Mono- and polyunsaturated lipids are widely distributed in Nature, and are structurally and functionally a diverse class of molecules with a variety of physicochemical, biological, medicinal and nutritional properties. High resolution NMR spectroscopic techniques including 1H-, 13C- and 31P-NMR have been successfully employed as a structural and analytical tool for unsaturated lipids. The objective of this review article is to provide: (i) an overview of the critical 1H-, 13C- and 31P-NMR parameters for structural and analytical investigations; (ii) an overview of various 1D and 2D NMR techniques that have been used for resonance assignments; (iii) selected analytical and structural studies with emphasis in the identification of major and minor unsaturated fatty acids in complex lipid extracts without the need for the isolation of the individual components; (iv) selected investigations of oxidation products of lipids; (v) applications in the emerging field of lipidomics; (vi) studies of protein-lipid interactions at a molecular level; (vii) practical considerations and (viii) an overview of future developments in the field.

A library of thiosemicarbazide derivatives of isoniazid 3–27, was synthesized and evaluated for their anti-inflammatory and urease inhibition activities, by using in vitro bioassays. Among these compounds 9, 10, 12, 21, and 26 were identified as new derivatives. Prolonged use of non-steroidal anti-inflammatory drugs (NSAIDs) and infections caused by Helicobacter pylori (ureolytic bacteria), are the two most significant causes of gastric and peptic ulcers. We focused on the identification of the dual inhibitors of inflammation and urease enzyme. Compound 23 was identified as the best dual inhibitor of inflammation (ROS; IC₅₀ = 12.3 µg/mL), and urease enzyme inhibition activity (IC₅₀ = 22.4 µM). Many of these compounds showed comparable activities to the standard anti-inflammatory drug (ibuprofen, IC₅₀ = 11.2 µg/mL) and urease inhibitor (thiourea/acetohydraoxamic acid, IC₅₀ = 21.1/20.3 µM). Compound 12 was found to be the most potent urease inhibitor (IC₅₀ = 12.3 µM) and good inhibitor of inflammation (IC₅₀ = 27.7 µg/mL). Compounds 19, 11, 13, 9, 17, 10, and 16, were also found to be potent inhibitors of urease. Cytotoxicity was also evaluated and all the compounds were found to be non-cytotoxic, except compound 18 and the parent drug isoniazid (IC₅₀ = 29.5 and 28.5 µM, respectively).

A combination of selective 1D Total Correlation Spectroscopy (TOCSY) and ¹H-¹³C Heteronuclear Multiple Bond Correlation (HMBC) NMR techniques has been employed for the identification of methyl linolenate primary oxidation products without the need for laborious isolation of the individual compounds. Complex hydroperoxides and diastereomeric endo-hydroperoxides were identified and quantified. Strongly deshielded C–O–O–H ¹H-NMR resonances of diastereomeric endo-hydroperoxides in the region of 8.8 to 9.6 ppm were shown to be due to intramolecular hydrogen bonding interactions of the hydroperoxide proton with an oxygen atom of the five-member endo-peroxide ring. These strongly deshielded resonances were utilized as a new method to derive, for the first time, three-dimensional structures with an assignment of pairs of diastereomers in solution with the combined use of ¹H-NMR chemical shifts, Density Functional Theory (DFT), and Our N-layered Integrated molecular Orbital and molecular Mechanics (ONIOM) calculations.