Cells, alkaloidal

The hybrid is able to produce more alkaloids than the basic callus, which is an undifferentiated mass of cells. Alkaloid production in cell cultures can be more successful with the immobihzation of plant cells and enzymes and by using bioreactor systems . Alkaloid produced in cell cultures can be isolated directly from this culture or from young plants grown from this culture. More than 250 alkaloids are reported to be produced by cell-culture techniques. Only a limited number of species have been researched in this respect. The species studied are known to produce alkaloids with special use in applications. The most researched alkaloids produced by cell cultures are mentioned in Table 25. 

Park and Cho [61] reported an extractive production system for benzo-phenanthridine alkaloids using cyclodextrins, in which production and some degree of separation occurred simultaneously. It was expected that the rapid removal of alkaloid produced from the suspension cultures was achieved by capturing alkaloid with cyclodextrins. In solid cultures of E. californica cells, alkaloid production was substantially enhanced (up to 40-fold) by the addition of /1-cyclodextrin. The enhancement of alkaloid production was also observed in suspension cultures, in which the major part of the alkaloids in the /J-cyclodex-trin treated cultures was present in the media, while the non-treated cultures contained the alkaloids in the cells. This indicated that /1-cyclodextrin not only captures the alkaloids but also helps in extracting them from cells. 

As we have discussed earlier that alkaloids are responsible for physiological effects in man or animals. The physiological effects are due to secondary metabolites arising from bio-chemical pathways operating in the plant cell. Alkaloids constitute the largest group of secondary chemical constituents. Basic structures of alkaloids are depicted below ... 

Ellipticine Arrest G2/M phase of the cell cycle, release of cyt-c and AIF, activation of caspases, A m dissipation, increase intracellular ROS levels, activation of ERK and JNK. RL95-2 human endometrial cancer cells Alkaloid isolated from Apocyanaceae plants with several anticancer mechanism reported topoisomerase II inhibition and formation of DNA adducts [131]. [94]... 

Haemanthamine and haemanthidine A P dissipation, cell cycle arrest with increased pl6 expression and Chkl Ser345 phosphoiylation Human leukemic Juikat cells Alkaloids isolated from plants of Amaryllidaceae family. Haemanthidine is more active that haemanthamine as apoptotic inductor. [134]... 

Lycopodine Increase of ROS levels, ATm dissipation, release of cyt-c, caspase-3 activation, chromatin condensation, inter-nucleosomal DNA fiagmentation HeLa cells Alkaloid isolated from plant Lycopodium clavatum [135]. [136]... 

Matrine A Pm dissipation, release of cyt-c, ratio Bcl-2/Bax protein decreased caspase-3 activation. Human multiple myeloma cells Alkaloid isolated from the traditional Chinese herb Sophora flavescens. [141]... 

Streptochlorin Up-regulation of pro-apoptotic Bax and FasL, A /n, dissipation, degradation PARP, caspase-3 activation. Human leukemic U937 cells. Alkaloid isolated from marine Streptomyces sp. with antiangiogenic activity reported. [147]... 

Tetrandiine Up-regulation of Bax, Bak, and Back and down-regulation of Bcl-2 and Bcl-xl, release of cyt-c and activation of caspase-3 and -9. Human gastric cancer BGC-823 cells Alkaloid isolated from the dried root of Hang-Fang-Chi (Stephania tetrandm) with apoptotic action in vitro a nd in vivo [149,150] [149]... 

The influences of herbicides on cell division fall into two classes, ie, dismption of the mitotic sequence and inhibition of mitotic entry from interphase (G, S, G2). If ceU-cycle analyses indicate increases in abnormal mitotic figures, combined with decreases in one or more of the normal mitotic stages, the effect is upon mitosis. Mitotic effects usually involve the microtubules of the spindle apparatus in the form of spindle depolymerization, blocked tubulin synthesis, or inhibited microtubule polymerization (163). Alkaloids such as colchicine [64-86-8J,viahla.stiae [865-21-4] and vincristine [57-22-7] dismpt microtubule function (164). Colchicine prevents microtubule formation and promotes disassembly of those already present. Vinblastine and vincristine also bind to free tubulin molecules, precipitating crystalline tubulin in the cytoplasm. The capacities of these dmgs to interfere with mitotic spindles, blocking cell division, makes them useful in cancer treatment. 

Experimental procedures have been described in which the desired reactions have been carried out either by whole microbial cells or by enzymes (1—3). These involve carbohydrates (qv) (4,5) steroids (qv), sterols, and bile acids (6—11) nonsteroid cycHc compounds (12) ahcycHc and alkane hydroxylations (13—16) alkaloids (7,17,18) various pharmaceuticals (qv) (19—21), including antibiotics (19—24) and miscellaneous natural products (25—27). Reviews of the microbial oxidation of aUphatic and aromatic hydrocarbons (qv) (28), monoterpenes (29,30), pesticides (qv) (31,32), lignin (qv) (33,34), flavors and fragrances (35), and other organic molecules (8,12,36,37) have been pubflshed (see Enzyp applications, industrial Enzyt s in organic synthesis Elavors AND spices). 

Chemotherapeutic agents are grouped by cytotoxic mechanism. The alkylating agents, such as cyclophosphamide [50-18-0] and melphalan [148-82-3] interfere with normal cellular activity by alkylation deoxyribonucleic acid (DNA). Antimetabohtes, interfering with complex metaboHc pathways in the cell, include methotrexate [59-05-2] 5-fluorouracil [51-21-8] and cytosine arabinoside hydrochloride [69-74-9]. Antibiotics such as bleomycin [11056-06-7] and doxombicin [23214-92-8] h.a.ve been used, as have the plant alkaloids vincristine [57-22-7] and vinblastine [865-21-4]. 

Biotransformations are carried out by either whole cells (microbial, plant, or animal) or by isolated enzymes. Both methods have advantages and disadvantages. In general, multistep transformations, such as hydroxylations of steroids, or the synthesis of amino acids, riboflavin, vitamins, and alkaloids that require the presence of several enzymes and cofactors are carried out by whole cells. Simple one- or two-step transformations, on the other hand, are usually carried out by isolated enzymes. Compared to fermentations, enzymatic reactions have a number of advantages including simple instmmentation reduced side reactions, easy control, and product isolation. 

The first step in this study has involved experiments which synthesize alkaloids in vitro under quasi-cellular conditions, using reactions which can proceed in the living cell and compounds which actually occur in the cell or which are supposed to be intermediates in the plant metabolism. Such synthesesaredesignatedassyntheses under physiological conditions. ... 

A characteristic of all the above reactions is that the yield of the aldoliza-tion product depends on the pH of the reaction mixture (324), the maximum yield usually occurring near pH 7. Such reactions have been carried out in vitro in dilute aqueous buffer under so-called physiological conditions, i.e., conditions attainable in the living cell. Although this oversimplified technique for the study of alkaloid biogenesis is now being abandoned in favor of experiments in vivo with labeled precursors, such reactions are still of interest to organic chemists. 

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