Attached
This thesis covers the phytochemical studies and
some biological studies of two medicinal plants belonging
to the family Apocynaceae namely, Ae~Lonia mac~ophyeea
and Ae~Lonia ~choea~i~. The second part of this thesis
describes the estimation of vasicine content in AdhaLoda
va~ica and its seasonal variation in the plant.
The second chapter describes the taxonomy and
chemical characteristics of the genus Ae~Lonia. The
biosynthesis of indole alkaloids including the formation
of strictosidine and the plausible biogenetic pathways
of some Ae~Lonia alkaloids are given in detail.
General methods of extraction of alkaloids that
have been used so far, their advantages, disadvantages
and more advanced and improved techniques are discussed
in the fifth chapter.
According to the pharmacological reports on
Ae~ionia alkaloids,it is evident that the two plants
we have studied have significant medicinal value. In the first part of the eigth chapter, the method
of extraction, fractionation and isolation of alkaloids
of A. mac~ophyiia and A. ~choia~i~ described in detail
including the precautions undertaken to isolate alkaloids
in their genuine form. Structures of twelve alkaloids
have been elucidated from these two plants. One of which
is a new alkaloid, 19-hydroxyvincamajine. In these
studies we have found that local A. mac~ophyiea is
different from the same species found in other countries
due to the presence of talcarpine, vincamajine,19-
hydroxyvincamajine, vincorine and cabucraline. Talcarpine and picraline deacetyl are reported for the first
time from the genus Ae~tonia. These studies give us
significant evidences for chemotaxonomic relationships among different species of At~tonia and some
other genera such as 7age~naemontana, St~ychno~, Pieioca~pa and A~pido~p6~ma.
The effect of alkaloidal extracts of these two
plants (leaf and stem bark) on alternative and classical
pathways of human complement was tested in vitro. These
findings suggest that these two plant alkaloids can be
used as immunomodulating agents.
