Abstract
BackgroundFlavone C-glycosides are difficult to be deglycosylated using traditional chemical methods due to their solid carbon–carbon bond between sugar moieties and aglycones; however, some bacteria may easily cleave this bond because they generate various specific enzymes.ResultsA bacterial strain, named W12-1, capable of deglycosylating orientin, vitexin, and isovitexin to their aglycones, was isolated from human intestinal bacteria in this study and identified as Enterococcus faecalis based on morphological examination, physiological and biochemical identification, and 16S rDNA sequencing. The strain was shown to preferentially deglycosylate the flavone C-glycosides on condition that the culture medium was short of carbon nutrition sources such as glucose and starch, and its deglycosylation efficiency was negatively correlated with the content of the latter two substances.ConclusionThis study provided a new bacterial resource for the cleavage of C-glycosidic bond of flavone C-glycosides and reported the carbon nutrition sources reduction induced deglycosylation for the first time.
Highlights
Flavone C-glycosides are difficult to be deglycosylated using traditional chemical methods due to their solid carbon–carbon bond between sugar moieties and aglycones; some bacteria may cleave this bond because they generate various specific enzymes
Screen and isolation of target strain The fecal samples from 10 healthy young people were screened by deglycosylation test in combination with activity assay
Only one sample from a 25-year-old male volunteer was found to deglycosylate orientin and vitexin (Fig. 1). This sample was isolated by plate streaking, and about 50 bacterial colonies which had developed on the plates were picked up
Summary
Flavone C-glycosides are difficult to be deglycosylated using traditional chemical methods due to their solid carbon–carbon bond between sugar moieties and aglycones; some bacteria may cleave this bond because they generate various specific enzymes. Glycosides inevitably interact with the bacteria in the intestinal tract in the case of oral administration. Some species of these microbes are capable of mediating the cleavage of glycosides to their aglycones by means of deglycosylating enzymes. This reaction is considered to improve the bioavailability and bioactivities of glycosides [21, 23,24,25]; the resultant sugar molecules can provide carbon nutrition source for the intestinal flora [26]. It is informative and meaningful to find these unusual microbes and study the characteristics of the reaction catalyzed by them
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