Effect of a casbane diterpene isolated from Croton nepetaefolius on the prevention and control of biofilms formed by bacteria and Candida species

This study aimed to evaluate the effect of the compound 1,4-dihydroxy-2E,6E,12E-trien-5-one-casbane (CD1CN), a casbane diterpene isolated from Croton nepetaefolius stalks, on the biofilm formation or preformed biofilms of bacteria and yeasts. Minimum inhibitory concentration results showed that CD1CN inhibited the growth of single cultures of Staphylococcus aureus and Candida albicans at 125 and 500 μg/mL, respectively, as well as dual cultures of S. aureus with C. albicans or Candida glabrata at 500 and 250 μg/mL, respectively. In general, CD1CN reduced biofilm biomass when applied to preformed biofilms or when applied during the biofilm formation of single and dual cultures in concentrations ranging from 31.25 to 250 μg/mL, depending on the culture. CD1CN was more effective in reducing the cfu of S. aureus in single and dual biofilms (62.5-250 μg/mL) than that of Pseudomonas aeruginosa, although this reduction was also significant. For yeasts, CD1CN was generally more effective in reducing C. glabrata cfu in single or dual cultures when compared to C. albicans. SEM images of the dual-species biofilms confirmed these results. In conclusion, CD1CN could be an effective alternative to conventional antimicrobial agents against infectious biofilms, in particular those attributed to mixed cultures.