New Enynolic Acids from Acanthosyris. Structures and Chemistry¹

Identification of nine acetylenic fatty acids, 9‐hydroxystearic acid and 9,10‐epoxystearic acid in the seed oil ofJodina rhombifolia hook et arn. (Santalaceae)

“…Furthermore, the pairs of 13C NMR signals at 62.77: 62.68 ppm (CH-O-) and 37.78:37.62 ppm (CH 2) suggested the occurrence of at least two FA with a -C-C-CH(OH)structure (10). This assignment was supported by the ~H NMR signal at 4.4 ppm (t), which can also be attributed to the latter type of structure element (10,11). Further details of the assignments of the NMR data are described in the following section.…”

“…In addition, the OXFA derivatives were examined by GC/MS, which enables the unequivocal location of the double bond(s) (5). Identification of the unusual FA (Peaks 7, [10][11][12][13][14][15][16][17][18][19]. TLC analysis of the total FAME showed two main bands under UV (FAME-A with Re = 0.81 and FAME-B with Rf = 0.32}.…”

“…The fractions FAME-A1 and FAME-A2 lacked the IR absorption for the OH group, and the typical terminal vinyl absorption band (910 cm -1) was absent in FAME-A1/FAME-B1 but was strongly enhanced in FAME-A2 and FAME-B2. Comparison of the NMR spectral data of the fractions FAME-A and FAME-B with the literature data for usual FAME (13,14), acetylenic FAME (9,15,16), conjugated acetylenic-hydroxy FAME (10,11) and hydroxy FAME (17), together with the APT and 2D H/C NMR experiments, allowed the assignments of the signals to individual hydrogen and carbon atoms ( Table 2). The 1H NMR spectrum of both fractions showed a doublet at 5.43 ppm (J 15 Hz) and a doublet-triplet at 6.1 ppm (J 15; 7 Hz) in equal intensities.…”

“…The absence of a methylene signal at about 19 ppm, indicated that the hydroxyl group must be in conjugation with the acetylenic bond. GC analysis demonstrated that the FAME-A fraction consists of the normal FA (Peaks 1-6, 8-9) and contains furthermore two major (Peaks 10, 12) and three minor FA with unusual ECL-values ( Peaks 7,11,13). The five unusual FA 15-19 with high ECL values belong to the FAME-B fraction (Fig.…”

“…After silylation of the latter fraction, all GC peaks appeared at lower retention times, confirming the presence of a hydroxyl group. According to the weak signals in the IR and NMR spectra for the terminal vinyl group, it was concluded that only the small unknown peaks of the GC ( Peaks 7,11,13,15,16,18)could come into question for the FA with this type of unsaturation. FA 14 appeared only in the GC of the total FAME, suggesting different structural properties.…”