M. R. Vikneswaran

Review on Polygonum minus. Huds, a commonly used food additive in Southeast Asia.

Polygonum minus (Polygonaceae), generally known as ′kesum′ in Malaysia is among the most commonly used food additive, flavoring agent and traditionally used to treat stomach and body aches. Raw or cooked leaves of P. minus are used in digestive disorders in the form of a decoction and the oil is used for dandruff. The pharmacological studies on P. minus have demonstrated antioxidant, in vitro LDL oxidation inhibition, antiulcer activity, analgesic activity, anti-inflammatory activity, in vitro antiplatelet aggregation activity, antimicrobial activity, digestive enhancing property and cytotoxic activity. The spectroscopic studies of essential oil of P. minus showed the presence of about 69 compounds, which are responsible for the aroma. The phytochemical studies showed presence of flavonoids and essential oils. This review is an effort to update the botanical, phytochemical, pharmacological and toxicological data of the plant P. minus.

New cholinesterase inhibitors from Garcinia atroviridis.

A triflavanone, Garcineflavanone A (1) and a biflavonol, Garcineflavonol A (2) have been isolated from the stem bark of Garcinia atroviridis (Clusiaceae), collected in Peninsular Malaysia. Their structures were established using one and two-dimensional NMR, UV, IR and mass spectrometry and evaluated in vitro for their acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes inhibitory activity. Molecular docking studies of the isolated compounds were performed using docking procedure of AutoDock to disclose the binding interaction and orientation of these molecules into the active site gorge.

Poly[[aquadi-μ3-malonato-hexaphenyl­ditin(IV)] acetone solvate]

The asymmetric unit of the title polymeric complex, {[Sn2=(C6H5)6(C3H2O4)(H2O)]·C3H6O}n, comprises of two Sn cations, one malonate anion and a non-coordinating acetone solvent molecule. Both crystallographically independent Sn cations are five-coordinated by two O and three C atoms in a distorted trigonal-bipyrimidal geometry. One of the Sn cations is bridged by the malonate units, affording polymeric chains which run along [001]. Weak intramolecular C—H⋯π interactions stabilize the molecular structure. In the crystal structure, adjacent chains are interconnected by intermolecular O—H⋯O and C—H⋯O hydrogen bonds into a three-dimensional supramolecular structure. A weak intermolecular C—H⋯π interaction is also observed.

Ferrocene-1-carbaldehyde thio­semi­carbazone

The asymmetric unit of the title compound, [Fe(C5H5)(C7H8N3S)], consists of two crystallographically independent molecules, A and B. The cyclopentadienyl (Cp) rings in both molecules adopt an eclipsed conformation and are parallel to each other, forming dihedral angles of 2.5 (3) and 1.1 (3)°, respectively. The mean plane of the semicarbazone group is coplanar with the attached Cp ring in molecule A, whereas it is twisted away in molecule B. In the crystal structure, intermolecular N—H⋯S hydrogen bonds link the molecules into two-dimensional planes parallel to the ab plane. The structure is further consolidated by C—H⋯π interactions.

Evaluation of analgesic, anti-inflammatory, antipyretic and antiulcer effect of aqueous and methanol extracts of leaves of Polygonum minus Huds. (Polygonaceae) in rodents

Background: Polygonum minus (Kesum) is an annual plant that grows throughout South East Asian countries. The Leaf of P. minus is commonly used as diet ingredient in Malaysia. Traditionally the decoction of leaves of this plant is used to treat stomach ache and digestive problems. The plant has known antioxidant activity, and its pharmacological properties are remaining unclear. Hence the study is planned to evaluate the analgesic, anti-inflammatory, antiulcer and antipyretic activity of kesum. Materials and methods: P. minus leaves was extracted with methanol and distilled water by simple maceration. The dried extract was used for further phytochemical and pharmacological analysis. The analgesic effect of methanol and aqueous extract of P. minus was studied using acetic acid, tail immersion and formalin induced pain in rats. The anti-inflammatory effect of both extracts was studied using carrageenan induced paw edema in rats. The pyloric ligation model was used to study the antiulcer effect. The antipyretic effect was studied using Brewer′s yeast induced pyrexia. Results: The percentage yield of aqueous and methanol extract of P. minus leaves were 1.15 and 2.57% w/w respectively. Both the extract showed significant analgesic effect against acetic acid writing, tail immersion and formalin induced pain methods, but the effect was not equivalent to that of standard. Aqueous extract showed significant anti-inflammatory action and methanol extract showed significant anti-ulcer effect. Conclusion: The aqueous extract of the P. minus has significant analgesic and anti-inflammatory action, whereas methanolic extract showed presence of analgesic and anti-ulcer activity. Both aqueous and methanolic extract did not show any significant antipyretic activity.

Ferrocene-1-carbaldehyde 4-ethyl-thio-semi-carbazone.

