Solanine
Encyclopedia
Solanine is a glycoalkaloid
poison
found in species of the nightshade
family (Solanaceae
), such as the potato
(Solanum tuberosum). It can occur naturally in any part of the plant, including the leaves
, fruit
, and tuber
s. Solanine has fungicidal
and pesticidal
properties, and it is one of the plant's natural defenses
. Solanine was first isolated in 1820 by Desfosses from the berries
of the European black nightshade (Solanum nigrum
), after which it was named.
, stomach cramps, burning of the throat, cardiac dysrhythmia
, headache and dizziness. In more severe cases, hallucination
s, loss of sensation, paralysis
, fever
, jaundice
, dilated pupils, hypothermia
and death have been reported.
In large quantities, solanine poisoning can cause death. One study suggests that doses of 2 to 5 mg per kilogram of body weight can cause toxic symptoms, and doses of 3 to 6 mg per kilogram of body weight can be fatal.http://ntp-server.niehs.nih.gov/index.cfm?objectid=6F5E930D-F1F6-975E-7037ACA48ABB25F4
Symptoms usually occur 8 to 12 hours after ingestion, but may occur as rapidly as 30 minutes after eating high-solanine foods.
The lowest dose to cause symptoms of nausea is about 25 mg solanine for adults, a life-threatening dose for a regular-weight adult ranges about 400 mg solanine.
membranes. Experiments show that solanine exposure opens the potassium channel
s of mitochondria, decreasing their membrane potential
. This in turn leads to Ca2+ being transported from the mitochondria into the cytoplasm, and it is this increased concentration of Ca2+ in the cytoplasm that triggers cell damage and apoptosis
.
(which increases solanine and other glycoalkaloid
levels) and the incidence of congenital
spina bifida
in humans. However, other studies have shown no correlation between potato consumption and the incidence of birth defects.
, including the potato
(Solanum tuberosum), tomato
(Solanum lycopersicum), eggplant (Solanum melongena), and bittersweet nightshade (Solanum dulcamara
).
Potatoes naturally produce solanine and chaconine
, a related glycoalkaloid, as a defense mechanism
against insect
s, disease
, and predators
. Potato leaves
, stems
and shoot
s are naturally high in glycoalkaloids.
When potato tuber
s are exposed to light, they turn green and increase glycoalkaloid production. This is a natural defense to help prevent the uncovered tuber from being eaten. The green colour is from chlorophyll
, and is itself harmless. However, it is an indication that increased level of solanine and chaconine may be present.
Some diseases, such as late blight
, can dramatically increase the levels of glycoalkaloids present in potatoes. Mechanically damaged potatoes also produce increased levels of glycoalkaloids. This is believed to be a natural reaction of the plant in response to disease and damage.
Commercial varieties of potatoes are screened for solanine levels, and most have a solanine content of less than 0.2 mg/g. However, potatoes that have been exposed to light and started to green can show concentrations of 1 mg/g or more. In these situations a single unpeeled potato can result in a dangerous dose.
In potato tubers, 30–80% of the solanine develops in and close to the skin.
Showing green under the skin strongly suggests solanine build-up in potatoes, although each process can occur without the other. A bitter taste in a potato is another, potentially more reliable indicator of toxicity. Because of the bitter taste and appearance of such potatoes, solanine poisoning is rare outside conditions of food shortage. The symptoms are mainly vomiting
and diarrhea
, and the condition may be misdiagnosed as gastroenteritis
. Most potato poisoning victims recover fully, although fatalities are known, especially when victims are undernourished or do not receive suitable treatment. Fatalities are also known from solanine poisoning from other plants in the nightshade family, such as the berries of Solanum dulcamara
(woody nightshade).
The United States National Institutes of Health
's information on solanine says to never eat potatoes that are green below the skin.
Deep frying
potatoes at 170°C (306°F) is known to effectively lower glycoalkaloid levels (because they move into the frying fat), whereas microwaving
is only somewhat effective, freeze drying
or dehydration
has little effect, and boiling has no effect.
es and tomato leaves contain solanine. However, Dr. Mendel Friedman of the federal Department of Agriculture contradicts this claim stating that tomatine
, a relatively benign alkaloid, is the tomato alkaloid while solanine is found in potatoes. Food science writer Harold McGee
has found scant evidence for tomato toxicity in the medical and veterinary literature.
and pesticidal
properties, and solanine hydrochloride (a salt of solanine) has been used as a commercial pesticide, but never on a large scale.
