Berry Phenolics: Antimicrobial Properties and Mechanisms of Action Against Severe Human Pathogens

Abstract

Antimicrobial activity and mechanisms of phenolic extracts of 12 Nordic berries were studied against selected human pathogenic microbes. The most sensitive bacteria on berry phenolics were Helicobacter pylori and Bacillus cereus. Campylobacter jejuni and Candida albicans were inhibited only with phenolic extracts of cloudberry, raspberry, and strawberry, which all were rich in ellagitannins. Cloudberry extract gave strong microbicidic effects on the basis of plate count with all studied strains. However, fluorescence staining of liquid cultures of virulent Salmonella showed viable cells not detectable by plate count adhering to cloudberry extract, whereas Staphylococcus aureus cells adhered to berry extracts were dead on the basis of their fluorescence and plate count. Phenolic extracts of cloudberry and raspberry disintegrated the outer membrane of examined Salmonella strains as indicated by 1-N-phenylnaphthylamine (NPN) uptake increase and analysis of liberation of [14C]galactose- lipopolysaccharide. Gallic acid effectively permeabilized the tested Salmonella strains, and significant increase in the NPN uptake was recorded. The stability of berry phenolics and their antimicrobial activity in berries stored frozen for a year were examined using Escherichia coli and nonvirulent Salmonella enterica sv. Typhimurium. The amount of phenolic compounds decreased in all berries, but their antimicrobial activity was not influenced accordingly. Cloudberry, in particular, showed constantly strong antimicrobial activity during the storage.

Effect of dietary fiber on the bioaccessibility of phenolic compounds of mango, papaya and pineapple fruits by an in vitro digestion model

“…Plenty of studies have shown that plant origin foods are important sources of bioactive compounds, also known as phytochemicals (Dembitsky et al, 2011a, b;Gayosso-García Sancho et al, 2011;Hossain & Rahman, 2011;Nohynek et al, 2006). Among the most common bioactive compounds occurring in plant origin foods are phenolic compounds (PCs), carotenoids, xanthophylls, and chlorophylls, among others (Hossain & Rahman, 2011).…”

“…Hence, there has been a classification of PCs according their ease of extraction: extractable (EPC) and non extractable (NEPC) (Bravo, 1998). Tropical fruits are plenty and diverse, and recent research suggests that an appropriate consumption of them may confer different health benefits (Das et al, 2012;Leifert & Abeywardena, 2008;Nohynek et al, 2006). These compounds can also have antioxidant capacity (ADXC) and protect against oxidative stress in different body tissues, if they are adequately released from the food matrix and absorbed in the small intestine (Palafox-Carlos et al, 2011).…”

Antioxidant properties of fruits of raspberry and blackberry grown in central Europe

“…Phytochemicals present in black raspberries reduce vascular endothelial growth factor (VEGF) expression, which contributes to metastasis inhibition [23,24]. Many raspberry and blackberry phenolics exhibit antimicrobial [25,26] and antiviral [27] activities. Due to a high content and large diversity of health-beneficial phenolic compounds, raspberry and blackberry fruits can be regarded as natural functional food.…”

Antimicrobial Activity of Thinned Strawberry Fruits at Different Maturation Stages

“…Strawberry extract inhibited the growth of gram-negativebacteria, especially Escherichia coli, and Salmonella enterica ser. Typhimurium, Campylobacter jejuni, and Candida albicans (Nohynek et al, 2006;Puupponen-Pimiä et al, 2001. In addition, the antimicrobial effect on 1D TLC bioassay plates for ethanol extract of unripe fruit was greater than that of the extract of ripe fruit (Terry et al, 2004).…”