View with images and charts Tulsi: An important medicinal plant 1.1 General introduction: History of many drugs can be traced back to their natural origin. At the very dawn of civilization, coexistence of disease with the emergence of life in the earth compelled the primitive man to search a cure from his surroundings. Since then plant was being used as remedy for many diverse disease ranging from simple skin infection to such formidable foes as heart diseases and cancers. The medicinal use of some plants by Indo-Aryans was noted in the Rig Veda (4500-1600BC) and the medicinal value of many plant constituents used by Egyptians was recorded in Papyrus Abus (1500BC).The great physician Hippocrates, who is called ‘the father of medicinal science’, also used plants for treatment of many diseases. In this respect medicine can be considered as an ancient art consisting of plant materials.1 Starting from the stone-age, the use of plants as traditional medicine has increased with the age of civilization. Herbal medicines are still in use in many societies. Although most of the modern medicines are simple compounds, but in many cases the drugs have been originated from the nature, more specifically from plant sources. Plants are considered as natural chemical factory, because synthetic process in biological systems particularly in plants is going on by nature’s ordinary condition of temperature and pressure. The laboratory synthesis of anti-malarial drug quinine requires an intensive work extending over half a century but chicona plant can do it everyday without difficulty. Till today, extensive phytochemical analysis of plants yielded diversified chemical compounds as steroids, terpenoids, flavonoids, chalcones, alkaloids, glycosides etc. clinically used plant metabolites such as taxol isolated from Taxes brevifolia, Vineristine and Vinblastine obtained from Vinca rosea Linn. and digitalis derived from Digitalis purpura are only few of the many striking examples of developing life saving drugs from plant sources.2 Once the plant medication was provided to the ancient people in the crude form, it often exhibited many unwanted effects due to the presence of some toxic components beyond the active constituent. Extensive phytochemical investigation and isolation of active component in the pure form thus became necessary to avoid untoward effects and to ensure safe use of herbal medicines, phytochemical studies of medicinal plants got a rapid pace and the presence of many chemical compounds of diversified nature including many new compounds came in light. These plant derived compounds often played an important role in directing laboratory synthesis of many new classes of drug molecules. In some cases, the plant components became the starting material in the synthetic process of industrial production of many drug molecules. For example, the use of sterol diosgenin, isolated from Mexican yam, for laboratory synthesis of oral contraceptive progesterone reduce the cost of progesterone from a value of $80 per gram to $1.75 per gram.3 Sometimes phytochemical analysis for many plants yielded such chemical constituent having no remarkable therapeutic interest. Sometimes the crude drugs containing several constituents were found to be ineffective in case of therapy for which it is used. The phytochemical investigation of periwinkle plant (Vinca rosea), once used traditionally as an anti-diabetic drug, was found to contain alkaloidal constituents having hypoglycemic potency in minute quantities. The dried seeds of plant Amni visanaga was used as diuretic and antispasmodic in renal collie in Eastern Mediterranean countries and in Arabia, but the research carried out by
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