Solanine has sedative
and anticonvulsant
properties, and has been used as a treatment for asthma
, as well as for cough
and cold
medicines. However, its effectiveness for either use is questionable.
Glycoalkaloid
Glycoalkaloids are a family of poisons commonly found in the plant species Solanum dulcamara . There are several glycoalkaloids that are potentially toxic. A prototypical glycoalkaloid is called solanine , which is found in potato...
poison
Poison
In the context of biology, poisons are substances that can cause disturbances to organisms, usually by chemical reaction or other activity on the molecular scale, when a sufficient quantity is absorbed by an organism....
found in species of the nightshade
Solanum
Solanum, the nightshades, horsenettles and relatives, is a large and diverse genus of annual and perennial plants. They grow as forbs, vines, subshrubs, shrubs, and small trees, and often have attractive fruit and flowers. Many formerly independent genera like Lycopersicon or Cyphomandra are...
family (Solanaceae
Solanaceae
Solanaceae are a family of flowering plants that include a number of important agricultural crops as well as many toxic plants. The name of the family comes from the Latin Solanum "the nightshade plant", but the further etymology of that word is unclear...
), such as the potato
Potato
The potato is a starchy, tuberous crop from the perennial Solanum tuberosum of the Solanaceae family . The word potato may refer to the plant itself as well as the edible tuber. In the region of the Andes, there are some other closely related cultivated potato species...
(Solanum tuberosum). It can occur naturally in any part of the plant, including the leaves
Leaf
A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....
, fruit
Fruit
In broad terms, a fruit is a structure of a plant that contains its seeds.The term has different meanings dependent on context. In non-technical usage, such as food preparation, fruit normally means the fleshy seed-associated structures of certain plants that are sweet and edible in the raw state,...
, and tuber
Tuber
Tubers are various types of modified plant structures that are enlarged to store nutrients. They are used by plants to survive the winter or dry months and provide energy and nutrients for regrowth during the next growing season and they are a means of asexual reproduction...
s. Solanine has fungicidal
Fungicide
Fungicides are chemical compounds or biological organisms used to kill or inhibit fungi or fungal spores. Fungi can cause serious damage in agriculture, resulting in critical losses of yield, quality and profit. Fungicides are used both in agriculture and to fight fungal infections in animals...
and pesticidal
Pesticide
Pesticides are substances or mixture of substances intended for preventing, destroying, repelling or mitigating any pest.A pesticide may be a chemical unicycle, biological agent , antimicrobial, disinfectant or device used against any pest...
properties, and it is one of the plant's natural defenses
Plant defense against herbivory
Plant defense against herbivory or host-plant resistance describes a range of adaptations evolved by plants which improve their survival and reproduction by reducing the impact of herbivores. Plants use several strategies to defend against damage caused by herbivores...
. Solanine was first isolated in 1820 by Desfosses from the berries
Berry
The botanical definition of a berry is a fleshy fruit produced from a single ovary. Grapes are an example. The berry is the most common type of fleshy fruit in which the entire ovary wall ripens into an edible pericarp. They may have one or more carpels with a thin covering and fleshy interiors....
of the European black nightshade (Solanum nigrum
Solanum nigrum
Solanum nigrum is a species in the Solanum genus, native to Eurasia and introduced in the Americas, Australasia and South Africa.-Description:Black...
), after which it was named.
Symptoms
Solanine poisoning is primarily displayed by gastrointestinal and neurological disorders. Symptoms include nausea, diarrhea, vomitingVomiting
Vomiting is the forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose...
, stomach cramps, burning of the throat, cardiac dysrhythmia
Cardiac dysrhythmia
Cardiac dysrhythmia is any of a large and heterogeneous group of conditions in which there is abnormal electrical activity in the heart. The heart beat may be too fast or too slow, and may be regular or irregular.Some arrhythmias are life-threatening medical emergencies that can result in cardiac...
, headache and dizziness. In more severe cases, hallucination
Hallucination
A hallucination, in the broadest sense of the word, is a perception in the absence of a stimulus. In a stricter sense, hallucinations are defined as perceptions in a conscious and awake state in the absence of external stimuli which have qualities of real perception, in that they are vivid,...
s, loss of sensation, paralysis
Paralysis
Paralysis is loss of muscle function for one or more muscles. Paralysis can be accompanied by a loss of feeling in the affected area if there is sensory damage as well as motor. A study conducted by the Christopher & Dana Reeve Foundation, suggests that about 1 in 50 people have been diagnosed...
, fever
Fever
Fever is a common medical sign characterized by an elevation of temperature above the normal range of due to an increase in the body temperature regulatory set-point. This increase in set-point triggers increased muscle tone and shivering.As a person's temperature increases, there is, in...
