Page 63 - Demo

SECTION I: MOLECULAR GENETIC ENGINEERING AND BIOCHEMICAL TECHNOLOGY 67The location of the methoxy group was confirmed at C-3 according to the HMBC correlation between H-2 with C-3. Thus the hydroxy group was established at C-4. Based on the above evidences and upon comparison of the reported values [26], the structure of 1 was elucidated to be 4-hydroxy-3-methoxybenzoic acid or vanillic acid. Compound 2 was obtained as pale yellow powder. The 1H NMR of compound 2 displayed signals for a flavanol with 3 rings A, C and B (C6-C3-C6). Two meta coupling aromatic protons of ring A appeared at %u03b4H 5.94 (1H, d, J = 2.1 Hz, H-8), 5.93 (1H, d, J = 2.1 Hz, H-6). Signals of four protons of ring B were observed at %u03b4H 7.37 (2H, d, J = 8.5 Hz, H-2%u2032, H-6%u2032), 6.88 (2H, d, J = 8.6 Hz, H-3%u2032,H-5%u2032) suggested signals of a para substituted ring. Signals of ring C including an oxymethine proton at %u03b4H 5.43 (1H, dd, J = 12.9, 3.0 Hz, H-2), two nonequivalent ethylene protons at %u03b4H 3.16 (1H, dd, J = 17.1, 12.9 Hz, H-3a), 2.71 (1H, dd, J = 17.1, 3.0 Hz, H-3b). Signals of a chelated hydroxyl proton appeared at %u03b4H 12.14 (1H, s, 5-OH). The 13CNMR and HSQC of compound 2 indicated the presence of 15 carbons, including signals of a carbonyl carbon at %u03b4C 196.4 (C-4), four aromatic carbinols at %u03b4C 166.8 (C-5), 164.4 (C-9), 163.5 (C-7), 158.0 (C-4%u2019); two non-protonated aromatic carbons at %u03b4C 129.7 (C-1%u2019), 102.2 (C-10); six aromatic methines at %u03b4C 128.1 (C2%u2019, C-6%u2019), 115.3 (C-3%u2019, C-5%u2019), 96.0 (C-6), 95.0 (C-8); one oxymethine carbon at %u03b4C 79.0 (C-2) and one aliphatic methylene at %u03b4C 42.6 (C3). The NMR spectra of 2 (Table 1) suggested the existance of a flavone with three hydroxyl group.