[A statistic study of airborne pollen grains]

Since 1969, authors have been doing a statistical analysis of airborne pollen grains, aiming at the clarification of their atmospheric behaviors, in connection with an increase in a number of pollinosis cases. The airborne pollens were collected three times a week starting from January 1 and ending December 31 with the help of cascade impactor, by which 6001 of air was suctioned at the rate of 51 per min for 2 h from 10:00 a.m. to 12:00 at the rooftop of one of the buildings (16 m high) in the Narashino Campus of Toho University, Funabashi, Chiba. The collected airborne pollens were numerated and classified under microscope according to the Ikuse's classification system for Japanese pollens. The number of days (n) was plotted as a function of daily number of a certain type of airborne pollens (x), not fitting to a simple normal distribution. However, the data were found to approximate a normal distribution when x was log-transformed as ln (x + 1). Among the statistical methods tested, semilogarithmic plot, Weibull plot, Edwards' plot and circular graph method were found to be useful in the follow-up of seasonal variation of environmental pollen grains, especially when used in combination.

Improved extraction procedures for polychlorinated biphenyls in solid samples with aqueous sodium hydroxide under autoclave conditions

The efficacy of the extraction of polychlorinated biphenyls (PCBs) from varnish-infiltrated insulating papers as a model of solid materials with an aqueous sodium hydroxide (NaOH) by autoclaving at 121 degrees C for 30 min was compared with those for the conventional procedures, i.e., saponification with 1 N ethanolic NaOH in a boiling water bath for 60 min and extraction with benzene in a Soxhlet apparatus. The newly invented autoclaving method was found to be superior to the conventional ones, yielding approximately 5- to 6-fold cumulative PCB congeners without being accompanied by extended decomposition. Therefore, the autoclave-based sample treatment is recommended for more accurate determination of PCBs in the case of PCB-impregnated solid materials such as hardened oils and resin-coated or -infiltrated papers instead of being treated conventionally.

Evanescent field excitation and measurement of dye fluorescence in a metallic probe near-field scanning optical microscope

We introduce a method of dye fluorescence excitation and measurement that utilizes a near-field scanning optical microscope (NSOM). This NSOM uses an apertureless metallic probe, and an optical system that contains a high numerical aperture (NA) objective lens (NA= 1.4). When the area which satisfies NA < 1 is masked, the objective lens allows for the rejection of possible transmitted light (NA < 1) through the sample. In such conditions, the focused spot consists of only the evanescent field. We found that this NSOM system strongly reduces the background of the dye fluorescence and allows for the measurement of the fluorescence intensity below the diffraction limit of the excitation source.

Gold-bead scanning near-field optical microscope with laser-force position control

We have developed a scanning near-field optical microscope with an optically trapped metallic particle that has a small diameter compared to the wavelength of visible light. In this microscope we employed spot illumination to enhance the intensity of light scattered from a probe particle so we could reduce the diameter of the probe particle to 40 nm. We detected slight irregularities of the surface of the cover glass near 10-nm depth. Also, we observed gold colloidal particles on the surface of the cover glass.

Near-field optical microscope with a multiheight scanning imaging mode

A near-field scanning optical microscope has been developed to yield optical images with various gap distances between the probe and the sample surface. The microscope uses an apertureless metallic probe, the position of which is controlled by regulation of the tunneling-electron current from the probe to the sample and by computer-generated bias voltage. Experimental results of near-field optical imaging with the developed microscope at different gap distances are shown. Thirteen images at gap distances of 0 to 500nm demonstrate that the near-field image depends strongly on the gap distance. The imaging characteristics of a near-field imaging system are shown with the spatial-frequency spectra of images. Future investigation of the developed microscope is also discussed.

Differential contribution of metal complexation and dimerization to the chemotherapeutic potential of bicyclen-Zn2II complex against human immunodeficiency virus

1,1'-(m-Xylenediyl)-bis(1,4,7,10-tetraazacyclododecane)-Z n2II complex (m-xylenediyl-bicyclin-Zn2II), a potent inhibitor of human immunodeficiency virus (HIV), was obtained from cyclin by a combination of dimerization and metal complexation. The ratio of median cytotoxic concentration against host cells (CC50) and median effective concentration against HIV cytopathogenicity (EC50), referred to as the selectivity index (SI), was regarded to be a measure of anti-HIV activity. These two chemical modifications contributed to a potent, in vitro anti-HIV activity of m-xylenediyl-bicyclin-Zn2II by respectively increasing the CC50 and decreasing the EC50 in comparison with those of cyclin.

