Neem (Azadirachta indica A. Juss. Meliaceae) is native to South Asia, specifically India. Neem tree is known to Indians as a sarva roga nivarini "living pharmacy" or "the curer of all ailments," because of its wide use alone or in combination with turmeric to treat several skin ailments, and bacterial infections.

Neem's role as a wonder drug can be traced back to 4,500 years ago. The ancient documents Caraka-Samhita and Susruta Samhita, the books of the Indian medical system of Ayurveda mentioned the Neem fruits, seeds, oil, leaves, roots and bark for their advantageous medicinal properties.

One of the world's largest Neem plantations is reported to be in Saudi Arabia, where approximately 50,000 trees were planted on the Plains of Arafat. It is also grown through out the tropical and sub-tropical Asia, Africa, the Middle East and South America. Neem trees grow well in warm, frost-free areas and are normally propagated by seeds, or vegetative cuttings. It grows well in sub-humid to semiarid conditions without irrigation and very little rainfall. Neem has a distinct odor, and a strong bitter taste. The leaves are serrated, flowers white, and fruits are ellipsoidal drupes green in color turning to a bright yellow when ripe.

Hindus believe that measles, smallpox and/or mumps are symptoms and manifestations of the anger of goddess Mari. Traditionally, Neem leaves are steeped in water and used to bathe the infected. The Neem leaves are also soaked in water and used for drinking. On the first day of a Hindu new year, ugadhi or Chaitra Vishnu, which comes in March/April, people decorate their homes with fresh Neem leaves and flowers and eat the bitter Neem leaves and flowers with a little jaggery (molasses) to symbolize acceptance of the sweetness with the bitterness or the good with the bad in life.

Almost every part of the Neem plant is used as food or medicine. Neem flowers are dried and stored in bottles for use throughout the year for culinary purposes. Rasam made with Neem flowers is very popular in South India. From time immemorial to this day, tender Neem twigs are chewed so that the fibres of the stick are made into a tooth -brush. After brushing, pieces of fiber along with the saliva are spit out. A decoction of the Neem leaves is used to prevent premature graying of hair, hair loss, lice infestation and dandruff. Other cosmetic and personal care products commercially prepared with Neem leaf extracts or oil include bath powders, soaps, shampoos, skin creams, powders, extracts, insect repellents, pet care products, toothpastes and mouthwashes.

Ancient ayurvedic practitioners believed high sugar levels in the body caused skin disease and that Neem's bitter quality could counteract the sweetness of blood. Many of the secondary metabolites isolated from Neem have biological activity, but azadirachtin is the most ecologically important. Neem's function as a fungicide is due to the presence of the compounds gedunin and nimbidol in its leaf. Neem leaf extracts and oil are also reported to be anti-viral and anti-inflammatory and effectively relieve athlete's foot, ringworm and yeast-like fungi that can develop internally.

Recent studies on Neem provide evidence that it could be of benefit in diabetes mellitus in controlling the blood sugar or may also be helpful in preventing or delaying the onset of the disease (1), treatment of liver damage (2), as a chemopreventive reducing gastric and oral carcinogenesis (3-5), and the possible use as oral contraceptive (6-7). Due to Neem's antibacterial properties (8) it is effective in fighting most epidermal dysfunctions such as acne, psoriasis and eczema. The use of Neem twigs as toothbrush guards against periodontal disease (9).

References
1. Khosla et al., 2000. A study of hypoglycamic effects of Azadirachta indica (Neem) in normal and alloxan diabetic rabbits. Indian J Physiol Pharmacol. 44:69-74.
2. Bhanwra et al., 2000. Effect of Azadirachta indica (Neem) leaf aqueous extract on paracetamol-induced liver damage in rats. Indian J Physiol Pharmacol. 44:64-8
3. Arivazhagan et al., 2000. Garlic and Neem leaf extracts enhance hepatic glutathione and glutathione dependent enzymes during N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced gastric carcinogenesis in rats. Phytother Res.14:291-3
4. Balasenthil et al. 1999. Chemopreventive potential of Neem (Azadirachta indica) on 7,12-dimethylbenz[a]anthracene (DMBA) induced hamster buccal pouch carcinogenesis. J Ethnopharmacol. 67:189-95
5. Kusamran et al., 1998. Effects of Neem flowers, Thai and Chinese bitter gourd fruits, and sweet basil leaves on hepatic monooxygenases and glutathione S-transferase activities, and in vitro metabolic activation of chemical carcinogens in rats. Food Chem Toxicol. 36:475-84
6. Mukherjee et al., 1999. Early post implantation contraceptive effects of a purified fraction of Neem (Azadirachta indica) seeds, given orally in rats: possible mechanisms involved. J Ethnopharmacol. 67:287-96
7. Talwar et al., 1997. Plant immunomodulators for termination of unwanted pregnancy and for contraception and reproductive health. Immunol Cell Biol. 75:190-2
8. Das et al., 1999. Neem (Azadirachta indica) extract as an antibacterial agent against fish pathogenic bacteria. Indian J Exp Biol. 37:1097-100
9. Venugopal et al., 1998. Epidemiological study of dental caries Indian J Pediatr. 65:883-9

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