Biosynthesis of cyanidin in cell cultures of Haplopappus gracilis

-Dihydroquercetin proved to be a good precursor for light-stimulated cyanidin biosynthesis in cell suspension cultures of Haplopappus gracilis. Wit     

Biosynthesis of cardenolides in Digitalis lanata

[8-³H]-Cholesterol was synthesized. A doubly labelled sample of [8-³H, 4-¹⁴C]-cholesterol was administered to Digitalis lanata plants and the cardenolides were isolated. Biosynthesized digitoxigenin and digoxigenin retained all the tritium. Barring the migration of the tritium in biosynthesis the results are interpreted as indicative that neither intermediates with δ7, δ⁷ or δ⁸⁸⁽¹⁴⁾ are participating in the elaboration of cardenolides.     

Biosynthesis of lathyrine in lathyrus tingitanus

Possible mechanisms in the biosynthesis of lathyrine are discussed. An in vitro system for the specffic 4-hydroxylation of diamino acids is reporte     

Biosynthesis of hydroxyphaseollin and related isoflavanoids in disease-resistant soybean hypocotyls

Phenylalanine-U-¹⁴C and isoliquiritigenin-9-¹⁴C were readily incorporated into the antifungal pterocarpan hydroxyphaseollin in soybean hypocotyls that were inoculated with incompatible strains of the phytopathogenic fungus Phytophthora megasperma var. sojae. Hydroxyphaseollin accounted for over half of the phenylalanine and isoliquiritigenin incorporated into ethyl acetate soluble compounds. Daidzein, coumestrol, and sojagol were identified as major compounds which accumulated coordinately with hydroxyphaseollin and contained significant amounts of radioactivity from the labelled isoflavanoid precursors. Hydroxyphaseollin was not present in healthy soybean plants and was not detected until ca. 16 hr after inoculation with the fungus. The pterocarpan then accumulated rapidly between 16 and 48 hr after inoculation, while the greatest accumulations of daidzein, coumestrol, and sojagol occurred between 48 and 72 hr after inoculation, when hydroxyphaseollin accumulation had ceased. Although soybean hypocotyls contained the anthocyanin malvin, neither this compound nor any other flavone pathway product was observed to accumulate after fungus-inoculation. The results therefore indicate that the accumulation of hydroxyphaseollin in fungus-inoculated soybean hypocotyls involves the activation of isoflavanoid biosynthesis with 'direction' of metabolic intermediates to biosynthesis of the pterocarpan.     

维生素B型氨基酸衍生维生素的生物合成及功能研究

氨基酸衍生维生素是以氨基酸为前体合成的维生素,主要为维生素B和E家族的维生素,其生物合成方式主要为氨基酸整合和转氨作用。氨基酸衍生维生素在大多数真核生物中主要是作为辅被用物和辅因子,缺乏某些维生素会使动植物患病。本文主要对氨基酸衍生维生素中的维生素B家族的生物合成及功能进行综述,概述了氨基酸在B族维生素生物合成中的作用、不同物种中B族维生素的含量水平以及B族维生素的作用。     

Biosynthesis of limonoids in Citrus

Analyses of citrus leaves and fruits, and radioisotope tracer work showed that the leaves could synthesize limonoids and that the trees could translocate limonoids from leaves to the fruit. These results suggest that limonoids in citrus fruit tissues are synthesized in leaves and translocated to the fruit. No evidence was found to support the presence of limonoid biosynthetic systems in the fruit tissues.     

Biosynthesis of papaverine

Tracer experiments have shown that in Papaver somniferum papaverine arises from (−)-norreticuline via norlaudanidine and norlaudanosine.     

Biosynthesis of meteloidine

Tropine-3β-³H, N-methyl-¹⁴C was fed to Datura meteloides plants. After 7 days radioactive meteloidine, scopolamine, hyoscyamine, and 7β-hydroxy-3α,6β-ditigloyloxytropane were isolated from the plants and found to have essentially the same ³H/¹⁴C ratio as in the administered tropine. Degradation of the meteloidine established that all its tritium was located at C-3 and all the ¹⁴C was on the N-methyl group, indicating that tropine is a direct precursor of teloidine.     

