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There are many plants in Kashmir valley which have been shown to
possess medicinal properties. Among them is Euphorbia helioscopia
which is known for its medicinal values. At present drug resistance
is a worldwide problem and much emphasis is being laid on the
natural plant sources to act as antibiotics which can overcome this
problem. Euphorbia helioscopia which is known for its medicinal
values has febrifuge and vermifuge activities in its roots and stem
respectively. The root is anti helminthic. The milky sap is applied
externally to skin eruptions. The seeds, mixed with roasted pepper,
have been used in the treatment of cholera and the oil from the
seeds has purgative properties. However, isolation of any
antibacterial protein has not been reported till date. The essence
of the work was to check the antibacterial activity of the plant
following its purification and characterization from leaves using
conventional protein purification techniques. The lectin is a
homodimer (Mr 65000Da), thermostable between 0 C- 40 C but exhibits
a narrow range of pH stability being optimally active at pH 7. The
lectin shows antimicrobial activity against P. aeruginosa,
K.pneumoniae and E. coli.
Lectins are carbohydrate-binding proteins of non-immune origin that
agglutinate cells or precipitate glycoconjugates.Based on
evolutionary and structural relatedness, seven lectin families have
been distinguished, of which legume lectins are the best
characterized. Lectins typically constitute a large fraction of the
total protein in most leguminous seeds and plant storage tissues
where they play an important role in several defense mechanisms. A
lectin from the seeds of Indigofera heterantha, member of family
leguminosae was isolated, purified, partially characterized and its
antimicrobial activity evaluated. The lectin is a homotetramer with
a molecular weight of about 70 KDa. The lectin shows a reasonable
temperature stability and is stable in the pH range of 2-9. It
demonstrates a remarkable antibacterial activity against E.coli,
K.pneumonia, S.aureus, and B.subtilis and also inhibits the growth
of phytopathogens Aspergillis niger, Aspergillis oryzie and
Fusarium oxysporum. These results point out that future findings on
applications of lectins isolated from leguminous plants can be of
great importance for clinical microbiology and possible therapeutic
applications.
Lectins are sugar-binding proteins that are highly specific for
their sugar moieties. They play a role in biological recognition
phenomena involving cells and proteins. For example, some viruses
use lectins to attach themselves to the cells of the host organism
during infection. Lectins may be disabled by specific mono- and
oligosaccharides, which bind to them and prevent their attachment
to cell membranes.Lectins serve many different biological functions
in animals, from the regulation of cell adhesion to glycoprotein
synthesis and the control of protein levels in the blood. They may
also bind soluble extracellular and intercellular glycoproteins.The
large concentration of lectins in plant seeds decreases with
growth, and suggests a role in plant germination and perhaps in the
seed's survival itself.Since lectins specifically recognize cell
surface sugars, they have the potential of being used as
antimicrobials as well as anticancer agents.Foods with high
concentrations of lectins, may be harmful if consumed in excess in
uncooked or improperly cooked form. Adverse effects may include
nutritional deficiencies, and immune (allergic) reactions due to
gastrointestinal distress.
Medicinal plants are being used in traditional treatments to cure
variety of diseases from thousands of years. Screening of
antimicrobial and antioxidant activities performed on Elsholtzia
densa crude extracts which is traditionally used as herb shows that
they are endowed with potentially utilizable antimicrobial and free
radical scavenging activity. Accordingly, this implies the
inhibition of microbial pathogenesis and cellular oxidation that is
linked to pathological incidents such as heart disease, aging and
cancer. It was seen that the ethylacetate extract showed the
maximum inhibitory effects against both bacterial and fungal
growth. This may be due to the presence of such ingredients in the
said extracts like flavonoids, terpenes, tannins, polyphenolic
compounds, alkaloids, etc. The crude extracts of the plant possess
radical scavenging activity as estimated by in vitro antioxidant
assays like DNA damage assay, lipid peroxidation assay, DPPH assay,
FTC assay, etc. Hence, Elsholtzia densa extracts could be used as
an easy accessible source of natural antioxidants and antimicrobial
agent.
Lectins are proteins or glycoproteins of non immune origin which
have a wide distribution in animals, plants, and microorganisms.
Their medicinal role extends from simple antimicrobial action to
anti- tumour properties.In view of the advancement in understanding
the potential medicinal role of the plant lectins, a lectin from
the leaves of Prunella vulgaris was isolated, purified, partially
characterized and its antimicrobial activity evaluated. The lectin
is specific for galactose and N-acetyl-galactosamine The molecular
weight of the lectin as determined by SDS-PAGE was 32500 Da and
that estimated from Sephadex G-100 gel filtration column was 65000
Da indicating that the purified lectin is a homodimer. The purified
lectin also shows a significant antimicrobial activity against the
infectious agents of some common diseases such as Salmonella typhi,
Klebseilla pnuemonea and Escherhia coli.
Plant lectins are a heterogeneous group of proteins or
glycoproteins that share in common their ability to recognize and
bind specific sugar residues. At present hundreds of plant lectins
have been isolated and characterized with respect to their
molecular structures and carbohydrate-binding specificities. Since
the unique biological properties of lectins can be exploited in the
investigation of numerous biochemical and cellular phenomena,
intense efforts are being made in many labs to isolate lectins with
unique and unusual sugar-binding specificities. The study deals
with the purification and partial characterization of a lectin from
Crotalaria pallida belonging to Leguminoseae. Conformational
changes and changes in biological properties by chemical
modification of the lectin are also a part of the study. The lectin
is a monomeric galactose and blood group A specific glycoprotein
with about 4% carbohydrate and a molecular weight of 43 kDa. The
activity yield of the lectin was about 4.6% with nearly three fold
purification. Conformational changes were investigated by gel
filtration, viscometery and UV absorption spectroscopy.
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