Improved production of phenomycin by a genetically engineered Escherichia coli

We established an improved production of an antitumor polypeptide anti biotic, phenomycin (PHM), by using a genetically engineered Escherichia coli. Phenomycin consists of 89 natural amino acids without intramolecular disulfide bridge. PHM gene was synthesized as a fusion gene in which PHM at the C-terminus and the residues 1 approximately 20 of Hirudin variant 1 (HV1) at the N-terminus connected by a factor Xa recognition sequence (Ile-Glu-Gly-Arg). E coli JM 109 transformed with a plasmid containing the synthesized gene expressed a fusion protein and the trypsinization of the fusion protein purified by ultrafiltration and ion-exchange chromatography gave efficiently recombinant PHM at a final yield of 50 mg/liter of culture. This PHM yield was six times higher than that obtained by a natural PHM producing strain of Streptoverticillium baldacci. Recombinant PHM was not distinguishable from natural PHM in all aspects observed.

Structures of nine oxygenated 4-methylene sterols from Hachijo marine sponge Theonella swinhoei

Nine new sterols have been isolated from a marine sponge, Theonella swinhoei. Of these, seven sterols were found to be conicasterol derivatives [(24R)-4-methylene-24-methyl-8(14)-cholesten-3 beta-ol] oxygenated at carbon-7 and/or carbon-15. The other two were (24R)-7 beta,8 beta-epoxy-14 alpha-methoxy-4-methylene-24-methylcholestan- 3 beta-ol and (24R)-8,14-seco-8,14-dioxo-4-methylene-24-methylcholestan-3 beta-ol.

Reversal of daunomycin and vinblastine resistance in multidrug-resistant P388 leukemia in vitro through enhanced cytotoxicity by triterpenoids

Examined in vitro were the effects of some triterpenoids from Panax (Araliaceae) and Glycyrrhiza (Leguminosae) spp. on the sensitivity to daunomycin (DAU) and vinblastine (VBL) of adriamycin (ADM)-resistant P388 leukemia cells (P388/ADM), which were resistant to multiple anticancer drugs. Quasipanaxatriol, 20(S)-protopanaxatriol, ginsenoside Rh2, and compound K greatly enhanced the cytotoxicity of the anti-cancer drugs in P388/ADM cells. The extent of enhancement was different among the triterpene compounds; the 4- to 46-fold increase in DAU cytotoxicity was observed in P388/ADM cells in the presence of non-toxic or marginally toxic concentrations of individual compounds, while those for VBL were in the ratios of 2- to 37-fold. The maximum increase in cytotoxicity was observed with 50 microM quasipanaxatriol; the resistance indices defined to be the ratios of the IC50 values for P388/ADM and P388 parental cells decreased from 79 to 1.7 and from 180 to 4.9 in the cases of DAU and VBL, respectively. The reversal of DAU resistance in P388/ADM by quasipanaxatriol could be explained by the effective accumulation of the drugs mediated by the DAU-efflux blockage.

Structure-activity correlationship and strain specificity of polyoxometalates in anti-human immunodeficiency virus activity

The anti-human immunodeficiency virus (HIV) activity of polyoxometalates of representative structural families, such as Keggin, lacunary Keggin, trivacant Keggin, Keggin sandwich, Wells-Dawson and Wells-Dawson sandwich, was determined using two strains of HIV type 1 (HIV-1HTLV-IIIB and HIV-1SF-2H). The compounds were preferably selected to cover both polyoxotungstates and polyoxomolybdates in each structural family. In general, polyoxotungstates of Keggin, lacunary Keggin, trivacant Keggin, Keggin sandwich, Wells-Dawson and Wells-Dawson sandwich structures showed anti-HIV-1HTLVIIIB activity, whereas most compounds not included in these structural categories were inactive. Among the compounds with a potent anti-HIV-1HTLV-IIIB activity, those of Keggin and its closely related structural families (lacunary Keggin, trivacant Keggin and Keggin sandwich) inhibited the cytopathogenicity and syncytium formation caused by HIV-1SF-2 to a much higher extent compared with HIV-1HTLV-IIIB-related ones. The difference between the spectra of anti-HIV-1HTLV-IIIB activity and the specificity for HIV-1SF-2H might result from differential structural requirements in these functions.

