α-Chaconine is a steroidal

glycoalkaloid Glycoalkaloids are a family of chemical compounds derived from alkaloids to which sugar groups are appended. Several are potentially toxic, most notably the poisons commonly found in the plant species '' Solanum dulcamara'' (bittersweet nightshad ...

that occurs in plants of the family

Solanaceae Solanaceae (), commonly known as the nightshades, is a family of flowering plants in the order Solanales. It contains approximately 2,700 species, several of which are used as agricultural crops, medicinal plants, and ornamental plants. Many me ...

. It is a natural

toxicant A toxicant is any toxic substance, whether artificial or naturally occurring. By contrast, a toxin is a poison produced naturally by an organism (e.g. plant, animal, insect, bacterium). The different types of toxicants can be found in the air, so ...

produced in green

potatoes The potato () is a starchy tuberous vegetable native to the Americas that is consumed as a staple food in many parts of the world. Potatoes are underground stem tubers of the plant ''Solanum tuberosum'', a perennial in the nightshade famil ...

and gives the potato a bitter taste.

Tubers Tubers are a type of enlarged structure that plants use as storage organs for nutrients, derived from stems or roots. Tubers help plants perennate (survive winter or dry months), provide energy and nutrients, and are a means of asexual reprod ...

produce this glycoalkaloid in response to stress, providing the plant with insecticidal and fungicidal properties. It belongs to the chemical family of

saponin Saponins (Latin ''sapon'', 'soap' + ''-in'', 'one of') are bitter-tasting, usually toxic plant-derived secondary metabolites. They are organic chemicals that become foamy when agitated in water and have high molecular weight. They are present ...

s. Since it causes physiological effects on individual organism, chaconine is considered to be a defensive

allelochemical Allelopathy is a biological phenomenon by which an organism produces one or more biochemicals that influence the germination, growth, survival, and reproduction of other organisms. These biochemicals are known as allelochemicals and can have ben ...

Solanine Solanine is a glycoalkaloid poison found in species of the Solanaceae, nightshade family within the genus ''Solanum'', such as the potato (''Solanum tuberosum''). It can occur naturally in any part of the plant, including the Leaf, leaves, frui ...

, a related substance also found in potatoes, has similar properties.

Symptoms and treatment

Symptoms resemble those seen following solanine ingestion including abdominal pain, diarrhea, and headache. There is currently no

antidote An antidote is a substance that can counteract a form of poisoning. The term ultimately derives from the Greek term φάρμακον ἀντίδοτον ''(pharmakon antidoton)'', "(medicine) given as a remedy". An older term in English which is ...

for detoxification but if it is just after consumption, taking laxatives or gastric lavage could be effective. The symptoms could last several days.

Toxicity

The presence of more than 20 mg/100 g tuber glycoalkaloids is toxic for humans. There have been instances of fatal poisoning cases from potatoes with high glycoalkaloid content. However, such cases are rare. Some research shows teratogenic effects on humans, but epidemiological investigations have produced conflicting research, as well. Levels of glycoalkaloids most likely differ by cultivar, storage conditions (especially exposure to sunlight), and processing techniques.

Difference from solanine

Structural difference

Although α-chaconine and α-solanine are both derived from

solanidine Solanidine is a poisonous steroidal alkaloid chemical Chemical compound, compound that occurs in plants of the family Solanaceae, such as potato and ''Solanum americanum''. The sugar portion of glycoalkaloids hydrolyses in the body, leaving the so ...

, the difference appears in 3 groups attached to the terminal oxygen in solanidine. For α-chaconine, these groups are one -glucose and two -rhamnose whereas in α-solanine, they are -galactose, -glucose, and -rhamnose.

Difference in toxicity

In an experiment demonstrating the feeding-inhibition effect of solanine and chaconine on snails, chaconine had a greater effect than solanine. However, a mixture of chaconine and solanine had a synergistic effect. The mixture had a significantly higher effect of deterred feeding than using solanine and chaconine on their own.

Ratio of ɑ-chaconine to ɑ-solanine in potato

On average, it is between 1.2 and 2.6 to 1, meaning the amount of ɑ-chaconine is greater than ɑ-solanine. However, the average ratio for the peel was 2.0 whereas that for the flesh was nearly 1.5. Also, the ratio was not consistent and depended on cultivar, growth condition, and method of storage.

