Characterization by NMR of Ozonized methyl linoleate

Abstract

No presente estudo o linoleato de metila ozonizado com índice de peróxidos de 1.800 mmol-equiv. kg -1 foi caracterizado quimicamente. Os efeitos do ozônio sobre o linoleato de metila produz hidroperóxidos, ozonideos e aldeídos, os quais foram identificados por técnicas de ressonância magnética nuclear de 1 H e 13 C, mono-e bidimensional. O linoleato de metila padrão e o linoleato de metila ozonizado mostram espectros muito similares, excetuando os valores de ressonância (δ 9,7 e δ 9,6) que correspondem aos hidrogênios aldeídicos (δ 5,7 e δ 5,5) e olefínicos de hidroperóxidos (δ 5,2). Outras atribuições estão baseadas nas conectividades fornecidas pelas constantes de acoplamento. Estes resultados indicam que a espectrometria de RMN pode oferecer informação valiosa a respeito da quantidade de compostos oxigenados formados à partir do linoleato de metila ozonizado para o uso em ozonoterapia e na química de óleos vegetais ozonizados.In the present study ozonized methyl linoleate with peroxide index of 1,800 mmol-equiv kg -1 was chemically characterized. Ozonation of methyl linoleate produced hydroperoxides, ozonides and aldehydes which were identified by 1 H and 13 C NMR two-dimensional. The standard methyl linoleate and ozonized methyl linoleate shown very similar 1 H NMR spectra except for the signals at δ 9.7 and δ 9.6 that correspond to aldehydic hydrogen, δ 5.7 and δ 5.5 (olefinic signals from hydroperoxides) and δ 5.2 ppm (multiplet from ozonides methynic hydrogen). Other resonance assignments are based on the connectivities provided by the hydrogen scalar coupling constants. These results indicate that NMR spectroscopy can provide valuable information about the amount of formed oxygenated compounds in the ozonized methyl linoleate in order to use it to follow up ozone therapy and chemistry of ozonized vegetable oil. 5,6 However, data on the spectra of ozonized fatty acids is scarce in the literature. KeywordsThe reaction of ozone with vegetable oil and lipids occurs almost exclusively with the carbon-carbon double bonds present in unsaturated fatty acids. Different kinds of oxygenated products are formed (hydroperoxides, ozonides and aldehydes) that probably are responsible for the biological activity of ozonized fatty acids.7-9 The mechanism of this reaction is well known (Criegee mechanism, Figure 1), as well as the conditions necessary to enhance the preferential formation of any of these oxygenated compounds. 10,11 Of all the natural fatty acids, linoleic acid is one of the most widely distributed and is present in practically all lipids. For this reason, methyl linoleate was chosen as a model compound to be ozonized and chemically Experimental General ozonization procedureA mixture of 1.6 mL (0.0048 mol L -1 ) of methyl linoleate (99%) and 0.16 mL of water were introduced into a bubbling reactor where ozone reaction took place at room temperature. 7,8 The reaction was continued during 7.25 minutes and one sample was taken at applied ozone doses 245 mg g -1 . The samples were stored at -80 °C until NMR ...

Correlation of structural characterization and viscosity measurements with total unsaturation: An effective method for controlling ozonation in the preparation of ozonated grape seed and sunflower oils

“…The increasing signals corresponding to the newly formed protons surrounding the ozonides showed a complex signal pattern due the mixture of the two ozonides for the linoleic acid and the single ozonide for the oleic as cis/trans isomers [19]. These protons appeared at 1.64 ppm for the methylene attached to the ozonide, at 2.04-2.18 ppm for the methylene bonded to the ozonides, and a multiplet signal system at 5.12-5.19 ppm, 5.22-5.33 ppm, and 5.42-5.47 ppm assigned to the ozonide protons.…”

Bioactive constituents from Harpephyllum caffrum Bernh. and Rhus coriaria L

“…The isolated compounds 1-6 were identified by comparison of MS, IR, 1 H-NMR, and 13 C-NMR data to previously reported ones and were identified as hendecane 1 ,[28] methyl linoleate 2 ,[2930] betulonic acid 3 ,[31] 3-acetyl- methyl betulinate 4 ,[32] lupenone 5 ,[31] and lupeol 6 . [3233] It is noteworthy to mention that these compounds are isolated for the first time from the leaves of H. caffrum .…”

Secondary Metabolites From Rice Culture of Aspergillus Sp. Isolated From Melaleuca Subulata (Cheel) Craven Leaves and Their Anticancer Activity

“…In addition to the 1) showed a doublet signal at δH 5.01 for sp3 oxygenated methine proton (H-25) and doublet triplet signal at oxygenated one (H-20) together with one sp3 methylene group at 4. 30 were identified as methyl lineolate and respectively based on their spectroscopic data and comparison with authentic sample and published data [16][17][18][19].…”