Ocimum tenuiflorum, Holy Basil (also tulsi, tulasī), is an aromatic plant in the family Lamiaceae which is native throughout the Old World tropics and widespread as a cultivated plant and an escaped weed. It is an erect, much branched subshrub, 30–60 cm tall with hairy stems and simple, opposite, green leaves that are strongly scented. Leaves have petioles, and are ovate, up to 5 cm long, usually slightly toothed. The flowers are purplish in elongate racemes in close whorls. The two main morphotypes cultivated in India and Nepal are green-leaved (Sri or Lakshmi tulsi) and purple-leaved (Krishna tulsi). Tulsi is cultivated for religious and medicinal purposes, and for its essential oil. It is widely known across South Asia as a medicinal plant and an herbal tea, commonly used in Ayurveda, and has an important role within the Vaishnavite tradition of Hinduism, in which devotees perform worship involving tulsi plants or leaves.
Recent studies suggest tulsi may be a COX-2 inhibitor, like many modern painkillers, due to its high concentration of eugenol (1-hydroxy-2-methoxy-4-allylbenzene). One small study showed it to reduce blood glucose levels in type 2 diabetics when combined with hypoglycemic drugs. The same study showed significant reduction in total cholesterol levels with tulsi. Another study showed its beneficial effect on blood glucose levels is due to its antioxidant properties. Tulsi also shows some promise for protection from radiation poisoning and cataracts.It has anti-oxidant properties and can repair cells damaged by exposure to radiation. The fixed oil has demonstrated antihyperlipidemic and cardioprotective effects in rats fed a high fat diet. Experimental studies have shown an alcoholic extract of tulsi modulates immunity, thus promoting immune system function. Some of the main chemical constituents of tulsi are: oleanolic acid, ursolic acid, rosmarinic acid, eugenol, carvacrol, linalool, β-caryophyllene, β-elemene (c.11.0%), β-caryophyllene (about 8%), and germacrene D (about 2%). β-Elemene has been studied for its potential anticancer properties, but human clinical trials have yet to confirm its effectiveness.
Tulsi has been used for thousands of years in Ayurveda for its diverse healing properties. It is mentioned in the Charaka Samhita, an ancient Ayurvedic text. Tulsi is considered to be an adaptogen, balancing different processes in the body, and helpful for adapting to stress. Marked by its strong aroma and astringent taste, it is regarded in Ayurveda as a kind of "elixir of life" and believed to promote longevity. Tulsi extracts are used in ayurvedic remedies for common colds, headaches, stomach disorders, inflammation, heart disease, various forms of poisoning, and malaria. Traditionally, tulsi is taken in many forms: as herbal tea, dried powder, fresh leaf, or mixed with ghee. Essential oil extracted from Karpoora tulsi is mostly used for medicinal purposes and in herbal cosmetics, and is widely used in skin preparations due to its antibacterial activity. For centuries, the dried leaves have been mixed with stored grains to repel insects.
The leaves of holy basil, known as kraphao in the Thai language , are commonly used in Thai cuisine.
Kraphao should not be confused with horapha , which is normally known as Thai basil,
or with Thai lemon basil . The best-known dish made with this herb is phat kraphao — beef, pork or chicken, stir-fried with Thai holy basil.