Inhibition of the growth of cariogenic bacteria in vitro by plant flavanones

Phytoalexins, defensive compounds produced by plants against microbial infections, were purified from Sophora exigua (Leguminosae) and their growth inhibitory effects on oral cariogenic bacteria were determined in vitro. Among three isolated compounds, 5,7,2',4'-tetrahydroxy-8-lavandulylflavanone completely inhibited the growth of oral bacteria including primary cariogenic mutans streptococci, other oral streptococci, actinomycetes, and lactobacilli, at concentrations of 1.56 to 6.25 micrograms/ml.     

Halogenated chalcones with high-affinity binding to P-glycoprotein: potential modulators of multidrug resistance

Previous studies have shown that flavonoids are modulators of the transmembrane P-glycoprotein (P-gp) which mediates cell multidrug resistance. Some structural elements have been identified which seem to contribute to these compounds' activity. In the present study, a series of halogenated chalcones was prepared to further explore the structural requirements for the P-gp modulation. Four halogenated chalcones have been synthesized and evaluated as potential modulators of P-gp-mediated multidrug resistance of cancer cells by in vitro assays using a purified recombinant domain of the transporter containing the modulator binding site. Halogenated chalcones exhibited high-affinity binding, the 2',4', 6'-trihydroxy-4-iodochalcone behaving as the most potent compound with a KD value in the nanomolar range.     

Xanthones from Hypericum japonicum and H. henryi

From the aerial part of Hypericum japonicum, one new xanthone glycoside, 1,5-dihydroxyxanthone-6-O-beta-D-glucoside, one novel dimer xanthone, bijaponicaxanthone, and the first natural prenylated xanthone, 1,3,5,6-tetrahydroxy-4-prenylxanthone, were isolated together with the four known xanthones, 1,5,6-trihydroxyxanthone, isojacereubin, 6-deoxyisojacareubin and 4',5'-dihydro-1,5,6-trihydroxy-4',4',5'-trimethylfurano (2',3':4,5) xanthone. five previously known xanthones, kielcorin, cadensin, 1,7,-dihydroxyxanthone, 1,5-dihydroxy-4-methoxyxanthone and 1,2,5-trihydroxyxanthone were also found in the dichoromethane extract of the stems and leaves of H. henryi. Their structures were elucidated by spectroscopic and chemical methods. Some of the compounds from H. japonicum were found to exert an interesting coagulant activity in an in vitro test. The chemotaxonomic value of xanthones is discussed briefly.     

Anti-Candida activity of synthetic hydroxychalcones

The antifungal activity of different synthetic hydroxychalcones was determined against Candida species. It was revealed that the presence of hydroxyl groups at C-2, C-4, and C-2' in chalcone was essential to inhibit Candida growth. Among the chalcone derivatives examined, 2,4,2'-trihydroxy-5'-methylchalcone showed the most intensive anti-Candida activity, suggesting that it could be a potential therapeutic agent for candidosis.     

Effects of Sho-saiko-to, San''o-shashin-to and Scutellariae Radix on intracellular Ca2+ mobilization in C6 rat glioma cells

Glial cells have a role in maintaining the function of neural cells. This study was undertaken to clarify the effects of baicalin and baicalein, flavonoids isolated from an important medicinal plant Scutellariae Radix (the root of Scutellaria baicalensis Georgi), on glial cell function using C6 rat glioma cells. Baicalin and baicalein caused concentration-dependent inhibition of a histamine-induced increase in intracellular Ca2+ concentrations ([Ca2+]i). The potency of baicalein was significantly greater than that of baicalin. The noradrenaline- and carbachol-induced increase in [Ca2+]i was also inhibited by baicalein and both drugs inhibited histamine-induced accumulation of total [3H]inositol phosphates, consistent with their inhibition of the increase in [Ca2+]i. These results suggest that baicalin and baicalein inhibit [Ca2+]i elevation by reducing phospholipase C activity. The inhibitory effects of baicalin and baicalein on [Ca2+]i elevation might be important in the interpretation of their pharmacological action on glial cells, such as inhibition of Ca2(+)-required enzyme phospholipase A2.     

