Tylophora indica (family Apocynaceae) is a perennial climbing plant and has been used in the Ayurvedic system of medicine. The leaves of the plant have been extensively used in the treatment of various inflammatory and allergic disorders like bronchial asthma, bronchitis, and whooping cough (Chopra et al., 1958). The extracts of the leaves of T. indica have antiasthmatic and antiallergic potential (Shivpuri et al., 1969, 1972). The plant extracts also inhibited the Schultz-Dale reaction and systemic anaphylaxis in guinea pigs (Haranath and Shyamalakumari, 1975). The extract of T. indica leaves showed inhibition of cellular immune responses in experimental models (Ganguly and Sainis, 2001). Tylophorine is a major alkaloid obtained from the plant T. indica and has been reported to have anti-inflammatory, antiasthmatic, and antianaphylactic potential in experimental studies (Gopalakrishnan et al., 1979, 1980; Raina and Raina, 1980).
Tylophora indica (Burm. f.) Merr. resides in Asclepiadaceae of angiosperm family. The plant is a curative climber originally established in the plain and hilly areas of forest found in the Eastern and Southern India extending to an elevation of 900 m. Various synonyms of the plant include Cynanchum indicum Burm. f., T. asthmatica (L. f.) Wight and Arn. in Wight, Asclepias asthmatica L. f. and A. prolifera Rottl. ex Ainslie. Its common English name is ‘emetic swallow-wort’ (Sasidharan 2004). Due to its excessive medicinal use, attempts were made to standardize micropropagation protocols in this plant by using different explants (Thomas and Philip 2005; Thomas 2006, 2009). Plant secondary metabolites are chemical compounds having negligible function in the perpetuation of fundamental life activities in plants which manufacture it. However, it has crucial task in the intercommunication of the plant with its habitat. The synthesis of these compounds is usually a little (less than 1% dry weight), and it has tremendous influence on the physiological and developmental state of the plant (Dixon 2001; Oksman-Caldentey and Inzé 2004). The major alkaloid present in T. indica is phenanthroindolizidine type, and its heterocyclic ring consists of indolizidine ring fused to a phenanthrene ring. This alkaloid was isolated and named as ‘tylophorine’ by Ratnagiriswaran and Venkatachalam (1935) for the first time. Along with tylophorine, they had isolated alkaloid ‘tylophorinine’ also from the aerial parts of T. indica. The roots and foliage of the plant yield 0.2–0.46% tylophorine, tylophorinine and tylophrinidine (Gopalakrishnan et al. 1979). The plant is conventionally employed for the medication of several respiratory disorders such as bronchitis, seasonal cough and cold, hay fever and asthma (Haranath and Shayamalakumari 1975; Gupta et al. 1979; Rao et al. 1980). The roots along with leaves of the plant are further employed to alleviate jaundice and liver disorders (Devprakash et al. 2012). Tylophorinine, a minor alkaloid, was isolated and characterized from T. asthmatica by Govindachari et al. (1961). Dhiman et al. (2013) isolated and characterized a novel phenanthroindolizidine alkaloid, 3-O-demethyl tylophorinidine (VI), from the leaves and stems of T. indica by utilizing various chromatographic and spectroscopic techniques. Zhen et al. (2002) reported that phenanthroindolizidine alkaloids like tylophoridicine A, O-methyl tylophorinidine and tylophorinidine possessed prominent anticancer activity towards different cell lines
Tylophorine is an alkaloid obtained from T. indica. In addition, the plant contains tylophorinine, tylophrinidine, septicine and isotylocrebrine. Major alkaloid tylophorine possesses many properties including immunosuppressive, antitumour, antifeedant, antibacterial, antifungal, antiamoebic, diuretic and hepatoprotective activities. As an important alkaloid, it has different potential medical applications. Although various methods have been standardized for the biotechnological production and extraction of tylophorine, an efficient and cost-effective protocol still needs to be standardized. Moreover, the quantitative improvement of tylophorine still remains as a challenge.