Novel assay system favorable for the study of cell-to-cell transmission of HIV-1 and its application to the evaluation of anti-HIV drugs

The cell-to-cell transmission of human immunodeficiency virus type 1 (HIV-1) was studied using MOLT-4 cells chronically infected with a variant strain of HIV-1SF-2 (MOLT-4/HIV-1SF-2H) and CD4+ human lymphoid MT-4 cells. MOLT-4/HIV-1SF-2H cells produced less than 1 TCID50 infectious particles per day as determined by the cytopathogenicity in MT-4 cells. However, the expression of envelope glycoproteins gp120 and gp41 on the MOLT-4/HIV-1SF-2H cell membrane was satisfactory for syncytium formation with the uninfected MOLT-4 cells. When MOLT-4/HIV-1SF-2H and MT-4 cells were co-cultured, severe cytopathogenicity was observed in MT-4 cells without being accompanied by the formation of multi-nucleated cells. Thus, the system consisting of MOLT-4/HIV-1SF-2H and MT-4 cells is convenient for exclusive study of the mechanism of cell-to-cell transmission of HIV-1. Using various compounds, it was confirmed that cell-to-cell transmission required both gp120/gp41-CD4 binding and de novo DNA synthesis.

Molecular cloning and expression in Escherichia coli of bleomycin-resistance gene from a methicillin-resistant Staphylococcus aureus and its association with IS431 mec

A gene that confers bleomycin resistance was cloned from the chromosomal DNA of methicillin-resistant Staphylococcus aureus (MRSA) B-26 into the plasmid pUC18. It is of chromosomal origin rather than plasmid and exists in the chromosome making a cluster with the kanamycin-resistance gene. We found that the nucleotide sequence of the bleomycin-resistance gene from the chromosome of MRSA B-26 is identical to that from a staphylococcal plasmid, pUB110. The partial sequence of IS431mec was also found upstream from the DNA fragment containing the bleomycin- and kanamycin-resistance genes.

Susceptibility of methicillin-resistant Staphylococcus aureus clinical isolates to various antimicrobial agents. IV. Aminoglycoside-modifying enzyme AAC(6')/APH(2") is responsible for arbekacin-resistance enhanced by bleomycin

Resistance patterns against various antimicrobial agents including beta-lactams, aminoglycosides, tetracyclines, fluoroquinolones, macrolides were examined for 58 strains of methicillin-resistant Staphylococcus aureus (MRSA) isolated at Hiroshima University Hospital from April to November 1992. All the MRSA strains produced type II-coagulase but not beta-lactamase. Regarding aminoglycoside-modifying enzymes, 7 strains (12%) appeared to be producing aminoglycoside 4',4"-adenyltransferase AAD(4',4") encoded by aadD without coproduction of bifunctional aminoglycoside 6'-acetyltransferase/2"-phosphotransferase AAC(6')/APH(2") encoded by aacA-aphD (referred to as tobramycin-resistant type, TOBr). The remaining 51 strains (88%) were phenotypically producers of both enzymes (i.e., mix-resistant type, Mixr). AAD(4',4"), encoded by aadD which was reported to be closely linked with bleomycin (BLM)-resistance determinant, could be seen in 100% MRSA strains and ca. 90% strains expressed AAC(6')/APH(2"). BLM endowed Mixr-type but not TOBr-type MRSA strain with enhanced resistance to arbekacin (ABK) dose-dependently, presumably by modifying the production of AAC(6')/APH(2"). The manifestation of ABK-resistant phenotype by Mixr-type MRSA required the coexistence of BLM. Therefore, ABK must be administered carefully to cure MRSA infection in patients who have been treated with BLM.

