Picrate Paper Research Articles

Analysis of Cyanide in Bulbs of Gadung Crackers For sale in Pelem Village, Tulungagung Regency using Complex Formation Titration Method

Gadung tubers or Dioscorea hispida are tubers that originally grew in the forest and are used as alternative food ingredients to replace rice and corn. One of the preparations from gadung tubers that is popular with the community is gadung tuber crackers. Before being processed into food, gadung tubers must be processed properly so that the cyanide content is reduced. Cyanide is a goitrogenic substance that is naturally found in foodstuffs. The purpose of this study was to determine the cyanide content in gadung root crackers. In this study, 3 samples were sold in Pelem Village, Tulungagung Regency. Cyanide analysis was carried out by qualitative test using picrate paper and quantitative test using complex formation titration. The cyanide content in the sample was 2.124 mg/kg; 0.9 mg/kg; 1,386 mg/kg.

Effectiveness of Levilactobacillus brevis fermentation on antinutrients and protein quality of leaves of selected cassava varieties

This study aimed to determine the effect of fermentation using an isolated Levilactobacillus brevis strain on the antinutrients and the protein quality of cassava leaves. Cassava leaves from tajirika and kibandameno variety which are considered bitter and sweet varieties, respectively, were fermented using the probiotic isolate and spontaneous fermentation was used as a control. The antinutrients of interest were cyanide and phytic acid whereas the protein quality of the leaves was analyzed in terms of the total crude protein and in-vitro digestibility. These were analyzed using standard procedures namely; picrate paper method for cyanide, spectrophotometry for phytic acid, Kjedahl method for the crude protein, and trypsin and pepsin enzymes simulation for the actual human digestion process for the in vitro protein digestibility. The data obtained was analyzed using the SPSS software and means separated at p < 0.05. The results obtained showed a decrease in the level of both the cyanide and phytic acid as the fermentation time increased. The cyanide levels were reduced by >37% with the L. brevis isolate for both cassava varieties which was higher than 20–33% for the spontaneous fermentation (control). The crude protein in both the varieties ranged between 28% and 32% and improved up to 43% on fermentation. Upon digestion of the cassava leaves, the in vitro protein digestibility improved from 63% up to 94%. The findings of this study therefore indicates that the Levilactobacillus brevis isolate can reduce cyanide and phytic acid as well as improve the protein quality by increasing the crude protein content and enhancing the digestibility of protein in cassava leaves of kibandameno and tajirika varieties, hence can be used to detoxify cassava leaves and for food formulation.

Impact of Seasonal Variation and Processing Methods on the Cassava-Derived Dietary Cyanide Poisoning, Nutritional Status, and Konzo Appearance in South-Kivu, Eastern D.R. Congo

This study aimed at evaluating the impact of seasons on the nutritional status and on dietary cassava-related cyanide exposure in Burhinyi and Idjwi, two areas in the eastern Democratic Republic of the Congo, witnessing similarly high cassava-derived cyanide poisoning but differently affected by konzo and malnutrition. Cyanide content in cassava roots and flour, and urinary thiocyanate levels (uSCN) of 54 subjects (40 from Burhinyi and 14 from Idjwi, aged 28.7 (12.1) years, 63% women) were measured during the rainy season (RS) and dry season (DS), using picrate paper kits A and D1. Local processing methods proved to be efficient in removing cyanogenic compounds in fresh cassava roots during the RS. However, the cyanide content in flour samples significantly increased during DS, with ~50% of samples containing unsafe levels (&gt;10 ppm) of cyanide content. Strikingly, the uSCN (µmol/L), from being comparably high in RS (~172.0), slightly decreased during DS in Burhinyi (~103.2; p = 0,3547), but not in Idjwi (~172; p = 0,1113). Furthermore, serum proteins and albumin levels significantly decreased during the DS, witnessing a worsening of nutritional status, in Burhinyi but not in Idjwi. The consumption of bitter cassava roots (OR = 5.43, p = 0.0144) and skipping heap fermentation (OR = 16.67, p = 0.0021) were independently associated with very high uSCN levels during the DS. Thus, restoring the traditional processing methods, and complying with them in either season should ensure the safe consumption of cassava.

