Malvalic acid

Malt syrups Malt whiskey Malvalic acid... 

Malvalic acid - [SOYBEANS AND OTHER OILSEEDS] (Vol 22) -in cottonseed [SOYBEANS AND OTHER OILSEEDS] (Vol 22)... 

Malvaceae). Malvalic acid is produced from sterculic acid by chain shortening from the carboxyl end (Figure 3.14). Sterculic acid is an inhibitor of the A9-desaturase which converts stearic acid into oleic acid and is potentially harmful to humans in that it can alter membrane permeability and inhibit reproduction. 

Glycyrrhizic acid (= Glycyrrhinic acid Glycyrrhizin Glycyrrhizinic acid) (triterpene glycoside saponin) Malvalic acid (= 7-(2-... 

This type of fatty acid is usually found at low levels (around 1%) in plant oils that contain cyclopropene acids. Cyclopropene acids are characteristic for oils from the Malvalaceae, Stercu-liaceae, Bombaceae, Tiliaceae, and Sapicidaceae families with sterculic acid (9,10-methyleneoctadec-9-enoic acid) and mal-valic acid (8,9-methyleneheptadec-8-enoic acid) as two major compounds. Sterculic acid is more abundant (about 50% of the total fatty acids in Sterculiafoetida oil). 2-Hydroxysterculic acid may also be present in this oil as a possible intermediate in the biosynthesis of malvalic acid (through a-oxidation of sterculic acid). 

Cyclopropenoid Fatty Acids. Cotton, and other plants in the Malvaceae family, contain a pair of unique cyclopropene fatty acids (CPFA). These two fatty acids, sterculic and malvalic acid, are generally referred to collectively as cyclopropenoid fatty acids. Sterculic acid is the most active of the two fatty acids whose general action is to inhibit the desaturation of stearic to oleic fatty acid in the animal body with a resultant alteration in membrane permeability or an increase in the melting point of fats. 

Whilst the potential for synthesis of cyclopropene under volcanic conditions on primeval earth is recognized , the extent to which the ring system occurs in nature is known for only four classes of compounds, one of which involves cyclopropenone derivatives. Plants of the order Malvales contain varying amounts of the biologically active and homologous cyclopropene fatty acids sterculic acid (2) and malvalic acid (3). The... 

The cyclopropenoid fatty acids, malvalic acid and sterculic acid, exist in hexane-defatted meal at levels of 21—76 ppm (70). In rainbow trout, the cyclopropenoid acids cause cancer of the liver either alone or by acting synergistically with aflatoxin However, similar effects in mammals or humans have not been demonstrated (63). 

Malvalic acid (systematic name is 2-octyl-1-cyclopropene-1-heptanoic acid) has = 7 and m = 6... 

Figure 6 Malvalic acid or 2-octyl-1-cyclopropene-1-heptanoic acid.

Figure 5.1 Structures of naturally occurring cyclic fatty acids. I, Cyclopropane acids a, 9,10-methylenehexadecanoic acid b, 11,12-methyleneoctadecanoic (lactobacillic) acid c, 8,9-methy-leneheptadecanoic (dihydromalvalic) acid d, 9,10-methyleneoctadecanoic (dihydrosterculic) acid. II, Mycolic (2-alkyl-3-hydroxy) acid. Ill, Cyclopropene acids a, 9,10-methyleneoctadec-9-enoic (sterculic) acid b, 8,9-methyleneheptadec-8-enoic (malvalic) acid. IV, Cyclopentenyl acids a, ll-cyclopent-2-enyl-undecanoic (hydnocarpic) acid b, 13-cyclopent-2-enyl-tridecanoic (chaulmoogric) acid c, 13-cyclopent-2-enyl-tridec-6-enoic (gorlic) acid. V a, 11-cyclohexyl-undecanoic acid b, 11-cycloheptylundecanoic acid.

A popular method is to analyse the total fatty acid methyl esters by CjC after reaction with silver nitrate/anhydrous methanol for 2 h at 30°C (Bianchini, Ralaimanarivo and Gaydou, 1981 Eisele et aL, 1974 Gaydou, Bianchini and Ralaimanarivo, 1983 Ralaimanarivo, Gaydou and Bianchini, 1982). Most fatty esters remain unchanged, but cyclopropene esters are converted to later-eluting methoxy ether derivatives and small amounts of ketone derivatives. Two partially resolved peaks, those from sterculic acid eluting later, are observed for each type of derivative from each cyclopropene acid and can be quantified and used to determine the proportion of sterculic and malvalic acids in the untreated oil. Verification of the identities of the acids can be determined from GC-MS of the methyl esters of the products (Ahmad et al., 1979 Eisele et ai, 1974) but prominent allylic ions in the mass spectra of the DMOX derivatives of the methoxy ethers are more readily interpretable to reveal the positions of the cyclopropene rings (Spitzer, 1995). 

Ahmad, M. S., Ahmad, M. U., Osman, S. M. and Ballantine, J. A. (1979) Eriolaena hookeriana seed oil a rich source of malvalic acid. Chem. Phys. Lipids, 25, 29-38. 

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