In vitro antimicrobial activity of two dibutyltin(IV) complexes of kaurenic acids derivatives

The antimicrobial activity in vitro of ent-kaurenic, KA [1] and grandiflorenic acid, GA [2], two natural products obtained from Espeletia semiglobulata Cuatrec., and two dibutyltin (IV) complexes [3] and [4] derived from natural products synthesis, ent-kaurenic acid and grandiflorenic acid, respectively, against strains of Escherichia coli, Pseudomonas aeruginosa, both pathogens for man, and Trametes versicolor, a fungus responsible of white wood rotting. For the human pathogens, an agar diffusion disk was used, with a 30 µg/mL concentration. There was an improved activity with the dibutyltin(IV) with grandiflorenic acid [4] against E. coli; while the anti-fungal activity against T. versicolor was done by a gel dilution method with surface plate inoculation getting an improved anti-fungal activity with 120 µg/mL concentration. The new compounds were characterized with FTIR spectroscopy, 1H, 13C unidimensional and bidimensional NMR experiments for the natural products [1], [2] and the organotin complexes [3] and [4].