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 t ...
found in
garlic (''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. Necrosis is caused by factors external to the cell or tissue, such as infection, or trauma which result in the unregulated dige ...
. 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 or stops their growth. Antimicrobial medicines can be grouped according to the microorganisms they act primarily against. For example, antibiotics are used against bacteria, and antifungals a ...
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 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'' 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 tro ...
activity, but at high concentrations it has cytotoxic
Cytotoxicity is the quality of being toxic to cells. Examples of toxic agents are an immune cell or some types of venom, e.g. from the puff adder (''Bitis arietans'') or brown recluse spider (''Loxosceles reclusa'').
Cell physiology
Treating cel ...
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
Aflatoxin B1 is an aflatoxin produced by ''Aspergillus flavus'' and '' A. parasiticus''. It is a very potent carcinogen with a TD50 3.2 μg/kg/day in rats. This carcinogenic potency varies across species with some, such as rats and monkeys, seem ...
-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 with the 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 oxide layer ( pass ...
, 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-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 interaction through which a drug substance produces its pharmacological effect. A mechanism of action usually includes mention of the specific molecular targ ...
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