Mandala Of Indic Traditions
Medicinal properties of Neem: New Findings
by D.P. Agrawal
For thousands of years the beneficial properties of Neem (Azadirachta indica
A. Juss) have been recognized in the Indian tradition. Each part of the neem
tree has some medicinal property. Biswas et al (2002) have recently reviewed
the biological activities of some of the neem compounds, pharmacological actions
of the neem extracts, and clinical studies and plausible medicinal applications
of neem. This included a safety evaluation of the Neem.
Neem has two closely related species: A. indica A. Juss and M. azedarac.
The former is popularly known as the Indian Neem (Margosa tree) or Indian Lilac,
and the other as the Persian Lilac. Neem has been extensively used in ayurveda,
unani, and homoeopathic medicine. The Sanskrit name of the Neem tree is Arishtha
meaning 'reliever of sickness' and hence is considered as Sarbaroganibarini.
The tree is still regarded as 'village dispensary' in India. The importance
of the neem tree has been recognized by the US National Academy of Sciences,
which published a report in 1992 entitled 'Neem – a tree for solving global
More than 135 compounds have been isolated from different parts of the 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, and aliphatic compounds.
Biological activity of some Neem compounds
Nimbidin, a major crude bitter principle extracted from the oil of seed kernels
of A. indica demonstrated several biological activities. From this crude
principle some tetranortriterpenes, including nimbin, nimbinin, nimbidinin,
nimbolide and nimbidic acid have been isolated.
Biological activity of Neem compounds
Anti-inflammatory; Antiarthritic; Antipyretic; Hypoglycaemic; Antigastric ulcer;
Spermicidal; Antifungal; Antibacterial; Diuretic; Antimalarial; Antitumour;
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, and constipation. They have also been used as general health promoters.
Its use for the treatment of rheumatism, chronic syphilitic sores and indolent
ulcer has also been evident. Neem oil is also used to control various skin
infections. Bark, leaf, root, flower and fruit together cure blood morbidity,
biliary afflictions, itching, skin ulcers, burning sensations and pthysis (see
The aqueous extract of neem bark and leaf also possesses anticomplement and
immunostimulant activity. Neem oil has been shown to possess activity by selectively
activating the cell-mediated immune mechanisms to elicit an enhanced response
to subsequent mitogenic or antigenic challenge.
Aqueous extract of neem leaves significantly decreases blood sugar levels and
prevents adrenaline as well as glucose-induced hyperglycaemia. Recently, a
hypoglycaemic effect was observed with leaf extract and seed oil, in normal
as well as alloxan-induced diabetic rabbits.
Neem leaf and bark aqueous extracts produce highly potent antiacid secretory
and antiulcer activity.
Intra-vaginal application of neem oil, prior to coitus, can prevent pregnancy.
It could be a novel method of contraception.
Neem seed and leaf extracts are effective against both choroquin-resistant
and sensitive strain malarial parasites.
Extracts of neem leaf and neem oil seed kernels are effective against certain
fungi including Trichophyton, Epidermophyton, Microspor
Trichosporon, Geotricum and Candida.
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.
Aqueous leaf extract offers antiviral activity against Vaccinia virus, Chikungemya,
and measles virus.
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.
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.
Possible medicinal applications of neem
Its effective in curing ringworm, eczema and scabies. Lotion derived from neem
leaf, when locally applied, can cure these dermatological diseases within three
to four days in acute stage or in a fortnight in a chronic case. A paste prepared
with neem and turmeric was found to be effective in the treatment of scabies
in nearly 814 people.
Neem leaf extract has been prescribed for oral use for the treatment of malaria
by Indian ayurvedic practitioners from time immemorial. Recently, a clinical
trial has been carried out to see the efficacy of neem extract to control hyperlipidemia
in a group of malarial patients severely infected with P. falciparum.
The lipid level, especially cholesterol, was found to be lower during therapy
when compared to non-malaria patients. Reports are available regarding the use
of neem to treat patients suffering from various forms of cancer. One patient
with parotid tumor and another with epidermoid carcinoma have responded successfully
when treated with neem seed oi1.
