Alkaloid Metabolism Research Articles

Metabolism and Function of Alkaloids in Plants

Metabolism and Function of Alkaloids in Plants

Expression of Secondary Metabolism as Part of the Differentiation Processes During the Idiophase Development of Penicillium cyclopium Westling

Summary The development of emerged cultures of Penicillium cyclopium Westling on nutrient solution comprises three phases: the germination phase, a period of vigorous growth of the hyphae (trophophase), and a period of specialization (idiophase). The differentiation programs proceeding in the idiophase involve the formation of penicilli, the detachment and ripening of conidia, and the formation of enzymes catalyzing alkaloid biosynthesis. The beginning of the idiophase in emerged cultures is characterized by a decline of nucleic acid and protein synthesis to about 30–50% of the maximal value 48–72 hours after inoculation. In spite of pronounced differences with respect to the contents and rates of synthesis of proteins and nucleic acids under different nutrient conditions the time of triggering and the qualitative and quantitative relations between the individual features of idiophase development are barely influenced The most prominent morphogenetic feature at the beginning of the idiophase development is the specialization of the growth processes to the formation of penicilli and conidia. The penicilli contain a phenol oxidase, which presumably participates into the synthesis of the green pigment in the ripening conidia. The detachment of the conidia by unequal partition of the apical cells of the penicilli takes about two hours per conidium and involves as constitutive components the synthesis of saccharase and of the enzymes of cyncol biosynthesis. The ripening of the conidia is indicated by the formation of their pigment and by the synthesis of a peculiar enzyme of alkaloid metabolism, cyclopenase, which catalyzes the transformation of benzodiazepine to quinoline alkaloids and which is restricted to the conidia only.

Biosynthesis and metabolism of the hemlock alkaloids

Biosynthesis and metabolism of the hemlock alkaloids

Metabolism of pyrrolizidine alkaloids in the ovine rumen. IV. Effects of chloral hydrate and halogenated methanes on rumen methanogenesis and alkaloid metabolism in fistulated sheep

Five halogenated methane analogues (bromoform, chloroform, iodoform, carbon tetrabromide, and carbon tetrachloride) have been shown to inhibit methane formation in the sheep's rumen as well as in rumen fluid in vitvo. On a molar basis the methane analogues were 100-200 times as effective as chloral hydrate in vitro, but in the rumen this difference was reduced by a factor of 10 with four of the compounds and to parity with chloral hydrate in the case of carbon tetrachloride. When rumen methanogenesis was inhibited by administration of chloral hydrate, bromoform, or iodoform, the time taken for metabolism of 2 g of Heliotropium europaeum alkaloids was reduced to 25-40% of that taken in animals not so treated. These results support the conclusion that inhibition of methanogenesis may be a useful protective measure for sheep ingesting plants which contain hepatotoxic pyrrolizidine alkaloids.

Metabolism of pyrrolizidine alkaloids in the ovine rumen. III. The competitive relationship between Heliotrine metabolism and methanogenesis in the rumen fluid in vitro

Inclusion of up to 80% hydrogen in the gas phase markedly stimulated the in vitro metabolism of heliotrine in sheep rumen fluid. The maximal rate of heliotrine breakdown under these conditions was twice that obtained when cyanocobalamin was added and 10 times the rate in unsupplemented rumen fluid. A maximal rate of heliotrine metabolism equal to that in the presence of 80% hydrogen gas could be obtained with a pure carbon dioxide atmosphere if certain inhibitors of methanogenic bacteria were added to the rumen fluid. It is concluded that the heliotrine-metabolizing bacteria are normally at a disadvantage in competition with the methanogenic bacteria for metabolic hydrogen, and that inhibition of the latter organisms in vivo could provide a basis for development of effective prophylaxis in sheep at risk with Heliotropium europaeum in the field.

Alkaloid biosynthesis and metabolism in an organelle fraction in Papaver somniferum

The pellet produced by centrifuging suitably diluted latex at 1000–3000 g has been shown capable of synthesizing morphine from dihydroxyphenylalanine in vitro and preliminary studies indicate that a lutoid-like organelle is involved in this synthesis. Evidence is also produced to show that the further metabolism of morphine (described earlier 1 1 J.W. Fairbairn and S. El Masry, Phytochem. 6, 499 (1967). ) takes place in the stem latex and its 3000 g fraction rather than in the capsule latex.

Metabolism of pyrrolizidine alkaloids in the ovine rumen. I. Formation of 7-α-hydroxy-1-α-methyl-8-α pyrrolizidine from heliotrine and lasiocarpine

In vitro studies have demonstrated that the rate of metabolism of pyrrolizidine alkaloids in sheep's rumen fluid varies greatly. Fluids from sheep at pasture display much higher activity than do those from chaff-fed animals. Addition of dried Heliotropium europaeum to a chaff ration leads to a marked increase in the in vitro rate of alkaloid degradation by the rumen fluid but activity rapidly declines again when the H. europaeum is withdrawn. Thus a major factor limiting multiplication in the rumen of bacteria responsible for alkaloid breakdown appears to be lack of their specific substrates. N-oxides of pyrrolizidine alkaloids are rapidly reduced to tertiary bases in rumen fluid, even in samples from sheep not previously exposed to these substrates. The stimulation of the alkaloid-metabolizing system by vitamin B12 also varies greatly, both in whole rumen fluid and in fluids with activity reduced by removal of coarsely particulate matter. It is concluded that the B12 effect is not related to a specific requirement of the alkaloid-utilizing bacteria but to stimulation of other species which produce a metabolite essential for pyrrolizidine alkaloid metabolism.

