**2. Why plant cell cultures?**

The capacity of plant cell, tissue and organ cultures to produce and accumulate many of the valuable chemical compounds has been recognized almost since the inception of in vitro technology. The strong and growing demand in today's market place for natural, renewable products has refocused attention on in vitro cell cultures as potential factories for phytochemical production. The advantage of producing plant metabolites in vitro has been in understanding the biology of their biosynthetic activity which ultimately can be enhanced by regulating physical, chemical, nutritional and genetic parameters. Medicinal compounds localized in morphologically specialized tissues or organs of native plants have been produced in culture systems not only by inducing specific organized cultures but also by undifferentiated callus/cell cultures.

The advances in plant cell culture technologies has made possible the production of a wide variety of pharmaceuticals like alkaloids, terpenoids, steroids, saponins, phenolics, flavonoids, and amino acids. The production of plant metabolites through cell cultures offer several advantages such as it makes possible to select genotypes with higher production of secondary metabolites, which can be generated on a continuous year round basis under controlled environment. Plant cell cultures eliminate potential political boundaries or geographic barriers which are otherwise to the production of a crop, such as the restriction of natural rubber production to the tropics or anthocyanin pigment production to climates with high light intensity. Many cost effective parameters have been tried for their economic production at large scale or by possible use of plant cell cultures for biotransformation of natural compounds [3].

## **3. Production of phytochemicals through cell culture technologies**

#### **3.1 Callus/cell suspension**

Callus/cell suspension cultures have been the prime focus of various studies aimed at the production of phytochemicals of not only medicinal value but also of other industrially important metabolites. Callus is a proliferating mass

*Production of Medicinal Compounds from Endangered and Commercially Important Medicinal… DOI: http://dx.doi.org/10.5772/intechopen.90742*

of undifferentiated cells, which can be established from different explants of a plant species under in vitro conditions on suitable nutrient media. Once the callus is derived from high metabolite producing explants, their suspension cultures can be established by transferring those calli into liquid media under continuous agitation. Zenk [4] successfully established cell lines of different plants capable of producing high yields of secondary compounds in cell suspension cultures. The production of solasodine from calli of *Solanum elaeagnifolium* and cephaeline and emetine from callus cultures of *Cephaelis ipecacuanha* were successfully achieved [5]. Some of the notable cell culture methods which have been employed for large scale production of metabolites are production of taxol from cell suspension cultures of *Taxus mairei* [6]; production of paclitaxel and its related taxanes from different Taxus species; production of berberine through cell suspension culture of *Coptis japonica*; production of vincristine and vinblastine from *Catharanthus roseus* [7, 8], and production of taxoids from cell suspension cultures of *Taxus cuspidate* [9] (**Table 1**).
