Inhibitory effects of active substances isolated from Cassia garrettiana heartwood on tumor growth and lung metastasis in Lewis lung carcinoma-bearing mice (Part 1).

A methanol extract (500 mg/kg x 2/day) of the heartwood of Cassia garrettiana inhibited the tumor growth and metastasis to the lung in Lewis lung carcinoma (LLC)-bearing mice. We isolated the two active substances from the methanol extract of C. garrettiana: compound 1 was identified as Cassigarol A and the determination of the structure of compound 2 is now in progress. We examined the effect of the active substance (compound 1, Cassigarol A) on tumor growth and lung metastasis in LLC-bearing and primary tumor-removed mice and found that Cassigarol A (50 mg and 100 mg/kg x 2/day) inhibited the tumor growth and metastasis to the lung. In addition, Cassigarol A inhibited the plasmin activity and the formation of capillary-like networks of human umbilical vein endothelial cells (HUVECs) at concentrations of 10 to 100 microM. Therefore, it is suggested that the antitumor and antimetastatic activities of Cassigarol A might be due to the inhibition of plasmin activity and formation of tubes (angiogenesis) from HUVECs.