Biosynthesis of piperlongumine

The incorporation of l-[U-¹⁴C]lysine and l-[U-¹⁴C]phenylalanine into piperlongumine has been demonstrated in Piper longum. The subsequent stepwise degradation to methyl-(3,4,5-trimethoxyphenyl)-propanoate and δ-aminovaleric acid revealed that the C₆-C₃ moiety of the alkamide arises from phenylalanine; the heterocyclic ring is biosynthesised from lysine. It has also been shown that dl-[2-¹⁴C]tyrosine and [2-¹⁴C]sodium acetate are poor precursors of piperlongumine.     

Biosynthesis of the phytoalexin wyerone in Vicia faba

In contrast to earlier results [1-¹⁴C] acetate, [2-¹⁴C] malonate and [n 9,10-³H] oleate show significant incorporations into wyerone and related Vicia faba phytoalexins, following infection by Botrytis cinerea.     

Biosynthesis of amaranthin in Celosia plumosa

Seedlings of a yellow betaxanthin-producing variety of Celosia plumosa when fed with appropriate precursors are capable of synthesizing the red-violet pigment normally present in red varieties of the same species, namely amaranthin. Synthesis of amaranthin occurs in seedlings following administration of betanidin and betanin but much greater accumulation was observed after feeding cycloDOPA and its 5-O-β-d-glucoside. Possible pathways in the biosynthesis of amaranthin are discussed.     

Biosynthesis of Se-Methylselenocysteine in lima beans

It has been shown that maturing seeds of lima beans synthesize Se-methylselenocysteine, the selenium analogue of S-methyleysteine. The latter amino acid is a natural constituent of these seeds. The leaves of lima beans do not contain detectable amounts of S-methylcysteine, and in this tissue Se-methionine appears to be the principal product of selenate assimilation.     

Biosynthesis of gramine in Phalaris arundinacea

The administration of L-tryptophan-[3-¹⁴C] to Phalaris arundinacea L. (Vantage strain) for 9 days resulted in the formation of radioactive gramine (8.2% absolute incorporation). A systematic degradation of the alkaloid indicated that essentially all its activity was located on the methylene group, indicating that its biosynthesis is the same as that occurring in Hordeum species and Lupinus hartwegii.     

Biosynthesis of 3-methoxycarbonylpropylglucosinolate in an Erysimum species

Incorporation of DL-2-aminohexanedioic acid, DL-2-amino-5-methoxycarbonyl-pentanoic acid and DL-methionine into 3-methoxycarbonylpropylglucosinolate have been demonstrated using an Erystmum species. The data support the following sequence of biosynthetic reactions: 2-aminohexanedioic acid is methylated by methionine; the resulting 2-amino-5-methoxycarbonyl-pentanoic acid is then converted into the glucosinolate. 2-Amino-5-methoxycarbonyl-pentanoic acid has been tentatively identified as a natural product in the plant.     

Biosynthesis of cannabinoid acids

Malonic acid, mevalonic acid, geraniol and nerol were incorporated into tetrahydrocannabinolic acid and cannabichromenic acid in Cannabis sativa. The pathway from cannabigerolic acid to tetrahydrocannabinolic acid via cannabidiolic acid was established by feeding labelled cannabinoid acids. Cannabichromenic acid was shown to be formed on a side pathway from cannabigerolic acid.     

Biosynthesis of triterpenoid sapogenols in soybean and alfalfa seedlings

By incubation of germinating soybeans with mevalonate-[2-¹⁴C] (MVA), radioactivity was incorporated into four sapogenols which were identified by TLC. Unequivocal evidence for the identity of three of the four sapogenols was provided by co-crystallization to constant specific radioactivity. The partition of incorporated radioactivity into lipid- and water-soluble fractions and the pattern of radioactivity of individual sapogenols varied with the mode of administering labeled substrates to soybean seedlings, such as incubation of germinating soybeans with MVA-[2-¹⁴C], immersion of roots into MVA-[2-¹⁴C] or foliar application of squalene-[¹⁴C]. When alfalfa seedlings were incubated with MVA-[2-¹⁴C], about two-thirds of the radioactivity incorporated into the sapogenols was associated with medicagenic acid.     

