The Antimicrobial Activity and MICs of Black/Red Sour Cherry (Prunus cerasus L.) Extracts: III. Measurement of Sensitivity and Attenuation of Gram-Positive and Gram-Negative Bacteria and C. albicans in Culture

On a prior occasion, we have measured the antimicrobial activities of sweet cherry extracts (SCEs) on grampositive/ negative bacteria and C. albicans using disk diffusion method, in addition to the minimum inhibitory concentrations (MICs) in broth cultures. In this study, the MICs of sour cherries were assessed @ 24 hrs. following bacterial/fungus inoculations. Extracts were subdivided into the following categories: Whole juice (WJE), methanol-extracted (MEJ), ddH2O-extracted pomace (dPOM) and methanol-extracted pomace (mPOM). Black sour cherries – WJE: MICs (1/16 – 1/32) for gram-positive and (1/2 – 1/32) for gram-negative bacteria; MIC for fungus was 1/32. MEJ: MICs (1/2 – 1/32) for gram-positive and (undiluted – 1/32) for gram-negative bacteria; MIC for fungus was 1/32. dPOM: MICs (undiluted – 1/16) for gram-positive and (1/2 – 1/16) for gram-negative bacteria; MIC for fungus was 1/4. mPOM: MICs (undiluted – 1/32) for gram-positive and (undiluted – 1/16) for gram-negative bacteria; MIC for fungus was 1/2. Red sour cherries – WJE: MICs (undiluted – 1/16) for gram-positive and (undiluted – 1/32) for gram-negative bacteria; MIC for fungus was 1/2. MEJ: MICs (undiluted – 1/4) for gram-positive and (1/4 – 1/16) for gram-negative bacteria; MIC for fungus was 1/2. dPOM: MICs (1/4 – 1/16) for gram-positive and (1/2 – 1/16) for gram-negative bacteria; MIC for fungus was 1/32. mPOM: MICs (1/8 – 1/32) for gram-positive and (1/4 – 1/16) for gram-negative bacteria; MIC for fungus was 1/8. These results confirm the measurable attenuating effect of P. cerasus extracts on the differential resistance/sensitivity of grampositive and gram-negative bacteria and C. albicans in broth cultures.