Phenolic substances and cyanogenesis in galled and non-galled tissue of the fern species Microgramma vacciniifolia.

Galls, neo-formed plant structures that can occur in different organs, are generated by species-specific interaction with an inducing organism. Inducers manipulate the metabolism of its host. Microgramma vacciniifolia (Langsd. & Fisch.) Copel. is a Neotropical epiphytic fern that hosted two stem galls, one induced by a midge species (Diptera) and other by a micromoth species (Lepidoptera). The aim of this study was to evaluate the impact of these two gall-inducing insects on the biochemistry of phenolic acids and the cyanogenesis in galls, stems and leaves of M. vacciniifolia. High performance liquid chromatography (HPLC) indicated a total of 14 phenol derivatives, including caffeic and coumaric acid. Principal Coordinates Analysis (PCoA) of the phenolic substances indicated three groups consisting (1) non-galled stems and micromoth-induced galls; (2) midge-induced galls; (3) midge-induced galls with parasitoids. Regarding the frequency of cyanogenesis assessed by the picrate paper test, the chi-squared test showed significant difference between fertile leaves (8.3%), sterile leaves (27.7%), non-galled stems (0%) and galls. Among galls, only the midge-induced galls analyzed were cyanogenic (15%). Our results indicated that the different gall-inducers (midge and micromoth) promote species-specific alterations to the phenolic substance composition of the host fern.

Comparison of cyanide content in arbila beans (Phaseolus lunatus l) of East Nusa Tenggara using picrate and acid hydrolysis methods

Arbila beans contains cyanogenic compounds in the form of linamarin (cyanoglucosides), acetone cyanohydrin, and free cyanide, all together constitute total cyanide content. The objective of this study was to compare the cyanide content in arbila beans analyzed by picrate and acid hydrolysis methods. Picrate method measures total cyanide only. Cyanide content was identified by using a picrate paper, which turned into yellow. The absorbance was measured by a spectrophotometer at 510 nm. Acid hydrolysis method measures cyanide in arbila beans in the form of linamarin, acetone cyanohydrin, and free cyanide. Linamarin wa hydrolyzed in H3PO4 solution. Estimated cyanide levels was measured by using a colorimetric procedure. Data was analyzed using Independent sample t-test (SPSS v.16). The results showed that, there was no difference in the total level of cyanide in both methods. Total cyanide measured by picrate and acid hydrolysis method was 2705.17 ppm and 2693.29 ppm, respectively. In addition, the three forms of cyanide content were as follows: linamarin 926.22 ppm, cyanohydrin 556.01 ppm, and free cyanide 1211.06 ppm. Based on the results, both methods can be used for total cyanide analysis. To determine the form of cyanide other than total cyanide, it is recommended to use the acid hydrolysis method.

Cyanogenic Glycoside Analysis in American Elderberry.

Cyanogenic glycosides (CNGs) are naturally occurring plant molecules (nitrogenous plant secondary metabolites) which consist of an aglycone and a sugar moiety. Hydrogen cyanide (HCN) is released from these compounds following enzymatic hydrolysis causing potential toxicity issues. The presence of CNGs in American elderberry (AE) fruit, Sambucus nigra (subsp. canadensis), is uncertain. A sensitive, reproducible and robust LC-MS/MS method was developed and optimized for accurate identification and quantification of the intact glycoside. A complimentary picrate paper test method was modified to determine the total cyanogenic potential (TCP). TCP analysis was performed using a camera-phone and UV-Vis spectrophotometry. A method validation was conducted and the developed methods were successfully applied to the assessment of TCP and quantification of intact CNGs in different tissues of AE samples. Results showed no quantifiable trace of CNGs in commercial AE juice. Levels of CNGs found in various fruit tissues of AE cultivars studied ranged from between 0.12 and 6.38 µg/g. In pressed juice samples, the concentration range measured was 0.29–2.36 µg/mL and in seeds the levels were 0.12–2.38 µg/g. TCP was highest in the stems and green berries. Concentration levels in all tissues were generally low and at a level that poses no threat to consumers of fresh and processed AE products.