Inhibitory effect of some triterpenoid saponins on glucose transport in tumor cells and its application to in vitro cytotoxic and antiviral activities

The effects of some triterpenoid saponins on glucose transport in Ehrlich ascites tumor (EAT) cells were examined by measuring 2-deoxy-D-glucose (2-DG) uptake. The correlation of the effects with those on the growth of a human T-cell line (MT-4) and the replication of human immunodeficiency virus in MT-4 cells was also studied. Chikusetsusaponin Ia isolated from rhizomes of Panax japonicus C. A. Meyer (Araliaceae) inhibited the 2-DG uptake (IC50 = 76.3 microM) in a competitive fashion with respect to 2-DG (Ki = 0.32 mM) and the growth of MT-4 cells with CC50 of 84.4 microM, whereas it did not show any significant anti-HIV-1 activity. In contrast, zingibroside R1 isolated from rhizomes of Panax zingiberensis Wu et Feng (Araliaceae) showed some anti-HIV-1 activity, which was found to be superior to that of glycyrrhizin, as well as the inhibitory effects on the 2-DG uptake by EAT cells (IC50 = 91.3 microM) and the growth of MT-4 cells (CC50 = 46.2 microM).

Inhibition of human immunodeficiency virus proliferation by macrocyclic polyamines and their metal complexes

The macrocyclic polyamines, cyclen and cyclam, and their derivatives have been tested for inhibitory activity against the cytopathogenic effect (CPE) of human immunodeficiency virus type 1 strain HTLV-IIIB (HIV-1IIIB) on CD4+ human lymphoblastoma MT-4 cells. Cyclam and its derivatives were complexed with a variety of transition metal ions NiII, ZnII, CuII, FeIII and CoIII. The divalent metal complexes effected lower toxicity and greater anti-HIV-1 activity, while the trivalent metal complexes had no effect on HIV-1-dependent CPE. When dimerized, the anti-HIV activity of monomers was significantly enhanced. A potent inhibition of CPE by biscyclam was transiently observed 4 d after the virus infection, but was not seen at 6 d due to severe toxicity. The toxicity of biscyclam, referred to as delayed toxicity, could be overcome by a metal complexation. The strain specificities of biscyclams were further studied by testing their effects on syncytium formation between HIV-infected and uninfected human acute lymphoblastic leukemia MOLT-4 cells. The 50% inhibitory concentrations of biscyclams against HIV-2GH-1-dependent syncytium formation were less than one hundredth those for the other HIV strains (HIV-1IIIB, HIV-1RF and HIV-1SF-2).

Susceptibility of methicillin-resistant Staphylococcus aureus clinical isolates to various antimicrobial agents. III. Novel, inducible resistance to macrolide-lincosamide-streptogramin B (MLS) antibiotics

Resistance patterns against 25 antimicrobial agents consisting of beta-lactams, aminoglycosides, tetracyclines, fluoroquinolones, macrolides and etc. were examined for 69 strains of methicillin-resistant Staphylococcus aureus (MRSA) isolated at Hiroshima University Hospital from July 1991 to April 1992. Regarding overall resistance (the percentage of highly and moderately resistant strains), the following antimicrobial agents were no more effective chemotherapeutics for MRSA infections (%resistance): methicillin (100), flomoxef (100), kanamycin (100), tobramycin (100), amikacin (100), isepamicin (100), gentamicin (78), dibekacin (100), ofloxacin (99), levofloxacin (99), temafloxacin (99), erythromycin (100), clarithromycin (100), tetracycline (93), minocycline (93) and fosfomycin (100). Further spread of arbekacin-resistant strain, which was isolated in April 1991, into a clinical environment could not be recognized during the period covered in the present study. All the MRSA strains were resistant either constitutively (26 strains) or inducibly (43 strains) to macrolide-lincosamide-streptogramin B (MLS) antibiotics. When expression is constitutive, the strains are resistant to all MLS antibiotics. In contrast, 16-membered macrolide (i.e., jasamycin), lincomycin and mikamycin B escape resistance in the strains with a typical inducible resistance overcome in the presence of 14-membered macrolides by a translational attenuation mechanism. Three of 4 beta-lactamase-positive strains, however, can not be classified in these two resistance groups, being exclusively resistant to mikamycin B. The strains grown in the presence of any inducing MLS antibiotic became susceptible to mikamycin B even in the inducer-free culture.

