The electronic and magnetic states of an epitaxially grown full-Heusler alloy Co 2 MnSi ͑CMS͒ 1.1 nm ͑4 ML͒ thick ultrathin film and a CMS 50-nm-thick film both facing an epitaxial MgO͑001͒ tunnel barrier were element-specifically studied by means of x-ray absorption spectroscopy ͑XAS͒ and x-ray magnetic circular dichroism ͑XMCD͒. The observed XAS and XMCD spectra revealed that both the CMS films were not oxidized. The Co and Mn spin magnetic moments for the 4 ML thick CMS film obtained by applying the sum rules were close to those for the 50-nm-thick one and the theoretical values for bulk CMS with the L2 1 structure. These results indicate that 4 ML thick CMS ultrathin films facing a MgO barrier still retain the electronic and magnetic states for the L2 1 structure. © 2008 American Institute of Physics. ͓DOI: 10.1063/1.2836676͔Co-based Heusler alloys ͑Co 2 YZ͒ are promising ferromagnetic electrode materials for spintronic devices. [1][2][3][4][5][6][7][8] This is because of their potentially high spin polarization arising from the half-metallic ferromagnetic nature theoretically predicted for some of these alloys, and because of their high Curie temperatures, which are well above room temperature ͑RT͒. We have recently developed fully epitaxial magnetic tunnel junctions ͑MTJs͒ with a Co 2 YZ thin film and a MgO͑001͒ tunnel barrier, and demonstrated a relatively high tunnel magnetoresistance ratio at RT. [3][4][5][6][7][8] The spin-dependent tunneling characteristics in MTJs are very sensitive to the electronic and magnetic states of the interfacial region of ferromagnetic electrodes with a tunnel barrier.Recently, x-ray absorption spectroscopy ͑XAS͒ and x-ray magnetic circular dichroism ͑XMCD͒ have proved to be effective techniques for obtaining microscopic information about the element-specific electronic and magnetic states in the interfacial region of MTJs. [9][10][11][12] In this work, we fabricated an epitaxial Co 2 MnSi ͑CMS͒ 1.1 nm ͑4 ML͒-thick ultrathin film and a CMS 50-nm-thick film with an epitaxial MgO barrier in order to investigate the interfacial region selectively by XAS and XMCD measurements at the Mn-L 2,3 and Co-L 2,3 edges.The sample layer structure was grown on a MgO͑001͒ single-crystal substrate and, from the substrate side, consisted of MgO buffer ͑10 nm͒ / Fe underlayer ͑50 nm͒/CMS ultrathin film ͑4 ML͒/MgO barrier ͑2 nm͒ / Ru cap ͑2 nm͒. A monolayer of Co 2 MnSi consists of a Co plane and a Mn-Si plane, and a unit cell of CMS, whose lattice parameter is 0.5654 nm ͑Ref. 13͒, corresponds to 2 ML of CMS. We grew the 4-ML-thick CMS ultrathin film on the Fe underlayer to stabilize its ferromagnetism at RT. Each layer in the sample layer structure was successively deposited in an ultrahigh vacuum chamber ͑base pressure: about 6 ϫ 10 −8 Pa͒ through the combined use of magnetron sputtering ͑for Fe, CMS, and Ru͒ and electron beam evaporation ͑for MgO͒; the fabrication procedure was the same as in previous work. [3][4][5][6][7][8]14 The CMS film deposited at RT were annealed in situ at 325°C for...

A screening of 30 crude extracts of marine sponges against human promyelocytic leukemia cells (HL-60) yielded an EtOAc extract of the sponge Callyspongia sp. (Callyspongiidae) with significant activity. Further bioassay-guided fractionation of the EtOAc extract led to the isolation of three polyacetylene metabolites: a new polyacetylene diol, callyspongidiol (1), along with two known compounds, siphonodiol (2) and 14,15-dihydrosiphonodiol (3). Their structures were determined by a combination of spectroscopic analyses. Compounds 1-3 exhibited antiproliferative activity against HL-60 with IC(50) values of 6.5, 2.8, and 6.5 microg/ml, respectively. These metabolites induce apoptosis in HL-60 cells. Dendritic cells (DC) differentiated with 1-3 enhance the differentiation of naïve T cells towards the Th1 type.