1887. Metabolism of betel nut alkaloids: Boyland, E. & Nery, R. (1969). Mercapturic acid formation during the metabolism of arecoline and arecaidine in the rat. Biochem. J.113, 123

1887. Metabolism of betel nut alkaloids: Boyland, E. & Nery, R. (1969). Mercapturic acid formation during the metabolism of arecoline and arecaidine in the rat. Biochem. J.113, 123

Metabolism of pyrrolizidine alkaloids in the ovine rumen. II. Some factors affecting rate of alkaloid breakdown by rumen fluid in vitro

When the pyrrolizidine alkaloids heliotrine and lasiocarpine were incubated in vitro with sheep's rumen contents, a common metabolic product was formed. This compound was also found as an end-product of metabolism in the rumen contents of sheep fed on a ration containing the plant Heliotropium europaeum. Previously described rumen metabolites of the Heliotropium alkaloids were 1-methylenepyrrolizidine derivatives, e.g. l-goreensine. The newly found product represents a further stage of reduction of l-goreensine in which the 1-methylene group has been replaced by a 1-methyl group. This compound has been identified as 7�-hydroxyla- methyl-8�-pyrrolizidine, a previously unknown pyrrolizidine derivative.

Cobalt pellets and Heliotropium europaeum poisoning in penned sheep.

SummaryTwenty‐five sheep in single pens were fed for up to 16 months a ration containing up to 40% (air dry weight basis) of Heliotropium europaeum.Thirteen of these sheep had two cobalt pellets administered into their rumen before commencement of feeding. The other twelve sheep constituted the control group and were not treated in any way.The sheep in both groups developed the characteristic live pathology of chronic pyrrolizidine alkaloidosis to varying degrees.The median chronic lethal oral dose of Heliotropium europaeum alkaloids for sheep was found to be 23–33 g/kg body weight, expressed as heliotrine equivalent. This is 15–20 times the established mean total lethal parenteral dose of heliotrine when chronically administered to rats.Prior administration of cobalt pellets did not reduce morbidity or mortality rate. Thus it is concluded that cobalt pellets are unlikely to be an effective prophylactic agent for sheep exposed to H. europaeum grazing.This finding is discussed in relation to present knowledge of pyrrolizidine alkaloid metabolism in the rumen.

The Biochemistry of Alkaloids.

Historical Introduction Methods in Biosynthetical Research The Biochemical Genetics of Alkaloids Regulation of Alkaloid Metabolism Compartmentation and Channelling in Alkaloid Biosynthesis Storage of Alkaloids The Ecological Significance of Alkaloids Metabolism of Amino Acids Related to Alkaloid Biosynthesis Basic Principles of Alkaloid Biosynthesis Alkaloids Derived from Ornithine Lysine-derived Alkaloids Alkaloids Derived from Nicotinic Acid Alkaloids Derived from Tyrosine and Phenylalanine Alkaloids Derived from Tryptophan Alkaloids Derived from Anthranilic Acid Alkaloids Derived from Purines Alkaloids Formed from Histidine Isoprenoid Alkaloids.

Examination of the metabolism of tropane alkaloids. X. Activity of enzymes splitting nortropacocaine in mouse organs during development

Examination of the metabolism of tropane alkaloids. X. Activity of enzymes splitting nortropacocaine in mouse organs during development

Metabolism of xanthine alkaloids in man

Metabolism of xanthine alkaloids in man

Biosynthesis and Metabolism of Some Radioactive Veratrum viride Alkaloids

Biosynthesis and Metabolism of Some Radioactive Veratrum viride Alkaloids

A Polarographic Study of Some Veratrum Viride Alkaloids

The results of a study of the polarographic behavior of jervine, veratramine, and veratrosine dissolved in a mixture of alcohol and a suitable buffer solution are reported. The method described was designed for later application to a study of the metabolism of the Veratrum viride alkaloids, but it demonstrates that polarographic analysis may be utilized satisfactorily in alkaloidal determination if the pure alkaloids are present in uncontaminated solutions. The Veratrum viride alkaloids investigated yielded characteristic reduction waves in at least two stages in the pH range studied.

Alkaloidbildung in der Pflanzenwurzel

Graftings between alkaloid-producing and non-alkaloid plants of theSolanaceae family have indicated the importance of the root and other subterraneous plant organs for the formation of alkaloids. If, for example, black nightshade(Solanum nigrum) is grafted on tobacco(Nicotiana Tabacum), the otherwise non-nicotinous scions ofSolanum nigrum contain considerable quantities of nicotine. If on the other hand the black nightshade is used as stock and the tobacco as scion, the nicotine completely disappears from the graftings. Similar results have been obtained from experiments with tomatoes(Solanum Lycopersicum) on one hand and thorn-apples(Datura Stramonium) and deadly nightshades(Atropa Belladonna) on the other. Morphological and histochemical investigations have likewise drawn attention to the subterraneous plant organs as centres of alkaloid formation. In this way hordenine is formed and stored only in the roots ofHordeum murinum, and berberine is to be found almost exclusively in the roots ofMahonia Aquifolium. Graftings which are carried out withNicotiana Tabacum, which contains nicotine, and withNicotiana glauca, which contains anabasine, have demonstrated the pronounced reciprocal influence of the alkaloid metabolism of scion and stock. These results are, however, not so conclusive as those obtained from graftings of non-alkaloid and alkaloid-producing scions or stocks. Nevertheless the following conclusions can be drawn from these investigations: A final decision whether the plants in question form the corresponding alkaloids or their precursors, or indeed both, in their subterraneous organs, can at present not yet be given. The investigation of these questions will also clarify in each individual case the migration of these alkaloids. Further experiments are here required, as it appears that the various plants react differently in this respect on being grafted. Perhaps it will be possible to throw light on this question by means of other methods.