Cyanogenic Research Articles

Influence of secondary compounds in the phloem sap of cassava on expression of antibiosis towards the mealybug Phenacoccus manihoti

AbstractIdentification and assay of cyanogenic and phenolic compounds in phloem sap of cassava (Manihot esculenta Crantz, Euphorbiaceae) and in honeydew of the cassava mealybug Phenacoccus manihoti Matt. Ferr. (Homoptera, Pseudococcidae) were realised.Cyanogenic glucosides and three flavonoid glycosides (rutin, kaempferol glycoside‐1 and kaempferol glycoside‐2) were found to be translocated in cassava phloem sap and consumed by the mealybug. Differences in profiles of secondary compounds of phloem sap and honeydew samples, characterised mainly by the appearance of free cyanide and of a free flavonoid, suggest the metabolic processing of at least some of the ingested compounds.The relationship between foliar concentrations of these different compounds and expression of the antibiotic resistance of cassava towards P. manihoti was also investigated in 7 varieties of cassava and in the ‘faux‐caoutchouc’ hybrid. Infestation by mealybug was followed by a clear increase in levels of both rutin and kaempferol glycoside‐2, while no modification in cyanide contents was noted. The best rank correlation between antibiotic resistance (measured by the intrinsic rate of increase rc) and secondary compounds analyzed is observed with rutin contents of infested plants (***ρ=‐0.73; p=0.05). The possible implication of this compound in the biochemical mechanisms accompanying cassava defence reaction to mealybug attack is discussed.RésuméCe travail présente l'identification et le dosage des substances secondaires (composés cyanés et phénoliques) présentes dans la sève phloémienne du manioc (Manihot esculenta Crantz, Euphabiaceae) et dans le miellat de la cochenille farineuse Phenacoccus manihoti Matt. Ferr. (Homoptera, Pseudococcidae).Des glycosides cyanogéniques et trois flavonoïdes glycosylés majeurs (rutine, kaempferol glycoside‐1 et kaempferol glycoside‐2) sont transportés par la sève phloémienne du manioc et consommés par la cochenille. Le profil sensiblement différent des composés secondaires du meillat de la cochenille, en particulier l'apparition d'un flavonoide libre et de cyanure, suggère une modification de certains composés lors du transit intestinal.La relation entre les teneurs de ces différentes substances dans le liquide foliaire de 7 variétés de manioc et du ‘faux‐ caoutchouc’(hybride de M. esculenta et de M. glaziovii) et l'expression de leur résistance antibiotique vis‐à‐vis de P. manihoti a également été étudiée. L'infestation par la cochenille se traduit par une importante augmentation des teneurs en rutine et en kaempferol glycoside‐2, alors qu'aucune modification des teneurs en cyanure libre n'est enregistrée. La meilleure corrélation entre la résistance par antibiose, exprimée par la capacité intrinsèque d'accroissement rc, et les teneurs en substances secondaires analysées est observée avec les teneurs en rutine des plants infestés (***ρ=‐0.73; p=0.05). L'association éventuelle de ce glycoside aux mécanismes biochimiques de défense du manioc à la cochenille farineuse est discutée.

Cyanogenic Plants in the Galápagos Islands: Ecological and Evolutionary Aspects

A representative part (65%) of the indigenous Galapagos flora was screened for contents of cyanogenic compounds by incubation of fresh crushed leaf material with β-glucuronidase and by analysis of released HCN. Most species with HCN development (cyanogenic species) were subsequently incubated with pure water to test for contents of glycosidases in the leaf. Plants with positive reaction were termed cyanophoric. The endemic part of the flora proved to have a higher percentage of cyanogenic and cyanophoric plants than the native part. The absence of mammalian leaf herbivores in the herbivore regime made us assume that cyanogenic compounds would be redundant

β-Cyano-l-alanine and N-(γ-l-glutamyl)-β-cyano-l-alanine, neurotoxic constituents of Clitocybe acromelalga

The neurolathyrogens, β-cyano-l-alanine and its γ-l-glutamyl peptide were isolated from a toxic mushroom, Clitocybe acromelalga, along with acromelic acids. The unique symptoms caused by ingestion of this mushroom might be attributed in part to these cyanogenic compounds from a consideration of their toxic properties.

