Effects of oleanolic acid and ursolic acid on inhibiting tumor growth and enhancing the recovery of hematopoietic system postirradiation in mice

Two triterpene acids, oleanolic acid (OA) and ursolic acid (UA) were examined for their ability to inhibit the tumor growth and modify hematopoiesis after irradiation in three experimental systems: (a) in vivo anti-tumor activity of implanted tumor by ascitic cells was found to be augmented by addition of OA and UA at a high concentration and inhibited in a dose-dependent manner; (b) in the sublethal whole-body irradiated mice treated with the drugs in the 30 min preirradiation period, enhanced effects of OA and UA on peripheral leukocytes were observed by a different significance, and (c) when these chemicals were administered i.p. to mice 30 min before 4 Gy irradiation, both OA and UA enhanced the postirradiation responses of splenic blastogenesis by PHA. UA was a more potent tumorigenic inhibitor than OA. Combining with the γ-irradiation, however, there was no significant synergetic effect on their anti-tumor activity. The beneficial effects of OA and UA on hematopoiesis and immunocompetence under this study, suggested they might partially play a role in anti-cancer and, furthermore, with the ability to decrease undesirable radiation damage to the hematopoietic tissue after radiotherapy.