Experimental reproduction of cyanogenic poisoning by star grass (Cynodon nlemfuensis Vanderyst var. nlemfuensis cv. “Florico”) in cattle

ABSTRACT: We experimentally reproduced star grass (Cynodon nlemfuensis Vanderyst var. nlemfuensis cv. “Florico”) poisoning in cattle. Star grass was planted in four shaded (1, 2, 3, and 4) and three sunny paddocks (5, 6, and 7) and were fertilized with the equivalent of 0, 750, 200, or 100 kg/ha urea. Fresh plant leaves were collected from each paddock and fed to 8 calves aged 5 months to 1 year at 10g/kg live weight. Clinical examinations were performed pre- and post-feeding. Fresh leaves were also subjected to sodium picrate paper and diphenylamine tests to evaluate hydrocyanic acid and nitrate concentration, respectively. Clinical signs of poisoning by the star grass cv. “Florico” in cattle were observed 5-15 minutes after ingestion; these included wobbling, muscle tremors, frequent and/or dripping urination, tachycardia, ruminal atony, depression, red ocular mucous membranes, and bright red venous blood. Three animals became severely ill, 4 manifested mild to moderate clinical signs, and 1 did not become ill. The 3 severely ill bovines received a thiosulfate and sodium nitrite solution at a dose of 40ml/100 kg live weight, intravenously (IV). Florico star grass poisoned bovines and the reaction to the sodium picrate paper and diphenylamine tests was more significant for samples cultivated in the shade and with high nitrogen fertilization. Florico grass utilization should be avoided in a silvopastoral system.

Evaluation of Cyanide Levels in Two Cassava Varieties (&lt;i&gt;Mariwa&lt;/i&gt; and &lt;i&gt;Nyakatanegi&lt;/i&gt;) Grown in Bar-agulu, Siaya County, Kenya

Mannihot esculenta Crantz (Cassava) is the second highest producer of carbohydrates after sugarcane. However, some varieties have high levels of cyanogenic glycosides and therefore are potentially toxic for human consumption. Nyakatanegi is one of the local varieties cultivated in Bar-agulu village in Siaya County (Kenya) and has been severally in the recent past reported to cause fatal cyanide toxicity. The other variety which is rarely associated with cassava poisoning is Mariwa. The objective of the current study was to determine cyanide levels in the two cassava varieties (Mariwa and Nyakatanegi) which are locally cultivated in Siaya County. The study was based on three laboratory assays: the picrate paper, picrate in solution and titration. Whole root cassava tubers were collected from a farmer in Bar-agulu village, Siaya County, packaged separately and transported to Mount Kenya University Pharmaceutical Chemistry Laboratory for analysis. Voucher specimens were authenticated in the cassava laboratories at Jomo Kenyatta University of Agriculture and Technology. It was observed that all the cortex samples of Nyakatanegi variety had the highest concentrations of cyanide giving 400 ppm for the picrate paper assay, 14.10 mg/Kg for the picrate in solution and 63 mg/Kg for the titration assays. On the other hand, the cortex samples of Mariwa reported cyanide concentrations of 30 ppm, 11.20 mg/Kg and 27.20 mg/Kg for the picrate paper, picrate in solution and titration assays respectively. The results showed higher amounts of cyanide in the tested cassava varieties than the WHO recommended levels (10 mg/Kg) especially the Nyakatanegi variety. Based on these results, sensitization campaigns are necessary to minimize cases of cyanide poisoning following cassava consumption.