Chromatographic techniques for preparation of linustatin and neolinustatin from flaxseed: standards for glycoside analyses

Cyanogenic glycosides, which are major antinutrients of flaxseed, were extracted from the meal using 80% (v/v) ethanol. After silicic acid and subsequent RP-8 chromatography, cyanogenic glycosides along with soluble sugars were separated. Two cyanogenic glycosides, namely, linustatin and neolinustatin, were subsequently separated on a silica gel column with chloroform/methanol/water (65:35:10, v/v/v). Cyanogenic compounds so prepared may be used as chromatographic standards for glycoside analyses.

Fate of Cyanogenic Compounds in Beans during the Manufacturing Process of Bean Paste

The fate of cyanogenic compounds in butter beans and baby lima beans (Phaseolus lunatus L.) during the manufacturing process of bean paste on a laboratory scale was investigated. Linamarin, the main cyanogenic glycoside in the beans, was analyzed by FID-GC after trimethylsilylation and free cyanide was analyzed by ECD-GC using the head-space method.The changes of linamarin and free cyanide contents showed similar decreasing tendencies in both beans though there was a six-fold difference of cyanogen content between butter beans and baby lima beans. Linamarin and free cyanide decreased greatly during the soaking and refining processes, but they decreased little during the boiling process. The percentage of residual cyanogen in the final bean paste was 0.3% in both kinds of beans. Linamarin was the main cyanogenic component in the original beans and at each step.

Cyanogenic compounds in flaxseed

The seeds of 10 flax cultivars (Andro, Flanders, AC Linora, Linott, McGregor, Noralta, NorLin, NorMan, Somme, and Vimy) grown at Portage la Prairie, MB, in 1987, 1988, and 1989 and at Beaverlodge, AB, and Indian Head, SK, in 1989 were analyzed for content of cyanogenic glucosides by HPLC. The main cyanogenic compound was the diglucoside linustatin at 213-352 mg/100 g of seed, accounting for 54-76% of the total content of cyanogenic glucosides. The content of neolinustatin ranged from 91 to 203 mg/100 g of seed

Mechanisms underlying Phalaris aquatica “sudden death” syndrome in sheep

Twenty outbreaks of Phalaris aquatica "sudden death" syndrome in sheep were investigated between 1981 and 1991. Four were confirmed and one was suspected, to be a cardiac disorder; 5 were confirmed and 3 were suspected, to be a polioencephalomalacic disorder; the aetiology of the remaining 7 outbreaks could not be determined. Potentially toxic levels of hydrocyanic acid (20 to 36 mg/100 g) were measured in the 3 toxic phalaris pastures tested. The measurement of potentially toxic levels of nitrate nitrogen (2920 micrograms/g) in toxic phalaris pastures by others, was noted. It is suggested that phalaris "sudden death" syndrome could have as many as 4 different underlying mechanisms, and that these might reflect the presence in the plant of a cardio-respiratory toxin, a thiaminase and amine co-substate, cyanogenic compounds, and nitrate compounds.

Endogenous evolution of HCN during pre‐germination periods in many seed species

Both cyanogenic (Malus pumila Mill) and acyanogenic (Oryza sativa L., Hordeum vulgare L., Zea mays L., Glycine max Merr., Lactuca sativa L., and Xanthium pennsylvanicum Wallr. etc.) seeds evolve HCN gas during the early periods of water imbibition. All tested seeds contained reserve cyanogens which liberated HCN upon hydrolysis with H2SO4 and with β‐glucosidase and/or lipase. The amounts of liberated HCN were roughly comparable to those of unidentified cyanogens. It is thus conceivable that the cyanogens within seeds are available as precursors for free HCN evolved in the pre‐germination period. The amounts of HCN evolved in the acyanogenic seeds were only 0.002 to 1% of that in apple, but the contents of the cyanogenic compounds in rice and cocklebur increased temporarily during the pre‐germination period, then decreased and, finally, disappeared completely with the start of germination.

