title: Structure determination of bioactive galloyl derivatives by NMR spectroscopy.
abstract: The investigation of the chemical constituents of Symplocos racemosa Roxb led to the isolation of two new glycosides, symcomoside A (1) and symcomoside B (2), together with one known glycoside, tortoside C (3), which is reported for the first time from this plant. The structures of the new compounds were determined by 1D and 2D homonuclear and heteronuclear NMR spectroscopy, from chemical evidence and by comparison with published data for closely related compounds. Symcomoside B (2) showed potent inhibitory activity against alpha-glucosidase in a concentration-dependent fashion with an IC50 value of 0.733 +/- 0.033 mM whereas symcomoside A (1) showed very weak inhibitory activity against alpha-glucosidase (9.90% in 0.70 mM).
authors.affiliation: H.E.J. Research Institute of Chemistry, International Center for Chemical Sciences, University of Karachi, Karachi-75270, Pakistan. vuahmad@cyber.net.pk
authors.forename: Viqar Uddin
authors.initials: VU
authors.lastname: Ahmad
authors.forename: Muhammad
authors.initials: M
authors.lastname: Zubair
authors.forename: Muhammad
authors.initials: M
authors.lastname: Athar Abbasi
authors.forename: Muhammad
authors.initials: M
authors.lastname: Abid Rashid
authors.forename: Nasir
authors.initials: N
authors.lastname: Rasool
authors.forename: Shamsun
authors.initials: S
authors.lastname: Nahar Khan
authors.forename: M
authors.initials: M
authors.lastname: Iqbal Choudhary
authors.forename: Farzana
authors.initials: F
authors.lastname: Kousar
mesh_terms: D002247:Carbon Isotopes; D005707:Gallic Acid / Q000031:analogs & derivatives* / Q000737:chemistry* / Q000302:isolation & purification; D005960:Glucosides / Q000737:chemistry* / Q000302:isolation & purification; D006027:Glycosides / Q000737:chemistry* / Q000302:isolation & purification; D009682:Magnetic Resonance Spectroscopy / Q000379:methods* / Q000592:standards*; D019684:Magnoliopsida / Q000737:chemistry*; D008968:Molecular Conformation; D010936:Plant Extracts / Q000737:chemistry* / Q000302:isolation & purification; D011522:Protons; D012015:Reference Standards
chemical_list: D002247:Carbon Isotopes; D005960:Glucosides; D006027:Glycosides; D010936:Plant Extracts; D011522:Protons; C502054:symcomoside A; C502055:symcomoside B; D005707:Gallic Acid