Medicinal plants transformation

However, one might take the time to think back and to ask if the extensive use of such techniques might not have failed to characterize important lead compounds from plants, and especially medicinal plants. As a matter of fact, a molecule inactive in vitro might, after metabolic transformation in vivo, be effective in abrogating metastasis. The opposite is true, and promising in vitro results have often led to disappointing clinical trials. 

Zagari, A. Medicinal plants. Vol 4, 5th ed., Tehran University Publications, No 1810/4, Tehran, Iran 1992 969 pp. Stalay, A. E. Starch granulation. Patent-Neth Appl-73 10,688 1975. Savchenko, G. E. Effect of chloramphenicol on the accumulation and transformation of protochlorophyll in barley leaves. Biol Nauch-Tekhn Progress 1974 60. 

TISSUE CULTURE OF MEDICINAL PLANTS MICROPROPAGATION, TRANSFORMATION AND PRODUCTION OF USEFUL SECONDARY... 

In the next chapter, micropropagation, production of useful secondary metabolites by in vitro culture and transformation of medicinal plants by Agrobacterium for alternative sources of pharmaceuticals are described with special reference to ipecac plants. 

In this section, transformation of some medicinal plants with A. rhizogenes and production of useful secondary metabolites by transformed root cultures are described. In addition, production of transgenic plants is discussed. 

Kala, C.P. (2004). Revitalization traditional herbal therapy by exploring medicinal plants A case study of Uttaranchal state in India. In Indigenous Knowledge Transforming the Academy, pp. 15-21. Proceedings of an International Conference, Pennsylvania State University, Pennsylvania, USA. 

Quercetin, a flavonoid component of St. John s wort and several other medicinal plants, has been implicated as a mutagen. However, St. John s Wort aqueous ethanolic extract showed no mutagenic effects in mammalian cells. Tests used included the HGPRT (hypoxanthine guanidine phosphoribosyl transferase) test, the UDS (unscheduled DNA synthesis) test, the cell transformation test uring Syrian hamster embryo cells, the mouse fur spot test, and the chromosome aberration test using Chinese hamster bone marrow cells (Okpanyi et al., 1990). 

For centuries, mankind has searched for the cure of illnesses in herbs. In that sense, approximately one third of drugs actually in use are from plant origin [1]. In the last decades, however, most of the drugs incorporated to the therapeutic arsenal come from synthetic sources. Nevertheless, in recent years a remarkable interest in the study of medicinal plants has appeared, mainly due to the concern about the destruction of rain forest habitats, with the risk of extinction of numerous species. Another fact is the loss of the knowledge related to the use of plant remedies by the people from native settlements, that is very common when they are incorporated to the urban life, and/or when their environmental conditions are seriously transformed. 

After their discovery, the Vinca alkaloids became the first natural anticancer agents to be clinically used, and they are still an indispensable part of most curative regimens used in cancer chemotherapy nowadays. On the other hand, the plant producing these alkaloids, C. roseus, has become one of the most extensively studied medicinal plants. The levels of vincristine and vinblastine in the plant revealed to be extremely low and, for pharmaceutical production, approximately half a ton of dry leaves is needed to obtain 1 g of vinblastine [4]. This feet stimulated intense investigation in alternative methods for the production of vinblastine and vincristine, namely chemical synthesis and plant cell cultures. However, chemical synthesis showed not to be viable due to the high number of transformations involved, and the anticancer alkaloids were never detected in cell cultures, which express alkaloid metabolism very poorly [5, 6]. The biosynthetic pathway of terpenoid indole alkaloids in C. roseus has also been intensively studied with the objective of developing a manipulation strategy to improve the levels of the anticancer alkaloids in the leaves of the plant [5, 7-10]. 

In the early 90 s, a clinical trial on Feibao syrup , which contains H. diffusa together with Radix astragali and other medicinal plant extracts, was reported. In this study, Feibao syrup was used to treat reversal respiratory tract infection in children. The clinical research proved that after taking the medicine, the general condition was improved and if the disease occurred, the symptoms were mild and the disease course was short. The efficacy of the medicine was 92.5%. Furthermore, experiment on mice indicated that the medicine could enhance the macrophage phagocytic activity and lymphocyte transformation rate [41]. 

Increasing the concentration of the alkaloid scopolamine in medicinal plants has been the target of much research. First results were obtained in the late 1980s when somatic hybridization was used to increase the content in Datura species, and the transformation of Atropa belladonna with the enzyme hyoscyamine-6-beta-hydroxylase lead to a shift from hyoscyamine to a nearly exclusive production of scopolamine (Figure 2.7) [60]. 

Gene silencing requires that the plant be amenable to efficient transformation. Since a number of medicinal plants cannot be stably transformed by either Agrobacterium or particle bombardment technology, this strategy is unfortunately not universally apphcable to the elucidation of all biosynthetic pathways of natural products. Additionally, suppression of a large number of genes requires a selection or screen that can rapidly assess the natural product profiles of the transformed cell lines. 

Rajesh, M., Jeyaraj, M., Sivanandhan, G., Subramanyam, K. et al. (2013) Agrobacterium-mediated transformation of the medicinal plant Podophyllum hexandrum Royle (syn. 

U. tomentosa is a significant traditional medicinal plant that is an important source of monoterpenoid oxindole alkaloids (MOAs) with bioactivities including immunomodulatory, cytotoxic, anti-HIV, and antileukemic activities [100]. It will be of interest to understand biosynthetic insights of bioactive compounds of this plant as an example here. Studies have reported the regulation of biosynthesis of sterols and triterpenes in U. tomentosa [100]. Administration of pectin to U. tomentosa cell suspension cultures increased the activity of isopentyl diphosphate isomerase of ursolic and oleanolic acid. The treated cells also transformed a higher percentage of labeled mevalonic acid precursors into triterpenes and resulted in the decrease in activity of far-nesyl diphosphatase by a factor of two when compared to the control. The... 

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