Unit:
ΠΜΣ με ειδίκευση ΑΠΟΜΟΝΩΣΗ, ΑΝΑΠΤΥΞΗ, ΠΑΡΑΓΩΓΗ ΚΑΙ ΕΛΕΓΧΟΣ ΒΙΟΔΡΑΣΤΙΚΩΝ ΦΥΣΙΚΩΝ ΠΡΟΪΟΝΤΩΝLibrary of the School of Science
Author:
Ορφανού Ιωάννα-Μαρία
Supervisors info:
Ιωάννα Χήνου Καθηγήτρια (Επιβλέπουσα), Ελένη Σκαλτσά Καθηγήτρια, Προκόπιος Μαγιάτης Αναπλ. Καθηγητής
Original Title:
Φυτοχημική μελέτη (απομόνωση και καθορισμός χημικής δομής) φυσικών προϊόντων από το ελληνικό ενδημικό φυτό Onosma kaheirei Teppner (Boraginaceae)
Translated title:
Phytochemical study (isolation and identification of the chemical structure) of the natural products from the greek endemic plant Onosma kaheirei Teppner (Boraginaceae)
Summary:
In the framework of our studies on Greek Boraginaceae plants we present in this
scientific work, the chemical constituents of the rare endemic Greek species of
Onosma kaheirei Teppner which studied herein for the first time. Boraginaceous
plants are known to contain pyrrolizidine alkaloids (PAs), phytochemicals
responsible for hepatotoxicity effects in humans and animals and also suspected
for carcinogenicity. In addition, alkannins and shikonins – effective wound
healing compounds – are typically found in their roots .
In specific, the dried aerial part of O. kaheirei was sequentially extracted by
soaking in cyclohexane (Ch), dichloromethane (DCM) and methanol (MeOH).
Preliminary TLC examination of the MeOH extract and its visualization with the
Mattocks-Molyneux spray reagent confirmed the presence of PA N-oxides. The
methanolic extract was subjected to column chromatography and prep. TLC,
yielding allantoin (5), three PA N-oxides [7-O-acetylechinatine (8),
7-epi-echimiplatine (10) and 3΄-O-acetylechinatine (12) N-oxides] and two
flavonoids [apigenin 7-O-rutinoside (6) and luteolin 7-O-rutinoside (7)]. Among
them, 3΄-O-acetylechinatine N-oxide (12) is a new natural product, while the
two flavonoids are novel within Onosma genus and the whole Boraginaceae family.
After induction of small aliquots of the isolated PA N-oxides the bases of all
the three PAs were also identified as: 7-O-acetylechinatine (9),
7-epi-echimiplatine (11) and 3-Ο-acetylechinatine (13) and the RI values of 11
and 13 were determined by GC on a DB-5 column for the first time: 2268 for 11
and 2242 for 13 respectively. Moreover 3-Ο-acetylechinatine (13) was isolated
and chemically determined through modern spectral means within Onosma genus for
the first time.From the dichloromethane extract, lupenone (3) and β-sitosterol
(4) were isolated likewise, while the cyclohexane extract afforded lupeol (2)
and the isobutyrylalkannin (1) as red residue. Allantoin, PA N-oxides and
alkannins are typical metabolites of the Boraginaceae species and could be used
as chemotaxonomic agents. All structures were identified by modern spectral
means of 1D 1H-/13C- and 2D NMR spectra, assisted also by ESI-MS spectrometry.
Keywords:
Onosma kaheirei Teppner, Greek endemic Boraginaceae plant, 3?-Ο-acetylechinatine (new natural product), Pyrrolizidine alkaloids, Hepatotoxicity
Number of references:
182
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