Hydrogen peroxide as a new defensive compound in "benzoyl cyanide" producing polydesmid millipedes.

Hydrogen peroxide was newly and simultaneously demonstrated with well-known hydrogen cyanide as a component of defensive secretions of "benzoyl cyanide" producing polydesmid millipedes. Presence of hydrogen peroxide was successively evidenced by Trinder reagent's spray with colorless as well as oily smears of defensive secretions containing benzoyl cyanide and hydrogen cyanide by alkaline picrate paper treatment. Linear correlation was demonstrated between quantities of hydrogen peroxide and benzoyl cyanide. By qualitative assay, seven benzoyl cyanide containing polydesmidans (six species of adults and one species of a nymph at stadium I) tested positive to Trinder reagent, indicative of the presence of hydrogen peroxide (together with hydrogen cyanide), while two cyanogenic species without benzoyl cyanide exhibited negative responses to the reagent. Two types of millipedes were elucidated as species of cyanogenic Polydesmida.

THE CYANOGENIC POTENTIAL OF ROOTS AND LEAVES OF NINETY NINE CASSAVA CULTIVARS

Studies on cyanogenic potential (CP) of roots and leaves of Indonesian cassava germplasm are still inadequate in relation to food toxicity and on human health. The CP of leaves of 99 cassava cultivars was analyzed using picrate paper kits. Effort to reduce CP of cassava leaves by boiling them was also conducted. The results showed that roots and leaves had low and moderate level of CP. There was a significant correlation between the CP of leaves (Y) and roots (X) of 45 cassava cultivars with regression equation Y = 36.214 + 1.3085 X (r = 0.5228). The CP content was high in the young leaves (241 ppm) and low in the older ones (99 ppm). The proximal portion of the roots had the highest CP content (300 ppm), and that in the distal end was the lowest (56 ppm). The root part close to cortex had highest CP content (550 ppm), whereas the central part was the lowest (35 ppm). Boiling cassava leaves for 20 minutes significantly reduced the CP up to 75%, indicating that for safety, cassava should be completely processed or cooked. This study implied that CP content should be considered in cassava breeding programs. Forty two of 99 cassava cultivars have CP below 50 ppm which is safe for consumption.&lt;br /&gt;&lt;br /&gt;

THE CYANOGENIC POTENTIAL OF ROOTS AND LEAVES OF NINETY NINE CASSAVA CULTIVARS

Studies on cyanogenic potential (CP) of roots and leaves of Indonesian cassava germplasm are still inadequate in relation to food toxicity and on human health. The CP of leaves of 99 cassava cultivars was analyzed using picrate paper kits. Effort to reduce CP of cassava leaves by boiling them was also conducted. The results showed that roots and leaves had low and moderate level of CP. There was a significant correlation between the CP of leaves (Y) and roots (X) of 45 cassava cultivars with regression equation Y = 36.214 + 1.3085 X (r = 0.5228). The CP content was high in the young leaves (241 ppm) and low in the older ones (99 ppm). The proximal portion of the roots had the highest CP content (300 ppm), and that in the distal end was the lowest (56 ppm). The root part close to cortex had highest CP content (550 ppm), whereas the central part was the lowest (35 ppm). Boiling cassava leaves for 20 minutes significantly reduced the CP up to 75%, indicating that for safety, cassava should be completely processed or cooked. This study implied that CP content should be considered in cassava breeding programs. Forty two of 99 cassava cultivars have CP below 50 ppm which is safe for consumption.&lt;br /&gt;&lt;br /&gt;

Environmental Contamination from Industrial Bitter Cassava: Implications for Moisture-Pressure Combination Treatments

