Dissertation committee:
Βασίλειος Ρούσσης Καθηγητής (Επιβλέπων), Όλγα Τζάκου Καθηγήτρια, Ευσταθία Ιωάννου Επίκουρη Καθηγήτρια
Summary:
Mollusks of the genus Aplysia (Anaspidea, Aplysiidae) have been proven to be a
rich source of secondary metabolites, mostly of dietary origin. These sea hares
preferentially thrive upon red algae of the genus Laurencia (Ceramiales,
Rhodomelaceae) and therefore their metabolites are often related to the
chemistry of Laurencia species.
Aplysia depilans (Gmelin, 1791) occurs in the Eastern Atlantic Ocean and the
Mediterranean Sea. The name “depilans” refers to the belief of fishermen that
it caused hair loss (depilatory Aplysia).
The scope of the present thesis was the isolation and structure elucidation of
secondary metabolites from the gastropod A. depilans, as well as the evaluation
of their biological activity. For the implementation of the study, specimens of
A. depilans were collected from Skyros Island in the North Sporades complex of
the Aegean Sea, Greece from a depth 2-4 m. The animals were exhaustively
extracted with mixtures of CH2Cl2/MeOH. Subsequently, the organic extract was
subjected to a series of chromatographic separations that led to the isolation
of 77 compounds. The structure elucidation of the natural products was based on
extensive analyses of their NMR and MS data, along with comparison with
literature data.
Among the 77 isolated secondary metabolites, 56 belong to the class of
terpenes, with 34 being sesquiterpenes, 19 being diterpenes and 3 being
steroids, while 21 belong to the class of C15 acetogenins. Among these, 29
metabolites are new natural products, 4 are new natural products albeit already
reported as semisynthetic products, 28 are reported for the first time from the
genus Aplysia, whereas 14 are reported for the first time from the species A.
depilans.
Keywords:
Aplysia depilans, Gastropod, Structure elucidation, Terpenes, Acetogenines
