Biomedical subjects
Publications and source records attributed to H Itokawa.
A new cyclic heptapeptide, segetalin E, cyclo(-Gly-Tyr-Val-Pro-Leu-Trp-Pro-), has been isolated from the seeds of Vaccaria segetalis and the structure elucidated by extensive two-dimensional NMR methods and chemical degradation.
Four new limonoids, 1-tigloyl-3,20-diacetyl-11-methoxymeliacarpinin, 3-tigloyl-1,20-diacetyl-11-methoxymeliacarpinin, 1-cinnamoyl-3-hydroxy-11-methoxymeliacarpinin, and 1-deoxy-3-methacrylyl-11-methoxymeliacarpinin, together with a known limonoid, 1-cinnamoyl-3-acetyl-11-methoxymeliacarpinin, were isolated from the extract of the root bark of Melia azedarach. The structures were elucidated by spectroscopy.
The new anthraquinones, 6,7-dimethoxy xanthopurpurin, 6-hydroxy-7-methoxy rubiadin, 5-hydroxy-6-hydroxymethyl anthragallol 1, 3-dimethyl ether, 7-carboxy anthragallol 1,3-dimethyl ether, anthragallol 1-methyl ether 3-O-beta-D-glucopyranoside, anthragallol 1-methyl ether 3-O-rutinoside, anthragallol 3-O-rutinoside and alizarin 1-methyl ether 2-O-primeveroside were isolated from the CH2Cl2 and n-BuOH extracts of Galium sinaicum roots and their structures were established by various spectroscopic techniques. In addition, two known anthraquinones were also isolated and fully characterized.
A 50% EtOH extract of Eucalyptus globulus leaves yielded eight phloroglucinol--sesquiterpene-coupled constituents, including three novel compounds named macrocarpals, H, I, and J. Some of these compounds possessed antibacterial activity against oral pathogenic microorganisms with MIC values ranging from 0.20 micrograms/mL to 6.25 micrograms/mL. Inhibition of glucosyltransferase activity by these compounds was also noted.
Antitumor activities on Sarcoma 180A of a series of cyclic pentapeptides, astins, isolated from the roots of Aster tataricus, were examined. The activities on various congeners of the dichlorinated proline residues prepared by chemical conversion and a hepatic microsomal biotransformation in rats suggested that 1,2-cis dichlorinated proline residues of astins A, B and C play an important role in the antitumor activity of astins.
Four years after undergoing a superficial temporal artery-middle cerebral artery bypass procedure, this patient presented with a ruptured aneurysm at the anastomosis site. The ruptured aneurysm caused subarachnoid and intracerebral hemorrhages and was treated by surgically clipping its neck. Characteristics of the aneurysm included: 1) a relatively large size (8 x 6 x 6 mm): 2) a thickened wall; 3) a location apart from the suture line; 4) a projection in a direction consistent with hemodynamic stress; and 5) a time interval from bypass surgery to rupture that lasted 4 years. These features, along with the well-known fact that hemodynamic stress can cause aneurysms, led the authors to believe that this aneurysm was a true one. The authors present a case of this unusual complication following bypass surgery and provide a brief review of the literature.
A new cariostatic compound named eucalyptone was isolated from the leaves of Eucalyptus globulus. The structure of this compound was elucidated by spectroscopic methods.
The antitumor activities of some Fe(II)/Fe(III) complexes containing 1,3-diacetyl-2H-benzimidazole-2-thione along with a few derivatives of 1,2,4-triazol, 1,3,4-oxadiazole and 1,3,4-thiadiazole as co-ligands have been investigated. Antibacterial and antifungal activities of disulfido-/dichloro-bridged dinuclear Fe(III)/Fe(II) complexes containing similar heterocycles as terminal ligands have also been investigated.
