Common buckwheat (
Fagopyrum esculentum
Moench) seeds are important nutritious grains that are widely spread
in several human food products and livestock feed. Their health benefits
are mainly due to their bioactive phenolic compounds, especially rutin
and quercetin, which have a positive impact on heart health, weight
loss, and diabetes management. In this study, we evaluated different
media and light treatments for the
in vitro
cultures
of common buckwheat (CB) in order to find the most optimum one producing
the highest yield with the highest purity of these compounds. The
subcultured treated samples included in this study were shoots, leaves,
stems, hairy roots, and calli. From the several treated samples and
under different light stress conditions, the best production was achieved
by growing the shoots of common buckwheat in hormone-free media containing
activated charcoal and exposing to blue light, attaining 4.3 mg and
7.0 mg/g of extracts of rutin and quercetin, respectively, compared
to 3.7 mg of rutin/g of extract and traces of quercetin in the seeds
of CB. Continuous multiplication of CB shoots in the media containing
charcoal and different concentrations of kinetin produced an extract
with 161 mg/g of rutin and 26 mg/g of quercetin with an almost 20-fold
increase in rutin content. The rutin content under these conditions
reached up to 16% w/w of the extract. The hairy root cultures of the
leaves exposed to red light showed a significantly high yield of quercetin
attaining 10 mg/g of extract. Large-scale production of CB shootlets
under the best conditions were carried out, which enabled the isolation
of pure quercetin and rutin using a simple chromatographic procedure.
The identity and purity of the isolated compounds were confirmed through
NMR and HPLC analyses.