Caspase-3-dependent apoptosis of citreamicin ε-induced HeLa cells is associated with reactive oxygen species generation.

Citreamicins, members of the polycyclic xanthone family, are promising antitumor agents that are produced by Streptomyces species. Two diastereomers, citreamicin ε A (1) and B (2), were isolated from a marine-derived Streptomyces species. The relative configurations of these two diastereomers were determined using NMR spectroscopy and successful crystallization of citreamicin ε A (1). Both diastereomers showed potent cytotoxic activity against HeLa (cervical cancer) and HepG2 (hepatic carcinoma) cells with IC50 values ranging from 30 to 100 nM. The terminal deoxynucleotidyl transferase dUTP nick-end labeling assay confirmed that citreamicin ε A (1) induced cellular apoptosis, and Western blot analysis showed that apoptosis occurred via activation of caspase-3. The 2,7-dichlorofluorescein diacetate assay indicated that citreamicin ε substantially increased the intracellular concentration of reactive oxygen species (ROS). To confirm the hypothesis that citreamicin ε induced apoptosis through an increase in the intracellular ROS concentration, the oxidized products, oxicitreamicin ε A (3) and B (4), were obtained from a one-step reaction catalyzed by Ag2O. These products, with a reduced capacity to increase the intracellular ROS concentration, exhibited a significantly weakened cytotoxicity in both HeLa and HepG2 cells compared with that of citreamicin ε A (1) and B (2).

Ethyl 2-[6-(4-methyl-benzo-yl)-7-phenyl-2,3-di-hydro-1H-pyrrolizin-5-yl]-2-oxo-acetate.

In the title compound, C25H23NO4, the pyrrolizine ring is approximately planar with an r.m.s deviation from planarity of 0.0053 Å, while the fused di-hydro-pyrrolizine ring adopts an envelope conformation with the C atom connected to two CH2 as the flap. The dihedral angles between the fused ring system and the phenyl and methyl-benzoyl rings are 41.65 (11) and 66.30 (8)°, respectively. In the crystal, weak C-H⋯O hydrogen bonds and C-H⋯π inter-actions occur. One mol-ecule is linked to five adjacent ones through eight hydrogen bonds, forming a three-dimensional network.

Methyl 3-[(chloro-meth-oxy)carbon-yloxy]-7-hy-droxy-cholan-24-oate.

The title compound, C27H43ClO6, is a derivative of urso-deoxy-cholic acid, in which the OH group at the 3-position is substituted by a chloro-meth-oxy-carbon-yloxy substituent and the carb-oxy-lic acid group at the 24-position is methyl-ated. The A and B rings are cis-fused, while all other rings are trans-fused. In the crystal, two adjacent mol-ecules located along the b-axis direction are inter-locked head-to-tail due to weak C-H⋯O hydrogen bonds. Therefore each mol-ecule is linked to four neighbouring mol-ecules by four C-H⋯O hydrogen bonds, with the OH group at the 7-position and the carbonyl O atom of the ester group acting as the acceptor sites.

(6,6-Dimethyl-1-phenyl-6,7-di-hydro-5H-pyrrolizin-2-yl)(thio-phen-2-yl)methanone.

In the title compound, C20H19NOS, the pyrrolizine ring is essentially planar (r.m.s. deviation = 0.001 Å) while the fused dihydro-pyrrolizine ring adopts an envelope comformation with the C atom bearing the methyl substituents as the flap. The dihedral angles between the pyrrolizine and the phenyl and thio-phene rings are 34.54 (7) and 44.93 (7)°, respectively. In the crystal, weak C-H⋯O hydrogen bonds link the mol-ecules into infinite zigzag chains parallel to the b-axis direction.

Four new antibacterial xanthones from the marine-derived actinomycetes Streptomyces caelestis.

Four new polycyclic antibiotics, citreamicin θ A (1), citreamicin θ B (2), citreaglycon A (3), and dehydrocitreaglycon A (4), were isolated from marine-derived Streptomyces caelestis. The structures of these compounds were elucidated by 1D and 2D NMR spectra. All four compounds displayed antibacterial activity against Staphylococcus haemolyticus, Staphylococcus aureus, and Bacillus subtillis. Citreamicin θ A (1), citreamicin θ B (2) and citreaglycon A (3) also exhibited low MIC values of 0.25, 0.25, and 8.0 µg/mL, respectively, against methicillin-resistant Staphylococcus aureus (MRSA) ATCC 43300.

(1-{[2-(6-Methoxynaphthalen-1-yl)ethyl]amino}ethylidene)oxidanium bromide monohydrate.

The title salt, C(15)H(18)NO(2)(+)·Br(-)·H(2)O, is an analogue of the antidepressant drug agomelatine. The cation is protonated at the carbonyl O atom of its amide group. The side chain at the 1-position adopts an extended conformation, with all non-H atoms lying in the same plane as the naphthalene ring. This is in contrast with the crystal structures known for three agomelatine polymorphs, and also with two known cocrystals containing agomelatine. The structure displays three types of hydrogen bond, namely C=O-H···O, N-H···Br and O-H···Br, which define a two-dimensional network parallel to the (100) plane. The naphthalene rings interdigitate in a `zipper-like' fashion between these hydrogen-bonded networks, forming an offset arrangement. Direct face-to-face π-π contacts between naphthalene rings are not present in the structure.

