Genotoxic action of the sesquiterpene lactone glaucolide B on mammalian cells in vitro and in vivo

Glaucolide B is a sesquiterpene lactone isolated from Vernonia eremophila Mart. (Vernonieae, Asteraceae) and has schistosomicidal, antimicrobial and analgesic activities. This study examined the cytotoxic and clastogenic activities of glaucolide B in human cultured lymphocytes and in bone marrow cells from BALB/c mice. The mitotic index (MI) and chromosomal aberrations were analyzed in both of the above systems, whereas sister chromatid exchanges (SCE) and the proliferation index (PI) were determined only in vitro. In human cultured lymphocytes, glaucolide B concentrations greater than 15 mu g/ml of culture medium completely inhibited cell growth. At 4 mu g/ml and 8 mu g/ml of culture medium, glaucolide B significantly increased the frequency of chromosomal aberrations in lymphocytes and was also cytotoxic at concentrations greater than or equal to 8 mu g/ml; there was no increase in the frequency of SCE. Glaucolide B (160-640 mg/kg) did not significantly increase the frequency of chromosomal aberrations in mouse bone marrow cells nor did it affect cell division. Since glaucolide B showed no clastogenic action on mammalian cells in vivo but was cytotoxic and clastogenic in vitro, caution is needed in its medicinal use.