Showing papers on "Indole alkaloid published in 2000"

Indole alkaloid biosynthesis in Catharanthus roseus: new enzyme activities and identification of cytochrome P450 CYP72A1 as secologanin synthase.

Abstract: Summary The molecular characterization of CYP72A1 from Catharanthus roseus (Madagascar periwinkle) was described nearly a decade ago, but the enzyme function remained unknown. We now show by in situ hybridization and immunohistochemistry that the expression in immature leaves is epidermis-specific. It thus follows the pattern previously established for early enzymes in the pathway to indole alkaloids, suggesting that CYP72A1 may be involved in their biosynthesis. The early reactions in that pathway, i.e. from geraniol to strictosidine, contain several candidates for P450 activities. We investigated in this work two reactions, the conversion of 7-deoxyloganin to loganin (deoxyloganin 7-hydroxylase, DL7H) and the oxidative ring cleavage converting loganin into secologanin (secologanin synthase, SLS). The action of DL7H has not been demonstrated in vitro previously, and SLS has only recently been identified as P450 activity in one other plant. We show for the first time that both enzyme activities are present in microsomes from C. roseus cell cultures. We then tested whether CYP72A1 expressed in E. coli as a translational fusion with the C. roseus P450 reductase (P450Red) has one or both of these activities. The results show that CYP72A1 converts loganin into secologanin.

Promotion of indole alkaloid production in Catharanthus roseus cell cultures by rare earth elements

Abstract: Production of the indole alkaloids, ajmalicine or catharanthine, in cell suspension cultures of Catharanthus roseus was enhanced by cerium (CeO2 and CeCl3), yttrium (Y2O3) and neodymium (NdCl3). The yield of ajmalicine in these treated-cultures reached 51 mg l−1 (CeO2), 40 mg l−1 (CeCl3), 41 mg l−1 (Y2O3) and 49 mg l−1 (NdCl3) while catharanthine production reached to 36 mg l−1 (CeO2) and 31 mg l−1 (CeCl3). A major portion of increased alkaloids was released into medium in these treatments. But Sm2O3, SmCl3, La2O3, LaCl3, complex of chromium (III)-titanium (IV) and NaSeO4 treatments had little effect on alkaloid production of C. roseus cell cultures.

A new gluco indole alkaloid, 3, 4-dehydro-5-carboxystrictosidine, from Peruvian Uña de Gato (Uncaria tomentosa).

Abstract: A new gluco indole alkaloid, 3, 4-dehydro-5-carboxystrictosidine, was obtained from Peruvian Una de Gato(Cat's Claw, original plant : Uncaria tomentosa) together with two known gluco indole alkaloids. This compound was the first example of isolation of a gluco monoterpenoid indole alkaloid having a 3, 4-dihydro-β-carboline ring system from nature. A characteristc feature of the compound was the quick replacement of the methylene hydrogens on C-14 with deuterium that was observed when it was dissolved in CD3OD. We demonstrated a similar proton-deuterium exchange on a model compound, 1-methyl-3, 4-dihydro-β-carboline, in CD3OD solution.

Chemical studies on the analgesic indole alkaloids from the traditional medicine (Mitragyna speciosa) used for opium substitute

Abstract: The leaves of a tropical plant, Mitragyna speciosa Korth. (Rubiaceae), have been traditionally used as a substitute for opium. By phytochemical studies on the constituents of the plant growing in Thailand as well as in Malaysia, several 9-methoxy-Corynanthe-type monoterpenoid indole alkaloids including new natural products were isolated. The structures of these new compounds were elucidated by the modern spectroscopic methods and/or chiral-total syntheses. The chiral total synthesis of (-)-mitragynine, a major component of this plant, was achieved. Potent opioid agonistic properties of mitragynine, which acts on mu- and delta-opioid subtype receptors, and of mitragynine pseudoindoxyl, whose analgesic activity is more potent than that of morphine, were clarified in in vitro experiments. The essential structural features in mitragynine for revealing the analgesic activity were elucidated by pharmacological evaluation of the natural and synthetic mitragynine derivatives.

Metabolic Engineering of Crops with the Tryptophan Decarboxylase of Catharanthus Roseus

Abstract: A wide variety of plant families produce aromatic and indole amines via the decarboxylation of their respective amino acids. These reactions which are catalyzed by aromatic amino acid decarboxylases are commonly the first steps in the biosynthesis of many thousands of different plant alkaloids, which have a number of important physiological effects. In order to create crops that make useful alkaloids, genetic engineering methods for the production and accumulation of aromatic and indole amines need to be developed. This report describes the results of several transformation experiments to express the tryptophan decarboxylase gene in different species of plants.