Analysis of glycosylated flavonoids extracted from sweet-cherry stems, as antibacterial agents against pathogenic Escherichia coli isolates

Abstract

The aim of this study was to evaluate the bioactivity of flavonoids extracted from sweet-cherry stems, which is often used by traditional medicine to treat infections from gastro-intestinal and urinary but without any consistent scientific evidences, moreover the information about the class of phenolics, their content and the potential bioactivity of such material is very scarce. Thus, in this context, we set a research study in which we evaluate the profile and content of phenolics extracted from sweet-cherry stems through a conventional (70ºC and 20 minutes) and ultrasound assisted extraction (40 kHz, room temperature and 20 minutes) methods. After, the extracts were phytochemical characterized by HPLC-DAD-UV/VIS, and assayed trough the in vitro minimum inhibitory concentration (MIC) bioassay, against Escherichia coli isolates. Simultaneously the total antioxidant activity were measured using the assay of 2,2′-azinobis-3-ethylbenzothiazoline-6-sulphonate (ABTS●+) radical cation. Our results showed that sweet-cherry stems presented higher content of sakuranetin, ferulic acid, p-coumaric acid, p-coumaroylquinic acid, chlorogenic acid and it´s isomer neochlorogenic acid. Their average levels were highly affected by the extraction method (p<0.001) used. The same trend was observed for total antioxidant activity and MIC values. The extracts produced under ultrasound presented both higher total antioxidant activity and lower minimum inhibitory concentration. The statistical analyses of our results showed a significant correlation (p<0.01) of total antioxidant activity and minimum inhibitory concentration with phenolics in the extracts studied. Thus, we can conclude that cherry stems can be further exploited to purify compounds and produced coproducts with enhanced biological added valuefor pharmaceutical industry.