Plant enzymes are able to catalyse regio- and stereospecific reactions and can be applied to the production of pharmaceutically important compounds.This paper summarizes the results of such biotransformations in freely suspended cells.The factors affecting bioconversion capabilities of cells are also discussed.Special attention is paid to permeabilization and the problems of poorly water-soluble precursors.
Transformed roots in axenic culture would prove to be a good model for the study of the aspects of secondary metabolism. They are morphologically differentiated and have the advantage of high growth in the liquid standard media without growth regulators. Hairy root cultures can express root-specific pathways and have stable production of alkaloids, polyacetylenes, sesquiterpenes, naphthoquinones and other natural products. They can also convert xenobiotics into bioactive metabolites. Thus, new compounds not found in the parent plants could be obtained. Despite encouraging results, no commercial application of hairy root cultures for production of secondary metabolites have been developed, so far. A lot of further work is required to optimize bioreactor design for differentiated plant organ and to improve productivity of hairy roots.
Ammi visnaga (Umbelliferae) are subtropical annual plants, which contain two groups of pharmaceutically important substances: furanochromones and piranocoumarins. In order to check the possibility of the production of secondary metabolites, in vitro cultures of callus and cell suspension were established. The study was concentrated on the induction of production of secondary metabolites by exposing callus and cell suspension cultures to abiotic elicitors: acetylsalicylic acid, jasmonic acid and suspension of silicon dioxide and biotic elicitors: autoclaved lysates of Enterobacter sakazaki, and scleroglucan. Thin layer chromatography of methanol extracts of cultures of A. visnaga did not indicate high induction of secondary metabolites production. Treatment of the callus cultures of A. visnaga with acetylsalicylic acid or jasmonic acid induce accumulation of furanochromone - visnagin and piranocoumarin ? samidin. Exposing the callus and cell suspension cultures to the suspension of silicon dioxide indicated an induction of accumulation of furanochromone - kelolglucoside. Further research will concentrate on quantitative determination of the level of accumulated compounds.
Hemp (Cannabis sativa L.) is a species considered as having one of the most complicated mechanisms of sex determination. Peroxidase and esterase isoenzymes in leaves of the two sexual phenotypes of hemp were studied. Significant differences in isoperoxidase and isoesterase patterns were found between male and female plants, both in the number and stain intensity of bands. For both esterase and peroxidase, the isoenzymatic spectrum is richer for staminate plants. Also, some differences are obvious between the two sexes concerning catalase and peroxidase activities, as well as the level of soluble protein. The quantitative analysis of flavones, polyholozides and polyphenols emphasized differences depending not only on sex, but also on tested organ.
Biotechnology is one of science, technique and economic areas, which develops quickly and continuously. Important role in pharmaceutical sciences plays plant biotechnology which is advanced technology applying productive potential of alive cells in industrial processes, or serving for improvement of plants using genetic or epigenetic methods. It also gives many possibilities for obtaining new sources of secondary metabolites and opens up new areas in healthcare. Apart from many medicines produced by chemical synthesis, plant-derived natural substances are still of great importance in medicine. Such substances tend to have complicated chemical structures so that their chemical synthesis is uneconomic. Plant biotechnology offers an opportunity to exploit cells, tissues and organs or whole plants by growing them in vitro and to genetically manipulate them to obtain desired compounds. The development of new areas of molecular biology, for example functional genomic, gives a possibility of comprehensive investigations of biological systems. It could contribute to enhancing the production of known and novel secondary metabolites in plant cells. Moreover, an important branch of studies is the use of genetically modified plants to obtain edible vaccines in plants, antibodies, plant-derived recombinant proteins and biologically active substances.
Plant cell cultures in vitro produce secondary metabolites with varied effectiveness. Despite industrial application of only few cell suspension cultures, considerable progress in research on plant cell biotechnology has been made over the last few years. Transformed organ cultures, especially hairy roots, seem to be an interesting model for stable production of plant metabolites with high yield. In this paper, cultures of hairy roots of Salvia sclarea, S. officinalis, S. miltiorrhiza, S. przewalski, and Centaurium erythracea, as well as transformed shoots and plants of C. erythracea are presented. Also, production of secondary metabolites in these cultures is discussed.
The examples given in this presentation show that the levels of secondary metabolites can be modified by genetic engineering methods. In these methods, the specific genes encoding enzymes involved in key steps of biosynthetic pathway can be transferred and expressed in cell lines, hairy root cultures or transgenic plants of the same or another species. Overexpression of the enzymes may lead to the accumulation of intermediates of pathways and increased synthesis of desirable products. Best results will be obtained when the overproduced enzyme activity is clearly the rate-limiting step in the pathway. Therefore, better knowledge of the limiting steps of the pathways is required. The successful of biosynthetic pathways regulation may also be achieved by expressing antisense RNA which is complementary to the mRNA encoding pathway enzyme or by genetic manipulation of degradative pathways. It should be mentioned that genetic engineering also plays a role in the development of novel plant-derived drugs. As secondary metabolites are important in the defense of plants against pathogens, such engineered plants may show an increase in resistance against pathogens.
This paper reviews information from last decade world literature on the occurence in tissue cultures of some Lamiaceae species of secondary metabolites.The introductory part of paper gives information on the occurence of the biological active secondary metabolites in the native plant species from Lamiaceae family.
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