Catharanthine from Catharanthus roseus

Within the natural products field, the investigation of complete biosynthetic pathways at the enzyme level has been especially successful for plant alkaloids of the monoterpenoid indole alkaloid family generated from the monoterpene gluco-side secologanin and decarboxylation product of tryptophan, tryptamine [3-5]. The most comprehensive enzymatic data are now available for the alkaloids ajmalicine (raubasine) from Catharanthus roseus, and for ajmaline from Indian Rauvolfia serpentina [6] the latter alkaloid with a six-membered ring system bearing nine chiral carbon atoms. Entymatic data exsist also for vindoline, the vincaleucoblastin (VLB) precursor for which some studies on enzymatic coupling of vindoline and catharanthine exist in order to get the so-called dimeric Catharanthus indole-alkaloids VLB or vincristine [7-9] with pronounced anti-cancer activity [10, 11]. 

Extensive studies to quantitate the production of indole alkaloids in Catharanthus roseus hairy root cultures have revealed that they accumulate several compounds including ajmalicine, serpentine, catharanthine, tabersonine, horhammericine, and lochnericine.27, 28 The presence of tabersonine in hairy roots has raised speculations that this intermediate in vindoline biosynthesis, together with catharanthine, is transported from this potential site of biosynthesis through the vasculature to the stem and to the leaves where tabersonine is further elaborated into vindoline within laticifers and/or idioblasts.26 However, oxidized derivatives of tabersonine, such as horhammericine and lochnericine, are present at 5 to 15 times the levels of tabersonine in hairy roots,27 and presumably this prevents their transport and/or use for vindoline biosynthesis. In this context, it would be interesting to... 

Endo, T., Goodbody, A., Vukovic, J. and Misawa, M. (1986) Enzymes from Catharanthus roseus cell suspension cultures that couple vindoUne and catharanthine to form 3, 4 -anhydrovinblastine. Phytochemistry, 27,2147-9. 

If the C-15, C-16 bond is oxidatively cleaved, the secodine skeleton results (the proposed progenitor of the Aspidosperma and the iboga systems) through alternative Diels-Alder type cyclizations to afford tabersonine and catharanthine. The bisindole alkaloids of Catharanthus roseus reflect the union of vindoline and catharanthine to afford anhydrovinblastine modification affords the clinically significant alkaloids, vinblastine (VLB) and vincristine (VCR Fig. 39). The alkaloids, particularly VCR, are important as anticancer agents and have led to the development of the semisynthetic derivatives vindesine and vinorelbine (Fig. 40). Synthetic approaches are available to join the monomeric precursors. The enzymatically controlled sequence of reactions from tabersonine to vindoline has been elucidated. 

This reaction has been extensively studied in the case of the chlopromazine radical (R -mediated aminopyrine (S) oxidation [41], a typical reaction for xenobiotics, as well as in the case of the vindoline radical (R -mediated catharanthine (S) oxidation [42], a key reaction in the biosynthesis of the anticancer drugs, vinblastine and vincristine, which are obtained from Catharanthus roseus. 

Terpenoid Indole Alkaloids.—Crude preparations from Catharanthus roseus seedlings and from tissue cultures have been shown to be capable of synthesizing in good yield from tryptamine (110) and secologanin (111) with added co-factors, geisso-schizine (112) and ajmalicine (113), representatives of the first major class of terpenoid indole alkaloids (Corynanthe). Geissoschizine was metabolized to ajmalicine and several other unidentified alkaloids (for reviews of biosynthesis in intact plants see ref. 106). The catabolic turnover of vindoline and catharanthine in C. roseus has been studied. ... 

C46HjgN40 Mr 810.99, cryst., mp. 216°C, [alp +42 (CHCI3) a dimeric indole alkaloid from Catharanthus roseus (see Vinca alkaloids), composed of two parts vindoline and catharanthine with a 10,3 -linkage. V. is a cytostatically active trace alkaloid and is accompanied by demethylated, deformylated, and deacety-lated alkaloids. V. also occurs in other Catharanthus species such as C. ovalis. C. longifolius, C. trichophyl-lus. It is one of the most important monoterpenoid indole alkaloids. 