Flavonol glycosides from Dasymaschalon sootepense

Two novel flavonol glycosides have been isolated from a methanolic extract of Dasymaschalon sootepense leaves. They are the 3'-neohesperidoside and 3'(6G-alpha-rhamnosylneohesperidoside) of quercetin 3,7-dimethyl ether.     

Rationale for retention following orthodontic treatment

One pyranocoumarin (xanthyletin, 1) and two acridone alkaloids (2',2'-dimethyl-(pyrano5',6':3:4)-1,5-dihydroxy, 6-methoxy, 10-methylacridone, 3, and citpressine-I, 4), were isolated from the roots of Citrus deliciosa Ten (Rutacea). Their structures were elucidated by spectroscopic methods. Reported 13C NMR assignments of alkaloid 3 have been corrected and those of alkaloid 4 are reported for the first time Alkaloid 3 was found to have antispasmodic effect on isolated ileum segments excised from male rabbits.     

Flavone constituents in the seeds of Sophora vicii folia Hance

Four flavone compounds have been separated from the mature seeds of Sophora vicii folia. By means of physico-chemical and spectroscopic analysis, their structures have been identified as 5,7,3'-trihydroxy-4'-methoxyflavone (I); 7,3'-dihydroxy-1'-methoxyflavone (II); 7,4'-dihydroxyflavone (III) and 7,3',4'-trihydroxyflavone (IV). All of them are found in S. viciifolia for the first time, and I and II are found Sophora genus for the first time.     

Analysis of inhibitory effects of scutellariae radix and baicalein on prostaglandin E2 production in rat C6 glioma cells

Inhibitory mechanism of the water extract of Scutellariae Radix on prostaglandin E2 (PGE2) release was examined in C6 rat glioma cells. Scutellariae Radix reduced a Ca2+ ionophore A23187-induced PGE2 release by inhibition of arachidonic acid (AA) liberation. Sho-saiko-to and San'o-shashin-to, which contain Scutellariae Radix, also inhibited PGE2 release. A23187 caused phosphorylation of mitrogen-activated protein kinase (MAPK), resulting in activation of cytosolic phospholipase A2 (cPLA2). Scutellariae Radix and baicalein inhibited the phosphorylation of MAPK. Baicalein, but not baicalin, inhibited A23187-induced PGE2 release. These results suggest that baicalein in Scutellariae Radix reduces AA liberation through the inhibition of the MAPK-cPLA2 pathway.     

Flavonoid constituents from Eupatorium altissimum L. (Compositae)

An aqueous ethanol extract of Eupatorium altissimum L. (Compositae) showed confirmed activity in the P-388 lymphocytic leukemia assay in mice, and the chloroform solubles showed both cytotoxic activity in the 9KB carcinoma of the nasopharynx cell culture assay and antitumor activity in the P-388 lymphocytic leukemia assay. Two flavones, eupatorin and 5-hydroxy-3',4',6,7-tetramethoxyflavone, were isolated and identified. Both were devoid of cytotoxic and antitumor activity.     

Studies on the constituents of the leaves of Phellodendron japonicum Maxim

From the leaves of Phellodendron japonicum Maxim. (Rutaceae), six new flavonoid glycosides (I-VI) were isolated, together with eight known compounds. The structures of I-VI were shown to be 8-prenyl-3,4',5-trihydroxy-flavone 7-O-beta-D-(6-O-malonyl) glucopyranoside, (2R,3R)-8-prenyl-3,4',5-trihydroxyflavanone 7-O-beta-D-(6-O-malonyl) glucopyranoside, 8-[(S)-2,3-dihydroxy-3-methylbutyl]-3,4',5-trihydroxyflavone 7-O-beta-D-glucopyranoside, 8-[(R)-2,3-dihydroxy-3-methylbutyl]-3,4',5-trihydroxyflavone 7-O-beta-D-glucopyranoside (2R,3R)-8-[(S)-2,3-dihydroxy-3-methylbutyl]-3,4',5-trihydroxyflavanon e 7-O-beta-D-glucopyranoside and (2R,3R)-8-[(R)-2,3-dihydroxy-3-methylbutyl]-3,4',5-trihydroxyflavanon e 7-O-beta-D-glucopyranoside, respectively, on the basis of the chemical and spectral data.     