&lt;p&gt;Commercial processing of cassava produces vast quantities of cyanide-laced waste which can adversely infiltrate water supplies and air breathed by factory workers. This study aimed to determine the comparative concentration of cyanogens in the cassava peel as opposed to that of the pith and the effect of the moisture-pressure combination treatments on cyanide concentration. A semi-quantitiative test using the picrate-spectrophotometer method was applied, where, at room temperature in a closed vial, reactions caused liberation of HCN which reacts with a picrate paper. The results showed a 25% higher level of cyanogen concentration in casssava peels compared to that of blended peels and pith. Treatments released cyanide from samples in the order: 2 h wetting at 50 °C + pressing &amp;gt; 4 h wetting at 25 °C + pressing = 2 h wetting at 40 °C + pressing &amp;gt; 2 h wet at 25 °C + pressing = 4h wet at 25 °C &amp;gt; 12 h pressing. In this manner, wetting for 2 h at 50 °C followed by pressure for 12 h released cyanide by at least 20% more than that of any other treatment. The combination of moisture and pressure enhanced the contact time between linamarin and linamarase to increase the release of HCN. Physiological cyanide overload in organisms from cassava processing occurs in water, land, and air. Therefore the reduction in concentration observed in this study, if applied at an early stage of the cassava processing, should reduce the rate of morbidity in environments at risk.&lt;/p&gt;

Grazing intensity contributes to cyanogenic toxicity in savannah grasses in Baringo county

The potential role of anti-herbivory mechanisms used by plants and their synergistic responses to grazing and interactive effects on herbivores are poorly understood. The aim of this study was to quantify the influence of grazing intensity on cyanogenic glycosides in Lake Bogoria, Baringo County Kenya. Field experiments were carried out in ten 50×10m enclosures. Grazing intensity was varied using simulated grazing method where two grazing treatments used; heavy grazing and light grazing. Grasses were categorized into two age classes; young and old. Cyanigenic glycocides (CNglc) were tested using impregnated picrate paper and their concentration determined by hydrolysis and trapping in 1M NaOH. Our findings showed that five of 16 sampled species produce cyanogenic glycosides; Cynodon dactylon, Cynodon plectostachyus, Digitaria scalarum, Sporobolus spicatus and Cyperus laevigatus. There was an inverse relation between Cyanide concentration and age of the plants. Young cuttings yield more Hydrogen Cyanide than older cuttings of the same grasses.Grazing intensity had a significant effect on the concentration of cyanogenic content in some grass species; C.dactylon (P=0.024) and S. laevigatus (P=0.003). The findings imply that grazing regime of managed pastures should consider the age of forage while allowing utilization of pastures preferably grazed on mature pastures with low levels of cyanogenic glycosides.

Spontaneous and experimental poisoning by Marsdenia megalantha Goyder & Morillo in ruminants and a pig

Marsdenia megalantha is a rupicolous shrub with succulent roots from the semiarid region of Brazil that is known to cause fatal poisoning in livestock. We reported spontaneous cases of poisoning by M. megalantha roots in bovine, caprine, ovine, and equine species. The clinical and pathological findings of experimental administration of M. megalantha to sheep, goats, a calf and a pig are reported. Three goats, two sheep and a calf were dosed once orally with freshly chopped roots at dose of 25 g wet plant/kg bw; another sheep and a pig were dosed with 10 g wet plant/kg bw. Poisoning occurred in all of the animals except the three goats. Clinical signs of poisoning included tachycardia, opisthotonus, ruminal bloat, dyspnea, nystagmus, mydriasis, ataxia, and recumbence with paddling movements. Pathological evaluation showed segmental laminar neuronal necrosis and spongiosis in the telencephalic cortex and degeneration of Purkinje cells. The picrate paper procedure detected no cyanide in the plant roots, but the reaction used for nitrate detection gave a strongly positive response. In conclusion, M. megalantha is a poisonous plant that produces acute poisoning characterized mainly by nervous disturbances. Livestock producers should offer alternative food during the dry and early rainy seasons to avoid the poisoning by this plant.

