| dc.description.abstract | There is a great attention to functional foods exerting health benefits. In this frame the claim ‘superfood’ to
characterize products with high nutritional value and bioactive phytochemicals is more and more used. In the
course of current PhD project, the chemical and biological profile of food plants, selected on the basis of their
growing interest, has been investigated.
During the first year, the chemical fingerprint of Portuaca oleracea L. (Portulacaceae), a widespread
herbaceous plant typically appreciated in the Mediterranean and Asiatic diet, showed the presence of complex
polar lipids and polyphenolic alkaloids, known as oleraceins. A deep investigation of both classes was carried
out with articulate extraction procedures and chromatographic steps. The methanol extract was fractionated by
SPE chromatography to obtain 2 lipid enriched fractions from leaves and stems. LC-HRMS analysis of the
obtained fractions highlighted the occurrence of phospholipids, glycerolipids, oxylipins and sphingolipids,
described in detail by accurate mass, molecular formulae and fragmentation pattern compared with literature
data. The polyphenolic alkaloids were studied by choosing the extract with high yield of oleraceins, through
HRMS flow injection analysis of several “green” extracts. The structures of oleraceins isolated by HPLC-UV
were elucidated by 1D and 2D NMR experiments.
During the second year, the chemical profiles of the sprouts of Raphanus sativus L., better known as daikon
and okra fruit (Abelmoschus esculentus L.), were studied. The methanol and “green” extracts of daikon showed
the occurrence of polyphenolics and glucosinolates reported for anticancer and antioxidant activity.
Preliminary studies about the radical scavenging activity of selected extracts were performed by Total Phenolic
content, DPPH and TEAC assays, providing high activity of green extracts. Okra fruit is used in oriental
traditional medicin for the treatment of diabetes. The inhibition of α-glucosidase in the intestinal tract could
be a target for reducing the assorbtion of glucose. In this view, the ability to inhibit α-glucosidase along with
antioxidant activity were evaluated. Moreover, the chemical profile of the species was investigated
highlighting the occurrence of polar lipids and phenolic acid derivatives.
During the third year, a quali-quantitative analysis of mangosteen fruit (Garcinia mangostana L.), reported as
source of bioactive xanthones, has been provided. In a first step, the isolation and the NMR characterization
of the main xanthones was performed to select the specific NMR signals of each isolated compound for further
quantitative approach. In the second step, several extracts, and commercially available supplements as
capsules, tablets and juices, were submitted to 1H and 2D NMR experiments and each compound was
accurately quantified. The EtOH extracts and hydroalcoholic mixtures showed the highest amount of alpha
and gamma mangostin, reported as bioactive xanthones. Regarding commercial food supplements, a certain
variability in the amount of biologically active xanthones (i.e. α-mangostin and -mangostin) could be
observed.
Moreover, in collaboration with the Division of Pharmacognosy of the University of Vienna, bioactivity assays
on portulaca and daikon extracts were carried out. The “green” extracts of daikon, in agreement with the
observed radical scavenging activity, showed a high capacity to activate Nrf2, involved in the trascription of
detoxyfying enzymes. The ability of portulaca extracts to interfere with Nrf2, NF-kB and PPAR-ɣ targets was
evaluated. The lipid enriched fractions resulted the most active in eliciting a concentration-dependent
induction of Nrf2 and in promoting PPAR- activation. [edited by Author] | it_IT |
