Names | |
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Preferred IUPAC name 3-Methyl-3-sulfanylbutan-1-ol | |
Other names 3-Mercapto-3-methylbutan-1-ol (no longer recommended [2] ) | |
Identifiers | |
3D model (JSmol) | |
Abbreviations | MMB |
ChEBI | |
ChemSpider | |
ECHA InfoCard | 100.157.543 |
EC Number |
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PubChem CID | |
UNII | |
CompTox Dashboard (EPA) | |
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Properties | |
C5H12OS | |
Molar mass | 120.21 g/mol |
Density | 0.985 g/mL at 20 °C |
Hazards | |
GHS labelling: | |
Danger | |
H302, H315, H318, H319, H335 | |
P261, P264, P270, P271, P280, P301+P312, P302+P352, P304+P340, P305+P351+P338, P310, P312, P321, P330, P332+P313, P337+P313, P362, P403+P233, P405, P501 | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
3-Mercapto-3-methylbutan-1-ol, also known as MMB, is a common odorant found in food and cat urine. The aromas ascribed to MMB include catty, [3] roasty, broth-like, meaty, and savory, [4] or similar to cooked leeks. [5]
MMB is an organosulfur compound with the formula C5H12OS. Its structure consists of isopentane with a primary alcohol group and a tertiary thiol group attached to a β-carbon relative to the alcohol. MMB is found in the urine of leopards and domestic cats, and is considered an important semiochemical in male scent-marking. [6] MMB is also a common odorant in food, including coffee, [7] passionfruit juice, [8] and Sauvignon Blanc wines. [5] As a tertiary thiol, MMB is structurally similar to other "catty" thiols, including 3-mercapto-3-methyl-2-pentanone, 4-mercapto-4-methyl-2-pentanone, 8-mercapto-p-menthan-3-one, and 2-mercapto-2-methylbutane. [4]
The compound can be produced through many methods. The most well-known reaction sequence begins with ethyl acetate, which is activated with lithium bis(trimethylsilyl)amide at the α-position and coupled with acetone to form ethyl 3-hydroxy-3-methylbutyrate. The 3-hydroxy-3-methylbutyrate is then brominated, treated with thiourea, and hydrolyzed to form 3-mercapto-3-methyl-butyric acid. The compound is then reduced with lithium aluminum hydride to form 3-mercapto-3-methylbutanol. [7]
Since MMB is most often synthesized for use as a standard in isotope dilution assays, [9] most instances of MMB synthesis in chemical literature involve acetone-d6 to form [2H6]-3-mercapto-3-methylbutanol.
Besides felinine, MMB was first identified in the plant kingdom in Vitis vinifera L. cv., Sauvignon Blanc. [10] [11]
3-mercapto-3-methylbutan-1-ol have been known to be used commercially as aromas for certain foods such as Sauvignon Blanc wine and coffee. MMB has also been identified in passion fruit juice along with its acetate. [12]
The synthesis of the MMB was formed by the action of the bacterial extract on CESFPs of passion fruit juice. One study looked at the influence of human whole saliva on odor-active thiols, specifically that of salivary enzymes breaking down MMB. [13] The degradation of MMB is thought to be induced by enzymatic activity, and it is much faster than other volatile thiols. [14] Another study found that the perception threshold of 3-mercapto-3-methylbutan-1-ol is 1500 ng/L. [15] This study found that MMB had a "catty" odor, had an orthonasal odor threshold of 2 μg/L in water, and was found in concentrations from 150-1500 μg/kg in coffee.
The synthesis of MMB in wine is brought on by the fermentation process. The pathway of formation for the aromatic precursors involves four important steps: enzymatic oxidation, metabolic processing of unsaturated fatty acids, cysteinlated or glutathionylated conjugation to aldehydes, and a β-lyase cleavage during alcoholic fermentation to release MMB. [16] In this fermentation process, strains of the certain bacterial species are characterized by an extra-cellular α-arabinofuranosidase, influencing the content of desirable varietal aromas and, in particular, Metschnikowia pulcherrima releases varietal thiols including MMB. [17] For Sauvignon Blanc, the contribution of volatile thiols to varietal aroma is quite significant as the levels in wine usually exceed the threshold of detection. Unlike most aroma compounds found in wine, volatile thiols are unique in the fact that they exist in trace amounts in the berries. [16] The intense passion fruit-type aroma of New Zealand Sauvignon Blanc wines are attributed to high concentrations of the varietal thiols. This vintner study found that aromas in wine caused by MMB diminish rapidly over just a year in its bottle. [18] [19]
MMB synthesis, within the biological system of a cat's bladder, is regulated by many different factors including cauxin, age, and sex.
Cauxin is an enzyme that acts as a nonspecific carboxylesterase abundant in feline urine which converts 3-methylbutanol-cysteinylglycine (3MBCG) to felinine, with a side product of glycine. Upon formation, felinine gradually degrades into MMB.
