Reference

Oxidative degradation of lignin

Oxidative degradation of lignin. VI. Demethylation mechanism of lignin with a hydroxyl radical. Tatsumi, Kenji; Terashima, Noritsugu (Natl. Res. Inst. Pollut. Resour., Yatabe 305, Japan). Mokuzai Gakkaishi, 30(7), 580-6 (English) 1984. CODEN: MKZGA7. ISSN: 0021-4795. DOCUMENT TYPE: Journal CA Section: 43 (Cellulose, Lignin, Paper, and Other Wood Products) Section cross-reference(s): 25 The oxidn. of veratric acid (I) [93-07-2] as model for lignin with H218O2 under UV irradn. at pH 5.0 resulted in the formation of 3 hydroxyveratric acids (II) with 18OH groups at the 2-, 5- and 6-positions.There are some reagents like 67370-98-3 is used in this study. The isotope presence in the OH group of these acids is ~90%, almost the same as that of H218O2 (91.1%). In the process of demethylation of I with OH radical, 18O was also incorporated into vanillic acid (III) [121-34-6] and isovanillic acid (IV) [645-08-9], and the isotope presence in OH group of 2 acids was 86%. It was demonstrated that replacement of a ring H atom by OH radical results in oxidn. yielding II, and that of a methoxy group by a OH radical in the same reaction mechanism results in demethylation to produce III and IV. .

Study on the chemical constituents of Ligularia platyglossa Hand

All Rights Reserved. Study on the chemical constituents of Ligularia platyglossa Hand.-Mazz. Liu, Jianqun; Zhang, Chaofeng; Zhang, Mian; Wang, Zhengtao; Qi, Huanyang (Department of Pharmacognosy, China Pharmaceutical University, Nanjing 210038, Peop. Rep. China). Zhongguo Yaoke Daxue Xuebao, 36(2), 114-117 (Chinese) 2005 Zhongguo Yaoke Daxue. CODEN: ZHYXE9.Several reagents with their cas registry numbers 645-08-9 and 474-58-8 are used here. ISSN: 1000-5048. DOCUMENT TYPE: Journal CA Section: 63 (Pharmaceuticals) Section cross-reference(s): 11 The bioactive compds. of Ligularia platyglossa were studied. Compds. were isolated by silica gel, Sephadex LH-20, and Rp-18 column chromatog., and purified by recrystn. Their structures were identified by NMR spectral data and other methods. Seven compds. were isolated and identified as eremophil- 1(10),7(11),8(9)-trien-12,8-olide, 8b-hydroxyeremophil- 7(11),9(10)-dien-12,8a-olide, 2-oxoeremophil-1(10),7(11),8(9)-trien-12,8-olide, fisetin, isovanillic acid, 7-angelyheliotridine, and daucosterol. All of the compds. were isolated from this plant for the first time, and, except for the 1st compd. and daucosterol, the rest were isolated from Ligularia genus for the first time. 2-Oxoeremophil-1(10),7(11),8(9)-trien-12,8-olide is a new natural entity. .