Research on glycoalkaloids

Controlling the amount of steroidal glycoalkaloids in potatoes

In 2014, a research group in Japan from the Institute of Physical and Chemical Research (or RIKEN) found

genes In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...

for

enzymes An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as pro ...

that are involved in the synthesis of

cholesterol Cholesterol is the principal sterol of all higher animals, distributed in body Tissue (biology), tissues, especially the brain and spinal cord, and in Animal fat, animal fats and oils. Cholesterol is biosynthesis, biosynthesized by all anima ...

, cycloartanol, and related steroidal glycoalkaloids (SGAs), SSR2. Since SGAs are biosynthesized from cholesterol, restricting those enzymes could reduce the amount of the SGAs in potato.

Level of glycoalkaloids

The research studied the effects of different cooking techniques on the amount of glycoalkaloids (containing more than 90% of both solanine and chaconine). The techniques studied were boiling, baking, frying, and microwaving. The research found that fried peel has the largest amount of glycoalkaloids (139–145 mg/100 g of product), whereas potatoes prepared with other methods contained an average amount of 3 mg/100 g product. Another research found the amount of SGAs is unaffected by baking, boiling, and frying. This research also showed very high level of SGAs with non-peeled potato tubers (200 mg kg⁻¹ FM). In 2004, one study that investigated the change in the amount of α-chaconine and α-solanine over 90 days. The result showed how the amount of both α-chaconine and α-solanine did not change significantly if it is kept in a cold and dark place. While the amount varied slightly, the research concluded that it is due to the cultivar.

Treating poisons in potato

Peels and sprouts usually contain high level of SGAs. Relatively larger amounts can be found if the tuber is exposed to sunlight. If tubers are not matured enough, those might contain high level of chaconine and solanine. Thus, sprouts on potato and peels should be removed and if there are green parts inside the potato, it should be removed as well. It should be preserved in a dark and cold place, but it does not have to be in the fridge. It is likely to germinate or degrade when the surrounding is above 20 °C. Heating might not be very effective towards SGAs, therefore, those contain high level of SGAs should be carefully removed. Also, if potatoes are kept in a fridge, it increases the amount of sugar. When cooked, such as frying or baking,

acrylamide Acrylamide (or acrylic amide) is an organic compound with the chemical formula CH2=CHC(O)NH2. It is a white odorless solid, soluble in water and several organic solvents. From the chemistry perspective, acrylamide is a vinyl-substituted primary ...

can form. When cooking potatoes, if it is fried at 210 °C for 10 minutes, the amount of solanine and chaconine is reduced to 60% of the original amount. If it is fried at 170 °C for 5 minutes, there was no significant change in the amount of solanine and chaconine. However, if it is fried for 15 minutes at the same temperature, solanine decreased to 76.1% and chaconine decreased to 81.5%. Thus, the break down of solanine and chaconine are considered to start around 170 °C. In another study, a solution containing α-solanine and α-chaconine is put into boiling water for 150 minutes. The study found no significant decrease in the amount of solanine and chaconine. Therefore, it can be considered that boiling potato is not effective to reduce the amount of solanine and chaconine. Also, since glycoalkaloids are soluble in water, soaking potatoes in water may cause SGAs to dissolve into the water.

Attempts to make toxin-free potato

Research was launched in 2015 attempting to make potatoes with no glycoalkaloids by

genome editing Genome editing, or genome engineering, or gene editing, is a type of genetic engineering in which DNA is inserted, deleted, modified or replaced in the genome of a living organism. Unlike early genetic engineering techniques that randomly insert ge ...

. Because glycoalkaloids heavily affect human health, it is necessary to test for the amount present in potatoes, an expense that would be saved if a glycoalkaloid-free potato were available, in addition to being a more healthy food. Part of the research involves trying to determine what advantage potatoes achieve from producing glycoalkaloids. Research has been published suggesting that potatoes benefit little from the production of glycoalkaloids, though other research have questioned that conclusion.

References

External links

*{{Commons category-inline Steroidal alkaloids Alkaloid glycosides Saponins Plant toxins Steroidal alkaloids found in Solanaceae