, jaundice
Jaundice
Jaundice is a yellowish pigmentation of the skin, the conjunctival membranes over the sclerae , and other mucous membranes caused by hyperbilirubinemia . This hyperbilirubinemia subsequently causes increased levels of bilirubin in the extracellular fluid...
, dilated pupils, hypothermia
Hypothermia
Hypothermia is a condition in which core temperature drops below the required temperature for normal metabolism and body functions which is defined as . Body temperature is usually maintained near a constant level of through biologic homeostasis or thermoregulation...
and death have been reported.
In large quantities, solanine poisoning can cause death. One study suggests that doses of 2 to 5 mg per kilogram of body weight can cause toxic symptoms, and doses of 3 to 6 mg per kilogram of body weight can be fatal.http://ntp-server.niehs.nih.gov/index.cfm?objectid=6F5E930D-F1F6-975E-7037ACA48ABB25F4
Symptoms usually occur 8 to 12 hours after ingestion, but may occur as rapidly as 30 minutes after eating high-solanine foods.
The lowest dose to cause symptoms of nausea is about 25 mg solanine for adults, a life-threatening dose for a regular-weight adult ranges about 400 mg solanine.
Mechanism of Action
One study suggests that the toxic mechanism of solanine is caused by the chemical's interaction with mitochondrialMitochondrion
In cell biology, a mitochondrion is a membrane-enclosed organelle found in most eukaryotic cells. These organelles range from 0.5 to 1.0 micrometers in diameter...
membranes. Experiments show that solanine exposure opens the potassium channel
Potassium channel
In the field of cell biology, potassium channels are the most widely distributed type of ion channel and are found in virtually all living organisms. They form potassium-selective pores that span cell membranes...
s of mitochondria, decreasing their membrane potential
Membrane potential
Membrane potential is the difference in electrical potential between the interior and exterior of a biological cell. All animal cells are surrounded by a plasma membrane composed of a lipid bilayer with a variety of types of proteins embedded in it...
. This in turn leads to Ca2+ being transported from the mitochondria into the cytoplasm, and it is this increased concentration of Ca2+ in the cytoplasm that triggers cell damage and apoptosis
Apoptosis
Apoptosis is the process of programmed cell death that may occur in multicellular organisms. Biochemical events lead to characteristic cell changes and death. These changes include blebbing, cell shrinkage, nuclear fragmentation, chromatin condensation, and chromosomal DNA fragmentation...
.
Correlation with birth defects
Some studies show a correlation between the consumption of potatoes suffering from late blightPhytophthora infestans
Phytophthora infestans is an oomycete that causes the serious potato disease known as late blight or potato blight. . Late blight was a major culprit in the 1840s European, the 1845 Irish and 1846 Highland potato famines...
(which increases solanine and other glycoalkaloid
Glycoalkaloid
Glycoalkaloids are a family of poisons commonly found in the plant species Solanum dulcamara . There are several glycoalkaloids that are potentially toxic. A prototypical glycoalkaloid is called solanine , which is found in potato...
levels) and the incidence of congenital
Congenital disorder
A congenital disorder, or congenital disease, is a condition existing at birth and often before birth, or that develops during the first month of life , regardless of causation...
spina bifida
Spina bifida
Spina bifida is a developmental congenital disorder caused by the incomplete closing of the embryonic neural tube. Some vertebrae overlying the spinal cord are not fully formed and remain unfused and open. If the opening is large enough, this allows a portion of the spinal cord to protrude through...
in humans. However, other studies have shown no correlation between potato consumption and the incidence of birth defects.
Solanine in potatoes
Solanine occurs naturally in many species of the genus SolanumSolanum
Solanum, the nightshades, horsenettles and relatives, is a large and diverse genus of annual and perennial plants. They grow as forbs, vines, subshrubs, shrubs, and small trees, and often have attractive fruit and flowers. Many formerly independent genera like Lycopersicon or Cyphomandra are...
, including the potato
Potato
The potato is a starchy, tuberous crop from the perennial Solanum tuberosum of the Solanaceae family . The word potato may refer to the plant itself as well as the edible tuber. In the region of the Andes, there are some other closely related cultivated potato species...
(Solanum tuberosum), tomato
Tomato
The word "tomato" may refer to the plant or the edible, typically red, fruit which it bears. Originating in South America, the tomato was spread around the world following the Spanish colonization of the Americas, and its many varieties are now widely grown, often in greenhouses in cooler...
