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Medicinal
properties of Neem: New Findings
by D.P. Agrawal
More than 135 compounds have been isolated from different parts of
neem and several reviews have also been published on the chemistry
and structural diversity of these compounds. The compounds have been
divided into two major classes: isoprenoids (like diterpenoids and
triterpenoids containing protomeliacins, limonoids, azadirone and
its derivatives, gedunin and its derivatives, vilasinin type of compounds
and C- secomeliacins such as nimbin, salanin and azadirachtin ) and
non-isoprenoids, which are proteins (amino acids) and carbohydrates
(polysaccharides), sulphurous compounds, polyphenolics such as flavonoids
and their glycosides, dihydrochalcone, coumarin and tannins, aliphatic
compounds, etc.
Medicinal Uses
Various
parts of the neem tree have been used as traditional Ayurvedic medicine
in India. Neem oil and the bark and leaf extracts have been therapeutically
used as folk medicine to control leprosy, intestinal helminthiasis,
respiratory disorders, constipation and also as a general health
promoter. Its use for the treatment of rheumatism, chronic syphilitic
sores and indolent ulcer has also been evident. Neem oil finds use
to control various skin infections. Bark, leaf, root, flower and
fruit together cure blood morbidity, biliary afflictions, itching,
skin ulcers, burning sensations and pthysis
Antiulcer
effect
Neem
leaf and bark aqueous extracts produce highly potent antiacid secretory
and antiulcer activity.
Antifertility effect
Intra-vaginal
application of neem oil, prior to coitus, can prevent pregnancy.
It could be a novel method of contraception.
Antimalarial activity
Neem
seed and leaf extracts are effective against both choroquin-resistant
and sensitive strain malarial parasites.
Antifungal activity
Extracts
of neem leaf, neem oil seed kernels are effective against certain
fungi including Trichophyton, Epidermophyton, Microspor Trichosporon,
Geotricum and Candida.
Antibacterial activity
Oil
from the leaves, seed and bark possesses a wide spectrum of antibacterial
action against Gram-negative and Gram-positive microorganisms, including
M. tuberculosis and streptomycin resistant strains. In vitro, it
inhibits Vibrio cholerae Klebsiella pneumoniae, M. tuberculosis
and M. pyogenes. Antimicrobial effects of neem extract have been
demonstrated against Streptococcus mutans and S. faecalis.
Antiviral activity
Aqueous
leaf extract offers antiviral activity against Vaccinia virus, Chikungemya
and measles virus.
Anticancer activity
Neem
leaf aqueous extract effectively suppresses oral squamous cell carcinoma
induced by 7, 12-dimethylbenz[a] anthracene (DMBA), as revealed
by reduced incidence of neoplasm. Neem may exert its chemopreventive
effect in the oral mucosa by modulation of glutathione and its metabolizing
enzymes.
Antioxidant activity
The
antioxidant activity of neem seed extract has been demonstrated
in vivo during horse- grain germination.
Effect on central nervous system
Varying
degrees of central nervous system (CNS) depressant activity in mice
was observed with the leaf extract. Fractions of acetone extract
of leaf showed significant CNS depressant activity.
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