Antifungal properties of Malaysian tualang honey and stingless bee propolis against Candida albicans and Cryptococcus neoformans

Abstract

Candida albicans and Cryptococcus neoformans can cause life-threatening infections, especially in immune-compromised patients. Treatment with currently available antifungal agents may lead to severe side-effects and emergence of resistant strains. The objective of this study was to evaluate the antifungal properties of MTH and SBP against C. albicans and C. neoformans. Broth dilution method was used to assess the antifungal properties of the MTH and propolis. Different concentrations of the MTH and propolis (0.78 mg/mL - 50.00 mg/mL) in two-fold dilutions were tested against each fungus to determine the Minimum Inhibitory Concentration (MIC) which was done by visual inspection and spectrophotometric (MIC95) reading at 620 nm. Minimum Fungicidal Concentration (MFC) was obtained by culturing on Sabouraud Dextrose Agar. Total phenolic acids and flavonoids contents were also determined by Folin-Ciocalteu and colorimetric assay respectively. The MICs of the MTH against C. albicans and C. neoformans by visual inspection were 6.25 mg/mL and 1.56 mg/mL respectively, meanwhile 6.25 mg/mL and 3.13 mg/mL by spectrophotometric reading. The MFCs of the MTH against C. albicans and C. neoformans were 12.50 mg/mL and 6.25 mg/mL respectively. The MICs of SBP against C. albicans and C. neoformans by visual inspection were both 1.56 mg/mL whereas spectrophotometric reading recorded MICs of 3.13 mg/mL and 1.56 mg/mL respectively. The MFCs of SBP against C. albicans was 6.25 mg/mL and 3.13 mg/mL for C. neoformans. The total phenolic acids and flavonoids contents of MTH were 275.6 mg gallic acid/kg and 71.8 mg quercetin/kg respectively whereas for SBP, the phenolic acids content was 1754.2 mg gallic acid/kg and the flavonoids content was 82.6 mg quercetin/kg. MTH and SBP exhibited significant antifungal activities against C. albicans and C. neoformans. Their antifungal activities might be attributed to the high phenolic acids and flavonoids. This result suggests that MTH and SBP could potentially be used as alternative therapeutic agents against these fungi.