Minimal inhibitory concentrations, polyphenolic prophile and antioxidative properties of the extracts of selected berries and their pomaces
Laen...
Kuupäev
2024
Kättesaadavus
Ajakirja pealkiri
Ajakirja ISSN
Köite pealkiri
Kirjastaja
Estonian University of Life Sciences
Abstrakt
The aim of the study was to establish minimal inhibitory concentrations (MIC) of the aqueous vs 30%
aqueous ethanolic extracts of Aronia melanocarpa (Michx.) Elliott i.e. chokeberry (CB), Ribes nigrum L. i.e.
blackcurrant (BC), and Sorbus aucuparia L. i.e. rowan berries (RB) and the corresponding pomaces (+P) against
bacterial species L. monocytogenes, S. aureus, E. coli, and C. jejuni. Polyphenolic prophile and antioxidative
properties of the extracts were also determined. Aqueous extracts and 30% aqueous ethanolic extracts were
prepared of the powders of dried berries and corresponding pomaces in the ratio 1:20 (w/v). The extracts were
chromatographically analyzed using a 1290 Infinity system (Agilent Technologies, Germany), coupled to an
Agilent 6450 Q-TOF mass spectrometer equipped with a Jetstream ESI source and to an Agilent 1290 Infinity
Diode Array Detector. The minimal inhibitory concentration (MIC) values of the extracts were determined against
tested bacteria by the broth microdilution method in 96-well microplates, according to the EVS-EN ISO 20776-
1:2020 guidelines. Analyses of antioxidative properties (AO) of plant extracts were performed using the DPPH
free-radical-scavenging method on an Infinite 200 Pro M Plex plate reader instrument (Tecan Austria Gmbh,
Austria). The total content of polyphenols (TCP) was significantly (P < 0.05) higher in the ethanolic extracts than
in the aqueous extracts. The TCP of plant extracts was in descending order as follows: CB > CBP > BC > BCP >
RB > RBP in etahnolic, whereas in aqueous extracts the order was different: CB > BC > CBP > RB > BCP >
RBP. The berry pomaces contained 60 – 70% of the polyphenols of the corresponding berries. The sensitivity of
tested bacteria to the extracts of berries and berry pomaces starting from the most sensitive bacteria was as follows:
S. aureus > L. monocytogenes > E. coli ≈ C. jejuni. No correlation was established between TCP and antibacterial
(AB) properties of the plant extracts. The antioxidative properties in extracts with both solvents from highest to
lowest were as follows: CB > CBP > BC > BCP ≈ RB > RBP. The AO properties were significantly (P < 0.05)
higher in the ethanolic extracts than in the aqueous extracts. TCP correlated strongly positively with AO, both in
aqueous (r = 0.92) and in 30% ethanolic extracts (r = 0.93). The extracts of CB and BC berries and berry pomaces
had higher TCP, they also had better AB and AO properties compared to RB and its pomace. Among studied plant
extracts TCP did not correlate with MIC values, indicating that other compounds besides polyphenols e.g. organic
acids can cause the AB effect in the studied plant extracts. As berry pomaces, left over from juice pressing contain
60 – 70% of the TCP of corresponding berries, they should be further used as a source of beneficial compounds
and not discarded as waste.
Kirjeldus
Märksõnad
MIC values, chokeberry, blackcurrant, rowan berries, berry pomaces, abstracts