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Crude protein extract from a recently isolated ruminal bacterium identified as Selenomonas ruminantium subsp. lactilytica specifically cleaved DNA. This ability was due to the presence of two site-specific restriction endonucleases. Sr/I, a NaeI schizomer, recognizes the 5'-GCCGGC-3' sequence. Sr/II, a NsiI schizomer, recognizes 5'-ATGCAT-3'.     

Inhibitory activity of unsaturated fatty acids and anacardic acids toward soluble tissue factor-factor VIIa complex

Five compounds, which inhibited the amidolytic activity of soluble tissue factor/activated factor VII complex (sTF/VIIa), were isolated from two traditional Chinese medicinal plants commonly used in the treatment of cardiovascular and cerebrovascular diseases. The active compounds were found to be linolenic, linoleic, and oleic acids from roots of Salvia miltiorrhiza; and two anacardic acids, 6-(8'Z-pentadecenyl)- and 6-(10'Z-heptadecenyl)-salicylic acids, from leaves of Ginkgo biloba. The IC50 values were in the range 30-80 micromol/L. Palmitic acid, isolated from roots of Salvia miltiorrhiza, and 2-[(3',7',11',15'-tetramethyl)-2'E,6'E,10'E, 14'E-hexadecatetraenyl]-1,4-hydroquinone, isolated from the marine sponge Adocia viola, did not inhibit sTF/VIIa. Further expansion of the structure-activity relationship to include anacardic acids, 6-(8'Z,11'Z-heptadecadienyl)- and 6-(8'Z, 11'Z, 14'Z-heptadecatrienyl)-salicylic acids from leaves of Anacardium spondias, and other fatty acids demonstrated that at least one cis double bond was essential for inhibitory activity, and that fatty acids containing two or three cis double bonds were optimal. Evidence from preincubation studies implied that these fatty acids may exert their effect by binding to VIIa and consequently preventing binding of sTF to VIIa.     

Molecular cloning and nucleotide sequencing of a novel aminoglycoside 6'-N-acetyltransferase gene from an R-plasmid of Salmonella typhimurium S24 isolated in Taiwan

A conjugative aminoglycoside resistance plasmid pST2 has been isolated from Escherichia coli K-12 14R525, which was mated with a clinical isolate of Salmonella typhimurium S24. A novel resistance gene of aminoglycoside 6'-N-acetyltransferase[AAC(6')] was cloned from plasmid pST2 on a 1,393 kilobase (kb) of SphI-SalI fragment into vector pACYC184 and pUC18. This novel AAC(6') gene in plasmid pST2 acetylated kanamycin, amikacin, dibekacin, tobramycin, gentamicin, netilmicin, and sisomicin. The complete nucleotide sequence of the novel AAC(6') gene and its neighboring sequences were also determined. Minicell experiments detected only one protein of 24.7 kilodaltons (kDa) translated from an open reading frame of the 618 base pairs (bp) gene.     

