Vinyldithiins, more precisely named 3-vinyl-4''H''-1,2-dithiin and 2-vinyl-4''H''-1,3-dithiin, are

organosulfur Organosulfur compounds are organic compounds that contain sulfur. They are often associated with foul odors, but many of the sweetest compounds known are organosulfur derivatives, e.g., saccharin. Nature abounds with organosulfur compounds—sulfur ...

phytochemicals Phytochemicals are chemical compounds produced by plants, generally to help them resist fungi, bacteria and plant virus infections, and also consumption by insects and other animals. The name comes . Some phytochemicals have been used as pois ...

formed in the breakdown of

allicin Allicin is an organosulfur compound obtained from garlic, a species in the family Alliaceae. It was first isolated and studied in the laboratory by Chester J. Cavallito and John Hays Bailey in 1944. When fresh garlic is chopped or crushed, th ...

from crushed

garlic Garlic (''Allium sativum'') is a species of bulbous flowering plant in the genus '' Allium''. Its close relatives include the onion, shallot, leek, chive, Welsh onion and Chinese onion. It is native to South Asia, Central Asia and northeas ...

(''Allium sativum''). Vinyldithiins are Diels-Alder dimers of thioacrolein, H₂C=CHCH=S, formed in turn by decomposition of allicin. In garlic supplements, vinyldithiins are only found in

garlic oil Garlic oil is the volatile oil derived from garlic. It is usually prepared using steam distillation and can also be produced via distillation using ether. It is used in cooking and as a seasoning, a nutritional supplement, and also as an insectic ...

macerates that are made by incubation of crushed garlic in oil. __TOC__

Structure and occurrence

When a garlic clove is crushed, the

enzyme Enzymes () are proteins that act as biological catalysts 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 products ...

alliinase In enzymology, an alliin lyase () is an enzyme that catalyzes the chemical reaction :an ''S''-alkyl-L-cysteine ''S''-oxide \rightleftharpoons an alkyl sulfenate + 2-aminoacrylate Hence, this enzyme has one substrate, ''S''-alkyl-L-cysteine ...

is released forming allicin from the cysteine sulfoxide

alliin Alliin is a sulfoxide that is a natural constituent of fresh garlic. It is a derivative of the amino acid cysteine. When fresh garlic is chopped or crushed, the enzyme alliinase converts alliin into allicin, which is responsible for the aroma ...

. Allicin breaks down into additional organosulfur compounds. In the presence of oil or organic solvents, among the compounds formed are the

isomer In chemistry, isomers are molecules or polyatomic ions with identical molecular formulae – that is, same number of atoms of each element – but distinct arrangements of atoms in space. Isomerism is existence or possibility of isomers. Is ...

ic vinyldithiins and

ajoene Ajoene is an organosulfur compound found in garlic (''Allium sativum'') extracts. It is a colorless liquid that contains sulfoxide and disulfide functional groups. The name (and pronunciation) is derived from "ajo", the Spanish word for garlic. I ...

. As shown in the Scheme, allicin (1) decomposes into 2-propenesulfenic acid (2) and thioacrolein (3). Compound 2 reforms allicin while 3 gives Diels-Alder dimers 3-vinyl-4''H''-1,2-dithiin (4) and 2-vinyl-4''H''-1,3-dithiin (5). Garlic cloves yield about 2.5-4.5 mg of allicin per gram when crushed. One fresh garlic clove weighs 2-4 g. At temperatures above 400°C, both vinyldithiins undergo retro-Diels-Alder reactions and regenerate the thioacrolein 3.

Potential health benefits

Vinyldithiins have been investigated as a preventative for

cardiovascular disease Cardiovascular disease (CVD) is a class of diseases that involve the heart or blood vessels. CVD includes coronary artery diseases (CAD) such as angina and myocardial infarction (commonly known as a heart attack). Other CVDs include stroke, hea ...

and as

antioxidant Antioxidants are compounds that inhibit oxidation, a chemical reaction that can produce free radicals. This can lead to polymerization and other chain reactions. They are frequently added to industrial products, such as fuels and lubrica ...

s. In the early 1980s, it was noted that people in the

Mediterranean The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on ...