The products of cell culture of Catharanthus roseus are many and varied (Ellis, 1988) bisindole alkaloids and other products from cultures of this plant have been reviewed (Blasko and Cordell, 1990). Some lines fail to produce any of the alkaloids normally found in the whole plant. Ajmali-cine (7) and serpentine (8) (class 1 or Corynanthe-Xype alkaloids) often are the principal alkaloids produced in Catharanthus roseus tissue cultures (Blasko and Cordell, 1990 Ellis, 1988 Knobloch et al. 1982, Kurz et al. 1980). Taber-sonine (24) (a class 3 or Aspidosperma alkaloid) and catharanthine (10) (a class 5 or iboga alkaloid) have been found in relatively low yields in tissue cultures (DeLuca et al. 1986). Vindoline (9) (a class 3 or Aspidosperma alkaloid), a major alkaloid in Catharanthus roseus plant material, has never been found in plant tissue cultures. The pathways leading to vindoline appear to occur in the shoots of Catharanthus roseus plants, but are not known to occur in roots (DeLuca et al., 1986). 

Both vindoline (9) and catharanthine (10) are of great importance, as coupling of these two compounds (possibly via an iminium intermediate) leads to 3, 4 -anhydrovinblas-tine (57), a direct precursor to both vinblastine (57) and vincristine (56) (Fig. 34.15) (Blasko and Cordell, 1990 Stuart et al., 1978). Enzymes from cell-free systems of Catharanthus roseus have been demonstrated to carry out this coupling (Endo et al., 1988). The reaction also can be catalyzed by horseradish peroxidase (Goodbody et al, 1988) or... 

Lee CWT, Shuler ML (2000) The effect of inoculum density and conditioned medium on the production of ajmalicine and catharanthine from immobilized Catharanthus roseus cells. Biotechnol Bioeng 67 61-71. doi 10.1002/(SICI)1097-0290(20000105) 67 1 <61 AID-BIT7 >3.0.CO 2-J... 

When LEE is used, it is advisable to do either very quickly or from only a moderately alkaline aqueous solution, which was basified by sodium carbonate or ammonia. The Catharanthus alkaloids was prepared by LEE from the 75 % ethanol extract at pH 3.5, then adjusted the basic to pH 12 and finally extracted by chloroform [7]. Three major alkaloids, vinblastine and its monomeric precursors (vindoline and catharanthine), were monitored in transformed root cultures of Catharanthus roseus, after rapid sample preparation by LEE in our previous work [8]. The extraction method was the same as above. Other Catharanthus alkaloids, such as vindoline, catharanthine, and anhydrovinblastine, were prepared by LEE from the methanol extraction [9]. 

Ionic liquid-based ultrasound-assisted extraction (ILUAE) was successfully applied to the extraction of three alkaloids, vindoline, catharanthine, and vinblastine from Catharanthus roseus. Twelve ionic liquids, with different cations and anions were investigated in this work. In addition, ultrasound extraction parameters, including soak time, solid-liquid ratio, ultrasound power and time, and the number of extraction cycles, were optimized. ILUAE offered short extraction times (from 0.5 to 4 h) and remarkable efficiency. Therefore, the use of ionic hquids in the ultrasound-assisted extraction of key chemicals from medicinal plants shows great potential [12]. 

Fig. 34.3 Total ion chromatogram (a) and extracted ion chromatogram (b) of a standard mixture solution, and extracted ion chromatogram (c) of Catharanthus roseus extract by CE-MS. CE conditions capillary, 65 cm length and 50 pm i.d, buffer 20 mM s ammonium acetate aqueous with 1.5 % acetic acid, temperature room temperature, sample, 50 mbar for 5 s injection MS-conditions ESI positive, sheath gas 4 psi dry gas 6 L/min dry temperature 130 °C capillary voltage 3.5 kV sheath liquid methanol/water = 1/1, with 0.1 % acetic acid flow rate of sheath liquid 4 pL/min. Peak identification 1 vinblastine 2 catharanthine 3 vindoline (From Ref. 8)... 

Yang L, Wang H, Zu Y, Zhao C, Zhang L, Chen X, Zhang Z (2011) Ultrasound-assisted extraction of the three terpenoid indole alkaloids vindoline, catharanthine and vinblastine from Catharanthus roseus using ionic liquid aqueous solutions. Chem Eng J 172 705-712... 

Based on a biogenetic hypothesis, the dimerization of vindoline and catharanthine into vinblastine (extracted from Madagascar periwinkle, Catharanthus roseus) [ROB 98], a synthetic scheme was developed using a crucial biomimetic coupling for the development of the molecule as a drug... 

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