Menthofuran Menthol

The oil of Mentha piperita (peppermint) contains cineol, limonene, menthofuran, menthol, and menthone. It has been used as a carminative and antispasmodic for esophageal spasm and irritable bowel syndrome (10). 

Fig. 2 Fluorescence scan of a chromatogram of peppermint oil menthol (1), cineole (2), menthone (3), menthyl acetate (4), menthofuran/terpenes (5).

Mentha piperita subsp. citrata Briq. -horteia Tranquilizer Branch (infusion, ingested) Caboclos [57] Essential oils [138,139] flavonoid glycosides [140,141] menthol [142] menthofurolactone [143,144] pyridine-derivatives [145] mintlactone [146] flavones [147] triterpenes [148] terpenoids [149] sesquiterpenic hydrocarbons [150] menthofuran [151,152], Antimicrobial and antioxidant activities [138,265] antiallergic effect [140] anti-nociceptive and anti-inflammatory effects [266]... 

Composition 30-55% (-)-menthol, 14-32% (-)-menthone, 1.5-10% (-i-)-iso menthone, 2.8-10% menthyl acetate, 3.5-14% 1,8-cineole, 1-9% menthofuran, up to 4% pule-gone [220], as well as 3-octanol, trans-sabinene hydrate, piperitone, viridrflorol, mono- and sesquiterpene hydrocarbons. For further constituents see [221, 222, 223[. On the differentiation between peppermint oils and the detection of dementholised commint oil as a major adulterant see the results of Lawrence et al. [224], The ratio of 1,8-cineole limonene (min. 2) was even implemented in the European Pharmacopoeia. The latter also limits the isopulegol content for Mentha piperita oil to 0.2%. 

Composition 70-80 % (-)-menthol. The commercially available oils are dementholised and again rectified, contain mainly menthol (33 6%), menthone (18-32%), isomenthone (8-14%) and menthyl esters, and are employed for diluting the more expensive piperita oils. The composition of the unrectrfied oil is similar to that of piperita oil, whereas (E)-sabinene hydrate, viridiflorol and menthofuran are only present in traces. Isopulegol occurs up to 3%. 

Related studies record the change in monoterpene corporation during maturation of Sequoia spp.949 and the similar variations of menthol and its p-glucoside in Mentha.950 Hybridization experiments have shown that the occurrence of 60—90% pulegone in certain strains of Mentha spp. resulted from the lack of the genes necessary to reduce this ketone to menthone or to oxidize it to menthofuran.951 A detailed genetic analysis of menthone-isomenthone production in Mentha spp. has also been described.952... 

Lane 1 menthol, menthone lane 2 menthyl acetate, menthofuran lanes 3- 8 peppermint oils from different manufacturers... 

Carveol (5) is one of the minor components responsible for the odour of spearmint, and is easily prepared by reduction of carvone. Isopulegol (6) is prepared from citronellal, as discussed in the section on menthol below, and is a precursor to other materials in the group. The phenols carvacrol (7) and thymol (8) are important in some herbal odour types, but the major use for thymol is as a precursor for menthol q.v. Piperitone (9) and pulegone (10) are strong minty odorants, the latter being the major component of pennyroyal oil. 1,8-Cineole (11) is the major component of such eucalyptus oils as Eucalyptus globulus. These oils are inexpensive and so there is no need to prepare cineole synthetically. Menthofuran (12) is an important minor component of mint oils and can be prepared from pulegone. 

As in commint oil, the main component of peppermint oil is (-)-menthol (34— 46%) it also contains (-)-menthone (15-27%) and (-)-menthyl acetate (2.5-7 %). However, peppermint oil, unlike cornmint oil, has a higher content of (+)-menthofuran [17957-94-7] (0.5-6%). These data refer to oils of US type oils of other origins (China, India) may have slightly different compositions [628-6331]. 

Menthol (35%-4-5%), (-)nienthoue (10%-30%) with small amounts of isomenthone, menthyl acetate (3%-5%), menthofuran (2,5%-5%) pulegone, piperitoiie ( %), cineole (8%), pineiie, limonene, jasmone (0.1%), sabinenhydrate... 

An important junction in the menthol biosynthesis is the formation of (+)-menthofuran from (+)-pulegone, which is brought about by menthofuran synthase. This path is promoted by short daylight hours or low-intensity daylight, warm overnight temperatures, and shortage of water or nutrients, and results in a considerable quality loss of the peppermint oil. 

Once the understanding of the biosynthetic pathway to menthol was complete, this enabled the development of transgenic cell lines, which, by overexpression of certain enzymes on the triose-pyruvate pathway, produced up to 40 % higher yields of peppermint oU. In addition, the suppression of the menthofuran formation improved the product quality under stress conditions. 

The picture is somewhat similar for peppermint. According to investigations of Murray et al. (1988), components of the essential oil distilled from the stolons are highly comparable with the shoot oil. Major compounds of the stolon oil were menthofuran (46.1%), menthyl acetate (24.5%), and menthol (11.4%), which re ect only quantitative differences compared to the oil distilled from the herb or the leaves. These data refer to a relatively uniform biosynthetic process of these terpenoids in the whole shoot system developing underground or overground. 

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