Toxic Plant Compounds and the Diet of the Predominantly Herbivorous Whiptail Lizard, Cnemidophorus arubensis

The diet of the predominantly herbivorous whiptail lizard, Cnemidophorus arubensis, was examined at four sites on the Caribbean island of Aruba. The lizard's diet was compared with the abundance of each type of plant material at the sites and the presence of four classes of potentially toxic compounds in the plants. Flowers, fruit, and leaves make up 80-90% of the Aruban whiptail's diet. Foods were not taken in their proportion in the environment; some common potential foods were never or rarely eaten, and some rare plants were commonly consumed. Behavioral observations suggest that the lizards actively search for preferred food types. There was a significant relationship between presence of potential toxins in plant materials and their exclusion from the lizard's diet. Plant materials with large quantities of phenolics, saponin, or alkaloids were usually rarely or never eaten. However, some potentially toxic plant materials, including one containing a cyanogenic compound, were eaten. In a laboratory experiment, a chronic cyanide dose far greater than normally consumed by the lizards under natural conditions did not appear to cause hematological, physiological, or behavioral changes. Thus, some, but not all, types of secondary plant compounds appear to play a role in shaping the diet of C. arubensis.

Cyanogenesis in Plants

Several thousand plant species, including many economically important food plants, synthesize cyanogenic glycosides and cyanolipids. Upon tissue disruption, these natural products are hydrolyzed liberating the respiratory poison hydrogen cyanide. This phenomenon of cyanogenesis accounts for numerous cases of acute and chronic cyanide poisoning of animals including man. This article reviews information gathered during the past decade about the enzymology and molecular biology of cyanogenesis in higher plants. How compartmentation normally prevents the large-scale, suicidal release of HCN within the intact plant is discussed. A renewed interest in the physiology of these cyanogenic compounds has revealed that, in addition to providing protection for some species against herbivory, they may also serve as storage forms for reduced nitrogen.

Natural nitriles and their metabolism

The present work reviews the numerous nitrile compounds that have been isolated from plants and animals. Two kinds of potentially toxic molecules are widespread, namely the cyanogenic glycosides and cyanollpids. Many other aromatic and allphatic nitriles are synthesized to a lesser extent. Different studies on the synthesis and degradation of these cyanogenic compounds are also reviewed to emphasize the potential use of different microorganisms for the detoxification of food and foodstuff.

Cyanogenesis and Metabolization of Cyanogenic Compounds: an Example for Multifunctionality of Secondary Plant Products

Cyanogenesis and Metabolization of Cyanogenic Compounds: an Example for Multifunctionality of Secondary Plant Products

Reports of Cyanogenesis in Selected Basidiomycetes

(1988). Reports of Cyanogenesis in Selected Basidiomycetes. Mycologia: Vol. 80, No. 6, pp. 859-860.

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Acacia macracantha, A. pennatula, and A. cochliacantha (Fabaceae: Mimosoideae) Species Complexes in Mexico

Vegetative and floral features of specimens of Acacia macracantha, A. pennatula, and A. cochliacantha from Mexico, Central America, and the West Indies were scored and analyzed by principal components analysis (PCA). Specimens that came from areas where the three species are allopatric could be assigned to a species group by inspection; this procedure was confirmed by PCA. Acacia pennatula is subdivided into two subspecies with distinct geographic ranges; A. pennatula subsp. parvicephala being newly described. Acacia cochliacantha is divided into two largely sympatric forms; A. cochliacantha forma houghii is a new combination. It is postulated that these two subgroups are of hybrid origin involving A. macracantha. This is supported by intermediacy of vegetative and floral characters, and by the presence of cyanogenic compounds in subgroups of both species. These compounds are otherwise uncommon in A. pennatula and A. cochliacantha but are common in A. macracantha. Some plants of A. pennatula or A. cochliacantha, and A. macracantha from areas of sympatry are intermediate in character and seem to be F1 hybrids and/or backcrosses. With PCA, these putative hybrids are placed in positions intermediate to the other taxa.

