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1.  Epibisde­hydro­neotuberostemonine J 
The title compound, C22H29NO4, a stemona alkaloid, is composed of two lactone rings (A and E), a six-membered ring (B), a pyrrole ring (C) and a seven-membered ring (D). The five-membered rings A and E exhibit envelope conformations (C atoms as flaps) while ring C is planar. Ring B exhibits a twist-chair conformation due to fusion with pyrrole ring C while ring D adopts a chair conformation. The junction between rings A and B is cis. In the crystal, weak C—H⋯O inter­actions involving the two carbonyl groups, a methyl­ene and a methyl group give rise to a three-dimensional network.
doi:10.1107/S1600536813021077
PMCID: PMC3884435  PMID: 24427015
2.  3,8-Dimethyl-4-oxo-3,4-dihydro­quinazoline-6-carbonitrile 
In the title compound, C11H9N3O, the quinazoline unit is almost planar, with a mean deviation of 0.006 (1) Å from the least-squares plane defined by the ten constituent atoms. In the crystal, mol­ecules are linked by weak C—H⋯N hydrogen bonds.
doi:10.1107/S1600536812022088
PMCID: PMC3379508  PMID: 22719706
3.  14,15-Didehydro­hellebrigenin 
The title compound, C24H30O5, is the didehydro product of the steroid hellebrigenin (systematic name: 3β,5,14-trihy­droxy-19-oxo-5β-bufa-20,22-dienolide). It consists of three cyclo­hexane rings (A, B and C), a five-membered ring (D) and a six-membered lactone ring (E). The stereochemistry of the ring junctions are A/B cis, B/C trans and C/D cis. Cyclo­hexane rings A, B and C have normal chair conformations. The five-membered ring D with the C=C bond adopts an envelope conformation. Lactone ring E is essentially planar with a mean derivation of 0.006 (4) Å and is β-oriented at the C atom of ring D to which it is attached. There is an O—H⋯O hydrogen bond in the mol­ecule involving the hy­droxy groups. In the crystal, O—H⋯O hydrogen bonds link the mol­ecules into chains propagating along [010]. The chains are linked by C—H⋯O contacts into a three-dimensional network.
doi:10.1107/S1600536812018570
PMCID: PMC3379221  PMID: 22719419
4.  Brusatol 
The title compound, C26H32O11, is composed of an α,β-unsaturated cyclo­hexa­none ring (A), two cyclo­hexane rings (B and C), a six-membered lactone ring (D) and tetra­hydro­furan ring (E). Ring A exists in a half-chair conformation with a C atom displaced by 0.679 (2) Å from the mean plane through the remaining five atoms. Ring B exists in a normal chair conformation. Both rings C and D exist in a twisted-chair conformation due to the O-atom bridge and the carbonyl group in rings C and D, respectively. Ring E shows an envelope conformation with a C atom displaced by 0.761 (1) Å from the mean plane through the remaining five atoms. The ring junctions are A/B trans, B/C trans, C/D cis and D/E cis. An intra­molecular O—H⋯O hydrogen bond occurs. In the crystal, O—H⋯O hydrogen bonds involving the hy­droxy, lactone and ester groups and C—H⋯O inter­actions are observed.
doi:10.1107/S1600536812018582
PMCID: PMC3379203  PMID: 22719401
5.  Secohellebrigeninamide 
The title compound, C26H37NO5, was the reaction product of hellebrigenin with N,N-dimethyl­formamide. It consists of three cyclo­hexane rings (A, B and C), one five-membered ring (D) and one dihydro­pyran ring (E). The stereochemistry of the ring junctions is is A/B cis, B/C trans, C/D cis and C/E trans. The cyclo­hexane rings A, B and C have chair conformations. Both the five-membered ring D and the dihydro­pyran ring adopt an envelope conformation. Two orientations are found for the aldehyde group with occupancies of 0.608 (10) and 0.392 (10). In the crystal, short O—H⋯O hydrogen bonds and short C—H⋯O contacts involving the hy­droxy group, terminal methyl group and carbonyl group link the mol­ecules into a three-dimensional network.
