According to Ayurvedic system of medicines a large number of plants are employed in the traditional medicines for the treatment of several diseases like cancer (Kirtikar and Basu, 1935; MacDowell, 1958; Nandkarni, 1975; Chopra et al., 1982; Jain, 1997 and Sharma and Kumar, 2000), leprosy (Sanghi and Kumar, 2002), hepatic disease (Sharma and Kumar,2001), paralysis (Sharma and Kumar, 2001), urinary stone track disease (Mishra and Kumar, 2001), depression and other nervous disorder (Mishra and Kumar, 2000) and diabetes (Raghunandan and Mitra, 1982 and Gupta and Kumar, 2000, 2002) . Thar desert of Rajasthan is also highly rich in medicinal plant diversity. Some very important medicinal plants of potent medical value have been discovered through ethnobotanical survey of Thar desert in Rajasthan (Sinha and Gulati,1990 and Shivani and Kumar,2002). Ethnobotany in Rajasthan is still in its infancy. Even very little is known about its biodiversity. A large number of plant species which have high medicinal value and are used by local people of Rajasthan as tribal medicines are found in arid and semi arid regions of Rajasthan. REVIEW OF LITERATURE (a) National Status- Ancient literature Rigveda and Atharveda mention 67 and 290 medicinal plants respectively (Devraj, 1980 and Dash and Kashyap, 1988). In India the term ethnobotany was first used by Dr. S.K. Jain (1983) from NBRI Lucknow. He is known as "Father of Indian Ethnobotany”. Work on ethenobotany is further revised by Trivedi (2002,2004). Ocimum genus contains between 50 to 150 species of herbs and shrubs from the tropical regions of Asia (Bailey, 1924 and Darrah 1980). Plants have square stems, fragrant opposite leaves and whorled flower on spiked inflorescence (Darrah ,1980).The essential oil of basil extracted via steam distribution from the leaves and flavouring tops are used to flavour foods, dental and oral products, in fragrances and in traditional rituals and medicines (Guenther 1949 and Simon et al 1990). Extracted essential oils have also been shown to contain biologically active constituents that are insecticidal (Deshpande and Tipnis,1977;Chogo and Crank,1981; Chavan and Nikan,1982), nematicidal (Chatterjee et al., 1982) and fungistatic (Reuveni et al.,1984). These properties can be frequently attributed to predominate essential oil constitutes such as methyl chavicol, eugenol linalool, camphor and methyl cinnamate. Two minor components of the essential oil of sweet basils (Ocimum basilicum) : Juvocimene I and II, have been reported as potent juvenile hormone analogs (Nishida et al., 1984). Darrah (1980) classified the O. basilicum cultivars in seven types : Sweet basil , Italian basil , Bush basil , Thai basil , Purpurscens , Dark opal ( a possible hybrid between O. basilicum and O. forskolei) , Citriodorrem types, which includes lemon flavoured basils. Currently, O. basilicum and O. sanctum oils are being studied for their anti inflammatory and antiulcer activity (Singh and Majumdar, 1999), Basil is also proved to be valuable source of anticarcinogenic agents (Aruna and Sivaramakrishnan, 1992). According to Karthikeyan (1999) Holy basil (Ocimum sanctum) may have the ability to prevent the early events of carcinogenesis.Other studies provide evidence of potent anti HIV-I, (Yamasaki, 1998), antioxident (Maulik, 1997) hypoglycemic and hypo lipidemic (Rai, 1997) activities of basil leaves and leaf extracts. (b) International Status- Ancient literatures of world of medicine suggest that the primitive people of antiquity and those of earlier centuries have been using several kinds of medicinal plants for combating diseases. The herbal medicinal of ancient times practiced by the Assyrians (4000 B.C.), Sumerians (3500 B.C.) Indians (3500 B,.C.), Chinese (3000 B.C.) and Egyptians (2500 B.C.) and which was temporarily subdued under the impact of modern medicine have staged a come back and a `herbal renaissance' is blooming across the world. Sweet basil (Ocimum basilicum L.) a common garden herb is cultivated in the United States for culinary purposes as a fresh herb and as a dried spice. There are several