Potential for Hydrocyanic Acid Poisoning of Livestock by Indiangrass

Hydrocyanic acid or prussic acid poisoning of livestock by sorghums [Sorghum bicolor (L.)Moenchl and sudangrasses [Sorghum sudanese (Piper) StapfJ is caused by the digestive liberation of hydrocyanic acid (HCN) from the cyanogenic compound, dhurrin [(S)-p-hydroxymandelonitrile ,8-D-glucopyranosideI found in tissue of these plants. Recent research documented that dhurrin is also present in indiangrass [Sorghastrum nutans (L.) Nash] seedlings. The purpose of this study was to determine the hydrocyanic acid potential (HCN-p) of forage from established stands of indiangrass. Five cultivars representative of indiangrass germplasm of the Great Plains were sampled during the growing season for 2 years from 2 sites in eastern Nebraska. The HCN-p of the indiangrass sampled in this study exceeded 750 mg-1 kg dry wt. (dangerous level) only in spring when new growth was 20 cm tall or less. Levels were less than 500 mg-1 kg (safe) when new growth was at least 40 cm tall and were very low (<200 mg-1 kg) or not detected when the forage was over 1 m tall. Pure stands of indiangrass that are grazed when the new growth is less than 20 cm tall could be lethal to livestock.

自然界のシアン化合物

自然界のシアン化合物

Derivation and dispersal of Acacia (Leguminosae), with particular reference to Australia, and the recognition of Senegalia and Racosperma.

The morphology of seedlings, leaves, flowers and inflorescences, anatomy of the pod, the occurrence of extra‐floral nectaries, free amino acids of the seeds, flavonoid compounds in heartwoods, cyanogenic compounds and porate, colporate and extraporate pollen, and susceptibility to rusts, all indicate that three genera, Acacia Miller, Senegalia Raf. and Racosperma Martius, should be recognized. These correspond to currently accepted subgenera of Acacia. The size of these more narrowly circumscribed genera is in keeping with the size of genera of other tribes of low diversity in Leguminosae. Acacia and Senegalia arose independently from the Ingeae, with Racosperma being derived from Senegalia. Section Filicinae is more advanced than section Senegalia of Senegalia, and sections Racosperma and Pukhella, both with at least some species with bipinnate foliage, are the most advanced of Racosperma, while the other sections Pleurinervia and Lycopodiifolia have only phyllodinous species. Long‐range dispersal of Racosperma from the Australian region has occurred, but the broad pattern of distribution is interpreted in terms of plate tectonics. Racosperma was present in Australia in the late Cretaceous but did not become widespread until the general drying of the continent in the Miocene. The flora of SW Australia has been isolated from the rest of the continent by climatic barriers since the late Tertiary and has a high proportion of endemic species. Barriers to plant migration in the east have operated only intermittently and there is no area comparable in endemism to the southwest.

Occurrence of lotaustralin in the genus Hevea and changes of HCN-potential in developing organs of Hevea brasiliensis

The mean HCN-potential (HCN-p) of freshly collected seeds of Hevea brasiliensis is 104.8 μmol HCN per g dry weight. More than 90% of the cyanogenic compound is stored in the endosperm. During seedling development under aseptic conditions HCN-p of the entire seedling decreases to 15% within 19 days. The cyanogenic compounds are metabolized during germination to form noncyanogenic substances. Leaves of H. pauciflora, H. benthanaana, H. pauciflora x H. guianensis and H. spruceana contain both linamarin and (R)-lotaustralin, whereas lotaustralin was not detectable in leaves and seeds of H. brasiliensis.

Simple densitometric method for estimation of cyanogenic glycosides and cyanohydrins under field conditions

In this new design of the picrate test (Guignard Method) for small scale cyanide determination under field conditions, hydrolysis of the cyanogenic compounds is catalysed by ‘β-glucuronidase’, a commercial enzyme preparation from Helix pomatia. The method described facilitates the quantification of small amounts of cyanogenic compounds in plant material, with a detection limit about 60 ng of released HCN (equivalent to 1μg of amygdalin). False positive tests produced by hydrolysis products of glucosinolates could be excluded by inhibition of the myrosinae enzyme system present in plants that contain glucosinolates. The total weight of equipment needed for a total of 1000 determinations (in groups of eight) does not exceed 500 g, thus making the method convenient for field work.