John L. Frahn

Structure and toxicity of the alkaloids of Russian comfrey ( Symphytum x uplandicum Nyman), a medicinal herb and item of human diet

Eight pyrrolizidine alkaloids of hepatotoxic type have been indentified in leaves ofSymphytum × uplandicum The combined alkaloids exhibit chronic hepatotoxicity in rats.

Pyrrolizidine alkaloids inDanaus plexippus L. andDanaus chrysippus L.

Danaus plexippus L. andDanaus chrysippus L. have been found to store pyrrolizidine alkaloids obtained from adult food plants and it is suggested that the alkaloids contribute to the unpalatability of the butterflies to potential predators.

Corynetoxins causative agents of annual ryegrass toxicity; their identification as tunicamycin group antibiotics

The corynetoxins, formed in galled seeds of Lolium rigidum(annul ryegrass) occupied by Corynebacterium rathayi and responsible for annual ryegrass toxicity, are identified as new members of the tunicamycin group of antibiotics.

Preparative separation of the pyrrolizidine alkaloids, intermedine and lycopsamine, as their borate complexes

Abstract Intermedine and lycopsamine are diastereoisomers containing vicinal glycol groups of different configuration. The difference in the degree to which they complex with borate is the basis of two procedures for their separation from mixtures on a preparative scale. In the first, the mixture dissolved in chloroform is passed through a column of glass powder moistened with a solution of borax. Intermedine elutes first with chloroform and is cleanly separated from lycopsamine, the more strongly complexing of the pair. In the other procedure, in which lycopsamine elutes first, a mixture is dissolved in 0.1 M borax and the solution passed through a cation-exchange resin (Bio-Rad AG 50W-X2) impregnated with 0.1 M borax.

Structure elucidation of phomopsin A, a novel cyclic hexapeptide mycotoxin produced by Phomopsis leptostromiformis

Phomopsin A, the main mycotoxin isolated from cultures of Phomopsis leptostromiformis and the cause of lupinosis disease in animals grazing infected lupins, is a cyclic hexapeptide containing 3-hydroxyisoleucine, 3,4-didehydrovaline, N-methyl-3-(3-chloro-4,5-dihydroxyphenyl)-3-hydroxyalanine, E-2,3-didehydroaspartic acid, E-2,3-didehydroisoleucine, and 3,4-didehydroproline; its 13C n.m.r. spectrum was completely assigned and the amino-acid sequence established unambiguously by extensive heteronuclear 13C-{1H} selective population inversion n.m.r. experiments.

LUPINOSIS: CHEMICAL PROPERTIES OF PHOMOPSIN A, THE MAIN TOXIC METABOLITE OF Phomopsis leptostromiformis

I. ABSTRACT Phomopsin A, the main toxic metabolite of Phomopsis leptostromiformis responsible for lupinosis, has an empirical formula approximately C33H44N5O13Cl. There are 3 acidic centers per molecule which are probably phenolic, β-diketone or ββ-triketone in nature. Ultraviolet, infrared, and nuclear magnetic resonance spectra are described. These and the mild acid hydrolysis of phomopsin A to oxalacetic acid and an amine suggest that the metabolite is related to tenuazonic acid.

Paper electrophoresis of hydroxycarboxylic acids as their borate complexes with special reference to viridifloric, trachelanthic, lasiocarpic and heliotric acids : The importance of the “gem- dialkyl” effect in complex formation

Abstract The electrophoretic mobility of an α-hydroxycarboxylic acid in electrolytes containing boric acid is very dependent on the degree of substitution at the α-carbon atom. A study of eighteen α-hydroxy acids shows clearly that the “ gem -dialkyl” effect is operating to favour the formation of the strongly acidic boric acid complexes from the more densely substituted acids, the mobilities of whcih are thus more or less greatly enhanced. In general, the complexes from best at pH 2, but some are stable at higher levels. Of several that exist at pH 4.6, only the complexes of viridifloric, trachelanthic and lasiocarpic acids also survive paper electrophoresis at pH 9.2. These acids form 1:1 instead of the usual 1:2 complexes and they are further distinguished from the others by an unusually high degree of crowding at their α-carbons, and by containing a β- as well as the α-hydroxyl group.

Separation of some indolylalkylamines from their metho cation derivatives using neutral polystyrene resin : Application to the alkaloids of phalaris tuberosa (gramineae)

Abstract It is shown that some indolylalkylamines —N,N-dimethyltryptamine, 5-methoxy-N,N-dimethyltryptamine and the related bases, 2-methyl-1,2,3,4-tetrahydro-β-carboline and its 6-methoxy derivative— are each cleanly separable from their respective metho cation derivatives on a column of the neutral polystyrene resin, Porapak Q, using methanol-0.2 M ammonium hydroxide (1:1) as the eluent. The method was applied to the isolation of the metho cations of N,N-dimethyltryptamine and 5-methoxy-N,N-dimethyltryptamine occasionally extracted from the pasture grass Phalaris tuberosa, together with the parent tertiary bases and others which are common constituents of the grass at all stages of its growth cycle. The metho cation of 5-methoxy-N,N-dimethyltryptamine was identified by paper electrophoresis and that of N,N-dimethyltryptamine by mass spectrometry.

Curassavine, an alkaloid from Heliotropium curassavicum Linn. with a C8 necic acid skeleton

Curassavine, the major alkaloid of Heliotropium curassavicum Linn. is shown to be an ester of trachelanthamidine with 3-carboxy-4-methylhexane-2,3-diol (homoviridifloric acid), the first example of a monocarboxylic necic acid with a C8 skeleton; the minor alkaloids, coromandalin and heliovicine are esters of trachelanthamidine with (+)-viridifloric and (–)-trachelanthic acids, respectively, the former providing the first example of natural occurrence of a (+)-viridiflorate.

Electrophoresis of halides and phosphate on DEAE-cellulose application to elemental analysis of organic compounds by sodium fusion

Abstract Electrophoresis on strips of the weakly basic anion exchanger, diethylaminoethyl-cellulose, is used to separate the halides and phosphate in any of four electrolytes spanning a wide range of pH but most effectively in an electrolyte at pH 2 containing a mixture of formic and acetic acids. The anions on pherograms treated with silver nitrate and exposed to ultraviolet light react in different ways depending on the nature of the electrolyte remaining on dried strips and on the concentration of silver ions in the reagent applied. The method is adapted to the detection and identification of halogens and phosphorus present in organic compounds following sodium fusion on a micro-scale. The separation also facilitates quantitative estimation of the individual anions present in mixtures, and an example is given of the estimation of residual inorganic bromide present in a chicken feed following fumigation with methyl bromide.