Atractyloside (ATR) is a natural, toxic
glycoside
In chemistry, a glycoside is a molecule in which a sugar is bound to another functional group via a glycosidic bond. Glycosides play numerous important roles in living organisms. Many plants store chemicals in the form of inactive glycosides. ...
present in numerous plant species worldwide in the
daisy family including ''
Atractylis gummifera
''Chamaeleon gummifer'', also known as distaff thistle or stemless atractylis, is a thistle in the ''Chamaeleon'' genus. Formerly, it was placed in the ''Atractylis'' genus. It is native to the Mediterranean basin, where it can be found in variou ...
'' and ''
Callilepis laureola'',
and it's used for a variety of therapeutic, religious, and toxic purposes.
Exposure to ATR via ingestion or physical contact is toxic and can be fatal for both humans and animals, especially by kidney and liver failure.
ATR acts as an effective
ADP/ATP translocase
Adenine nucleotide translocator (ANT), also known as the ADP/ATP translocase (ANT), ADP/ATP carrier protein (AAC) or mitochondrial ADP/ATP carrier, exchanges free ATP with free ADP across the inner mitochondrial membrane. ANT is the most abund ...
inhibitor which eventually halts ADP and ATP exchange and the cell dies due to lack of energy. Historically, atractyloside poisoning has been challenging to verify and quantify toxicologically, though recent literature has described such methods within acceptable standards of forensic science.
Sources
![Atractylis gummifera](https://upload.wikimedia.org/wikipedia/commons/b/bb/Atractylis_gummifera.jpg)
Atractyloside is found in numerous plant species in the
daisy family e.g. ''
Atractylis gummifera
''Chamaeleon gummifer'', also known as distaff thistle or stemless atractylis, is a thistle in the ''Chamaeleon'' genus. Formerly, it was placed in the ''Atractylis'' genus. It is native to the Mediterranean basin, where it can be found in variou ...
'', ''
Callilepis laureola'', ''
Xanthium strumarium
''Xanthium strumarium'' (rough cocklebur, clotbur, common cocklebur, large cocklebur, woolgarie bur) is a species of annual plants of the family Asteraceae. Some sources claim it originates in southern Europe and Asia, but has been extensively na ...
'', ''
Iphiona alsoeri'', ''
Pascalia glauca'', ''
Wedelia glauca'', and ''
Iphiona aucheri'' among others. It is also found in very low concentrations in ''
Coffea arabica
''Coffea arabica'' (), also known as the Arabic coffee, is a species of flowering plant in the coffee and madder family Rubiaceae. It is believed to be the first species of coffee to have been cultivated and is currently the dominant cultivar, r ...
''.
The widespread regions across all of these plants' native areas of growth results in ATR's easy availability worldwide.
However the ATR concentration found in plants is dependent upon the species, season, and origin. For example, the ATR content measured in dried Atractlyis gummifera between Sardinia, Italy and Sicily, Italy revealed a higher content in the Sicilian region by nearly a factor of five, and a higher content in colder months across both regions.
Additionally, the preparation of plants with atractyloside in some traditional medicines affects the atractyloside content. The preparation technique, such as
decoction
Decoction is a method of extraction by boiling herbal or plant material (which may include stems, roots, bark and rhizomes) to dissolve the chemicals of the material. It is the most common preparation method in various herbal-medicine systems. De ...
or
infusion
Infusion is the process of extracting chemical compounds or flavors from plant material in a solvent such as water, oil or alcohol, by allowing the material to remain suspended in the solvent over time (a process often called steeping). An inf ...
, extracts the desired chemical compound, after which the contents could be diluted or concentrated.
History
Atractylosides have been used as poisons since at least 100 AD, though it was not isolated and characterized until 1868 by LeFranc, after extracting it from ''
Atractylis gummifera
''Chamaeleon gummifer'', also known as distaff thistle or stemless atractylis, is a thistle in the ''Chamaeleon'' genus. Formerly, it was placed in the ''Atractylis'' genus. It is native to the Mediterranean basin, where it can be found in variou ...
''.
After high-profile accidental poisonings—children in Italy and Algeria ate parts of the plant in 1955 and 1975, respectively—renewed interest in atractyloside resulted in future research.