In vitro antiviral activity of polyoxomolybdates. Mechanism of inhibitory effect of PM-104 (NH4)12H2(Eu4(MoO4)(H2O)16(Mo7O24)4).13H2O on human immunodeficiency virus type 1

A screening for inhibitors of human immunodeficiency virus type 1 (HIV-1) among various types of isopolyoxomolybdates and heteropolyoxomolybdates was carried out by using an in vitro assay system measuring the cytopathogenicity of HIV-1 in CD4+ human MT-4 cells. A novel heteropolyoxomolybdate named PM-104 with the chemical formula (NH4)12H2(Eu4(MoO4)(H2O)16(Mo7O24)4).13H2O was found to be associated with potent anti-HIV-1 activity. PM-104 interferes with virus infection at a very early step such as adsorption and/or penetration into the cells. In addition to the cytopathic effect of HIV-1 on MT-4 cells, syncytium formation between mock-infected MOLT-4 cells and MOLT-4 cells chronically infected with either HIV-1 or HIV-2 is suppressed by PM-104. PM-104 also blocks the replication of herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2). The antiviral properties of PM-104 could be attributed to the combined effect of europium atoms and its peculiar three-dimensional anion structure.

Susceptibility of methicillin-resistant Staphylococcus aureus clinical isolates to various antimicrobial agents. II. Isolation of arbekacin-resistant strain

Resistance patterns against 24 antimicrobial agents were examined for 50 strains of methicillin-resistant Staphylococcus aureus (MRSA) isolated at Hiroshima University Hospital during the period October 1990 and July 1991. Overall resistance (the percentage of highly and moderately resistant strains) to the antimicrobial agents is summarized as follows: methicillin 100%, flomoxef 100% (beta-lactams); kanamycin 94%, tobramycin 94%, amikacin 100%, isepamicin 94%, gentamicin 80%, dibekacin 94%, arbekacin 2% (basic oligosaccharide group/aminocyclitols); ofloxacin 96%, temafloxacin 96%, levofloxacin 96% (fluoroquinolones); erythromycin 98%, clarithromycin 98%, josamycin 30% (macrolides); vancomycin 0% (glycopeptide); tetracycline 94%, minocycline 94% (tetracyclines); fosfomycin 100%; mikamycin B 30%, nosiheptide 0% (peptide); rifampicin 2% (ansamycin); streptomycin 2% (basic oligosaccharide group); chloramphenicol 2%. Arbekacin resistance was observed in one case: the cross resistance was complete among the aminocyclitol antibiotics tested in this study and streptomycin, probably due to the ribosomal alteration.

A new anthracycline antibiotic, cinerubin R. Taxonomy, structural elucidation and biological activity

A novel anthracycline antibiotic, cinerubin R, was isolated from the fermentation broth of Streptomyces eurythermus strain H1715MY2. The structure of cinerubin R was elucidated to be 4"-aculosyl-4'-rhodinosyl-7-rhodosaminyl-epsilon-py rromycinone. Cinerubin R was active against Gram-positive bacteria and inhibited the growth of divergent multi-drug-resistant cells to the same extent as their parental cells.

Suppressive effect of polyoxometalates on the cytopathogenicity of human immunodeficiency virus type 1 (HIV-1) in vitro and their inhibitory activity against HIV-1 reverse transcriptase

One isopolyoxometalate and 42 heteropolyoxometalates consisting of 3 compounds with the trivacant Keggin structure, 2 with the lacunary Keggin structure, 30 with the Keggin structure, one with the Wells-Dawson structure and 6 with miscellaneous structures were tested for their suppressive effect on the cytopathogenicity of human immunodeficiency virus type 1 (HIV-1) in vitro and inhibitory activity against HIV-1 reverse transcriptase. In contrast to the leading interpretations which attribute the suppressive effect of polyoxometalates on the cytopathogenicity of HIV-1 to the inhibition of HIV-1 reverse transcriptase by these compounds, there was no distinct correlation observed between these two functions of polyoxometalates.