(Solanum lycopersicum), eggplant (Solanum melongena), and bittersweet nightshade (Solanum dulcamara
Solanum dulcamara
Solanum dulcamara, also known as bittersweet, bittersweet nightshade, bitter nightshade, blue bindweed, Amara Dulcis, climbing nightshade, fellenwort, felonwood, poisonberry, poisonflower, scarlet berry, snakeberry, trailing bittersweet, trailing nightshade, violet bloom, or woody...
).
Potatoes naturally produce solanine and chaconine
Chaconine
α-Chaconine is a steroidal glycoalkaloid chemical compound that occurs in plants of the Solanaceae family. It is a natural toxicant produced in green potatoes and gives the potato a bitter taste. Tubers produce this glycoalkaloid in response to stress, providing the plant with insecticidal and...
, a related glycoalkaloid, as a defense mechanism
Plant defense against herbivory
Plant defense against herbivory or host-plant resistance describes a range of adaptations evolved by plants which improve their survival and reproduction by reducing the impact of herbivores. Plants use several strategies to defend against damage caused by herbivores...
against insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
s, disease
Disease
A disease is an abnormal condition affecting the body of an organism. It is often construed to be a medical condition associated with specific symptoms and signs. It may be caused by external factors, such as infectious disease, or it may be caused by internal dysfunctions, such as autoimmune...
, and predators
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
. Potato leaves
Leaf
A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....
, stems
Plant stem
A stem is one of two main structural axes of a vascular plant. The stem is normally divided into nodes and internodes, the nodes hold buds which grow into one or more leaves, inflorescence , conifer cones, roots, other stems etc. The internodes distance one node from another...
and shoot
Shoot
Shoots are new plant growth, they can include stems, flowering stems with flower buds, and leaves. The new growth from seed germination that grows upward is a shoot where leaves will develop...
s are naturally high in glycoalkaloids.
When potato tuber
Tuber
Tubers are various types of modified plant structures that are enlarged to store nutrients. They are used by plants to survive the winter or dry months and provide energy and nutrients for regrowth during the next growing season and they are a means of asexual reproduction...
s are exposed to light, they turn green and increase glycoalkaloid production. This is a natural defense to help prevent the uncovered tuber from being eaten. The green colour is from chlorophyll
Chlorophyll
Chlorophyll is a green pigment found in almost all plants, algae, and cyanobacteria. Its name is derived from the Greek words χλωρος, chloros and φύλλον, phyllon . Chlorophyll is an extremely important biomolecule, critical in photosynthesis, which allows plants to obtain energy from light...
, and is itself harmless. However, it is an indication that increased level of solanine and chaconine may be present.
Some diseases, such as late blight
Phytophthora infestans
Phytophthora infestans is an oomycete that causes the serious potato disease known as late blight or potato blight. . Late blight was a major culprit in the 1840s European, the 1845 Irish and 1846 Highland potato famines...
, can dramatically increase the levels of glycoalkaloids present in potatoes. Mechanically damaged potatoes also produce increased levels of glycoalkaloids. This is believed to be a natural reaction of the plant in response to disease and damage.
Commercial varieties of potatoes are screened for solanine levels, and most have a solanine content of less than 0.2 mg/g. However, potatoes that have been exposed to light and started to green can show concentrations of 1 mg/g or more. In these situations a single unpeeled potato can result in a dangerous dose.
In potato tubers, 30–80% of the solanine develops in and close to the skin.
Showing green under the skin strongly suggests solanine build-up in potatoes, although each process can occur without the other. A bitter taste in a potato is another, potentially more reliable indicator of toxicity. Because of the bitter taste and appearance of such potatoes, solanine poisoning is rare outside conditions of food shortage. The symptoms are mainly vomiting
Vomiting
Vomiting is the forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose...
and diarrhea
Diarrhea
Diarrhea , also spelled diarrhoea, is the condition of having three or more loose or liquid bowel movements per day. It is a common cause of death in developing countries and the second most common cause of infant deaths worldwide. The loss of fluids through diarrhea can cause dehydration and...
, and the condition may be misdiagnosed as gastroenteritis
Gastroenteritis
Gastroenteritis is marked by severe inflammation of the gastrointestinal tract involving both the stomach and small intestine resulting in acute diarrhea and vomiting. It can be transferred by contact with contaminated food and water...
