Novel Lipid‐Peroxidation‐ and Cyclooxygenase‐Inhibitory Tannins from Picrorhiza kurroa Seeds

Abstract

From the AcOEt extract of the seeds of Picrorhiza kurroa were isolated picrorhiza acid (1), picrorhizoside A (2), picrorhizoside B (3), picrorhizoside C (4), (-)-shikimic acid (5), gallic acid (6), ellagic acid (7), isocorilagin (8), 1-O-galloyl-beta-D-glucose (9), 1-O,3-O,6-O-trigalloyl-beta-D-glucose (10), and 1-O,2-O,3-O,4-O,6-O-pentagalloyl-beta-D-glucose (11), and their structures were established by extensive NMR and chemical studies. Constituents 1-4 are novel compounds, and the known compounds 5-11 have been isolated for the first time from the seeds of P. kurroa. Compounds 2 and 3 were hydrolyzed and yielded 12, isochebulic acid. Compounds 1-12 showed 89.6, 77.3, 56.1, 50.5, 11.0, 86.4, 50.5, 29.2, 70.9, 50.5, 56.5, and 86.1% inhibition of lipid peroxidation at 5 microg/ml, respectively. The commercial antioxidants BHA (1.8 microg/ml), BHT (2.2 microg/ml), and TBHQ (1.66 microg/ml) inhibited lipid peroxidation at 85.6, 87.1, and 81.1%, respectively. The inhibition of cyclooxygenase-1 (COX-1) by 2-5, 7, 8, and 10-12 at 100 microg/ml was 41.9, 28.4, 32.9, 9.3, 70.7, 34.7, 16.0, 89.6, and 53.4%, respectively. Similarly, compounds 1-8 and 11 and 12, at 100 microg/ml, inhibited COX-2 by 12.6, 15.3, 25.1, 5.3, 13.2, 21.7, 2.0, 42.4, 43.4, and 36.9%, respectively.

Bioactive polyphenols in Ximenia americana and the traditional use among Malian healers

“…From the EtOAc soluble fraction of the EtOH crude extract of Ximenia americana leaves we isolated and identified by 1D and 2D NMR spectroscopy, corroborated by comparison with published values, sambunigrin (1) (Dellagreca et al, 2002), gallic acid (2) (Zhang et al, 2004) as well as the gallotannins ␤-glucogalline (3) (Pawlowska et al, 2006) and 1,6-digalloyl-␤-glucopyranose (4) (Owen et al, 2003). The following flavonoids were identified: quercetin (5) (identified by comparison with authentic sample), quercitrin (6) (Hasan et al, 2010), avicularin (7) (Pistelli et al, 1993), quercetin-3-O-␤-xylopyranoside (8) (Kadota et al, 1990), quercetin-3-O-(6 -galloyl)-␤-glucopyranoside (9) (Masuda et al, 2001) and kaempferol-3-O-(6 -galloyl)-␤-glucopyranoside (10) (Masuda et al, 2001).…”

Tannins: the new natural antioxidants?

“…Tannins have the ability to chelate metal ions such as Fe(II) and interfere with one of the reaction steps in the Fenton reaction and thereby retard oxidation [7]. The inhibition of lipid peroxidation by tannin constituents can act via the inhibition of cyclooxygenase [8].…”

“…Tannins have the ability to chelate metal ions such as Fe(II) and interfere with one of the reaction steps in the Fenton reaction and thereby retard oxidation [7]. The inhibition of lipid peroxidation by tannin constituents can act via the inhibition of cyclooxygenase [8].The antioxidative properties of tannin-rich extracts have been observed in meat model system studies. For example, a bearberry-leaf (Arctostaphylos uva-ursi) extract, characterized by the presence of condensed and hydrolysable tannins (,10%), at a 500-ppm…”

Elucidation of the Structures of Metabolites of Picroside II in Rat Bile by LC–ESI–IT–MS

“…It has been reported to have hepatoprotective, anticholestatic, antioxidant, and immune-modulating effects, among others [2][3][4][5]. Picroside II (b-D-glucopyranoside-1a,1b,2,5a,6,6a-hexahydro-6-[(4-hydroxy-3-methoxybenzoyl)oxy]-1a-(hydroxymethyl)oxireno [4,5]cyclopenta [1,2-c]pyran-2-yl; Fig. 1) is one of the main active constituents.…”