doi:10.1107/S160053681200520X
PMCID: PMC3295466  PMID: 22412577
6.  (Nitrato-κ2 O,O′)bis­(tryptanthrin-κN)silver(I) 
In the crystal structure of the title compound, [Ag(NO3)(C15H8N2O2)2], tryptanthrin (indolo[2,1-b]quinazoline-6,12-dione) and silver nitrate form a 2:1 complex. The silver ion is surrounded by two tryptanthrin ligands, each coordinating through the N atoms, with Ag—N bond lengths of 2.247 (3) and 2.264 (3) Å, and an anionic nitrate ligand coordinating through two O atoms, with Ag—O bond lengths of 2.499 (3) and 2.591 (3) Å. The N—Ag—N plane and the O—Ag—O plane are roughly perpendicular, making a dihedral angle of 81.6 (2)°. In the crystal, C—H⋯O inter­actions between aromatic H atoms and keto and nitrate O atoms as well as π–π inter­actions [centroid-centroid distance = 3.706 (4) Å] give rise to a three-dimensional network.
doi:10.1107/S1600536812001821
PMCID: PMC3274910  PMID: 22346857
7.  Evodiamide 
The title compound, C19H21N3O, was isolated from the fruits of Evodia rutaecarpa. The indole and benzene rings are both essentially planar with mean derivations of 0.0094 (4) Å and 0.0077 (3) Å, respectively. The dihedral angle between these two planes is 78.24 (9)°. The amide carbonyl plane is roughly parallel to the indole ring with a dihedral angle of 7.0 (2)°, but makes a dihedral angle of 82.9 (3)° with the benzene ring. Inter­molecular N—H⋯O hydrogen-bonding inter­actions involving the amino and carbonyl groups give rise to a three-dimensional network.
doi:10.1107/S1600536811055553
PMCID: PMC3274998  PMID: 22346943
8.  Gallic acid pyridine monosolvate 
In the title compound (systenatic name: 3,4,5-trihy­droxy­benzoic acid pyridine monosolvate), C5H5N·C7H6O5, the gallic acid mol­ecule is essentially planar (r.m.s deviation = 0.0766 Å for non-H atoms) and is linked to the pyridine mol­ecule by an O—H⋯N hydrogen bond. An intra­molecular O—H⋯O hydrogen bond occurs in the gallic acid mol­ecule. The gallic acid and pyridine mean planes make a dihedral angle 12.6 (3)°. Inter­molecular O—H⋯O and O—H⋯N hydrogen bonding involving the hy­droxy and carboxyl groups and the pyridine mol­ecule, and π–π inter­actions between inversion-related pyridines [centroid–centroid distance = 3.459 (6) Å] and between pyridine and benzene rings [centroid–centroid distance = 3.548 (6) Å], lead to a three-dimensional network in the crystal.
doi:10.1107/S1600536811043868
PMCID: PMC3247482  PMID: 22220100
9.  A statistical investigation of normal regional intra-subject heterogeneity of brain metabolism and perfusion by F-18 FDG and O-15 H2O PET imaging 
Background
The definite evaluation of the regional cerebral heterogeneity using perfusion and metabolism by a single modality of PET imaging has not been well addressed. Thus a statistical analysis of voxel variables from identical brain regions on metabolic and perfusion PET images was carried out to determine characteristics of the regional heterogeneity of F-18 FDG and O-15 H2O cerebral uptake in normal subjects.
Methods
Fourteen normal subjects with normal CT and/or MRI and physical examination including MMSE were scanned by both F-18 FDG and O-15 H2O PET within same day with head-holder and facemask. The images were co-registered and each individual voxel counts (Q) were normalized by the gloabl maximal voxel counts (M) as R = Q/M. The voxel counts were also converted to z-score map by z = (Q - mean)/SD. Twelve pairs of ROIs (24 total) were systematically placed on the z-score map at cortical locations 15-degree apart and identically for metabolism and perfusion. Inter- and intra-subject correlation coefficients (r) were computed, both globally and hemispherically, from metabolism and perfusion: between regions for the same tracer and between tracers for the same region. Moments of means and histograms were computed globally along with asymmetric indices as their hemispherical differences.
Results
Statistical investigations verified with data showed that, for a given scan, correlation analyses are expectedly alike regardless of variables (Q, R, z) used. The varieties of correlation (r's) of normal subjects, showing symmetry, were mostly around 0.8 and with coefficient of variations near 10%. Analyses of histograms showed non-Gaussian behavior (skew = -0.3 and kurtosis = 0.4) of metabolism on average, in contrast to near Gaussian perfusion.
Conclusion
The co-registered cerebral metabolism and perfusion z maps demonstrated regional heterogeneity but with attractively low coefficient of variations in the correlation markers.
doi:10.1186/1471-2385-6-4
PMCID: PMC1550222  PMID: 16836759

Results 1-9 (9)