Prior to sexual maturation of cats, cauxin and MMB are not produced at significant levels since this is a testosterone-dependent, although the specific role of testosterone is not well understood. [20] With little testosterone in the body in the first three months of their life, the concentrations of cauxin and 3-methylbutanol-cysteinylglycine are too low for proper reaction conditions. Biologically, this is logical as the ability to utilize pheromones such as MMB for territory marking and finding mates is not needed during kittenhood. The testosterone dependence also explains why female cats do not have nearly as much cauxin and MMB as male cats, and in turn, why their urine does not have a species-specific odor. It also explains why urine in neutered males, who are producing a lot less testosterone than their intact counterparts, do not have.
After a cat reaches sexual maturity, a positive correlation is found with age and MMB production due to an increase in cauxin production, and release in urine with 3-methylbutanol-cysteinylglycine, allowing for the reaction to occur more frequently. This is advantageous for older cats as it allowed them to potently leave a scent trail for female cats to follow, and male cats to stay away. [21]
Studies have also demonstrated some wider predator-prey responses to MMB, cementing this molecule's role in wider ecological relationships. In wildlife, one study established that African wildcats respond to MMB dispensers, marking the territory nearby at higher rates than dispensers without, establishing they recognize the scent. Small mammals have also demonstrated a recognition of the scent, rolling around in where the wildcats have urinated in order to utilize the scent of MMB to its advantage, disguising itself in the scent of a large predator to ward off its own predators. [6] Laboratory experiments have demonstrated that MMB has a does not have an expected repelling effect on mice, who are natural prey of cats, which complicates the narrative further since it is used for a repelling effect by small mammals as a defensive mechanism. [22] Further investigation into this dynamic is needed.
Cabernet Sauvignon is one of the world's most widely recognized red wine grape varieties. It is grown in nearly every major wine producing country among a diverse spectrum of climates from Australia and British Columbia, Canada to Lebanon's Beqaa Valley. Cabernet Sauvignon became internationally recognized through its prominence in Bordeaux wines, where it is often blended with Merlot and Cabernet Franc. From France and Spain, the grape spread across Europe and to the New World where it found new homes in places like California's Napa Valley, New Zealand's Hawke's Bay, South Africa's Stellenbosch region, Australia's Margaret River, McLaren Vale and Coonawarra regions, and Chile's Maipo Valley and Colchagua. For most of the 20th century, it was the world's most widely planted premium red wine grape until it was surpassed by Merlot in the 1990s. However, by 2015, Cabernet Sauvignon had once again become the most widely planted wine grape, with a total of 341,000 hectares (3,410 km2) under vine worldwide.
In organic chemistry, a thiol, or thiol derivative, is any organosulfur compound of the form R−SH, where R represents an alkyl or other organic substituent. The −SH functional group itself is referred to as either a thiol group or a sulfhydryl group, or a sulfanyl group. Thiols are the sulfur analogue of alcohols, and the word is a blend of "thio-" with "alcohol".
Sauvignon blanc is a green-skinned grape variety that originates from the city of Bordeaux in France. The grape most likely gets its name from the French words sauvage ("wild") and blanc ("white") due to its early origins as an indigenous grape in South West France. It is possibly a descendant of Savagnin. Sauvignon blanc is planted in many of the world's wine regions, producing a crisp, dry, and refreshing white varietal wine. The grape is also a component of the famous dessert wines from Sauternes and Barsac. Sauvignon blanc is widely cultivated in France, Chile, Romania, Canada, Australia, New Zealand, South Africa, Bulgaria, the states of Oregon, Washington, and California in the US. Some New World Sauvignon blancs, particularly from California, may also be called "Fumé Blanc", a marketing term coined by Robert Mondavi in reference to Pouilly-Fumé.
An aroma compound, also known as an odorant, aroma, fragrance or flavoring, is a chemical compound that has a smell or odor. For an individual chemical or class of chemical compounds to impart a smell or fragrance, it must be sufficiently volatile for transmission via the air to the olfactory system in the upper part of the nose. As examples, various fragrant fruits have diverse aroma compounds, particularly strawberries which are commercially cultivated to have appealing aromas, and contain several hundred aroma compounds.
Sotolon is a lactone and an extremely powerful aroma compound, with the typical smell of fenugreek or curry at high concentrations and maple syrup, caramel, or burnt sugar at lower concentrations. Sotolon is the major aroma and flavor component of fenugreek seed and lovage, and is one of several aromatic and flavor components of artificial maple syrup. It is also present in molasses, aged rum, aged sake and white wine, flor sherry, roast tobacco, and dried fruiting bodies of the mushroom Lactarius helvus. Sotolon can pass through the body relatively unchanged, and consumption of foods high in sotolon, such as fenugreek, can impart a maple syrup aroma to one's sweat and urine. In some individuals with the genetic disorder maple syrup urine disease, it is spontaneously produced in their bodies and excreted in their urine, leading to the disease's characteristic smell.