Potential toxic levels of cyanide in cassava (Manihot esculenta Crantz) grown in Kenya

Cassava (Manihot esculenta Crantz) is a cyanogenic plant which is toxic when consumed without sufficient processing. Cassava is characterized by the presence of linamarin, a cyanogenic glycoside which can be hydrolyzed by endogenous linamarase enzyme to release hydrogen cyanide, in a process known as cyanogenesis. The study determined levels of cyanide in the sweet cassava variety collected from different districts in Kenya. Determination of cyanide contents of cassava was carried out spectrophotometrically using modified picrate paper method. Levels of cyanide in cassava varied significantly (p < 0.05) (n = 324) across the geographical location. Cyanide content of cassava from Kakamega was highest [80.79 ± 4.55 mg hydrogen cyanide (HCN) equivalents/kg of fresh cassava weight] followed by those from Kitui (70.46 ± 2.21 mg HCN equivalents/kg of fresh cassava weight), while cassava from Kisii had the lowest cyanide concentration (43.27 ± 3.75 mg HCN equivalents/kg of fresh cassava weight). The cyanide concentrations of cassava from the rest of the regions such as Nairobi and Thika fall in the middle, 66.00 ± 2.12 and 54.84 ± 6.5 mg HCN equivalents/kg of fresh cassava weight respectively. Nonetheless, the cyanide contents of cassava from the sampled regions were greater than the accepted level (10 mg/kg) by the World Health Organization (WHO). Key words: Cyanogenic glycoside, linamarase, cyanide, linamarin, cassava.

Soaking and drying of cassava roots reduced cyanogenic potential of three cassava varieties at Jimma, Southwest Ethiopia

Detoxification of three cassava varieties (NR-44/72, NW-45/72 and NW-44/72) by traditional methods of processing to produce cassava flour was investigated at the college of agriculture, Jimma University during February-May, 2007. Total HCN quantitative determination in cassava flour was carried out using a simple enzymatic picrate paper method developed by Dr. Haward Bradbury. Results showed that varieties, soaking time and their interactions highly significantly reduced (P<0.01) total HCN content (ppm) in the flour. Soaking of cassava chips in water for about 24 hours prior to sun drying reduced the HCN from 108.37 to 10.83 ppm (reduced by 90 %), from 66.45 to 13.33 ppm (reduced by 79.94%) and from 58.63 to 15.0 (reduced by 74.42 %) for varieties NW-44/72, NR-44/72 and NW-45/72, respectively. It was noted that total HCN content in cassava flour can be substantially eliminated (by more than 80%) by soaking of cassava chips in water. The present study highlighted the importance of soaking of cassava chips for at least 24 hours prior to sun drying for a safe level of HCN in the flour. However, it is also important to develop new and improved processing techniques to reduce HCN substantially.

A genome scan for quantitative trait loci affecting cyanogenic potential of cassava root in an outbred population

BackgroundCassava (Manihot esculenta Crantz) can produce cyanide, a toxic compound, without self-injury. That ability was called the cyanogenic potential (CN). This project aimed to identify quantitative trait loci (QTL) associated with the CN in an outbred population derived from 'Hanatee' × 'Huay Bong 60', two contrasting cultivars. CN was evaluated in 2008 and in 2009 at Rayong province, and in 2009 at Lop Buri province, Thailand. CN was measured using a picrate paper kit. QTL analysis affecting CN was performed with 303 SSR markers.ResultsThe phenotypic values showed continuous variation with transgressive segregation events with more (115 ppm) and less CN (15 ppm) than either parent ('Hanatee' had 33 ppm and 'Huay Bong 60' had 95 ppm). The linkage map consisted of 303 SSR markers, on 27 linkage groups with a map that encompassed 1,328 cM. The average marker interval was 5.8 cM. Five QTL underlying CN were detected. CN08R1from 2008 at Rayong, CN09R1and CN09R2 from 2009 at Rayong, and CN09L1 and CN09L2 from 2009 at Lop Buri were mapped on linkage group 2, 5, 10 and 11, respectively. Among all the identified QTL, CN09R1 was the most significantly associated with the CN trait with LOD score 5.75 and explained the greatest percentage of phenotypic variation (%Expl.) of 26%.ConclusionsFive new QTL affecting CN were successfully identified from 4 linkage groups. Discovery of these QTL can provide useful markers to assist in cassava breeding and studying genes affecting the trait.