Historically, the ATR plant sources have been used for numerous reasons: whether for its therapeutic properties, magico-religious purposes, or its toxicity. While its therapeutic uses may be due to the coincidental presence of other compounds, some uses of ATR-containing plants include treating sinusitis, headaches, syphilitic ulcers, and whitening teeth among other applications. Separately, the ''
Atractylis gummifera
''Chamaeleon gummifer'', also known as distaff thistle or stemless atractylis, is a thistle in the ''Chamaeleon'' genus. Formerly, it was placed in the ''Atractylis'' genus. It is native to the Mediterranean basin, where it can be found in variou ...
'' is a traditional herb used in North Africa while ''
Callilepis laureola'' is well known to the
Zulu people
Zulu people (; zu, amaZulu) are a Nguni ethnic group native to Southern Africa. The Zulu people are the largest ethnic group and nation in South Africa, with an estimated 10–12 million people, living mainly in the province of KwaZulu-Natal ...
in South Africa for both therapeutical applications and its spiritual context to ward away evil spirits.
When in high dosages, ATR's toxicity has been utilized for suicide and murder, though there have been no especially high-profile incidents reported, at least somewhat due to difficulties identifying ATR poisoning. More commonly than suicide or murder, ATR is a result of accidental poisoning: livestock grazing can poison animals,
while an unintended overdose or exposure of a plant containing ATR can poison humans. Particularly, the ''
Atractylis gummifera
''Chamaeleon gummifer'', also known as distaff thistle or stemless atractylis, is a thistle in the ''Chamaeleon'' genus. Formerly, it was placed in the ''Atractylis'' genus. It is native to the Mediterranean basin, where it can be found in variou ...
'' is easily confused with wild artichoke and other vegetables, and its sweet-tasting roots facilitate its consumption.
Structure and reactivity
Atractyloside is a hydrophilic glycoside. A modified
glucose
Glucose is a simple sugar with the molecular formula . Glucose is overall the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, using ...
is linked to the hydrophobic
diterpene
Diterpenes are a class of chemical compounds composed of four isoprene units, often with the molecular formula C20H32. They are biosynthesized by plants, animals and fungi via the HMG-CoA reductase pathway, with geranylgeranyl pyrophosphate being ...
atractyligenin by a β1-
glycosidic bond
A glycosidic bond or glycosidic linkage is a type of covalent bond that joins a carbohydrate (sugar) molecule to another group, which may or may not be another carbohydrate.
A glycosidic bond is formed between the hemiacetal or hemiketal group ...
. A
carboxyl group
In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group () attached to an R-group. The general formula of a carboxylic acid is or , with R referring to the alkyl, alkenyl, aryl, or other group. Carboxylic ...
is positioned at the C4 position in the axial position. The glucose part is esterified with
isovaleric acid on the C2' atom, and
sulfuric acid
Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid ( Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen and hydrogen, with the molecular formu ...
on the C3' and C4' atoms. By
hydrolysis
Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution reaction, substitution, elimination reaction, elimination, and solvation reactions in which water ...
a molecule of
D-(+)-glucose, isovaleric acid, atractyligenin, and two molecules of sulfuric acid could be obtained. The two sulfate groups and the carboxyl group in ATR are in a
deprotonated
Deprotonation (or dehydronation) is the removal (transfer) of a proton (or hydron, or hydrogen cation), (H+) from a Brønsted–Lowry acid in an acid–base reaction.Henry Jakubowski, Biochemistry Online Chapter 2A3, https://employees.csbsju.edu ...
form under physiological conditions. Thus, ATR is triple negatively charged.
![Atractyligenin Numbered Diagram](https://upload.wikimedia.org/wikipedia/commons/c/cb/Atractyligenin_Numbered_Diagram.png)
A modified variant of the atractylenolide carries an additional carboxyl group at the C4 atom of the atractyligenin, which is then referred to as ''carboxy-atractyloside'' (CATR), sometimes referred to as "gummiferin". The ATR/CATR chemical structure on the right indicates this difference between compounds.
Mechanism of action
In biochemical studies of
mitochondria
A mitochondrion (; ) is an organelle found in the Cell (biology), cells of most Eukaryotes, such as animals, plants and Fungus, fungi. Mitochondria have a double lipid bilayer, membrane structure and use aerobic respiration to generate adenosi ...