Biosynthesis of carvone in Mentha spicata

Degradation of, and measurement of isotope ratios in, (?)-carvone that had been biosynthesized in Mentha spicata from ³H- and ¹⁴C-labelled geraniol and mevalonate indicate that (a) oxidation of limonene or its biogenetic equivalent to form carvone involves shift of the endocyclic double bond; (b) (+)-limonene and (?)-carvone are biogenetically related and are probably formed on divergent pathways from a common intermediate; and (c) the exocyclic double bond of carvone is not formed regiospecifically. These results enable the mechanisms for the introduction of the carbonyl group and for the formation of the isopropenyl side-chain to be delimited.     

Biosynthesis of auxin-induced ethylene in mung bean hypocotyls

The pathway of ethylene biosynthesis in auxin-treated mung beanhypocotyls was investigated by comparing the specific radioactivitiesof ethylene produced and S-adenosylmethionine (SAM) in the tissuefollowing the administration of 3,4-¹⁴C-methionine, and by analyzingthe methionine metabolites. When the rate of auxin-induced ethyleneproduction was low due to a low concentration of auxin, thespecific radioactivity of ethylene released was always higherthan that of SAM in the tissue. When the tissue was treatedwith auxin, the tissue produced and accumulated a methioninemetabolite which was converted into ethylene more efficientlythan methionine. The metabolite was identified as 1-aminocyclopropane-l-carboxylicacid (ACC) by means of paper and thin-layer chromatography,high voltage paper electrophoresis and co-crystallization. ACCformation was neither inhibited by low oxygen nor by the inhibitoryprotein of ethylene synthesis, but inhibited by aminoethoxyvinylglycine(AVG). ACC application to the tissue greatly reduced incorporationof 3,4-¹⁴C-methionine into ethylene. The control tissue thatwas not treated with auxin also converted ACC into ethyleneindicating that the enzyme which converts ACC into ethyleneis already present in the tissue and that auxin induced productionof the enzymatic system responsible for the conversion of methionineinto ACC. Ethylene synthesis from ACC was not inhibited by AVG,abscisic acid, cycloheximide or actinomycin D, but inhibitedby low oxygen and the inhibitory protein. (Received November 21, 1979; )     

Biosynthesis of ditigloyl esters of DI- and tri-hydroxytropanes in Datura

3α-Tigloyloxytropane-[¹⁴CO] [N-¹⁴Me], ratio 1·6:1 and valtropine-[¹⁴CO] [N-¹⁴Me], ratio 1·75:1 were separately fed via cotton wicks to 4-month-old Datura innoxia plants. After 8 days the root alkaloids 3α-tigloyloxytropane, 3α,6β-ditigloyloxytropane and 3α,6β-ditigloyloxytropan-7β-ol were isolated and the distribution of radioactivity in the acid and alkamine moieties was determined by hydrolysis. The precursor ratios were not maintained in the isolated ditigloyl esters, a result which does not support our hypothesis that the ditigloyl esters are formed by the progressive hydroxylation of 3α-tigloyloxytropane.     

Biosynthesis of shikonin in callus cultures of Lithospermum erythrorhizon

Administration of various supposed precursors to the callus cultures of Lithospermum erythrorhizon grown on the Linsmaier—Skoog medium supplemented with IAA and kinetin established that the constituent shikonin is formed via shikimic acid, p-hydroxybenzoic acid, m-geranyl-p-hydroxybenzoic acid and geranylhydroquinone. In a strain of callus culture lacking the capacity to synthesize shikonin and in callus cultures which have had this capacity but lost it due to cultivation on a medium supplemented with 2,4-D, substances up to m-geranyl-p-hydroxybenzoic acid in the biosynthetic sequence have been detected. Although illumination with white light also arrested shikonin production, traces of pigment were still formed presumably because light did not reach the innermost part of the callus cultures.