The distribution of Rhododendrin in birch (Betula) species

Rhododendrin (as rhododendrol) was identified in hydrolyzed bark of 14 species of birch. Betula, representing all taxonomic categories in the genus. Only B. lenta and B. nigra of Subsection Costatae lacked this compound.     

Fatty acid composition of roots and root nodules of Alnus species

Fatty acid composition of roots and root nodules from Alnus species is reported. Differences in total lipid content and in fatty acid composition w     

Stereochemistry of 2-aminopimelic acid and related amino acids in three species of asplenium

We previously reported two free D-amino acids, D-2-aminopimelic acid (D-APA) and trans-3,4-dehydro-D-2-aminopimelic acid (D-Δ-APA), from Asplenium unilaterale. In the present work we isolated 4-hydroxy-2-aminopimelic acid (OH-APA) from the same plant and determined it to be the α-L-form. We also investigated the configurations of these amino acids isolated from A. prolongatum and A. wilfordii which are morphologically distinct from A. unilaterale. In A. prolongatum, APA was the D- and OH-APA was the L-isomer. In contrast, APA from A. wilfordii was partially racemized and the degree of racemization was significantly different in plant material collected in July and November, L:D = 3:2 and 3:7, respectively. In A. wilfordii OH-APA was almost pure L- and Δ-APA was mostly the D-isomer.     

C31,-secodammarane-type triterpenoid saponins from the male flowers of Alnus pendula

Six C₃₁-secodammarane-type triterpenoid saponins, in addition to alnustic acid, were isolated from the male flowers of Alnus pendula. Two of these saponins were new and were shown to be the 12-O-(2′-O-acetyl)-β-d-xylopyranoside and the 12-O-(2′-O-acetyl)-β-d-glucopyranoside of alnustic acid, respectively, on the basis of their physico-chemical data.     

The biosynthesis of flavonoid pigments: On the incorporation of phloroglucinol and phloroglucinyl cinnamate into rutin in Fagopyrum esculentum

The problem of whether phloroglucinol is a direct biosynthetic precursor of flavonoids was reinvestigated. Phloroglucinol-2,4,6-¹⁴C was found to be incorporated into rutin in Buckwheat (Fagopyrum esculentum) but most of the activity was found in the sugar moiety, the remainder being approximately equally distributed among the A- and B-rings of the aglycone, quercetin. This indicates extensive degradation of the added phloroglucinol prior to its utilization in the biosynthesis of the flavonoid. The hypothesis of a bio-Fries rearrangement of phloroglucinyl cinnamate to a chalcone, and hence to flavonoids, was also eliminated by comparing the efficiency of incorporation of ¹⁴C-labelled phloroglucinyl cinnamate and those of labelled phloroglucinol and cinnamic acid.     

Methylation of anthocyanins by cell-free extracts of flower buds of Petunia hybrida

An O-methyltransferase activity which catalyses the methylation of anthocyanins was extracted from flowerbuds of Petunia hybrida. The methyltransferase uses S-adenosyl-l-methionine as methyl donor. Only anthocyanidin 3(p-coumaroyl)rutinosido-5-glucoside was methylated. No methylating activity towards anthocyanidins, anthocyanidin 3-glucosides, anthocyanidin 3-rutinosides, caffeic acid or p-coumaric acid could be detected.     

Aromatic compounds from Artemisia campestris subsp. Glutinosa

From the weakly acid fraction of the hexane extract from Artemisia campestris subsp. glutinosa, five new aromatics have been isolated. They hav     

Coumarins in artemisia caruifolia

Isolation of daphnethin 7-methyl ether, daphnetin dimethyl ether, daphnetin methylene ether, daphnetin 7-methyl-8(3,3-dimethylallyl) ether and 3,4-dimethoxy-2-hydroxycinnamic acid from Artemisia caruifolia is reported.     

