Cyanogenic Glycoside Content Research Articles

発育中の日本スモモの果肉と種子における青酸配糖体含量とβ-シアノアラニン合成酵素活性の消長

Changes in cyanogenic glycoside content and β-cyanoalanine synthase activity were determined in the flesh and seeds of Japanese plum(Prunus salicina Lindl.) during development. In the flesh, only prunasin was detected at levels as low as 0.6mg/g dw at the earliest sampling date (May 4) and became soon undetectable. Similarly β-cyanoalanine synthase activity, which showed 0.3μmol H2S/g fw/hr on May 4, gradually decreased to undetectable levels in late May, but a slight increase was noted during ripening. On the contrary, seeds had total amounts of cyanogenic glycosides as high as 75-100mg/g dw throughout the season. Prunasin was predominant in young seeds but the content began to reduce in early June and became barely detectable in early July. On the other hand, amygdalin appeared in early June and then increased rapidly to the maximum level (100mg/g dw) in late June. Such a corresponding increase in amygdalin content with decreasing prunasin concentrations suggests the conversion of prunasin to amygdalin. β-Cyanoalanine synthase activity in the seed was considerably higher than in the flesh. The activity in the seed was kept consistent at early stages (5.6-7.6 μmol H2S/g fw/hr) but further increased in parallel with the increasing amygdalin concentrations to the maximum level as high as 100μmol H2S/g fw/hr.

Determination of Cyanogenic Glycoside in Seeds by Molecular Absorption Spectrometry in the Gas Phase

Abstract As a means of evaluating cyanogenic glycoside content, cyanide was determined in apple, cherry, almond, and peach seeds. Sample preparation involved enzymatic hydrolysis and collection of hydrogen cyanide in strong base. For analysis, cyanide was converted to ammonium by addition of excess KMn04 followed by treatment with H2S04, and the resulting NH4+ was determined by the novel gas-phase molecular absorption spectrometric technique. An atomic absorption spectrophotometer, with a flow-through absorption cell replacing the flame, was used in the analysis. Recovery of amygdalin was 98.4 ± 1.2% complete. Cyanogenic glycoside contents determined in seeds (0.93% for apple, 2.05% for cherry, 2.43% for peach, and 0.00% for almond, reported in terms of amygdalin), were confirmed by a standard titration method. The lowest detectable concentration was 0.2 μg NH4+/mL, which corresponds to a detection limit of 0.5 mg amygdalin in the seed sample.

The cyanogenic glycoside contents of raw and processed limabean varieties

Eighteen varieties of limabean (Phaseolus lunatus), were subjected to the processes of cooking, autoclaving, soaking in water and germination for 6 days. The effects of these processes on the free and bound HCN contents of the raw limabean varieties were investigated. Total HCN in the raw varieties ranged from 265 mg kg −1 in TPL 071-33 and 553 mg kg −1 in TPL 13. Considerable variability was encountered in the different varieties and processing effects tended to make these varietal differences even more pronounced. Autoclaving gave a mean total loss of 53·9% in total HCN content while cooking effected a 64·8%–81·9% loss in total HCN content. Drastic reductions in both free and bound HCN contents were obtained in all cooked varieties. Soaking for 2 days effected the highest HCN loss in TPL 2 (40·1%), closely followed by TPL 13 (39·7%) and then TPL 3 (35·4%). All varieties, by the sixth day of soaking, lost between 61·3 and 86·4% of their total HCN contents. The effect of germination on HCN contents increased progressively from a mean total loss of 24·5% in day 2 to 55·6% in day 4 and 76·1% in day 6. Cooking and germination for 6 days appeared to be equally effective in reducing free and bound contents. Autoclaving was the least effective of all the processes studied.

Differential effects on the cyanogenic glycoside content of fermenting cassava root pulp by β-glucosidase and microbial activities

The degradation of cyanogenic glycosides was studied in spontaneously fermenting cassava root pulp and in fresh pulp samples pretreated to prevent either endogenous β-glycosidase activity, fermentation, or both. The rate of disappearance of the glycosides, as measured by hydrocyanic acid (HCN) production in situ, in membrane-sterilised media or in samples containing 1% sodium iodoacetate, was comparable with the untreated control in which 85% of the substrate was broken down within 72 h. Pretreatment of the fresh pulp with the β-glucosidase inhibitor 1,5-gluconolactone (1%) markedly reduced the rate of disappearance of the cyanogens while inclusion of glucose in this test medium at the 3% level appeared to induce some hydrolysis. Loss of bound (glycosidic) cyanide in sterilised medium containing the glucosidase inhibitor was negligible. The results suggest that the contribution of the fermentation process in cyanide detoxification of pulped cassava roots is minimal.

A pear rootstock trial in Israel

The pear cultivars ‘Spadona Estiva’, ‘Coscia’, ‘Beurré Superfin’ and a ‘Bartlett’ clone of South African origin (termed ‘Bartlett Sport’) were tested on 5 quince rootstock types, 5 Pyrus species and on 5 or 30 cm long interstocks of the pear cultivars ‘Bergamotte Esperen’ and ‘Spadona Estiva’ on quince MA, while ‘Dr. Jules Guyot’ was used as an interstock on ‘Bartlett’ seedlings. At the age of 10 years only ‘Spadona Estiva’ showed no signs of decline on quince rootstocks, ‘Coscia’ showed moderate decline, while the remaining cultivars had already declined severely. When the trunk circumference of ‘Beurré Superfin’ trees on the various quince clones was taken as an indicator for the degree of graft incompatibility, a negative correlation was found between this parameter and cyanogenic glycoside content in the stem bark of ungrafted quince plants belonging to the same clones. Pear interstocks on quince MA rootstocks did in some cases increase crops compared to the same quince alone, but did not prevent the decline of ‘Beurré Superfin’ and Bartlett Sport' on quince. The most vigorous and most prolific rootstock was Pyrus betulaefolia. However, with ‘Spadona Estiva’ differences in vigor between the rootstocks were only small and crops on the Israeli quince CI 7 were similar to those on Pyrus betulaefolia, but fruit size was larger on quince. Cropping of this cultivar at the age of 4 years was closely related to the intensity of flowering, whereas with ‘Coscia’ this relation was much less evident. Leaf fall in autumn and the opening of the vegetative buds of ‘Beurré Superfin’ in spring were earlier on quince than on Pyrus rootstocks.

Differential Sensitivity to Waterlogging and Cyanogenesis by Peach, Apricot, and Plum Roots1

Abstract Individual plants varied considerably, but peach and apricot were more sensitive to waterlogging than was plum. No differences were established between peach and apricot. All 3 species became more sensitive as temperature was increased between 17 and 27°C. More than half of the plum seedlings survived at 17°C whereas all plants of the other 2 species died. A scion of a more tolerant species did not overcome the sensitivity of the roots. Both cyanogenic glycoside content and the proportion of it that was hydrolyzed during waterlogging were higher in peach than in plum roots. Exposure of detached root systems of all 3 species to anaerobic conditions caused HCN to be released. The rate of cyanogenesis increased with both temperature and time. Peach and apricot roots were alike in HCN evolution whereas plum roots were lower, with release of HCN being barely detectable at 22°C. Cyanogenesis was significant in peach and apricot at as low as 17°C. A close association exists among differential sensitivity, glycoside hydrolysis, and cyanogenesis in the absence of O2. However, the latter may be secondary, though contributory, to cellular disorganization as a cause of sensitivity.