Effects of phytochemicals on in vitro anti-inflammatory activity of Bifidobacterium adolescentis

Abstract

Probiotics have been shown to improve the condition of not only the human gastrointestinal tract but also the entire body. We found that quercetin enhances the anti-inflammatory activity of Bifidobacterium adolescentis, which is abundant in human intestines. Here, we assessed whether certain phytochemicals could enhance the anti-inflammatory activity of B. adolescentis. Bifidobacteria were anaerobically cultured with phytochemicals for 3 h, and the anti-inflammatory activity of the supernatants was estimated by testing their ability to inhibit nitric oxide (NO) production by lipopolysaccharide-stimulated RAW264 macrophages. Of the 55 phytochemicals tested, phloretin, (+)-taxifolin, and (−)-epigallocatechin gallate as well as quercetin-3-O-glucoside and quercetin-4′-O-glucoside were similar to quercetin in promoting NO suppression by B. adolescentis. In addition, the phytochemicals excluding quercetin increased the concentrations of lactic and acetic acids in the co-culture supernatants. These results suggest that some phytochemicals may activate the anti-inflammatory function of B. adolescentis.

Functional properties of anti-inflammatory substances from quercetin-treated Bifidobacterium adolescentis

“…Biotransformation of polyphenols by intestinal bacteria has become important parts of the study of bioavailability, and the biological activities of its metabolites have received attention. We have reported that some polyphenols including quercetin enhanced in vitro anti-inflammatory activity of B. adolescentis [21,22]. According to our follow-up experiments to investigate the change in anti-inflammatory activity of the culture supernatant by modifying quercetin concentrations, culture duration, and bacterial number, we assumed that anti-inflammatory substances in the culture supernatant were derived from B. adolescentis primed by quercetin, but not quercetin metabolites by B. adolescentis.…”

“…The suppressive activity of the combination was similar to that of acetate. Acetate and the combination at 20 mM suppressed the NO production by 31% and 36%, respectively, whereas these acids at 5 mM, which are the same level of acetate and lactate in the culture supernatant of B. adolescentis with quercetin [22], were 9-12% suppression.…”

“…Several studies have already reported the anti-inflammatory activity of the culture supernatant from bifidobacterial species [10][11][12][13], while, to our knowledge, the enhancement of a biological function of the microbiota by polyphenols was first demonstrated. Furthermore, our previous investigation suggested that the anti-inflammatory substances are not acetic or lactic acids, indicating the presence of unidentified biomolecules [22]. Therefore, the aim of this study was to investigate physicochemical and functional aspects of the anti-inflammatory substances secreted from B. adolescentis.…”

“…Although polyphenols may regulate components of the microflora via suppressing growth of pathogenic bacteria with lesser effects on probiotic bacteria [20], the biological effects on the gut microbiota have been not fully investigated. We have found that some polyphenols, such as quercetin and (−)-epigallocatechin-3-gallate enhance in vitro anti-inflammatory activity of B. adolescentis [21,22]. The culture supernatant of B. adolescentis with quercetin markedly suppressed levels of nitric oxide (NO) production by lipopolysaccharide (LPS)-stimulated RAW264 cells.…”

The influence of phase II conjugation on the biological activity of flavonoids

“…Lactobacilli and Bifidobacteria are reported to prevent the growth of pathogenic organisms [187] and stimulate the production of beneficial organic acids such as lactate and acetate [188]. Some flavonoids are reported to further cause Bifidobacteria to excrete antiinflammatory substances, [189] as well as increase secretion of lactic and acetic acids [190], which can further be converted to butyrate by Firmicutes [191]. Flavonoids themselves can be cleaved into short-chain fatty acids, such as acetate, butyrate and proprionate [192] which are suggested to have positive health effects [193][194][195] and inhibit the production of pro-inflammatory cytokines in vitro [196,197].…”