The Antimicrobial Activity of Sweet Cherry (Prunus avium) Extracts: I. Measurement of Sensitivity and Attenuation of Gram-Positive and Gram- Negative Bacteria and C. albicans in Culture

To understand the effect of extracts of cherries (Prunus avium) on bacterial growth, the antimicrobial activities of sweet cherry extracts (SCE) were measured on a wide spectrum variety of gram-positive and gram-negative bacterial spp. and Candida albicans in culture. SCEs were subdivided into variables: whole juice extracts (WJE), methanolextracted juice (MEJ), ddH2O-extracted pomace (dPOM) and methanol-extracted pomace (mPOM). Bacteria/fungus were grown on Mueller-Hinton agar suitable for disk-diffusion method. WJE showed prominent inhibition on Enterococcus Group D, Escherichia coli and Proteus vulgaris, with minor attenuation of Streptococcus Group B and C. albicans. In contrast, MEJ exhibited more prominent inhibition on Bacillus subtilis, Enterococcus Group D, Citrobacter koseri, E. coli, E. coli ESBL and P. vulgaris, with minor attenuation of Streptococcus Group A and Klebsiella pneumoniae. No inhibitory/ attenuation effect was reported with dPOM on the entire spectrum of gram-positive bacteria; however, dPOM showed prominent inhibition of Enterobacter cloacae, E. coli, and E. coli ESBL, with minor effect on C. koseri and P. vulgaris. Notably, mPOM showed substantial inhibition of B. subtilis and Enterococcus Group D, with attenuation of Streptococcus Group B. Furthermore, mPOM significantly inhibited the growth of C. koseri, E. coli, E. coli ESBL and P. vulgaris. These results confirm the measurable attenuating effect of P. avium extracts on the differential growth of grampositive 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 in vitro.