Evaluation of cyanogenic potential and organoleptic properties in cassava (Manihot esculenta Crantz.) roots of improved varieties in Cte dIvoire

Fourteen cassava varieties (13 new improved cassava varieties and 1 local variety control) harvested at maturity in Cote d’Ivoire, were analysed for their cyanogenic potential of cassava root parenchyma with a picrate kit and organoleptic properties after boiling. Quantitative estimation of cyanogenic potential for cassava varieties was carried out by comparing the colour of picrate paper against those of known standard. The total cyanogens content of five improved varieties (98/2101, 98/0505, 98/0002, 96/1632 and TME419 with 9.1, 14, 10.5, 16.6 and 13.3 mg HCN kg-1 root fresh respectively) was significantly lower than that for the local variety control (ANADER2 with 36.2 mg HCN kg-1 root fresh) (p < 0.05). However, cyanogens levels in all cassava varieties were ranging from 9.1 to 36.2 mg HCN kg-1 root fresh, therefore, inferior to 50 mg HCN kg-1 root fresh, the safe level. All cassava varieties cooked, mealiness and melting qualities appear to be under genetic control. There were significant differences (p < 0.05) in the mealiness index between two improved varieties (98/0002 (1.8) and TME7 (1.7) and the local variety (ANADER2 (1.3). Results showed a strong correlation between mealiness and melting (R2 = 0.91), accordingly, melting could be predicted from mealiness. Key words: Cassava, improved varieties, cyanide, safe levels of cyanogens, mealiness, melting, Cote d’Ivoire.

Development of a sensitive picrate method to determine total cyanide and acetone cyanohydrin contents of gari from cassava

The sensitivity of the normal picrate method for determination of total cyanide in cassava was increased tenfold using a small 1 cm 2 picrate paper, eluted using 0.5 mL instead of 5 mL of water as in the normal method. The absorbance was measured in a 2 mm cuvette in the spectrophotometer. The sensitive method was calibrated against the normal picrate method. The total cyanide content in mg HCN equivalents/kg sample = ppm, is calculated from the absorbance (A) by the equation ppm = A × 45.7 which is applicable from 0.1 to 50 ppm. A new method to determine acetone cyanohydrin was developed based on irreversible denaturation of linamarase in 0.1 M HCl at 30 °C for 1 h. Five gari samples from Mozambique gave a mean total cyanide content of 12 ppm (range 6–15 ppm) and mean acetone cyanohydrin content of 11 ppm (range 5–14 ppm). Acetone cyanohydrin liberates cyanide quantitatively in the human intestine.

Cytotoxicity of purified cassava linamarin to a selected cancer cell lines

Cassava (Manihot esculenta Crantz) is a known source of linamarin, but difficulties associated with its isolation have prevented it from being exploited as a major source. A batch adsorption process using activated carbon proved successful in its isolation, with ultrafiltration playing a pivotal role in its purification. Thirty-two minutes of contact time was required for 60 g of extract, yielding 1.7 g of purified product. Picrate paper, infra-red and 'HNMR analysis confirmed the presence and structure of linamarin. Cytotoxic effects of linamarin on MCF-7, HT-29 and HL60 cells were determined using the MTT assay. Cytotoxic effects were significantly increased in the presence of linamarase (P-glucosidase), with a 10-fold decrease in the IC50 values obtained for HL-60 cells. This study thus describes a method for the isolation and purification of linamarin from cassava, as well as its cytotoxicity potential.