Azadirachta indica is a tree in the mahogany family Meliaceae. It is one of two species in the genus Azadirachta, and is native to India and Pakistan growing in tropical and semi-tropical regions. Its fruits and seeds are the source of neem oil. Other vernacular names include Neem (Nepali, Urdu), (Bengali), Nimm (Punjabi), Vembu (Tamil), Arya Veppu (Malayalam), Azad Dirakht (Persian), Nimba (Sanskrit, Oriya), Limdo (Gujarati language) Kadu-Limba (Marathi), Dongoyaro (in some Nigerian languages), Margosa, Neeb (Arabic), Nimtree, Vepu , Vempu, Vepa (Telugu), Bevu (Kannada),Kodu nimb (Konkani), (Kohomba, Sinhala), Tamar (Burmese), (Sdao, Khmer),(Sadaw, Thai), (Hebrew), Paraiso (Spanish), and Indian Lilac (English). In East Africa it is also known as Muarubaini (Swahili), which means the tree of the 40, as it is said to treat 40 different diseases, and in Somalia it is known as "Geed Hindi" which means "the Indian tree".
Neem is a fast-growing tree that can reach a height of 15–20 metres (49–66 ft), rarely to 35–40 metres (115–130 ft). It is evergreen, but in severe drought it may shed most or nearly all of its leaves. The branches are wide spread. The fairly dense crown is roundish or oval and may reach the diameter of 15–20 metres (49–66 ft) in old, free-standing specimens.
Neem is considered a weed in many areas, including some parts of the Middle East, and most of Sub-Saharan Africa including West Africa where in Senegal it has been used as a malarial drug and Tanzania and other Indian Ocean states where in Kiswahili it is known as 'the panacea', literally 'the tree that cures forty [diseases]', where ayurvedic uses are practiced. Ecologically, it survives well in similar environments to its own, for example replacing the babul acacia tree from India with African acacia species.
Indian scientists were the first to bring the plant to the attention of phytopharmacologists. In 1942, at the Scientific and Industrial Research Laboratory at Delhi University, three bitter compounds were extracted from neem oil, which were named nimbin, nimbinin, and nimbidin.The seeds contain a complex secondary metabolite azadirachtin.
All parts of the tree are said to have medicinal properties (seeds, leaves, flowers and bark) and are used for preparing many different medical preparations. The chemical constituents nimbidin and nimbin have some spermicidal activity Neem oil is used for preparing cosmetics (soap, neem shampoo, balms and creams such as Margo soap) and many oral health products. Besides its use in traditional Indian medicine, the neem tree is of great importance for its anti-desertification properties and possibly as a good carbon dioxide sink.Practitioners of traditional Indian medicine recommend that patients with chicken pox sleep on neem leaves. Neem gum is used as a bulking agent and for the preparation of special purpose food. Traditionally, slender neem branches have been chewed to clean one's teeth. Neem twigs are still collected and sold in markets for this use, and in India one often sees youngsters in the streets chewing on neem twigs(for the neem twigs and branches have great dental effects). Neem blossoms are used in Andhra Pradesh, Tamil Nadu and Karnataka to prepare Ugadi pachhadi. "Bevina hoovina gojju" (a type of curry prepared with neem blossoms) is common in Karnataka throughout the year. Dried blossoms are used when fresh blossoms are not available. In Tamilnadu, a rasam (veppam poo rasam) made with neem blossoms is a culinary specialty. A mixture of neem flowers and bella (jaggery or unrefined brown sugar) is prepared and offered to friends and relatives, symbolic of sweet and bitter events in the upcoming new year. Extract of neem leaves is thought to be helpful as malaria prophylaxis despite the fact that no comprehensive clinical studies are yet available. In several cases, private initiatives in Senegal were successful in preventing malaria. However, major NGOs and other organizations such as USAID are not supposed to use neem tree extracts unless the medical benefit has been proved with clinical studies. Neem extracts as insecticides. Neem products are unique in that they are not outright killers. Instead, they alter an insects behaviour or life processes in ways that can be extremely subtle. Eventually, however, the insect can no longer feed or breed or metamorphose & can cause no further damage. Azadirachtin : One of the first active ingredients isolated from neem, Azadirachtin has proved to be the trees main agent for battling insects. It appears to cause some 90% of the effect on most pests.
In India, the plant is variously known as "Sacred Tree," "Heal All," "Nature's Drugstore," "Village Pharmacy" and "Panacea for all diseases". Products made from neem trees have been used in India for over two millennia for their medicinal properties: neem products are believed to be anthelmintic, antifungal, antidiabetic, antibacterial, antiviral, contraceptive and sedative. Neem products are also used in selectively controlling pests in plants. It is considered a major component in Ayurvedic and Unani medicine and is particularly prescribed for skin disease.