2-{[3-Methyl-4-(2,2,2-trifluoro-eth-oxy)pyridin-2-yl]methyl-sulfan-yl}-1H-benzimidazole monohydrate.

The asymmetric unit of the title compound, C(16)H(14)F(3)N(3)OS·H(2)O, contains two independent mol-ecules (A and B) and two water mol-ecules, one of which is disordered over two positions in a 0.790 (8):0.210 (8) ratio. The mol-ecular conformations are close, the benzimidazole mean plane and pyridine ring forming dihedral angles of 1.8 (3) and 0.1 (2)° in mol-ecules A and B, respectively. The water mol-ecules are involved in formation of two independent hydrogen-bonded chains via N-H⋯O and O-H⋯N hydrogen bonds. Chains propagating along the a axis are formed by mol-ecule A and one independent water mol-ecule, while chains propagating along the b axis are formed by mol-ecule B and the other independent water mol-ecule. The crystal packing exhibits π-π inter-actions, as indicated by short distances of 3.607 (3) and 3.701 (3) Šbetween the centroids of the imidazole and pyridine rings of neighbouring mol-ecules.

3-(7-Meth-oxy-ß-carbolin-1-yl)propionic acid monohydrate.

In the title compound, C(15)H(14)N(2)O(3)·H(2)O [systematic name: 3-(7-meth-oxy-9H-pyrido[3,4-b]indol-1-yl)propanoic acid monohydrate], the fused rings make dhedral angles of 0.4 (1), 1.1 (2) and 1.4 (2)°. In the crystal, the water mol-ecule is involved in the formation of three independent hydrogen-bonded chains via O-H⋯O and N-H⋯O hydrogen bonds, while the carb-oxy group forms an inter-molecular O-H⋯N hydrogen bond.

1,3-Dihy-droxy-2-(hy-droxy-meth-yl)propan-2-aminium formate.

The title compound, C(4)H(12)NO(3) (+)·CHO(2) (-), was obtained from 1,3-dihy-droxy-2-(hy-droxy-meth-yl)propan-2-aminium acetate and ethyl formate. In the crystal, the cations and anions are held together by inter-molecular N-H⋯O and O-H⋯O hydrogen bonds.

Nortriterpenoids and lignans from Schisandra sphenanthera.

Nortriterpenoids, sphenadilactone C (1) and sphenasin A (2), together with four known lignans (3-6), were isolated from the leaves and stems of Schisandra sphenanthera. Their structures were elucidated by extensive analysis of 1D and 2D NMR spectroscopic data and compound 2 was further confirmed by single-crystal X-ray diffraction. Compound 1 features a partial enol moiety and an acetamide group in its structure. In addition, compounds 1, 3-6 showed weak anti-HIV-1 activity with EC(50) values in the range of 15.5-29.5 microg/mL.

Daphlongeranines A and B, two novel alkaloids possessing unprecedented skeletons from Daphniphyllum longeracemosum.

Two novel alkaloids, daphlongeranines A (1) and B (2), with an unprecedented ring system, were isolated from the fruits of Daphniphyllum longeracemosum. Their unique structures and relative stereochemistries were established on the basis of spectroscopic and single-crystal diffraction analysis. The proposed biosynthetic pathway was also discussed. Compounds 1 and 2 showed weak inhibition on platelet aggregation.

Crystal structure of 1,7,8,9-tetra-chloro-4-(2-fluoro-benz-yl)-10,10-dimeth-oxy-4-aza-tri-cyclo-[5.2.1.0(2,6)]dec-8-ene-3,5-dione.

In the title compound, C17H12Cl4FNO4, the configuration of the cyclo-alkene skeleton is endo,cis. The benzene ring is twisted by 71.01 (11)° from the attached pyrrolidine ring. In the crystal, one of the methine groups of the fused-ring system forms a weak C-H⋯O hydrogen bond. The other methine groups participates in a C-H⋯F inter-action to the same adjacent mol-ecule. Together, these generate [010] chains.

Crystal structure of 1,7,8,9-tetra-chloro-4-(3,5-di-chloro-benz-yl)-10,10-dimeth-oxy-4-aza-tri-cyclo-[5.2.1.0(2,6)]dec-8-ene-3,5-dione.

In the title compound, C17H11Cl6NO4, the configuration of the cyclo-alkene skeleton is endo,cis. The benzene ring is twisted by 58.94 (8)° from the attached pyrrolidine ring. Two carbonyl groups play a key role in the crystal packing. A short inter-molecular C⋯O distance of 3.017 (3) Šreveals that one carbonyl group is involved in dipole-dipole inter-actions, which link two adjacent enanti-omers into an inversion dimer. Another carbonyl group provides an acceptor for the weak inter-molecular C-H⋯O hydrogen bonds which link these dimers into layers parallel to (011).