Die Cardenolide von Acokanthera oppositifolia (LAM.) CODD. 3. Mitteilung . Isolierung weitere Cardenolide und teilweise Strukturaufklärung. Glykoside und Aglykone, 301. Mitt.

The presence of 19 cardenolides in the extracts from the seeds of Acokanthear oppositifolia (Lam.) CODD could be traced by means of paper chromatography. Thirteen of these cardenolides could be isolated in crystalline form, acovenoside A (= 2) being by far the major component. Of the other 12 crystalline substances, 5 could be identified with known cardenolides: 2′ = acofrioside L, 3 = acolongifloroside H, 14 = acovenoside C, 15 = acolongifloroside K, 16 = ouabain. The substances 1′, 1″, 4, 6, 7, 8 and 13 are very probably new compounds. Four of these were given trivial names and the following structures were proposed: 1″ = oppovenoside, probably 10 ; 4 = oppofrioside ( 5 ); 6 = acotaloside ( 6 ); 13 = opposide, probably 12 , cf. following publication [21]. Furthermore, the structure 8 has been proposed for acolongifloroside H.     

Die Glykoside der Wurzeln von Kanahia laniflora (FORSSK.) R. BR. 1. Mitteilung: Isolierungen. Glykoside und Aglykone, 299. Mitteilung

The roots of Kanahia laniflora (FORSSK .) R. BR . contain, in addition to small quantities of cardenolides, a large amount of ester glycosides which are difficulty separable from one another. However, two of these ester glycosides were obtained in a nearly pure form. The crude mixture of ester glycosides, after mild acidic hydrolysis, gave a mixture of acyl-genins and three sugars: D -oleandrose, D -digitoxose and D-canarose, all of which were obtained in crystalline form. Acetic acid, benzoic acid and another unidentified acid were obtained on alkaline hydrolysis of the mixture of acyl-genins along with 17-isolineolon, lineolon, deacetylmetaplexigenin and a small amount of sarcostin-ketone. Besides these known genins, three probably new genins (α, τ, λ) were obtained in small, but crystalline amounts.     

Massenspektren neuer Phloroglucide,insbesondere solcher mit Valerylseitenketten

Mass spectra of phloroglucinol derivatives recently isolated from African Dryopteris species are presented. Phloroglucides with n-valeryl side chain were found in these ferns for the first time. In the mass spectra they show strong peaks corresponding to loss of propene (C₃H₆) produced by McLafferty rearrangement, as shown in model compounds. Aside of the rottleron change (discussed formerly) this must be considered in order to avoid wrong interpretation, particularly when mass spectra are used to analyse mixtures of homologues, as usually present in the plants. If valeryl side chains are present other methods must be used therefore to measure the amount or show the absence of lower homologues with acetyl side chains.     

Die Glykoside der Samen von Dregea volubilis (L.) BENTH. ex HOOK. 2. Mitt. Isolierung weiterer Drevogenine Glykoside und Aglykone, 277. Mitteilung

A total of fifteen substances were identified through thin-layer chromatography, after mild acid hydrolysis of the chloroform extract from the seeds of Dregea volubilis (L.) BENTH . ex HOOK . Of these fifteen substances, eight (B, D, P, O; U, V, H and T) were isolated in crystalline form. Two of these were identical with the known genins drevogenin B (B) and drevogenin D (D). Drevogenin P (P) and the unknown substance O (probably a genin) were isolated for the first time. U proved to be identical with D -cymarose, V with the biose U1 obtained from Asclepias lilacina, and H with (+)-methyl-pachybioside. T was not investigated (probably a sugar derivative).     

2α, 3β, 19-Triacetoxy-14α-hydroxy-5α-card-20:22-enolid: Teilsynthese. Zusätzlicher Beweis für die Struktur des Calotropagenins. Glykoside und Aglykone, 324. Mitteilung

Coroglaucigenin, which is known to be a 3β, 14β, 19-trihydroxy-5α-card-20: 22-enolid, was transformed into 2α, 3β, 19-triacetoxy-14β-hydroxy-5α-card-20 : 22-enolid. The latter was identical with the known tri-O-acetyl-19-dihydro-calotropagenin. The structure of calotropagenin ( 1 ) is thus established through an independent way.     

Die Glykoside der Samen von Stapelia gigantea N. E. Br. Glykoside und Aglykone, 275. Mitteilung

The seeds of Stapelia gigantea are very rich in ester glycosides (ca. 5,9%). Mild acid hydrolysis gave a mixture of sugars which, after paper chromatography and electrophoresis, was found to be probably composed of cymarose, oleandrose, digitoxose, arabino-2,6-dideoxyhexose (= canarose) and pachybiose. The mixture of the raw genins gave after alkaline hydrolysis a mixture of about nine deacyl genins (C, D, E, F1, F2, F3, G, H, J); the acids split off during hydrolysis were not identified. The nine deacyl genins are probably closely related pregnane derivatives. The main component (E), C₂₁H₃₀O₄, was obtained in crystalline state, and was named stapelogenin. Its probable structure is reported in the following publication.     

Field-Desorption Mass Spectra of Fern Phloroglucinols Containing Three to Six Ring Constituents

It has been previously shown that the structural analysis of the title compounds by electron-impact ionization (EI)mass spectrometry is complicated by extensive, if not complete, thermal rottlerone-type rearrangement and/or fragmentation reactions. The use of a ‘softer’ ionization technique such as field desorption (FD) is, therefore, required in order that these compounds may be characterized in terms of their molecular size and composition. In this report, the FD mass spectra of typical representatives of this class of compounds are described along with the attempted suppression of undesirable thermal reactions by the optimization of the emitter temperatures.     

Drevogenin A und Drevogenin B,zusätzlicher Strukturbeweis. Glykoside und Aglykone, 306. Mitteilung

Drevogenin B is shown to be 11-O-acetyl-drevogenin P. The earlier derived structure for drevogenin A (11-O-acetyl-drevogenin P) is further confirmed by conversion of 3-O-acetyl-drevogenin A.     

Biosynthesis of digitoxose in Digitalis lanata EHRH. (Preliminary experiment). Deoxysugar. 39

Strongly radioactive digitoxin ( 6 ) could be isolated (without dilution) in crystalline form from young plants of Digitalis lanata after their inoculation with D-Glucose-[6-¹⁴C] using the wick method. Hydrolytic cleavage of this digitoxin gave digitoxigenin ( 11 ) and D-digitoxose ( 7 ), both being isolated in crystalline form (without dilution). The genin was found to be 4 times more active, pro mole, than the digitoxose. This can be best explained when one assumes that the plant converts 1 mole of D-glucose into 3 moles of acetic acid. After degradation of the digitoxose using NaJO₄, acetaldehyde (as the crystalline p-nitrophenylhydrazone) and formic acid (as the Pb salt) could be isolated. The acetaldehyde carried 65% and the formic acid 8,45% of the activity of the digitoxose. This is compatible with the assumption that digitoxose is formed in the plant from D-glucose without re-arrangement of the carbon chain. The appreciable activity of the formic acid could be derived from the relatively large proportion of radioactivity lost (ca. 38,9%), partly in the form of C₁-subunits, in the transformation of the intermediary lanosterol into digitoxigenin. This lost activity may be incorporated in unspecifically labelled D-glucose which then re-enters the biosynthetic pathway.