RESUMO
Reactions of 1,10-phenanthroline (phen) and 2-(3,4-dichlorophenyl)acetic acid (dcaH) with Mn(CO3) (M = LiI, NaI and MgII; n = 1 and 2) in MeOH yield the mononuclear lithium complex aqua[2-(3,4-dichlorophenyl)acetato-κO](1,10-phenanthroline-κ2N,N')lithium(I), [Li(C8H5Cl2O2)(C12H8N2)(H2O)] or [Li(dca)(phen)(H2O)] (1), the dinuclear sodium complex di-µ-aqua-bis{[2-(3,4-dichlorophenyl)acetato-κO](1,10-phenanthroline-κ2N,N')sodium(I)}, [Na2(C8H5Cl2O2)2(C12H8N2)2(H2O)2] or [Na2(dca)2(phen)2(H2O)2] (2), and the one-dimensional chain magnesium complex catena-poly[[[diaqua(1,10-phenanthroline-κ2N,N')magnesium]-µ-2-(3,4-dichlorophenyl)acetato-κ2O:O'] 2-(3,4-dichlorophenyl)acetate monohydrate], {[Mg(C8H5Cl2O2)(C12H8N2)(H2O)2](C8H5Cl2O2)·H2O}n or {[Mg(dca)(phen)(H2O)2](dca)·H2O}n (3). In these complexes, phen binds via an N,N'-chelate pocket, while the deprotonated dca- ligands coordinate either in a monodentate (in 1 and 2) or bidentate (in 3) fashion. The remaining coordination sites around the metal ions are occupied by water molecules in all three complexes. Complex 1 crystallizes in the triclinic space group P-1 with one molecule in the asymmetric unit. The Li+ ion adopts a four-coordinated distorted seesaw geometry comprising an [N2O2] donor set. Complex 2 crystallizes in the triclinic space group P-1 with half a molecule in the asymmetric unit, in which the Na+ ion adopts a five-coordinated distorted spherical square-pyramidal geometry, with an [N2O3] donor set. Complex 3 crystallizes in the orthorhombic space group P212121, with one Mg2+ ion, one phen ligand, two dca- ligands and three water molecules in the asymmetric unit. Both dcaH ligands are deprotonated, however, one dca- anion is not coordinated, whereas the second dca- anion coordinates in a bidentate fashion bridging two Mg2+ ions, resulting in a one-dimensional chain structure for 3. The Mg2+ ion adopts a distorted octahedral geometry, with an [N2O4] donor set. Complexes 1-3 were evaluated against urease and α-glucosidase enzymes for their inhibition potential and were found to be inactive.
RESUMO
In continuation to our study of the chemical and biological potential of the secondary metabolites isolated from Omani seaweeds, we investigated a marine brown alga, Padina boergesenii. The phytochemical investigation resulted in the isolation of a new secondary metabolite, padinolic acid (1), along with some other semi-pure fractions and sub-fractions. The planar structure was confirmed through MS and NMR (1D and 2D) spectral data. The NOESY experiments coupled with the biogenetic consideration were helpful in assigning the stereochemistry in the molecule. Compound 1 was subjected to enzyme inhibition studies using urease, lipid peroxidase, and alpha-glucosidase enzymes. Compound 1 showed low to moderate α-glucosidase and urease enzyme inhibition, respectively, and moderate anti-lipid peroxidation activities. The current study indicates the potential of this seaweed and provides the basis for further investigation.