Susceptibility of methicillin-resistant Staphylococcus aureus clinical isolates to various antimicrobial agents

Resistance patterns against 23 antimicrobial agents were examined for 42 strains of methicillin-resistant Staphylococcus aureus (MRSA). Thirty-four strains were isolated at Hiroshima University Hospital during 1984-1990 and 8 strains were collected in Tokushima city in 1986. Overall resistance to the antimicrobial agents in clinical use is summarized as follows: methicillin 100%, flomoxef 93% (beta-lactams); kanamycin 98%, tobramycin 88%, amikacin 83%, isepamicin 81%, gentamicin 60%, dibekacin 64%, arbekacin 0% (aminocyclitol aminoglycosides); ofloxacin 31%, TA-167 33% (fluoroquinolones); erythromycin 100%, clarithromycin 100%, josamycin 71% (macrolides); vancomycin 0% (glycopeptide); tetracycline 43%, minocycline 31% (tetracyclines); fosfomycin 93%. The MRSA strains remained susceptible to the non-clinical peptide group of antibiotics except for mikamycin B: mikamycin A 2%, mikamycin B 69%, nosiheptide 0%, bottromycin A2 0%, bottromycin D-1 0%, bottromycin D-2 0%. Since April 1990, the MRSA strains isolated at Hiroshima University Hospital showed a tendency to acquire resistance to tetracyclines and fluoroquinolones and to lose mikamycin B-resistance. As of August 1990, none of the MRSA strains isolated at Hiroshima University Hospital was resistant to vancomycin and arbekacin.

Complete amino acid sequence of phenomycin, an antitumor polypeptide antibiotic

The primary structure of phenomycin, an antitumor polypeptide antibiotic isolated from the culture broth of Streptomyces fervens var. phenomyceticus, was determined. Sequence analysis has revealed that it consists of 89 amino acid residues (Mr 9,524) and no disulfide bridge is present. The sequence of phenomycin at residues 48-70 was found to be hydrophilic, being surrounded by hydrophobic regions at both sides. Furthermore, clustering of half the lysine residues in this hydrophilic region and marked basicity of phenomycin imply the external disposition of this region. Phenomycin does not show significant sequence homology to any known proteins including antitumor polypeptide antibiotics.

Fluvirucins A1, A2, B1, B2, B3, B4 and B5, new antibiotics active against influenza A virus. III. The stereochemistry and absolute configuration of fluvirucin A1

Fluvirucin A1 was established as (2R,3S,6R, 10S)-3-[(3-amino-3,6-dideoxy-alpha-L-talopyranosyl)-oxy]-2,6-dimethyl-10 -ethyl-13-tridecanelactam by chemical, spectroscopic, and X-ray crystallographic analyses.

Antiviral activity of polyoxomolybdoeuropate PM-104 against human immunodeficiency virus type 1

A polyoxomolybdoeuropate PM-104 (NH4)12H2[Eu4(MoO4)(H2O)16(Mo7O24)4].13H2O was found to be a potent inhibitor of the growth of human immunodeficiency virus type 1 (HIV-1), a causative agent of acquired immunodeficiency syndrome (AIDS). On the basis of TI50 [median cytotoxic concentration (CC50)/median effective concentration (EC50)], the in vitro anti-HIV-1 activity of PM-104 is favorably comparable to that of a heteropolyoxotungstate PM-19 K7[PTi2W10O40].6H2O, which is one of the most potent HIV-1 inhibitors among the polyoxometalates so far tested. The heteropolyoxomolybdate with a potent anti-HIV-1 activity is introduced for the first time in this communication.

Inhibition of avian myeloblastosis virus reverse transcriptase by heterocyclic quinones: structure-activity correlation

Synthetic heterocyclic quinones (107 samples) consisting of o- and p-quinoline quinones, o-isoquinoline quinones and p-quinoxaline quinones as well as o- and p-naphthoquinones (3 samples) were tested for their inhibitory activities against avian myeloblastosis virus reverse transcriptase (AMV-RT) and cytotoxic activities against mouse lymphoblastoma L5178Y cells. In general, o-quinoline quinones (i.e., the 5,6-quinolinedione derivatives) are more potent inhibitors of AMV-RT than p-quinoline quinones (the 5,8-quinolinedione derivatives). Furthermore, the growth of L5178/Y cells were significantly refractory to the 8-methoxy-5,6-quinolinedione derivatives whose suppressive effects on AMV-RT function were fairly comparable to those of the other o-quinoline quinones. The longer the chain length of 7-alkyl substituent in o- or p-quinoline quinones, the lower the biological activities.