Time-course tracer studies on the metabolism of cinnamic acid in Cestrum poeppigii

Time-course tracer studies were performed on the metabolism of trans-cinnamic acid-[3-¹⁴C] and trans-p-coumaric acid-[2-¹⁴C] in the     

The biosynthesis of abscisic acid in Cercospora rosicola

1′-Deoxyabscisic acid (1′-deoxy-ABA) has been isolated from cultures of Cercospora rosicola which are actively synthesizing abscisic acid (ABA)     

Cinnamic acid intermediates as precursors to mesembrine and some observations on the late stages in the biosynthesis of the mesembrine alkaloids

Experiments with various labelled cinnamic acid derivatives establish, in conjunction with previous work, that the incorporation of phenylalanine into the 3a-aryl octahydroindole ring system of the mesembrine alkaloids occurs via the intermediacy of cinnamic acid and 4′-hydroxycinnamic acid. The major pathway to the 3′,4′-di-oxyaryl substituted alkaloids proceeds via 4′-hydroxydihydrocinnamic acid (4′-phloretic acid), and 3′4′-dioxy-genated cinnamic acids are not involved as intermediates on this major pathway. In accord with this latter finding, the 3′-aryl oxygen substituent is introduced at a late state in the biosynthesis as evidenced by the bioconversion in S. strictum of sceletenone to mesembrenol and other related alkaloids. The late stages in the biosynthesis of the alkaloids are shown to involve the sequence: sceletenone, 4′-O-demethylmesembrenone, mesembrenone. Mesembrenone is converted to mesembrine, mesembrenol and mesembranol.     

C-galactosylflavones from Polygonatum multiflorum

8-C-Galactosylapigenin and 6-C-galactosyl-8-C-arabinosylapigenin were isolated from the leaves of Polygonatum multiflorum (L.) All. Structural assignments for the latter compound were made on the basis of mass, CD and ¹³C-NMR spectra.     

The biosynthesis of melanin in Alternaria

A melanin which is insoluble in strong alkali has been isolated from Alternaria mycelium. Alkali fusion of the pigment produced p-hydroxybenzoa     

(3R,3′R)-astaxanthin from the yeast Phaffia rhodozyma

Astaxanthin isolated from the yeast Phaffia rhodozyma has the 3R,3′R-configuration, opposite to that of astaxanthin from other sources which have been so far investigated. This is the first example of a naturally occurring carotenoid biosynthesized in different optical forms. A possible explanation is advanced.     

The reaction between cytochrome C1 and cytochrome C

The kinetics of electron transfer between the isolated enzymes of cytochrome c₁ and cytochrome c have been investigated using the stopped-flow technique. The reaction between ferrocytochrome c₁ and ferricytochrome c is fast; the second-order rate constant (k₁) is 3.0 · 10⁷ M^?1 · s^?1 at low ionic strength (I = 223 mM, 10°C). The value of this rate constant decreases to 1.8 · 10⁵ M^?1 · s^?1 upon increasing the ionic strength to 1.13 M. The ionic strength dependence of the electron transfer between cytochrome c₁ and cytochrome c implies the involvement of electrostatic interactions in the reaction between both cytochromes. In addition to a general influence of ionic strength, specific anion effects are found for phosphate, chloride and morpholinosulphonate. These anions appear to inhibit the reaction between cytochrome c₁ and cytochrome c by binding of these anions to the cytochrome c molecule. Such a phenomenon is not observed for cacodylate. At an ionic strength of 1.02 M, the second-order rate constants for the reaction between ferrocytochrome c₁ and ferricytochrome c and the reverse reaction are k₁ = 2.4 · 10⁵ M^?1 · s^?1 and k_?1 = 3.3 · 10⁵ M^?1 · s^?1, respectively (450 mM potassium phosphate, pH 7.0, 1% Tween 20, 10°C). The ‘equilibrium’ constant calculated from the rate constants (0.73) is equal to the constant determined from equilibrium studies. Moreover, it is shown that at this ionic strength, the concentrations of intermediary complexes are very low and that the value of the equilibrium constant is independent of ionic strength. These data can be fitted into the following simple reaction scheme: cytochrome c²⁺₁ + cytochrome c³⁺ai cytochrome c³⁺₁ + cytochrome c²⁺.     