, the effect of atractyloside on the ADP/ATP transport was recognized even before the actual transporter was identified. ATR or CATR bind to the
ADP/ATP translocase
Adenine nucleotide translocator (ANT), also known as the ADP/ATP translocase (ANT), ADP/ATP carrier protein (AAC) or mitochondrial ADP/ATP carrier, exchanges free ATP with free ADP across the inner mitochondrial membrane. ANT is the most abund ...
, which is located on the
inner mitochondrial membrane
The inner mitochondrial membrane (IMM) is the mitochondrial membrane which separates the mitochondrial matrix from the intermembrane space.
Structure
The structure of the inner mitochondrial membrane is extensively folded and compartmentalized. T ...
. ATR binds competitively to the translocase
competitive
Competition is a rivalry where two or more parties strive for a common goal which cannot be shared: where one's gain is the other's loss (an example of which is a zero-sum game). Competition can arise between entities such as organisms, indivi ...
up to a concentration of 5
mmol
The mole, symbol mol, is the unit of amount of substance in the International System of Units (SI). The quantity amount of substance is a measure of how many elementary entities of a given substance are in an object or sample. The mole is define ...
while CATR binds in a
non-competitive manner. As a result, the exchange of
ADP and
ATP is no longer carried out and the cell dies due to lack of energy.
The chemical structure and charge distribution of atractyloside is similar to that of ADP: the sulfate groups correspond to the phosphate groups, the glucose part corresponds to the ribose part, and the hydrophobic atractyligenine residue corresponds to the hydrophobic purine residue of ADP.
The carboxyl group on the C4 atom of the atractyligenin is important for toxicity. If this is reduced to a
hydroxyl group
In chemistry, a hydroxy or hydroxyl group is a functional group with the chemical formula and composed of one oxygen atom covalently bonded to one hydrogen atom. In organic chemistry, alcohols and carboxylic acids contain one or more hydroxy g ...
(''atractylitriol''), the substance becomes non-toxic. Modification of any of the
sulfate
The sulfate or sulphate ion is a polyatomic anion with the empirical formula . Salts, acid derivatives, and peroxides of sulfate are widely used in industry. Sulfates occur widely in everyday life. Sulfates are salts of sulfuric acid and many ar ...
groups renders the compound non-toxic.
On the other hand, the free hydroxy group on the C6 atom of the
glucose
Glucose is a simple sugar with the molecular formula . Glucose is overall the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, using ...
moiety can be modified without loss of compound potency.
Poisoning
Symptoms
Consumption of atractyloside (ATR) in plants will oftentimes also contain
carboxyatractyloside
Carboxyatractyloside (CATR) is a highly toxic diterpene glycoside that inhibits the ADP/ATP translocase. It is about 10 times more potent than its analog atractyloside. While atractyloside is effective in the inhibition of oxidative phosphorylatio ...
(CATR), a highly toxic glycoside.
[
Ingestion of ''A. gummifera'', ''C. laureola'', ''Xanthium'', or their extracts, may result in symptoms of gastrointestinal pain, nausea, diarrhea, and vomiting. Also possible is ]respiratory depression
Hypoventilation (also known as respiratory depression) occurs when ventilation is inadequate (''hypo'' meaning "below") to perform needed respiratory gas exchange. By definition it causes an increased concentration of carbon dioxide (hypercapnia ...
which may cause hypoxemia, leading to tissue hypoxia, spasms, stiffness, and convulsions. In several cases, these symptoms are followed by coma
A coma is a deep state of prolonged unconsciousness in which a person cannot be awakened, fails to respond normally to painful stimuli, light, or sound, lacks a normal wake-sleep cycle and does not initiate voluntary actions. Coma patients exhi ...
. Postmortem analysis may indicate hepatocellular damage and renal failure
Kidney failure, also known as end-stage kidney disease, is a medical condition in which the kidneys can no longer adequately filter waste products from the blood, functioning at less than 15% of normal levels. Kidney failure is classified as eit ...
.
More recent literature has described sustained application of ATR on skin causing the symptoms described above, including hepatorenal injury.
