Purpose: This research compared the effects of extracts from cranberry, grape seed and pomegranate against Salmonella enterica serovars Typhimurium and Enteritidis.
Methods: Overnight bacterial cultures in Tryptic Soy Broth (TSB) were washed and resuspended in phosphate buffered saline (PBS, pH 7.2), and individually treated with grape seed extract (GSE, 1 or 2 mg/ml), pomegranate polyphenols, (PP, 2 or 4 mg/ml), cranberry proanthocyanidins (CPAC, 0.3 or 0.6 mg/ml) or PBS (untreated-control) at 37°C for 2, 4, 6, or 24 h. After each time point, bacteria were first serially diluted in TSB containing 10% beef extract, followed by serial dilutions in PBS, and plated on selective Xylose-Lysine Tergitol 4 (XLT4) agar. Each experiment was replicated thrice in duplicate. Data were statistically analyzed using Tukey’s test and ANOVA (P < 0.05).
Results: Both S. enterica serovars from initial titers of ~4.67 log CFU/ml were reduced to non-detectable levels with the two tested concentrations of all extracts after 24 h PP at 2 and 4 mg/ml and GSE at 2 mg/ml also showed complete reduction of both serovars after 4 and 6 h, but no significant reduction was observed (P > 0.05) after 2 h. CPAC (0.3 or 0. 6 mg/ml) showed complete reduction of both serovars after 24 h only. Overall, at the tested concentrations, GSE and PP were found to be more effective than CPAC against Salmonella.
Significance: These tested extracts show potential as therapeutic options against Salmonella enterica infections. However, the bioavailable physiological effects must be tested in vivo holistically before any health claims can be made.