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In a two-microelectrode voltage clamp with Xenopus laevis oocytes, a petroleum ether extract of Acorus calamus rhizomes enhanced the GABA-induced chloride current through GABA A receptors of the α 1 β 2 γ 2S subtype by 277% ± 9.7% (100 μg/mL). β-Asarone (1), (+)-dioxosarcoguaiacol (2), (+)-shyobunone (3), and (+)-preisocalamenediol (4) were subsequently identified as main active principles through HPLC-based activity profiling and targeted isolation. The compounds induced maximum potentiation of the chloride current ranging from 588% ± 126% (EC 50 : 65.3 ± 21.6 μM) (2) to 1200% ± 163% (EC 50 : 171.5 ± 34.6 μM) (1), whereas (−)-isoshyobunone (5) and (−)-acorenone (6) exhibited weak GABA A modulating properties (5: 164% ± 42.9%; EC 50 : 109.4 ± 46.6 μM and 6: 241% ± 23.1%; EC 50 : 34.0 ± 6.7 μM). The relative configuration of 2 was established as 4R*8S*10R* by NOESY experiments and conformational analysis.Acorus calamus L. (Acoraceae), commonly known as "sweet flag", is a polyploidic marsh plant indigenous to Asia and is now distributed along trade routes all over the northern hemisphere. 1 The aromatic rhizome has been widely used as an herbal remedy. It contains 1.7-9.3% of a volatile oil composed of monoterpenes, sesquiterpenes, and phenylpropanoids. The most characteristic constituent of the oil is β-asarone, even though Europe PMC Funders GroupAuthor Manuscript J Nat Prod. Author manuscript; available in PMC 2011 October 24. Europe PMC Funders Author ManuscriptsEurope PMC Funders Author Manuscripts its concentration may vary considerably (96% in the tetraploidic form found in eastern and tropical southern Asia, 5% in the triploidic form found in Europe, Himalayan, and temperate Indian regions, and 0% in the diploidic variety growing from North America to Siberia). [1][2][3][4] In European folk medicine, A. calamus rhizomes have been mainly used as "Amarum aromaticum" to alleviate gastrointestinal ailments such as acute and chronic dyspepsia, gastritis and gastric ulcer, intestinal colic, and anorexia. 5,6 Ayurvedic medicine and traditional Chinese medicine (TCM) use the drug preferably to treat central nervous system (CNS) related diseases such as epilepsy, insanity, mental weakness, or insomnia. 7-9 Several in vivo studies support a sedative and tranquillizing action of the essential oil and of ethanolic and aqueous extracts of A. calamus. [10][11][12] Up to now, the underlying mechanism of action has remained elusive despite various investigations, even though the pharmacological effect could be mainly attributed to α-asarone and β-asarone. 11,[13][14][15] GABA A receptors are pentameric ligand-gated chloride ion channels that are activated by GABA, the major inhibitory neurotransmitter in the CNS. Most likely more than 11 different receptor subtypes, assembled from five varying subunits, exist in the human brain. These are involved in distinct neuronal circuits and are targeted by numerous classes of drugs such as benzodiazepines, barbiturates, and some general anesthetics. The most abundant GABA...

Source of materialPbBr 2 and [Ph 3 P-CH=CH-PPh 3 ][Br 2 ] were both dissolved in aqueous HBr, the solutions were mixed and water was slowly evaporated. After several hours a fine crystalline yellow powder precipitated. For the preparation of single crystals 1.5 g of this product and 5 ml H2O were filled into a glass ampoule which was sealed and heated to 45 3 K. The ampoule was cooled with a rate of 10 K/min to ambient temperature. DiscussionLead atom is coordinated by four bromide ligands, in form of a trigonal ψ-bipyramide with one equatorial position occupied by the s 2 -pair. The axial Pb-Br bond lengths are 2.99 Ä, the equatorial lengths 2.70 Ä, Br(ax)-Pb-Br(eq) angles are in the range 95.53° to 99.42°, the bond angle between the two axial Br-atoms is 159.0°. The data agree with those observed in comparable bromoplumbates(II) [1]. The distorted ψ-bipyramide was so far not observed in the structure of lead bromides with organic cations. Cations and anions form waved layers, which are stacked along the α-axis in the order A,A,A. Bond distances and bond angles in the cation agree well with the data of Stang and Zhdankin [2], The compound was investigated with a differential scanning calorimeter. Between 153 Κ and 423 Κ no phase transition was detected.

C 3 8H 3 2Br 4 P2Pb, monoclinic, C12/cl (No. 15), a = 10.913(2) Ä, b = 17.618(4)Ä,c = 19.848(4)Ä,β = 99.97(3)°, V= 3758.5Ä 3 , Ζ = 4, /fgt(F) = 0.043, wR Kf (F 2) = 0.096, T= 293 K. Source of material PbBr 2 and [Ph 3 P-CH=CH-PPh 3 ][Br 2 ] were both dissolved in aqueous HBr, the solutions were mixed and water was slowly evaporated. After several hours a fine crystalline yellow powder precipitated. For the preparation of single crystals 1.5 g of this product and 5 ml H2O were filled into a glass ampoule which was sealed and heated to 45 3 K. The ampoule was cooled with a rate of 10 K/min to ambient temperature. Discussion Lead atom is coordinated by four bromide ligands, in form of a trigonal ψ-bipyramide with one equatorial position occupied by the s 2-pair. The axial Pb-Br bond lengths are 2.99 Ä, the equatorial lengths 2.70 Ä, Br(ax)-Pb-Br(eq) angles are in the range 95.53° to 99.42°, the bond angle between the two axial Br-atoms is 159.0°. The data agree with those observed in comparable bromoplumbates(II) [1]. The distorted ψ-bipyramide was so far not observed in the structure of lead bromides with organic cat-ions. Cations and anions form waved layers, which are stacked along the α-axis in the order A,A,A. Bond distances and bond angles in the cation agree well with the data of Stang and Zhdankin [2], The compound was investigated with a differential scanning calorimeter. Between 153 Κ and 423 Κ no phase transition was detected.

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