Identification / Quantification
The detection of herbal toxins has generally caused a diagnostic problem due to wide variety of plants and limited standard screening. For a long time, the identification of ATR poisoning was limited to postmortem analysis of one's kidneys or liver. Subsequent developments made to identify the presence of ATR in bodily fluids (blood or urine) only worked with high concentrations of ATR. Now, more recent research has established the necessary sensitivity and specificity to be applied to forensic toxicology.[
The development of the below procedure relied on findings from unsuccessful methods of identification, primarily traced to the following literature in which the specificity and sensitivity was improved over time. Due to the limited research on the subject of ATR identification, this literature represents the primary sources to review:
* 1999: Established first quantifiable measurement of atractyloside in whole blood with ]high-performance liquid chromatography
High-performance liquid chromatography (HPLC), formerly referred to as high-pressure liquid chromatography, is a technique in analytical chemistry used to separate, identify, and quantify each component in a mixture. It relies on pumps to pa ...
-tandem mass spectrometry
Tandem mass spectrometry, also known as MS/MS or MS2, is a technique in instrumental analysis where two or more mass analyzers are coupled together using an additional reaction step to increase their abilities to analyse chemical samples. A comm ...
(HPLC-MS-MS);
* 2001: GC-MS method required derivitization to detect atractyloside fragments;
* 2004: LC-MS (EI) using Waters Thermabeam detector resulted in complete fragmentation of the molecule; gentler ionization technique ( ESI) was successfully used to detect ATR after chromatographic separation;
* 2006: Further development of procedure with ESI, eluent composition, and other experimental conditions, though still lacking specificity for forensic science.
The procedure by ''Carlier et al.'' uses high-performance liquid chromatography
High-performance liquid chromatography (HPLC), formerly referred to as high-pressure liquid chromatography, is a technique in analytical chemistry used to separate, identify, and quantify each component in a mixture. It relies on pumps to pa ...
coupled with high-resolution tandem mass spectrometry
Tandem mass spectrometry, also known as MS/MS or MS2, is a technique in instrumental analysis where two or more mass analyzers are coupled together using an additional reaction step to increase their abilities to analyse chemical samples. A comm ...
(HPLC-HRMS/MS). After the extraction of ATR and CATR from the blood or urine sample, separation was performed by reverse-phase HPLC. The MS detection used a quadrupole-orbitrap high-resolution detector after heated electrospray in negative ionization mode. These extraction techniques yielded 71.1% and 48.3% of ATR and CATR, respectively, in which these results met acceptable international criteria for forensic science: precision (≤15% or ≤20% at the LLOQ) and accuracy (between 80 and 115% or 80-120% at the LLOQ).
For reference, additional sources have fully characterized atractyloside in NMR
Nuclear magnetic resonance (NMR) is a physical phenomenon in which nuclei in a strong constant magnetic field are perturbed by a weak oscillating magnetic field (in the near field) and respond by producing an electromagnetic signal with ...
, MS, IR, etc.
Lethality
The mean lethal dose
In toxicology, the lethal dose (LD) is an indication of the lethal toxicity of a given substance or type of radiation. Because resistance varies from one individual to another, the "lethal dose" represents a dose (usually recorded as dose per kilog ...
in rats ( i.p.) for ATR is 143 mg/kg and for CATR is 2.9 mg/kg. This lethal dose of ATR takes approximately 150–180 minutes after injection until acute tubular necrosis
Acute tubular necrosis (ATN) is a medical condition involving the death of tubular epithelial cells that form the renal tubules of the kidneys. Because necrosis is often not present, the term acute tubular injury (ATI) is preferred by pathologists ...
occurred. This lethal dose varies across species and method of exposure. For example, the mean lethal dose of ATR in rats ( s.c.) is 155 mg/kg. Published mean lethal doses of ATR in other species includes 250 mg/kg ( s.c.) for rabbit, 200 mg/kg ( i.p.) for guinea pig, and 15 mg/kg ( i.v.) for dog.[
]
See also
*Carboxyatractyloside
Carboxyatractyloside (CATR) is a highly toxic diterpene glycoside that inhibits the ADP/ATP translocase. It is about 10 times more potent than its analog atractyloside. While atractyloside is effective in the inhibition of oxidative phosphorylatio ...
References
{{reflist
Poisons
Carboxylate esters
Diols
Carboxylic acids
Alkene derivatives
Diterpene glycosides
Plant toxins
ADP/ATP translocase inhibitors
Sulfate esters