Biogenesis of the C-Glycoside leucodrin in Leucadendron Argenteum

Biogenetic pathways for leucodrin formation in Leucadendron spp. are discussed and were tested by feeding labelled d-galactose, d-glucose and l-ascorbic acid to cut stem ends of L. argenteum. It was shown that the two aldohexoses are better precursors and preferentially incorporated into that portion of leucodrin derivable from p-coumaric acid. When this route is suppressed by feeding the labelled sugars in the presence of a large amount of phenylalanine) label is predominantly incorporated in the carbohydrate part of leucodrin. The biogenesis of leucodrin therefore may proceed via coupling of l-galactono-γ-lactone and p-coumaric acid.     

Xanthones and C-glucosylflavones from Gentiana corymbifera

A new xanthone and twelve known compounds were isolated from the aerial parts of Gentiana corymbifera. The new xanthone was shown to be 3-methylcorymbiferin (1,8-dihydroxy-3,4,5-trimethoxy-9H-xanthen-9-one) by spectral and chemical procedures. The chemotaxonomic implications are discussed.     

Stereochemistry of strictic acid and related furano-diterpenes from conyza japonica and grangea maderaspatana

Extraction of Conyza japonica gave strictic acid, ent-2β-hydroxy-15,16-epoxy-3,13(16),14-clerodatrien-18-oic acid and 5,7-dihydroxy-3,8,4′-trimethoxyflavone. Extraction of Grangea maderaspatana gave (-)-hardwickiic acid, ent-15,16-epoxy-1,3,13(16),14-clerodatetraen-18-oic acid and 3-hydroxy-8-acetoxypentadeca-1,9,14-trien-4,6-diyne. The structure of ent-2β-hydroxy-15,16-epoxy-3,13(16),14-cleroclatrien-18-oic acid was deduced by spectroscopic methods and by partial synthesis from (-)-hardwickiic acid and the stereochemistries of strictic acid and (ent-15,16-epoxy-1,3,13(16),14-clerodatraen-18-oic acid were established by correlation with ent-2β-hydroxy-15,16-epoxy-3,13(16),14-clerodatrien-18-oic acid.     

Chlorogenic acid biosynthesis in Cestrum poeppigii

The chlorogenic acid content of Cestrum poeppigii, and its ability to form the acid from labelled t-cinnamic acid, was determined at different stages of growth. In contrast to mature plants, young plants showed great seasonal variation in their chlorogenic acid content. The incorporation of radioactivity from t-cinnamic into chlorogenic acid also differed greatly during the growth period. Trapping experiments with caffeic and p-coumaric acids were performed to study the effect of large pools of these acids on the incorporation of t-cinnamic acid-3-[¹⁴C] into chlorogenic acid. The kinetics of incorporation exclude a major role for caffeic acid in the biosynthesis of chlorogenic acid.     

In vitro biosynthesis of isopentenylacetophenones in Eupatorium rugosum

A cell free homogenate of Eupatorium rugosum leaves was prepared and utilized to study the biosynthesis of dehydrotremetone (1). Homogenates of young leaves were most efficient in the formation of 1. The furan ring and its side chain were derived from an isoprenoid unit, which appeared to be isopentenyl pyrophosphate and not dimethylallyl pyrophosphate. Potential aromatic precursors such as 4-hydroxyacetophenone and 4-hydroxy-3[isopenten-(2)-yl]-acetophenone were poorly utilized. However, tremetone, especially in the presence of the coenzyme NADP, was very efficiently converted to 1. An apparent intermediate in the pathway leading to 1 was isolated and appeared similar to 4-hydroxy-3[isopenten-(2)-yl]-acetophenone. It is proposed that the aromatic moiety of 1 is derived from acetate via a polyketide intermediate, which undergoes isoprenylation by isopentenyl pyrophosphate, followed by aromatization and furan ring closure.