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Sources of Drugs (Pharmacognosy:- 1) Notes


Knowledge of biological activities and/or chemical con-
stituents of marine organisms is important not only for the
discovery of new therapeutic agents but such information
may also be of immense value in exploring, new sources of
economic materials, precursors for the synthesis of complex
chemical substances and compounds of novel chemical
structure, thereby prompting the chemist for the synthe-
sis of a series of modified compounds of therapeutically
importance. Thus, in recent years, considerable importance
is attached to the discovery of new biodynamic agents from
marine source to search new source of drugs from sea.

survey of literature indicated that extracts from marine
organisms had been evaluated for various biological activi-
ties. This has led to the isolation of substances possessing
antimicrobial, antibiotic, antiviral, anticancer, cardioactive,
antiinflammatory, anthelmintic, anticoagulant neurophysi-
ological and insecticidal activities.
Although, numerous compounds have been isolated from
marine organisms and the biological activities attributed too
many of them; but still very few of them have been marketed
or are under development. There are number of reasons that
are why more number of compounds originating from marine
plants and animals has not been developed. There is no doubt
that much of the work undertaken in the 1960s, 1970s and
probably the early 1980s was driven by an interest in the
chemistry of new compounds rather than in their biological
activities. The earlier studies on chemistry of marine natural
products were limited to the isolation, structure elucidation
and phylogenetic relationship of specific substances, such
as quinonoid pigments and sterols. Now this field attracted
the attention of not only the natural product chemists but
also those of marine biologist, biochemist, pharmacologist,
etc. The invention of the aqualung and the advent of new
technology in the past few decades led to the awareness that
the oceans may be a new frontier of biomedical research,
as it has vast resources for the discovery of marine-derived
medicine. Increasing sophistication of the tools available to
explore the deep sea has expanded the habitats, which can
be sampled and has greatly improved the opportunities for
discovery of novel metabolites.
Much of the earlier work limited the biological testing
to antimicrobial activity, but this was often extended later to
testing for cytotoxic properties, which may provide useful
leads for anticancer drugs. This latter area is one that most
of the compounds in various stages of clinical trials are
located. Screening for other activities has of course, also
been undertaken, for example, for antiviral, antiinflamma-
tory, anticoagulant, antiparasitic and prostaglandins.
Many of the marine compounds have shown promis-
ing biological properties but have complicated chemical
structures, the synthesis of which would be hard and
expensive. These organisms are valuable as source of new
biologically active chemical structures, but unless either
the compounds or a derivative of them can be readily
synthesized, they are of little commercial interest to the
pharmaceutical industry.
Ara-A is a semisynthetic antiviral agent based on the arabino-
syl nucleoside isolated from the marine sponge Tethya crypta.
The compound shows a prominent therapeutic activity.
Eudistomins are the β-caboline derivatives which are iso-
lated from sponges and gorgonians Eudistoma olivaceum,
family Polycitoridae. These compounds are also found in
tunicates. Eudistomin compounds can be classified into
four groups, i.e. pyrrolyl substituted, pyrrolinyl-substituted,
unsubstituted and tetrahydro-β-carboline derivatives with
a 1,3,7- oxathiazepine ring.
Didemnin compounds are the promising antiviral and
antitumour agents isolated from Trididemnum Spp. family
Didemnidae. A compound Didemnin B is found to be a
potential antitumour agent during its clinical trials.
Subject:- Pharmacognosy 1

Semester:- Sem 3

Course:- Bachelor of pharmacy