Allixin is a
phytoalexin
Phytoalexins are antimicrobial substances, some of which are antioxidative as well. They are defined not by their having any particular chemical structure or character, but by the fact that they are defensively synthesized ''de novo'' by plants ...
found in
garlic
Garlic (''Allium sativum'') is a species of bulbous flowering plants in the genus '' Allium''. Its close relatives include the onion, shallot, leek, chives, Welsh onion, and Chinese onion. Garlic is native to central and south Asia, str ...
(''Allium sativum'') bulbs. It was first isolated and characterized in 1989.
When garlic is stored for long periods of time, it can form visible accumulations of crystalline allixin on its surface, particularly in areas where tissue has become
necrotic
Necrosis () is a form of cell injury which results in the premature death of cells in living tissue by autolysis. The term "necrosis" came about in the mid-19th century and is commonly attributed to German pathologist Rudolf Virchow, who is ...
. After 2 years of storage, the amount of allixin accumulated can approach 1% of the dry weight of the cloves. Since allixin has weak
antimicrobial
An antimicrobial is an agent that kills microorganisms (microbicide) or stops their growth (bacteriostatic agent). Antimicrobial medicines can be grouped according to the microorganisms they are used to treat. For example, antibiotics are used aga ...
activity,
[ these high concentrations are thought to be produced by the garlic bulb to protect itself from further damage from microorganisms.
Since allixin is found in high concentrations in garlic, there has been scientific interest in determining if it is responsible for any of the known health benefits of garlic. As a result of ongoing research, a variety of biological activities have been attributed to allixin. Pharmaceutical ]drug discovery
In the fields of medicine, biotechnology, and pharmacology, drug discovery is the process by which new candidate medications are discovered.
Historically, drugs were discovered by identifying the active ingredient from traditional remedies or ...
research based on derivatives of allixin has followed.
Laboratory synthesis
Two laboratory syntheses of allixin have been developed. In the first method, reported in 1997, allixin was synthesized in 22 steps starting from D-mannose. A shorter synthesis was developed in 1998 which involved only 5 steps, starting from 5-methylfurfural.
Biological activities
In ''in vitro
''In vitro'' (meaning ''in glass'', or ''in the glass'') Research, studies are performed with Cell (biology), cells or biological molecules outside their normal biological context. Colloquially called "test-tube experiments", these studies in ...
'' studies, allixin demonstrates neurotrophic
Neurotrophic factors (NTFs) are a family of biomolecules – nearly all of which are peptides or small proteins – that support the growth, survival, and differentiation of both developing and mature neurons. Most NTFs exert their trop ...
activity, but at high concentrations it has cytotoxic
Cytotoxicity is the quality of being toxic to cells. Examples of toxic agents are toxic metals, toxic chemicals, microbe neurotoxins, radiation particles and even specific neurotransmitters when the system is out of balance. Also some types of dr ...
effects.[ Allixin may therefore be a useful starting point for the development of pharmaceutical drugs for the treatment of neurodegenerative disorders or for neuronal regeneration in the brain.][
Pharmacological studies have demonstrated that allixin exerts an anti-promoting activity against skin tumors induced by the chemical 12-''O''-tetradecanoylphorbol-13-acetate (TPA) and an inhibitory effect on aflatoxin B1-induced ]mutagenesis
Mutagenesis () is a process by which the genetic information of an organism is changed by the production of a mutation. It may occur spontaneously in nature, or as a result of exposure to mutagens. It can also be achieved experimentally using lab ...
. Allixin may therefore be responsible, at least in part, for the tumor-preventative effects of garlic extract.
Allixin has also been shown to have a radical scavenging
Scavengers are animals that consume dead organisms that have died from causes other than predation or have been killed by other predators. While scavenging generally refers to carnivores feeding on carrion, it is also a herbivorous feeding be ...
effect.
Metal complexes
Metal complexes with allixin have been shown to have beneficial pharmacological effects in animal models of diabetes.[ A complex with ]vanadium
Vanadium is a chemical element; it has Symbol (chemistry), symbol V and atomic number 23. It is a hard, silvery-grey, malleable transition metal. The elemental metal is rarely found in nature, but once isolated artificially, the formation of an ...
, bis(allixinato)oxovanadium(IV), is a potent anti-diabetic agent. In studies in streptozotocin-induced diabetic mice, this vanadium complex was shown to be an insulin mimetic with hypoglycemic effects. Similarly, a zinc
Zinc is a chemical element; it has symbol Zn and atomic number 30. It is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodic tabl ...
-allixin complex, bis(allixinato)zinc(II), shows the same insulin mimetic effects.mechanism of action
In pharmacology, the term mechanism of action (MOA) refers to the specific biochemical Drug interaction, interaction through which a Medication, drug substance produces its pharmacological effect. A mechanism of action usually includes mention o ...
by which these complexes regulate insulin signaling pathways is unclear.[
File: VO(alx)2.svg, Bis(allixinato)oxovanadium(IV)
File:Zn(alx)2.svg, Bis(allixinato)zinc(II)
]
References
{{reflist
4-Pyrones
Phytoalexins