pharmacology of medicinal plants and natural products

S98
S. A. DAHANUKAR et al.,
of mangrove plant extracts for anti-immunodeficiency
virus activity. HIV infected MT-4 cells were incubated
with the extract and anti-viral activity was detected
using tetrazolium-based colorimetric assay. Seven
extracts were found to be effective five of which (bark
of Rhizophora mucronata and leaves of Excoecaria
agallocha, Ceriops decandra, Rhizophora apiculata,
Rhizophora lamarckii) completely inhibited the virus
adsorption to the cells.
14.4. Anti-protozoal agents
14.4.1. Antimalarial :
Ethanolic and petroleum extracts of Artemisia
japonica, Artemisia maritimia and Artemisia
nilegarica were tested for anti-malarial activity, both
in vivo and in vitro. In vivo studies were carried out in
Balb/c mice using the Rane test wherein all the compounds
prolonged the survival time of the mice. In
vitro, all 3 compounds inhibited schizont maturation
in chloroquine sensitive strains of Plasmodium falciparum
182 .
Ball shaped wood scrappings soaked in 5% Neem
oil (Azadirachta indica) diluted in acetone and placed
in water storage overhead tanks controlled the breeding
of Anopheles stephensi and Aedes aegypti in 45
days 183 . Similarly, application of a cream of
Azadirachta indica on exposed body parts at the rate
of 2.0 gm/person significantly protected against
Aedes, Culex and Anopheles musquitoe bites 184 .
14.4.2. Anti-leishmanial :
The methanolic extract of Swertia chirata was found
to inhibit the catalytic activity of topoisomerase I enzyme
of Leishmania donovani. On subjecting the
extract to fractionation, it yielded 3 secoiridoid
glycosides, amarogentin, amaroswerin and
sweroside of which amacogentin was found to be a
potent inhibitor of topoisomerase I and exerted its
effect by interacting with the enzyme, thus preventing
binary complex formation 185 .
14.4.3. Anti-trypanosomial
Crude 50% ethanolic extract of Parthenium
hysterophorus flowers exhibited trypanocidal activity
against Trypanosoma evansi both in vitro and in
vivo. Toxicity was seen only at 1g / kg dose 186 .
14.5. Anthelminthic agents
14.5.1. Anti-Nematodes
Kumar et al 187 has studied the mechanism of action
of palasonin, the active principle of Butea frondosa
seeds on Ascaridia galli. Palasonin inhibited glucose
uptake and depleted the glycogen content 187 and thus
the possible mechanism of its anthelminthic action
may be related to inhibition of energy metabolism.
Both aqueous and alcoholic extracts of the leaves of
Sencio nudicaulis Buch Ham were found to exert antifilarial
activity when tested against Setaria cervi
(Nematoda Filarioidea). The effective concentrations
differed for the aqueous and alcoholic extracts suggesting
the presence of a cuticular permeability barrier.
Both extracts also demonstrated micro-filaricidal
action in vitro. Their anti-filarial responses were similar
to diethylcarbamazine in that they too did not block
the stimulant effect of acetylcholine on the worm 188 .
Co-administration of Regulipid, a herbal formulation,
with diethylcarbamazine therapy to patients suffering
from filariasis was found to decrease chyluria in
these patients 189 .
Mustafa et al 190 injected the excretory-secretory products
released by the adult Setaria cervi, a bovine
filarial parasite, into rabbits to raise polyvalent antibodies.
These antibodies can be used to detect circulating
antigens in sera by counter immuno-electrophoresis
and serve as a diagnostic test for filariasis.
14.5.2. Anti-Trematode (fluke)
The root tuber extract of Flemingia vestita, an indigenous
medicinal plant in Meghalaya, exhibited antihelminthic
activity in vitro, against 2 species of flukes,
Artyfechinostomum sufrartyfex and Fasciolopsis
buski. It caused paralysis in both the species. Stereoscanning
observations on the tegumental surfaces
revealed sloughing off of most of the spines or their
deformation and wrinkling and rupture of the general
tegument 191 .
14.5.3. Agents with molluscicidal activity
The leaf, bark, cake and oil of Azadirachta indica and
synthetic pesticides derived from the plant demonstrated
both, dose and time dependent, molluscicidal
activity when tested against the snails, Lymnaea