Inhibition of proliferation of human immunodeficiency virus type 1 by novel heteropolyoxotungstates in vitro

Fifteen heteropolyoxotungstates were tested for their effects on the proliferation of human immunodeficiency virus type 1 (HIV-1) using an in vitro system consisting of MT-4 cells and HTLV-IIIb. Eight heteropolyoxotungstates (HPOTs) with the Keggin structure or dimerized deficient Keggin structure proved to be potent inhibitors of HIV-1. In contrast, seven non-Keggin HPOTs including HPA 23 did not have significant effects on HIV-1 proliferation at non-toxic doses. [PTi2W10O40]7- (PM-19) was the most potent inhibitor of HIV-1 among the 15 HPOTs tested. The inhibition of HIV-1 replication by PM-19 presumably results from impaired virus adsorption and/or penetration into target cells. Viral spread of HIV-1 and HIV-2 on cell-to-cell basis was also susceptible to PM-19. In combination, PM-19 and 3'-azido-3'-deoxythymidine were synergistic in inhibiting HIV-1 proliferation.

Conformational equilibria of the L-iduronate residue in non-sulphated di-, tetra- and hexa-saccharides and their alditols derived from dermatan sulphate

The conformation of the L-iduronate residue in non-sulphated di-, tetra- and hexa-saccharides and their alditol derivatives derived from rooster comb dermatan sulphate was investigated by 400 MHz 1H-n.m.r. spectroscopy. The ratio of conformational isomers is obtained by the average spin-spin coupling constants of a mixture of nearly isoenergetic conformers (1C4, 4C1 and 2S0). The non-reducing terminal L-iduronate residue in the tetrasaccharides (I-H-I-H and I-H-G-H) and their alditols (I-H-I-H-ol and I-H-G-H-ol) is in equilibrium with three conformers (1C4, 30%; 4C1, 40%; 2S0, 30%) of nearly equal population. Whereas the internal L-iduronate residue in the tetrasaccharides (I-H-I-H and G-H-I-H) exists as an equilibrium mixture of 1C4 (54%) and 2S0 (42-44%) conformers, that of their alditols (I-H-I-H-ol and G-H-I-H-ol) is in equilibrium between 2S0 conformer (66%) and 1C4 conformer (28%). The conformational population for the internal L-iduronate residue 2I in the hexasaccharide (3I-H-2I-H-1I-H) is also calculated and compared with that for the L-iduronate residue in native dermatan sulphate, which was calculated on the basis of the spin-spin coupling constants reported by Gatti, Casu, Torri & Vercellotti [(1979) Carbohydr. Res. 68, c3-c7].

Inhibition of replication of human immunodeficiency virus by a heteropolyoxotungstate (PM-19)

A Keggin polyoxotungstate PM-19 K7[PTi2W10O40].6H2O was found to be a potent inhibitor of the replication of human immunodeficiency virus (HIV), which causes acquired immunodeficiency syndrome (AIDS), in OKT4+ cells. In contrast, the effect of HPA 23 (NH4)17Na[NaSb9W21O86], an inhibitor of reverse transcriptase of HIV, was not significant.

Biological properties of streptonigrin derivatives. III. In vitro and in vivo antiviral and antitumor activities

Antitumor antibiotic streptonigrin (STN-COOH) is a potent inhibitor of avian myeloblastosis virus (AMV) and human immunodeficiency virus reverse transcriptases. The carboxyl group at 2'-position of STN-COOH was modified to give esters, hydrazide, amides and amino acid derivatives for biological studies. Against AMV reverse transcriptase, the hydrazide, amides and amino acid derivatives showed inhibitory activity, which compared favorably to that of STN-COOH, with the ID50 values ranging 2-8 micrograms/ml. In contrast, the esters lacked this activity except for those having a dimethylamino group in the substituent. Splenomegaly caused by Friend leukemia virus infection was significantly inhibited by STN-COOH and STN-COO(CH2)3N(CH3)2, but not STN-CONH(CH2)3N(CH3)2. Doxorubicin-resistant murine lymphoblastoma L5178Y cells showed collateral sensitivity to both STN-COOH and STN-COO(CH2)3N(CH3)2 not only in vitro but also in vivo.