had lower risk of cardiovascular disease. Since garlic is used extensively in the Mediterranean, it is hypothesized that the chemicals in garlic might have cardiovascular effects. Studies have been done measuring the use of garlic for controlling serum

cholesterol Cholesterol is any of a class of certain organic molecules called lipids. It is a sterol (or modified steroid), a type of lipid. Cholesterol is biosynthesized by all animal cells and is an essential structural component of animal cell memb ...

levels. Analysis of these studies show that vinyldithiins in garlic have little to no effect on serum

lipids Lipids are a broad group of naturally-occurring molecules which includes fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E and K), monoglycerides, diglycerides, phospholipids, and others. The functions of lipids in ...

. Vinyldithiins in garlic have been shown to significantly lower the incidence of

platelet aggregation Platelets, also called thrombocytes (from Greek θρόμβος, "clot" and κύτος, "cell"), are a component of blood whose function (along with the coagulation factors) is to react to bleeding from blood vessel injury by clumping, thereby ini ...

. Reduction of platelet aggregation may result in reduction of

myocardial infarction A myocardial infarction (MI), commonly known as a heart attack, occurs when blood flow decreases or stops to the coronary artery of the heart, causing damage to the heart muscle. The most common symptom is chest pain or discomfort which ma ...

ischemic stroke A stroke is a medical condition in which poor blood flow to the brain causes cell death. There are two main types of stroke: ischemic, due to lack of blood flow, and hemorrhagic, due to bleeding. Both cause parts of the brain to stop funct ...

. It is now known that

hydrogen sulfide Hydrogen sulfide is a chemical compound with the formula . It is a colorless chalcogen-hydride gas, and is poisonous, corrosive, and flammable, with trace amounts in ambient atmosphere having a characteristic foul odor of rotten eggs. The under ...

has cardioprotective effects in cases of ischemia related to its effects as an endogenous messenger molecule, primarily via its reduction of the rate of cellular metabolism. The masked dithioacetal functionality of the geminal vinyldithiin isomer can release small but biologically relevant amounts of hydrogen sulfide through a hydrolytic process. Furthermore, divalent organosulfur compounds themselves, such as vinyldithiins are known to reduce oxidative stress via a radical process, which would be relevant to the protection of the cardiovascular system. Ingestion of foods containing vinyldithiins and other organosulfur compounds may decrease the risk of gastric and colon

cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal b ...

. 2-Vinyl-4''H''-1,2-dithiin was found to exhibit inhibitory activity against

lipid Lipids are a broad group of naturally-occurring molecules which includes fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E and K), monoglycerides, diglycerides, phospholipids, and others. The functions of lipids in ...

hydroperoxide Hydroperoxides or peroxols are compounds containing the hydroperoxide functional group (ROOH). If the R is organic, the compounds are called organic hydroperoxides. Such compounds are a subset of organic peroxides, which have the formula ROOR. ...

(LOOH) formation in human

low-density lipoprotein Low-density lipoprotein (LDL) is one of the five major groups of lipoprotein that transport all fat molecules around the body in extracellular water. These groups, from least dense to most dense, are chylomicrons (aka ULDL by the overall densi ...

(LDL). A

copolymer In polymer chemistry, a copolymer is a polymer derived from more than one species of monomer. The polymerization of monomers into copolymers is called copolymerization. Copolymers obtained from the copolymerization of two monomer species are ...

of 2-vinyl-4''H''-1,2-dithiin and ''N''-vinylpyrrolidone has been patented as a biocompatible polymer with antithrombogenic (

antithrombotic An antithrombotic agent is a drug that reduces the formation of blood clots (thrombi).http://cancerweb.ncl.ac.uk/cgi-bin/omd?antithrombotic Antithrombotics can be used therapeutically for prevention (primary prevention, secondary prevention) or t ...

) and

antibiotic An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention ...

properties.Hermes RE. Antithrombogenic and antibiotic composition and methods of preparation thereof. US 4917921, January 1, 1990. http://www.osti.gov/bridge/product.biblio.jsp?osti_id=867345

References

{{reflist, 2 Organosulfur compounds Phytochemicals Vinyl compounds Anti-inflammatory agents Dietary antioxidants Pungent flavors Garlic Antifungals