Cyanogenic Glycosides: A Modern Take
🌿 Introduction
Cyanogenic glycosides are a class of natural compounds found in many plants. These compounds consist of a sugar molecule bound to a cyanide-containing molecule. When broken down by plant or digestive enzymes, cyanide is released.
While cyanogenic glycosides can be toxic in high doses, they may also have health benefits in moderation. The acute lethal dose of hydrogen cyanide (HCN) is estimated at 0.5–3.5 mg/kg body weight for humans and 0.66–15 mg/kg for animals (Reddy, 2006).
⚠️ Importance of Cyanogenic Glycosides
- Determination of Cause of Death: In forensic cases, detecting cyanogenic glycosides in post-mortem samples can reveal poisoning as a cause of death. Cyanide toxicity often leads to respiratory or cardiac failure (Ferslew et al., 2017).
- Exposure Assessment: Blood and urine analysis can assess exposure to toxic plants and related health effects (Jolly et al., 2020).
- Identification of Toxic Plants: Cyanogenic glycosides help identify harmful plant materials in poisoning cases, including suicides or abuse (Musshoff et al., 2018).
- Quantifying Toxicity: Tools like GC-MS and HPLC measure cyanogenic glycosides to determine toxin levels in plants (Zhou et al., 2019).
🌱 Sources of Cyanogenic Glycosides
🥔 Cassava
Cassava parts (leaves, stems, roots) are rich in cyanogenic glycosides like linamarin and lotaustralin, with levels ranging from 75 to 350 ppm, sometimes exceeding 1000 ppm depending on conditions.
🍠 Cocoyam
Cocoyam, a nutrient-rich tuber, contains low levels of cyanogenic glycosides (2.10–17.13 mg/100g), making it safer than cassava.
🎋 Bamboo Shoots
Bamboo shoots hold high levels of cyanogenic glycosides, particularly taxiphyllin (1000–8000 mg/kg HCN). Proper processing reduces toxicity.
🍎 Apple Seeds
Apple seeds contain amygdalin, releasing cyanide when digested. Levels vary from 1–4 mg/g in seeds to 0.001–0.08 mg/ml in apple juice.
☠️ Toxicity of Cyanogenic Glycosides
Cyanogenic glycosides release hydrogen cyanide (HCN) during breakdown, posing toxicity risks to humans and animals. This occurs through hydrolysis catalyzed by enzymes like β-glycosidase or under acidic conditions.
The reaction can be summarized as:
Cyanogenic glycoside + β-glycosidase → Cyanogenic aglycone + Glucose → HCN + Glucose
Studies show high levels of cyanide release during processing or digestion of certain plants:
- Cassava: Cassava leaves release toxic levels of HCN during processing (Siritunga et al., 2011).
- Bitter Cassava: Hydrolysis leads to HCN release, causing toxicity (Bekele et al., 2018).
🕵️♂️ Forensic Importance of Cyanogenic Glycosides
Cyanogenic glycosides play a significant role in forensic investigations, particularly in cases of plant poisoning and food safety. Their detection and quantification provide critical evidence for determining the source of toxicity and cause of death.
- Cassava Poisoning: Improperly processed cassava with high cyanogenic glycoside levels can lead to fatal poisoning. Detecting these compounds helps confirm the cause of death (Bentsi-Enchill et al., 2014).
- Plant Material Identification: Cyanogenic glycosides can serve as markers in forensic cases involving plant material, such as homicide investigations (Kusch et al., 2015).
- Food Safety: Regulatory limits on cyanogenic glycosides in foods, like almonds and apricot kernels, reduce toxicity risks (European Commission, 2002).
⚠️ Case Study: Mass Cyanide Poisoning from Bamboo Shoots
In a bamboo shoot pickling factory in central Thailand, an accident occurred when a worker dropped a 20 kg bag of fresh sliced bamboo shoots into a large pickling well. The well had a capacity of 27 m³ and was partially filled with 20 MT of bamboo shoots.
Several workers jumped into the well to rescue the first victim but immediately lost consciousness due to exposure to toxic cyanogenic glycosides. The scenario escalated as more people jumped in to help, resulting in multiple unconscious workers. Ultimately, the victims were rescued and transferred to the hospital 30 minutes later.
Initial clinical tests revealed metabolic acidosis, high anion gap, and symptoms like pulmonary edema and cardiac arrest in the most severely affected workers. Cyanide poisoning was suspected, and blood samples confirmed the diagnosis. Tragically, some victims died despite efforts, while others recovered after intensive care.
The case highlighted the critical importance of detecting cyanide levels in blood samples and promptly providing medical treatment for cyanide poisoning.
📚 References
- PENSIRIWAN SANG-A-GAD, SURIYA GUHARAT, WINAI WANANUKUL. A mass cyanide poisoning from pickling bamboo shoots, ResearchGate.
- Islamiyat Folashade Bolarinwa, Moruf Olanrewaju Oke, Sulaiman Adebisi Olaniyan, and Adeladun Stephen Ajala. A Review of Cyanogenic Glycosides in Edible Plants, ResearchGate.
- Manash Pratim Sharma. Analysis of Cyanide Concentration in Five Selected Bamboo Shoots Consumed in North East India, Medwin Publishers.
- Ming Ding and Kailiang Wang. Determination of cyanide in bamboo shoots by microdiffusion combined with ion chromatography–pulsed amperometric detection, The Royal Society Publishing.
- CYANOGENIC GLYCOSIDES - INFORMATION SHEET, New Zealand Food Safety Authority.
- Roslyn M. Gleadow and Birger Lindberg Møller. Cyanogenic Glycosides: Synthesis, Physiology, and Phenotypic Plasticity, Annual Review of Plant Biology.
- Onojah, P.K., and Odin, E. M. Cyanogenic Glycoside in Food Plants, International Journal of Innovation in Science and Mathematics.
- "Toxic Plants of North America" by George E. Burrows and Ronald J. Tyrl, Wiley & Sons.
- Bentsi-Enchill et al., 2014.
- Aremu, M. O., & Olaofe, O. (2021). Cyanogenic glycosides in cassava: potential health implications and management strategies. Journal of Food Science and Technology, 58(2), 399-408.
- Choudhury, M., & Gogoi, B. (2021). Cyanogenic glycosides in bamboo shoot: An overview. Current Research in Food Science, 4, 98-102.