Grapefruit mercaptan is a natural organic compound found in grapefruit. It is a monoterpenoid that contains a thiol functional group. Structurally a hydroxy group of terpineol is replaced by the thiol in grapefruit mercaptan, so it also called thioterpineol. Volatile thiols typically have very strong, often unpleasant odors that can be detected by humans in very low concentrations. Grapefruit mercaptan has a very potent, but not unpleasant, odor, and it is the chemical constituent primarily responsible for the aroma of grapefruit. This characteristic aroma is a property of only the R enantiomer.
Cats need to communicate for a variety of reasons, including to show happiness, to express anger, to solicit attention, and to observe potential prey; cats collaborate, play, and share resources with each other. When they communicate with humans, they do so to get what they need or want, such as food, water, attention, or play.
The Flavour and Fragrance Journal is a bimonthly peer-reviewed scientific journal published since 1985 by John Wiley & Sons. It publishes original research articles, reviews and special reports on all aspects of flavour and fragrance. The current Editor-in-Chief is Kerstin Steiner.
A cat pheromone is a chemical molecule, or compound, that is used by cats and other felids for communication. These pheromones are produced and detected specifically by the body systems of cats and evoke certain behavioural responses.
Felinine, also known as (R)-2-amino-3-(4-hydroxy-2-methylbutan-2-ylthio)propanoic acid, is an amino acid found in cat urine and a precursor via microbial lyase of the putative cat pheromone and thiol called 3-mercapto-3-methylbutan-1-ol (MMB). Felinine is excreted by some Felidae species, including bobcats, Chinese desert cats, the kodkod, and domestic cats.
Cauxin is a carboxylesterase that is excreted in large amounts in cat urine. There is also evidence that it can serve as a peptide hydrolase in the production of cat pheromone precursors. Cauxin has a mass of 70 kilodaltons and is composed of 545 amino acids. The protein can also exist as a multimeric protein complex connected by disulfide bonds with a mass of 300-350 kilodaltons. This is its primary form in non-reducing conditions. The proximal tubules of epithelial cells in the kidney express cauxin. This protein is secreted into the urine from the renal tubular cells. The gene for the protein is also found in several other mammalian genomes in various organs. However, the only mammals that have cauxin present in urine are cats. It is also the first carboxylesterase to be found in urine.
Wine tasting is the sensory examination and evaluation of wine. While the practice of wine tasting is as ancient as its production, a more formalized methodology has slowly become established from the 14th century onward. Modern, professional wine tasters use a constantly evolving specialized terminology which is used to describe the range of perceived flavors, aromas and general characteristics of a wine. More informal, recreational tasting may use similar terminology, usually involving a much less analytical process for a more general, personal appreciation.
The aromas of wine are more diverse than its flavours. The human tongue is limited to the primary tastes perceived by taste receptors on the tongue – sourness, bitterness, saltiness, sweetness and savouriness. The wide array of fruit, earthy, leathery, floral, herbal, mineral, and woodsy flavour present in wine are derived from aroma notes sensed by the olfactory bulb. In wine tasting, wine is sometimes smelled before taking a sip in order to identify some components of the wine that may be present. Different terms are used to describe what is being smelled. The most basic term is aroma which generally refers to a "pleasant" smell as opposed to odour which refers to an unpleasant smell or possible wine fault. The term aroma may be further distinguished from bouquet which generally refers to the smells that arise from the chemical reactions of fermentation and aging of the wine.
An odor or odour is caused by one or more volatilized chemical compounds that are generally found in low concentrations that humans and many animals can perceive via their sense of smell. An odor is also called a "smell" or a "scent", which can refer to either an unpleasant or a pleasant odor.
The sense of smell, or olfaction, is the special sense through which smells are perceived. The sense of smell has many functions, including detecting desirable foods, hazards, and pheromones, and plays a role in taste.
Benzyl mercaptan is an organosulfur compound with the formula C6H5CH2SH. It is a common laboratory alkylthiol that occurs in trace amounts naturally. It is a colorless, malodorous liquid.
A key odorant is a volatile compound that is present in concentrations higher than their specific flavor threshold.
Olmo grapes are wine and table grape varieties produced by University of California, Davis viticulturist Dr. Harold Olmo. Over the course of his nearly 50-year career, Dr. Olmo bred a wide variety of both grapes by means of both crossing varieties from the same species or creating hybrid grapes from cultivars of different Vitis species.
Isopropyl methoxypyrazine (IPMP) is a methoxypyrazine, a class of chemical compounds that produce odors. The odor is rather undesirable and is produced by the Asian lady beetle or by the actinomycete Streptomyces sp. It can be detected by human taste at concentrations of as low as 2 nanograms per litre.
4-Mercapto-4-methyl-2-pentanone is an aroma compound with the chemical formula C6H12OS. It has a tropical flavor. It is found in Sauvignon wines and is a potent odorant of new-world hops.
The prefixes 'mercapto' (–SH), and 'hydroseleno' or selenyl (–SeH), etc. are no longer recommended.