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

Previously, we have examined the antimicrobial activity of sweet cheery (Prunus avium L.) extracts on a wide spectrum of gram-positive and gram-negative bacteria in addition to the fungus, Candida albicans. To further understand the effect of a variety of extracts of sour black and red cherries (Prunus cerasus L.) on bacterial/fungus growth, the antimicrobial activities of red sour cherry extracts (SCE) were measured in culture in this study. SCEs were subdivided into variables: whole juice extracts (WJE), methanol-extracted juice (MEJ), ddH2O-extracted pomace (dPOM), and methanolextracted pomace (mPOM). Bacteria and fungus were grown on Mueller-Hinton agar suitable for disk-diffusion method. WJE showed attenuating inhibition on Bacillus subtilis, Enterococcus Group D, Staphylococcus aureus, Streptococcus Group B (GBS), Citrobacter koseri, Enterobacter cloacae, Escherichia coli, Klebsiella pneumoniae, Proteus vulgaris, and Pseudomonas aeruginosa, although inhibition of B. subtilis, C. koseri, and E. cloacae is less prominent, and there was no attenuation of C. albicans. By contrast, MEJ showed prominent inhibition on B. subtilis, Enterococcus Group D, S. aureus, Streptococcus Group A (GAS), GBS, C. koseri, E. cloacae, E. coli, E. coli ESBL, K. pneumoniae, P. vulgaris, and P. aeruginosa, although inhibition of B. subtilis, GAS, GBS, C. koseri, and P. aeruginosa is less attenuating, and there was strong inhibition of C. albicans. Furthermore, dPOM showed inhibition on B. subtilis, S. aureus, GAS, GBS, C. koseri, E. cloacae, E. coli, E. coli ESBL, K. pneumoniae, P. vulgaris, and P. aeruginosa, although inhibition of GAS, GBS, E. cloacae, and E. coli is less prominent, and there was no inhibition of C. albicans. Similarly, mPOM showed attenuating effect on B. subtilis, Enterococcus Group D, S. aureus, GAS, C. koseri, E. coli, E. coli ESBL, K. pneumoniae, P. vulgaris, and P. aeruginosa, although inhibition of gram-positive bacteria, C. koseri, and E. coli ESBL is less prominent, and there was no inhibition of C. albicans. These results confirm the attenuating effect of P. cerasus extracts on the differential growth of gram-positive and gram-negative bacteria. Since many of the aforementioned are pathogenic in their nature, cherry extracts are interestingly of value in regulating/attenuating the growth of microorganisms of medical importance.