The asymmetric unit of title compound, [Fe(C5H5)(C9H12N3S)], contains two crystallographically independent molecules, A and B. The two cyclopentadienyl (Cp) rings are parallel to each other in both molecules, forming dihedral angles of 2.3 (3) and 1.0 (3)°, respectively, and adopt an eclipsed conformation. The mean plane of the semicarbazone group is twisted slightly away from the attached Cp ring in both molecules, the dihedral angles between the mean plane and the Cp ring being 15.3 (2) and 10.8 (2)°. The ethyl group in molecule A is coplanar with the mean plane of the semicarbazone group [C—N—C—C torsion angle = −175.2 (4)°], whereas it is nearly perpendicular in molecule B [C—N—C—C torsion angle = 84.8 (6)°]. In the crystal structure, intermolecular N—H⋯S hydrogen bonds link the molecules into dimers. These dimers are further linked into chains via intermolecular C—H⋯S hydrogen bonds. The crystal studied was a non-merohedral twin with a refined ratio of the twin components of 0.265 (2):0.735 (2).

Bis(ferrocenecarbaldehyde 4-methyl­thio­semicarbazonato-κ2N1,S)zinc(II) methanol solvate

In the title compound, [Fe2Zn(C5H5)2(C8H9N3S)2]·CH3OH, the dihedral angles between the substituted and unsubstituted cyclopentadienyl rings are 89.34 (8) and 85.73 (9)°, respectively. The two Zn/S/C/N/N five-membered rings adopt envelope conformations, with the ZnII atom at the flap. Each methanol solvent molecule is linked to three ferrocene groups via intermolecular O—H⋯N, N—H⋯O and C—H⋯O hydrogen bonds. The crystal structure is further consolidated by C—H⋯π interactions.

Bis(ferrocenecarbaldehyde thio­semi­carbazonato-κ2N1,S)zinc

In the title compound, [Fe2Zn(C5H5)2(C7H7N3S)2], the Cp rings of each ferrocene residue have a nearly eclipsed conformation. The two thiosemicarbazone ligands each coordinate the Zn atom in a bidentate mode via the N and S atoms, thereby defining a distorted tetrahedral environment. N—H⋯S, N—H⋯N, C—H⋯S and C—H⋯N intra- and intermolecular interactions connect the molecules into a two-dimensional array parallel to (010).

Bis(1-ferrocenylmethyl­idene-4-phenyl­thiosemicarbazidato-κ2N1,S)zinc(II) monohydrate

In the title compound, [Fe2Zn(C5H5)2(C13H11N3S)2]·H2O, the ZnII ion is in a distorted tetrahedral geometry being coordinated by two thiosemicarbazone ligands via N and S atoms. One of the Cp rings is disordered over two positions with occupancies of 0.55 and 0.45. The dihedral angle between the substituted Cp rings is 56.1 (5)° and the two phenyl rings are orientated at a dihedral angle of 41.7 (4)°. In the crystal structure, intermolecular O—H⋯S, N—H⋯O and C—H⋯N hydrogen bonds link the molecules into chains along the b axis. The structure is further consolidated by O—H⋯π interactions.

Influence of extracting solvent on pharmacological activity and cytotoxicity of Polygonum minus, a commonly consumed herb in Southeast Asia

Objective: To investigate the antihyperlipidemic, antioxidant, and cytotoxic effect of aqueous and methanol extract of leaves of Polygonum minus. Materials and Methods: Acute antihyperlipidemic effect was studied on chemically induced hyperlipidemic rat model. Treated groups received aqueous and methanol extract of leaves of P. minus respectively (1000 mg/kg; oral) whereas standard treated group received atorvastatin (60 mg/kg; oral) for 3 consecutive days. Blood samples were collected at fixed intervals for lipid profile analysis. Antioxidant effects were studied using 1,1-diphenyl-2-picrylhydrazyl, 2,2-azinobis 3-ethylbenzothiazoline 6-sulfonate, and ferric reducing antioxidant power assays. The total flavonoids content and total phenolic contents were also estimated. Cytotoxicity of both extracts was studied on one normal and three cancer cell lines using 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT) assay method. Results: The methanol extract showed significant reduction in total cholesterol (P < 0.001), triglycerides (P < 0.01), LDL (P < 0.05), VLDL (P < 0.01), atherogenic index (P < 0.001), and elevation of HDL (P < 0.05) levels than the aqueous extract. Similarly, the antioxidant investigations also demonstrated that the methanol extract had higher antioxidant capacity than aqueous extract. Both extracts were not toxic to normal (EA.hy926) as well as to cancer (HCT116, HT29, and HeLa) cells. Significant correlation was demonstrated between total phenolic and total flavonoids contents with the antioxidant activity but not with the antihyperlipidemic effect, suggesting other groups of chemical constituents may be mainly responsible for the antihyperlipidemic effect of this plant. Conclusion: The study demonstrated that the presence and extent of bioactivities are influenced by solvents used for extraction. This study confirmed the antihyperlipidemic effect of leaves of P. minus in acute hyperlipidemic rat model. Abbreviations used: CVDs: Cardiovascular diseases, LDL: Low-density lipoprotein, DDPH: 1 ,1-Diphenyl-2-picrylhydrazyl radical, TPTZ : 2,4,6,-tris(1-pyridyl)-5-triazine, ABTS : 2,2?-Azino-di-[3-ethylbenzthiazoline Sulfonate], HDL: High-density lipoprotein, VLDL: Very low-density lipoprotein, TC: Total cholesterol, TG: Triglycerides, EC 50: Half maximal effective concentration, LD 50: Median lethal dose.