types of basil oil in internatiaonal commerce, each derived principally from different cultivars and chemotypes of sweet basil. The oils of commerce are known as European, French, Egyptian, Revnion or Comoro and to a lesser extent Bulgarian and Java basil oils (Heath 1981). A system of standardized descriptors which include volatile oils, has more recently been proposed by Paton (1992) and this should permit easy communication and identification of the different forms of basilicum. Investigations to revise the genus are underway at the Royal Botanical Garden, Kew, London (Paton, 1992) and at Delaware State University. The perfume,pharmacy and food industries (Simon and Reiss-Bubenheim, 1987) use aromatic essential oil extracted from the leaves and flowers of basil. O.basilicum and O. sanctum oils have anti microbial effects and may be a potential preservative in food preparations (Lachowicz,1998).Basil also possess anti diarrhoeal activities and blood sugar lowering agents(Llori 1996). The European type, a sweet basil is considered to have the highest quality aroma, containing linalool and methyl chamicol as major constituents (Simon et al, 1990). The traditional system of medicine in China is the most effective in curing - acute abdominal conditions, artheritic disorders, pneumonia, cardio vascular diseases, neurological disorders, hypertension, parasitic disease, eye disease and malaria. The National Cancer Institute Bathesda, Maryland is screening large number of plants obtained from various parts of world but mostly from south developing nations including Indian who are rich in biodiversity) for anti-cancer and anti-AIDS activity. A large number of plants provide a source of important crude drugs in traditional medicinal systems in different parts of globe (Anonymous, 1986). There are many herbs which have antimasque, anti-hepatic, anti-cancerous, hypogly caemic, psychelytic, hypolipidemic, psychedelic and immuno-modulating properties discovered from different parts came from the indigenous people and the traditional healers of world only. (c) Ocimum sanctum L. (d) Tulsi is a widely grown, sacred plant of India. It belongs to the lamiaceae family .It is also called by names like Manjari / Krishna Tulsi (Sanskrit), Trittava (Malayalam), Tulshi (Marathi) and Thulsi (Tamil and Telegu). It is called Holy Basil in English. The natural habitat of Tulsi varies from sea level to an attitude of 200 m. It is found growing naturally in moist soil nearly all over the globe. In India, hindus grow Tulsi as a religious plant in their homes, temples and their farms. They use Tulsi leaves in routine worship. (e) Three main forms are generally recognized Rama tulsi() with stems and leaves of green, Krishna tulsi() with stems and sometimes also leaves of purple and Vana tulsi() which is unmodified from its wild form. Variations in soil type and rainfall may also equate to a difference in the size and form of the plants as well as their medicinal strength and efficacy. The genus Ocimum , typically contain fragrant herbs and small herbs. It has nearly 30 species which are mainly found in the tropics and subtropics (Paton, 1992). Tulsi is a branched, fragrant and erect herb blasing hair all over. These are aromatic because of the presence of a kind of scented oil in them. A variety with green leaves is called Shritulsi and one with reddish leaves is called Krishna Tulsi. Because of it's medicinal virtues, Tulsi is used in Ayurvedic preparations. Tulsi leaves contain a bright yellow volatile oil. The oil contain eugenol, eugenal, carvaled, methyl chavicol, limatrol and Caryophylline and a number of sesquiterpenes. and monoterpenes viz., barnyl acetate, B-elemense, methylengenol, neral, B-pinene, comphene, A-pinene etc. Seeds contain an oil composed of fatty acids like ursolic acid, campesterol, cholestrol, stigmasterol, B-sitosterol , methyl esters etc.Oil of basil obtained from Ocimum basilicum L. is a useful sources of components like methyl chavicol, eugenol (E). methyl cinnamate, thymol linalool etc (Jansen, 1981). 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