. Most potato poisoning victims recover fully, although fatalities are known, especially when victims are undernourished or do not receive suitable treatment. Fatalities are also known from solanine poisoning from other plants in the nightshade family, such as the berries of Solanum dulcamara
Solanum dulcamara
Solanum dulcamara, also known as bittersweet, bittersweet nightshade, bitter nightshade, blue bindweed, Amara Dulcis, climbing nightshade, fellenwort, felonwood, poisonberry, poisonflower, scarlet berry, snakeberry, trailing bittersweet, trailing nightshade, violet bloom, or woody...
(woody nightshade).
The United States National Institutes of Health
National Institutes of Health
The National Institutes of Health are an agency of the United States Department of Health and Human Services and are the primary agency of the United States government responsible for biomedical and health-related research. Its science and engineering counterpart is the National Science Foundation...
's information on solanine says to never eat potatoes that are green below the skin.
Deep frying
Deep frying
Deep frying is a cooking method in which food is submerged in hot oil or fat. This is normally performed with a deep fryer or chip pan; industrially, a pressure fryer or vacuum fryer may be used....
potatoes at 170°C (306°F) is known to effectively lower glycoalkaloid levels (because they move into the frying fat), whereas microwaving
Microwave oven
A microwave oven is a kitchen appliance that heats food by dielectric heating, using microwave radiation to heat polarized molecules within the food...
is only somewhat effective, freeze drying
Freeze drying
Freeze-drying is a dehydration process typically used to preserve a perishable material or make the material more convenient for transport...
or dehydration
Drying (food)
Drying is a method of food preservation that works by removing water from the food, which inhibits the growth of microorganisms and hinders quality decay. Drying food using sun and wind to prevent spoilage has been practised since ancient times, and was the earliest form of food curing...
has little effect, and boiling has no effect.
Solanine in tomatoes
Some, such as the California Poison Control System, have claimed that tomatoTomato
The word "tomato" may refer to the plant or the edible, typically red, fruit which it bears. Originating in South America, the tomato was spread around the world following the Spanish colonization of the Americas, and its many varieties are now widely grown, often in greenhouses in cooler...
es and tomato leaves contain solanine. However, Dr. Mendel Friedman of the federal Department of Agriculture contradicts this claim stating that tomatine
Tomatine
Tomatine is a toxic glycoalkaloid found in the stems and leaves of tomato plants, which has fungicidal properties. Chemically pure tomatine is a white crystalline solid at standard temperature and pressure...
, a relatively benign alkaloid, is the tomato alkaloid while solanine is found in potatoes. Food science writer Harold McGee
Harold McGee
Harold McGee is an American author who writes about the chemistry, technique and history of food and cooking and has written two seminal books on kitchen science. His first book, On Food and Cooking: The Science and Lore of the Kitchen was initially published in 1984. A greatly revised second...
has found scant evidence for tomato toxicity in the medical and veterinary literature.
Other uses of solanine
Solanine has fungicidalFungicide
Fungicides are chemical compounds or biological organisms used to kill or inhibit fungi or fungal spores. Fungi can cause serious damage in agriculture, resulting in critical losses of yield, quality and profit. Fungicides are used both in agriculture and to fight fungal infections in animals...
and pesticidal
Pesticide
Pesticides are substances or mixture of substances intended for preventing, destroying, repelling or mitigating any pest.A pesticide may be a chemical unicycle, biological agent , antimicrobial, disinfectant or device used against any pest...
properties, and solanine hydrochloride (a salt of solanine) has been used as a commercial pesticide, but never on a large scale.
Solanine has sedative
Sedative
A sedative or tranquilizer is a substance that induces sedation by reducing irritability or excitement....
and anticonvulsant
Anticonvulsant
The anticonvulsants are a diverse group of pharmaceuticals used in the treatment of epileptic seizures. Anticonvulsants are also increasingly being used in the treatment of bipolar disorder, since many seem to act as mood stabilizers, and in the treatment of neuropathic pain. The goal of an...
properties, and has been used as a treatment for asthma
Asthma
Asthma is the common chronic inflammatory disease of the airways characterized by variable and recurring symptoms, reversible airflow obstruction, and bronchospasm. Symptoms include wheezing, coughing, chest tightness, and shortness of breath...
, as well as for cough
Cough
A cough is a sudden and often repetitively occurring reflex which helps to clear the large breathing passages from secretions, irritants, foreign particles and microbes...
and cold
Common cold
The common cold is a viral infectious disease of the upper respiratory system, caused primarily by rhinoviruses and coronaviruses. Common symptoms include a cough, sore throat, runny nose, and fever...
medicines. However, its effectiveness for either use is questionable.
External links
- a-Chaconine and a-Solanine, Review of Toxicological Literature - "Green tubers and sprouts"