an agent for preventing the cancer recurrence, for example, an agent and food and drink for preventing the implantation and/or metastasis of cancer cells existing in the transplanted organ, the graft and/or the transplanted cells in a recipient. According to the present invention, there is provided an agent for preventing the implantation of cancer cells, an agent for preventing the cancer recurrence, and food and drink for preventing the implantation of cancer cells and/or preventing the cancer recurrence, which comprises, as an active ingredient, a mixture of cyclic and/or straight chain poly lactic acids having a condensation degree of 3 to 19.

Abstract: The object of the present invention is to provide a radiation preventing agent and food and drink using the same, that have a function of giving protection against radiation and have no harmful side effects. The present invention provides a radiation protecting agent which comprises, as an active ingredient, a mixture of cyclic and/or straight chain poly lactic acids having a condensation degree of 3 to 19.

Abstract: Nitrobenzoic acid amide derivative represented by the formula ##STR1## wherein A is (CH.sub.2).sub.x NH(CH.sub.2).sub.y or (CH.sub.2).sub.x NH(CH.sub.2).sub.y NH(CH.sub.2).sub.z, n is 1 or 2, x, y and z are each 2 to 5, and pharmacologically acceptable acid salt thereof is an excellent radio-sensitizer.