1.1 Worldwide Distribution of Genus Ocimum
The Indian Himalaya is home to more than 8,000 species of vascular plants (Singh and Hajra 1996), of which 1748 are known for their medicinal properties (Samant et al. 1998). Higher plants have played key roles in the lives of tribal peoples living in the Himalaya by providing forest products for both food and medicine. Although numerous wild and cultivated plants have been utilized as curative agents since ancient times, they have gained more importance in recent days not only as herbal medicines but also as natural ingredients for the cosmetic industry. Plants have been used by humans from prehistoric times to get rid of suffering and cure various ailments. The folk medicines of almost around the world rely chiefly on herbal medicine even today. The therapeutic uses of plants are safe, economical, effective and easily available (Atal and Kapur 1982; Trivedi 2007; Joshi 2017). Ayurveda, the conventional system of medicine in India, is an indigenous, well known and explored system of alternative and complementary medicine. Dhanvantari, known as the physician of the God, is recognized as the founder of Ayurvedic medicine. Vedas, specially the Atharvaveda, mainly focus on curing the diseases through plant based remedies (Patwardhan et al. 2005). Species of genus Ocimum, family Lamiaceae, are prominently known as Basil (Chen et al. 2013). These are local to the tropical and warm mild areas and widely found in Asia, Africa, and Central and South America (Pandey et al. 2014; Beatovic et al. 2015). The genus Ocimum contains more than 150 species distributed throughout the tropical regions of Asia, Africa, and Central and South America (Darrah 1974; Vani et al. 2009; Prasad et al. 2012). Ocimum species are a rich wellspring of essential oils, the volatile liquid of aroma compounds extracted from the leaves and flowering tops of basil (Beatovic et al. 2015; Pandey et al. 2014). Essential oils extracted from different Ocimum species are used as flavoring or fragrance agents in foods and beverages, as well as in the pharmaceutical, perfumery and cosmetic industries (Beatovic et al. 2015; Pandey et al. 2014; Vieira et al. 2014). Even today, the home made remedy mostly depends on the homegrown medicinal plants. These plants are rich sources of medicines and expensive medicated supplements. The most well known components of home based medications are medicinal plants with lesser or no side effects. In the Indian system of medicine, Ayurveda, Homeopathy, Siddha and Unani together have taken the responsibility to deal with various ailments for centuries. Ocimum sanctum is known as the “Queen of Herbs” due to its tremendous medicinal properties that have been utilized in Ayurvedic system of medicine from the ancient period. Charaka, in his famous book Charaka Samhita, also mentioned about Tulsi and its various medicinal properties and actions. Five properties of Tulsi, namely, Rasa, Guna, Virya, Vipaka and Karma, are described in Ayurveda (Ayurvedic Pharmacopoeia of India; Anonymous 2016). It is a plant that is utilized for the religious as well as therapeutic purposes. The six species of Ocimum genus commonly found in India are O. americanum L. (syn. O. canum Sims), O. basilicum L., O. gratissimum L., O. killimandscharicum Baker ex Gürke, O. sanctum L. (syn. O. tenuiflorum L.) green and O. sanctum L. purple (Mahajan et al. 2013). Among these, O. sanctum (holy basil) is widely grown in India as a folk medicine and sacred plant, whereas O. basilicum (sweet basil) as a culinary and ornamental herb. Traditionally, Tulsi is also known as “the elixir of life” since it promotes longevity (Siddiqui 1993). The word “Tulsi” is from Sanskrit language which means “matchless” or the “incomparable one.” In Hindu mythology, Tulsi is also known as Vaishnavi (belonging to Lord Vishnu), Vishnu Vallabha, Haripriya (beloved to Lord Vishnu) and Vishnutulsi. The famous holy book Padma Purana describes the importance of Tulsi with Lord Vishnu by regarding it as the incarnation (avatar) of Lord Lakshmi (wife of Lord Vishnu). Its leaves are important in the Hindu religion. The leaves are used in every holy rituals and ceremonies, and given as religious offering known as Prasad. It is also mentioned that lighting a single stick of Tulsi lamp is equal to enlighting lakhs of lamps for Lord Vishnu (Siddiqui 1993; Sen 1993). Most of the Hindus grow Tulsi in their household or at the entrance of their house as they believe it provides positive energy. They also believe that god dwells in Tulsi plant. Different parts of the plant are used in Ayurveda and Siddha systems of medicine for prevention and cure of many illnesses and everyday ailments like common cold, headache, cough, influenza, earache, fever, colic pain, sore throat, bronchitis, asthma, hepatic diseases, malarial fever, flatulence, migraine headaches, fatigue, skin diseases, wound, insomnia, arthritis, digestive disorders, night blindness and diarrhea, and they are also used as antidotes for snakebite and scorpion sting (Gupta et al. 2002; Ali et al. 2012; Mandal et al. 2012; Parag et al. 2010; Farivar et al. 2006; Shokeen et al. 2005; Sawarkar et al. 2010; Yucharoen et al. 2011; Suzuki et al. 2009; Saini et al. 2009; Deo et al. 2011; Chandra et al. 2011). The tea made of Tulsi leaves rem...
