Herbs and human health can never be separated. Medicinal plants are now in a "come back" phase with the last two decades seeing people shifting their focus back to the forgotten traditional natural green remedies. Several plant drugs such as rawolfia (for mental diseases), podophyllum (a cathartic, cures cancerous tumors in mice), aloe (a cathartic, for the treatment of atomic radiation burn), veratrum (hypertensive agent), peyote (psychoactive drug) and several others. Sapogenins (closely related to steroids), obtained from many members of Dioscoreaceae and Agavaceae, have been effectively used for curing various ailments in modern times. The commonly used herbal medicines used by tribals of Rajasthan are belonging to the families Asclepiadaceae, Fabaceae, Asteraceae, Apiaceae, Cucurbitaceae, Euphorbiaceae, Acanthaceae, Papaveraceae, Capparidaceae and Solanaceae.

Hamburger (2008) reviewed the drug development based on plant derived natural products.

During the past two decades researchers have turned to the traditional folk medicines. The growing awareness of harmful side effects of chemotherapy has made people to explore the time tested remedies from traditional and alternative medicine.

The growth of Ayurvedic and traditioinal medicine and as well as the increase in western herbalists helped in the identification, quality selection and appropriate processing of crude drugs. India has about 45,000 plant species and among them, several thousands have been claimed to possess medicinal properties.

The white alarka could be presumably Calotropis gigantea which has generally white flowers. The description of the other two vetarka and arka probably represents Calotropis procera or its subdivisions. However, no subdivisions or subspecies of Calotropis procera have been recognized in literature.

Maharsi Caraka has categorized arka as bhedaniya- accumulation breaking herb, svedopaga - an adjunct to sweating therapy and vamanopaga - an adjunct to emesis (Caraka Samhita, Sutra, A-4) (Jain, 1996). It is cited to be useful for external application, in ascites (Astanga Sangraha, Cikitsa, 17). Arka is useful both, internally as well as externally. The poultice of its leaves effectively reduces the pain and swelling.

Calotropis has several medicinal uses in traditional as well as modern medicine system (Chitme et al., 2004). Medicine compounds derived from the plant have been found to have emeto-cathartic and digitalic properties. The principal active medicinals are asclepin and mudarin. Other compounds have been found to have bactericidal and vermicidal properties. The latex contains a proteolytic enzyme called caloptropaine. Primarily the root bark commonly called as mudar is used to treat a variety of ailments including menorrhagia, malaria, fever and snake bite. Root-bark is also very useful in treatment for elephantiasis and leprosy, and is efficacious in cases of chronic eczema. It is also used for curing diarrhoea and dysentery. The dry latex (DL) of Calotropis procera, a