A new cyclic octapeptide, pseudostellarin H [1], was isolated from the roots of Pseudostellaria heterophylla. Based on spectral evidence and chemical degradation, the primary structure of 1 was established as cyclo(Gly-Thr-Pro-Thr-Pro-Leu-Phe-Phe).
Bryostatins have been isolated from diverse Japanese coastal specimens of Bugula neritina guided by inhibitory activity against fertilized sea urchin egg cell division. B. neritina from the Gulf of Aomori, Japan, has been found to contain bryostatin 10 [1b] in high yield (10(-3)%) for this class of compounds. The 1H- and 13C-nmr signals of bryostatin 10 [1b] were reassigned by 2D nmr techniques. The conformation of bryostatin 10 [1b] in solution was revealed by nmr studies. This compound also exhibited activity in a steroidogenesis assay by increasing the production of adrenocortical hormones nearly twofold.
Methanol and ethyl acetate extracts of Wang Bu Liu Xing (seeds of Vaccaria segetalis, Caryophyllaceae) and cyclic peptides (named segetalins A and B) obtained from the extracts were shown to have an estrogen-like activity.
The ethanolic extract of the root bark of Melia azedarach exhibited cytotoxic activity against lymphocytic leukemia P388 cell lines in vitro. Systematic fractionation of the extract monitored by cytotoxic bioassay led to the isolation of two new azadirachtin-type limonoids, 1-tigloyl-3-acetyl-11-methoxymeliacarpinin (1) and 1-acetyl-3-tigloyl-11-methoxymeliacarpinin (2), together with three highly cytotoxic sendanin-type limonoids, 29-isobutylsendanin (3), 12-hydroxyamoorastin (4) and 29-deacetylsendanin (5). The acetylated derivatives of 4 also underwent cytotoxic bioassay.
Conformational analysis of antitumor cyclic pentapeptides, astins A (1) and C (3), was made by a combination of NMR and computational techniques. These results indicated that the backbone conformations of 1 and 3, with lower activity than astin B (2), were different from that of 2. The backbone conformation together with a cis 3,4-dichlorinated proline residue was considered to play an important role in the antitumor activities of astins.
A new peptide called astin J (1) was isolated from the roots of Aster tataricus. The structure was elucidated by spectroscopic methods and chemical transformation from a cyclic pentapeptide, astin C, isolated from A. tataricus to the analogous acyclic peptide, 2. Antileukemic activities of the series of acyclic peptides are also described.
Four antibacterial diterpenes, trichorabdals A, B, C and H were isolated from the leaves of Rabdosia trichocarpa and the relationship between their conformations analysed by spectroscopic and computational methods. Their antibacterial activity is discussed.
The isolation and structure elucidation of four cytotoxic aromatic triterpenes [1-4] along with three known quinoid triterpenes [5-7] from the South American medicinal plants Maytenus ilicifolia and M. chuchuhuasca are described. The structures of these aromatic triterpenes contained aromatized A rings and C-6 oxygenated B rings, and were elucidated by 1H- and 13C-nmr spectroscopic studies and by X-ray crystallographic analysis of 3.
A novel [Ile7]surfactin (1), which showed anti-human immunodeficiency virus activity, has been isolated from Bacillus subtilis natto. Structural and conformational analysis of the peptide backbone of [Ile7]surfactin was conducted by a combination of various two-dimensional (2D) nuclear magnetic resonance (NMR), circular dichroism (CD) spectroscopy and simulated annealing calculations, compared with a known [Leu7]surfactin (2). Both surfactins were shown to exist in different conformational states in both polar and apolar solvents.
The ethanolic extract of Rabdosia trichocarpa leaves showed antibacterial activity against cariogenic mutans streptococci and periodontopathic Porphyromonas gingivalis. Chromatographic separation and purification of the extract afforded ten diterpenes, including one novel ent-kauren type compound named trichoranin. Some of these compounds possess potent antibacterial activity against these oral micro-organisms, indicating that these diterpenes may be useful natural substances for the maintenance of oral health.