Ginkgo biloba extract EGb 761 is not active against Mycobacterium avium infection in C57BL/6 mice

In a recent study, Atzori et al. demonstrated in vitro and in vivo the efficacy of bilobalide, extracted from Ginkgo biloba leaves, against Pneumocystis carinii. G. biloba leaves contains terpenoids called ginkgolides and bilobalide. Studies of many plant-derived terpenoids have shown that compounds of this class can also display antibacterial or immunomodulating activities. Of note, derivatives of terpenoids have been shown to be microbicidal against mycobacteria. Therefore, we evaluated both the therapeutic activity of G. biloba extract EGb 761 alone or in combination with clarithromycin and its prophylactic activity against M. avium infection in mice. In both the therapeutic and the prophylactic studies, CFU counts in spleens and lungs of G. biloba-treated mice were not different from those in untreated controls at any time point. In the therapeutic study, the combination of G. biloba and clarithromycin was not more effective than clarithromycin alone.