Bactericidal properties of the chloroform fraction from rhizomes of Aristolochia paucinervis Pomel

The deffated chloroform fraction (APRC) obtained from the rhizomes of Aristolochia paucinervis Pomel (Aristolochiaceae) has a high bacteriostatic activity against bacterial strains like Clostridium perfringens ATCC 13124 and Enterococcus faecalis ATCC 29212. Here, we report the bactericidal activity of APRC against both strains which was evaluated by using time-to kill assays. The results showed that APRC produced an intense time-dependent bactericidal effect against C. perfringens, achieving over a 24 h-period a 5 log(10)-unit decrease in CFU/ml at a concentration greater than or equal to 1.25 x MIC. In contrast, when rested against E. faecalis, APRC exhibited a concentration-dependent killing activity at concentrations of 1.25 x MIC and 2.5 x MIC, yielding to a decrease of 1.5 and 2.5 log(10)-unit in CFU/ml at 4 h, respectively. However, substantial regrowth of E, faecalis occurred within 24 h. Ultrastructural alterations were observed for both exposed microorganisms by scanning and transmission electron microscopy. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.