title: 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.
authors.affiliation: Bioactive Natural Products and Phytoceuticals, Department of Horticulture and National Food Safety and Toxicology Center, Michigan State University, East Lansing, Michigan 48824, USA.
authors.forename: Yanjun
authors.initials: Y
authors.lastname: Zhang
authors.forename: David L
authors.initials: DL
authors.lastname: DeWitt
authors.forename: Sorimuthu
authors.initials: S
authors.lastname: Murugesan
authors.forename: Muraleedharan G
authors.initials: MG
authors.lastname: Nair
mesh_terms: D016861:Cyclooxygenase Inhibitors / Q000737:chemistry / Q000302:isolation & purification*; D015227:Lipid Peroxidation / Q000502:physiology*; D032261:Picrorhiza; D010936:Plant Extracts / Q000737:chemistry / Q000302:isolation & purification; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism; D012639:Seeds; D013634:Tannins / Q000737:chemistry / Q000302:isolation & purification*
chemical_list: D016861:Cyclooxygenase Inhibitors; D010936:Plant Extracts; D013634:Tannins; D011451:Prostaglandin-Endoperoxide Synthases