Lo Han Kuo is the fruit of the Siraitia grosvenori SWINGLE (formerly Momordica grosvenori SWINGLE) belonging to Cucurbitaceae species and used as a pulmonary demulcent and emollient for the treatment of dry cough, sore throat, dire thirst, and constipation in traditional Chinese medicine.1) Recently, some intriguing pharmacological characteristics such as anti-cancer and anti-hyperglycemic effects, and inhibition of oxidative modification of low density-lipoprotein were reported.2-4) Therefore it was suggested that a new kind of cancer chemopreventive agent might be developed. A number of cucurbitane triterpene saponins from the ripe fruits were previously obtained. [5][6][7][8][9][10][11][12] Some compounds among them are extremely sweet, such as mogroside V (7) and mogroside IVA (6), and their relative sweetnesses were more than 300 times as high as that of sucrose despite having minimal caloric content. However, it also contains minor tasteless, even bitter principle, such as mogroside III (5) and mogroside IIE (4). The ripe fruit mainly contains mogroside V (7), so it is very sweet. On the basis of these characteristics, its extract is commercially utilized as a sweet component in sugar substitute, that is widely used as additive and ingredient in health foods and beverages. Owing to the influence of cold weather during winter, some fruits cannot mature naturally. The unripe fruits have bitter taste, and at the place of cultivation, these may amount to one quarter of total production. Until now, no chemical constituent studies have been conducted on these fruits. Hence in unripe fruits, a study on the constituents was performed and provided two new cucurbitane triterpene glycosides, 20-hydroxy-11-oxomogroside IA 1 (1) and 11-oxomogroside IIE (2), along with five known cucurbitane glycosides, 11-oxomogroside IA 1 (3), mogroside IIE (4), mogroside III (5), mogroside IVA (6), mogroside V (7), and two flavonoid glycosides, kaempferol 7-O-a-L-rhamnopyranoside (8) and kaempferol 3,7-di-O-a-L-rhamnopyranoside (9). Their structures were determined on the basis of detailed analyses of 1D, 2D-NMR spectroscopic methods and by comparing with literature values.4-11) Compounds 2 and 4 are the main constituents of unripe fruits and contribute to bitter taste. This paper deals with the first investigation of unripe bitter Lo Han Kuo fruits.Fresh unripe fruits were extracted with methanol. A suspension of methanol-extract in water was subjected to a high-porous polystynene gel, Diaion HP-20, which was successively eluted with H 2 O and 30%, 80%, and 100% methanol. The 80% methanolic eluate was chromatographed on silica gel, Sephadex LH-20 and reverse phase silica gel to afford nine glycosides, compounds 1-9, in yields of 0.0002%, 0.0068%, 0.00064%, 0.0081%, 0.0024%, 0.00019%, 0.0005%, 0.00081% and 0.0011%, respectively.Compound 1, a white amorphous powder, [a] D ϩ113.3°( MeOH), showed a quasi-molecular ion peak at m/z 654 [MϩH] ϩ and 654.4398 [MϩH] ϩ in the positive HR-FAB-MS, corresponding to the molecular formula C 36 ...

Terpenes U 0200Cucurbitane Glycosides from Unripe Fruits of Lo Han Kuo (Siraitia grosvenori).-Two new cucurbitane triterpene glucosides, 20-hydroxy-11-oxomogroside IA 1 (I) and 11-oxomogroside IIE (II), are isolated from the unripe fruits of Lo Han Kuo (Siraitia grosvenori) thogether with five known cucurbitane glucosides.-(LI*, D.; IKE-DA, T.; MATSUOKA, N.; NOHARA, T.; ZHANG, H.; SAKAMOTO, T.; NONAKA, G.-I.; Chem.

The water extract of Pruni Cortex, which is obtained from the bark of Prunus jamasakura, is a major component in Brocin. We investigated the constituents of the water and methanolic extracts of Pruni Cortex. From the water extractive, two flavonoids (sakuranin and neosakuranin; major constituents of this extractive), four known lignans, and six aromatic compounds including one new compound were obtained. In addition, we also investigated the constituents of the flowers and the leaves of Prunus yedoensis.