Biological activities and medicinal properties of neem (Azadirachta indica)

Neem (Azadirachta indica A. Juss) is perhaps the most useful traditional medicinal plant in India. Each part of the neem tree has some medicinal property and is thus commercially exploitable. During the last five decades, apart from the chemistry of the neem compounds, considerable progress has been achieved regarding the biological activity and medicinal applications of neem. It is now considered as a valuable source of unique natural products for development of medicines against various diseases and also for the development of industrial products. This review gives a bird’s eye view mainly on the biological activities of some of the neem compounds isolated, pharmacological actions of the neem extracts, clinical studies and plausible medicinal applications of neem along with their safety evaluation. MEDICINAL plants are part and parcel of human society to combat diseases, from the dawn of civilization. Azadirachta indica A. Juss (syn. Melia azadirachta) is well known in India and its neighbouring countries for more than 2000 years as one of the most versatile medicinal plants having a wide spectrum of biological activity. A. indica A. Juss and M. azedarach are two closely related species of Meliaceae. The former is popularly known as Indian neem (margosa tree) or Indian lilac, and the latter as the Persian lilac. Neem is an evergreen tree, cultivated in various parts of the Indian subcontinent. Every part of the tree has been used as traditional medicine for household remedy against various human ailments, from antiquity 1–6 . Neem has been extensively used in ayurveda, unani and homoeopathic medicine and has become a cynosure of modern medicine. The sanskrit name of the neem tree is ‘Arishtha’ meaning ‘reliever of sickness’ and hence is considered as ‘Sarbaroganib arini’. 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 problems’. The advancement of neem research has earlier been documented 7,8