active components.
Fig. 3 presents the dose response curves for the “pH 3.5 MIX-es”
in HT29 cell line. In all cases, the prolonged exposure on plant juices
resulted in the stronger biological effect. The lowest cytotoxicity
exhibited the mixture containing citric acid, whose addition
reversed significantly growth inhibition induced by beetroot juice
alone i.e., the sample used as a reference in these experiments. This
may suggest that citric acid decreased biological potential of the
tested juice. Among “pH 3.5 MIX-es” acidified with fruit juices,
those containing lemon and blue-berried honeysuckle juices
exhibited the strongest ability to inhibit cell growth. This is not
suprising, since these fruit juices contain bioactive compounds that
are known to impose cytotoxic effect on cancer cells: lemon is the
rich source of flavonol glycosides, while blue-berried honeysuckle
flavan-3-ols and anthocyanins. Most probably betalains were not
phytochemicals responsible for cell growth inhibition because
these two mixtures did not contain the highest amounts of betalains
(Table 4). Cytotoxicity assessments again confirmed superiority
of fruit based acidity regulators over citric acid in terms of
bioactivity.