Antifungal activity of the Brazilian red propolis against Candida spp

Natural products have been a valuable source for development of new drugs and propolis from Apis mellifera emerges as a promising oral antifungal agent. Objective: This study evaluated the antimicrobial potential of Brazilian red propolis against Candida spp. Methods: The ethanolic extract of red propolis (EEP) and its respective fractions: hexane, dichloromethane and ethyl acetate were produced and chemically characterized by HPLC and GC/MS as type 13. The EEP and its fractions were tested against Candida collection (C. albicans CBS562, C. dubliniensis CBS7987, C. krusei CBS573, C. glabrata CBS07, C. parapsilosis CBS604, C. tropicalis CBS94), by Minimum Inhibitory Concentration (MIC) and Minimum Fungicide Concentration (MFC) grown in planktonic and biofilm forms. The biofilm morphology was evaluated by scanning electron microscope (SEM). Nystatin and vehicle were used as controls and the experiments were performed in triplicate of three independent assays. Results: The dichloromethane fraction showed the best fungicide result against all Candida tested on planktonic cells (minimum/maximum MIC values: 0.2 µg/mL for CBS573 / 7.8 µg/mL for CBS562 and CBS604; and minimum/maximum MFC values: 125 µg/mL for CBS562 and CBS7987 / 500 µg/mL for CBS604; respectively) and fungistatic action against Candida tested on forming biofilms (minimum/maximum MIC values: 1.0 µg/mL CBS07 and 31.3 µg/mL CBS604, respectively; excepting for CBS 573). The EEP had higher MIC/MFC values than dichloromethane did and the other fractions were negligible. The SEM assays showed that the dichloromethane fraction and EEP were the only ones capable of altering the forming biofilm, however they poorly affected the mature biofilm. Conclusion: The Brazilian red propolis has clearly demonstrated its antifungal activity against Candida spp. and although the dichloromethane fraction has shown greater effect it may be concluded that there is still bioactive compounds in EEP that can justify a synergistic effect against Candida spp. (FAPESP 08/51048-5; CNPq 302222/2008-1, Brazil).