NIM- 76, a refined product from neem oil, was studied in ten human volunteers,
to determine whether intra-vaginal application before sexual intercourse would
prevent pregnancy without an adverse effect on vagina, cervix and uterus. The
data suggested that intrauterine treatment is safe.
Safety evaluation with various parts of neem and neem products
Various studies have been reported on the safety evaluation of different parts
of neem as well as its various biologically active products.
Nimbidin produces sub-acute toxicity in adult rats after daily administration
of 25, 50 or 100 mg/kg for six weeks. A significant hypoglycemic effect was
observed by feeding nimbidin to fasting rabbits. Nimbidin also has spermicidal
activity. Nimbolide, a major chemical component of neem seed oil, and nimbic
acid were found to be toxic to mice when given intravenously or intraperitoneally.
They are, however, less toxic to rats and hamster. Nimbolide and nimbic acid
at a lethal dose cause death in most animals by dysfunction of kidney, small
intestine and liver as well as by marked and sudden drop of arterial blood pressure.
It is heartening to see that a traditional Indian plant medicine has now led
to several therapeutically and industrially useful preparations and compounds.
It has generated enough encouragement among the scientists in exploring more
information about this medicinal plant. As the global scenario is now changing
towards the use of nontoxic plant products having traditional medicinal use,
development of modern drugs from neem should be emphasized for the control of
various diseases. In fact, time has come to make good use of centuries-old
knowledge of neem through modern approaches of drug development. For the last
few years, there has been an increasing trend and awareness in neem research.
Quite a significant amount of research has already been carried out during the
past few decades in exploring the chemistry of different parts of neem. An extensive
research and development work should be undertaken on neem and its products
for better economic and therapeutic utilization.
Biswas, Kausik, Ishita Chattopadhyay, Ranajit K.Banerjee and Uday Bandyopadhyay.
2002. Biological activities and medicinal properties of Neem (Azadirachta
indica). Current Science 82(11): 1336-1345.
Other Relevant References:
1. Chopra, R. N., Nayer, S. L. and Chopra, I. C., Glossary of Indian Medicinal
Plants, CSIR, New Delhi, 1956.
2. Chopra, R. N., Chopra, I. C, Handa, K. L. and Kapur, L. D. (eds), Indigenous
Drugs of India, U.N. Dhur and Sons, Kolkata, 1958, pp.51-595.
3. Kirtikar, K. R. and Basu, B. D., in Medicinal Plants (eds Blatter,
E., Cains, J. F., Mhaskar, K. S.), Vivek Vihar, New Delhi, 1975, p.536.
4. Chatterjee, A. and Pakrashi, S. (eds), The Treatise on Indian Medicinal
Plants, 1994, vol. 3, p. 76.
5. Schmutterer, H. (ed.), The Neem Tree: Source of Unique Natural Products
for Integrated Pest Management, Medicine, Industry and Other Purposes, VCH,
Weinheim, Germany, 1995, pp. 1-696.
6. Singh, R. P., Chari, M. S., Raheja, A. K. and Kraus, W., Neem and Environment,
Oxford & IBH Publishing, New Delhi, 1996, Vols. I and II, pp. 1-1198.
7. Kraus, W., in The Neem Tree: Source of Unique Natural Products for Integrated
Pest Management, Medicine, Industry and Purposes (ed. Schmutterer, H.),
1995, pp 35-88.
8.Vanna, G. S., Miracles of Neem Tree, Rasayan Pharmacy, New Delhi,
9. Ketkar, A. Y. and Ketkar, C. M., in The Neem Tree: Source of Unique Natural
Products for Integrated Pest Management, Medicine, Industry and Other Purposes
(ed. Schmutterer, H.), 1995, pp.518-525.
10. Khan, M. and Wassilew, S. W., in Natural Pesticides from the Neem Tree
and Other Tropical Plants (eds Schmutterer, H. and Asher, K. R. S.), GTZ,
Eschborn, Germany, 1987, pp. 645-650.
11. Jacobson, M., in The Neem Tree: Source of Unique Natural Products for
Integrated Pest Management, Medicine, Industry and other Purposes (ed. Schmutterer,
H.), 1995, pp. 484-495.