Multiple methylated cap sequences in adenovirus type 2 early mRNA

The methylated constituents of early adenovirus 2 mRNA were studied. RNA was isolated from polyribosomes of cells double labeled with [methyl-3H]methionine and 32PO4 from 2 to 7 g postinfection in the presence of cycloheximide. Cycloheximide ensures that methylation and processing are performed by preexisting host cell enzymes. RNA was fractionated into polyadenylic [poly(A)]+ and poly(A)- molecules using poly(U)-Sepharose, and undergraded virus-specific RNA was isolated by hybridization to viral DNA in 50% formamide at 37 degrees C. Viral mRNA was digested with RNase T2 and chromatographed on DEAE-Sephadex in 7 M urea. Two 3H-labeled RNase T2-resistant oligonucleotide fractions with charges between -5 and -6 were obtained, consistent with two classes of 5' terminal methyl "cap" structures, m7G(5')ppp(5')NmpNp (cap 1) and m7G(5')ppp(5')NmNmpNp (cap 2) (Nm is a ribose 2'-O-methylation). The putative cap 1 contains all the methylated constituents of cap 1 plus Cm. The molar ratios of m7G to 2'-O-methylnucleosides is about 1.0 for cap 1 and 0.5 for cap 2, consistent with the proposed cap structures. Most significant, compositional analysis indicates four different cap 1 structures and at least three different cap 2 structures. Thus there is a minimum of seven early viral mRNA species with different cap structures, unless each type of mRNA can have more than one 5' terminus. In addition to methylated caps, early mRNA contains internal base methylations, exclusively as m6A, as shown by analyses of the mononucleotide (-2 charge) fraction. m6A was present in the ratio of 1 mol of m6Ap per 450 nucleotides. Thus viral mRNA molecules contain two to three internal m6A residues per methyl cap, since there is on the average 1 cap per 1,250 nucleotides.     

Nutrient composition and biological evaluation of mesta (Hibiscus sabdariffa) seeds

Differently substituted flavanones were isolated from Leguminosae and their antibacterial activity was comparatively studied against methicillin-resistant Staphylococcus aureus (MRSA). The minimum inhibitory concentrations (MICs) of phytochemical flavanones to clinical isolates of MRSA were determined by a serial agar dilution method. The structure-activity relationship has indicated that 2',4'- or 2',6'-dihydroxylation of the B ring and 5,7-dihydroxylation of the A ring in the flavanone structure are important for significant anti-MRSA activity and that substitution with a certain aliphatic group at the 6- or 8-position also enhances the activity. Among the thirteen flavanones tested, tetrahydroxyflavanones with these structural characteristics isolated from Sophora exigua and Echinosophora koreensis showed intensive activity to inhibit the growth of all MRSA strains at 3.13-6.25 micrograms/ml. The present hydroxyflavanones would be useful in the phytotherapeutic strategy against MRSA infections.     

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.     

Effects of flavonoids isolated from scutellariae radix on fibrinolytic system induced by trypsin in human umbilical vein endothelial cells

Studies on the effects of flavonoids isolated from the roots of Scutellaria baicalensis on the fibrinolytic system induced by trypsin in cultured human umbilical vein endothelial cells (HUVECs) showed that baicalein (1) strongly inhibited the reduction of t-PA production and the elevation of PAI-1 production induced by trypsin. The IC50 for PAI-1 production was 3.7 microM. In addition, wogonin (3), oroxylin A (5), skullcapflavone II (6), and 2',5,5',7-tetrahydroxy-6',8-dimethoxyflavone (7) inhibited the elevation of PAI-1 induced by trypsin, though less strongly; their IC50 were 105, 61, 110, and 88 microM, respectively. These findings suggest that baicalein prevents the thrombotic tendency induced by trypsin.     

Human DNA helicase VIII: a DNA and RNA helicase corresponding to the G3BP protein, an element of the ras transduction pathway

Human DNA helicase VIII (HDH VIII) was isolated in the course of a systematic study of the DNA unwinding enzymes present in human cells. From a HeLa cell nuclear extract a protein with an Mrof 68 kDa in SDS-PAGE was isolated, characterised and micro-sequenced. The enzyme shows ATP- and Mg2+-dependent activity is not stimulated by RPA, prefers partially unwound 3'-tailed substrates and moves along the bound strand in the 5' to 3' direction. HDH VIII can also unwind partial RNA/DNA and RNA/RNA duplexes. Microsequencing of the polypeptide showed that this enzyme corresponds to G3BP, an element of the Ras pathway which binds specifically to the GTPase-activating protein. HDH VIII/G3BP is analogous to the heterogeneous nuclear ribonucleoproteins and contains a sequence rich in RGG boxes similar to the C-terminal domain of HDH IV/nucleolin, another DNA and RNA helicase.     

Aminoglycoside resistance patterns of Serratia marcescens strains of clinical origin

Aminoglycoside resistance patterns of 147 Serratia marcescens strains of clinical origin were studied. All strains analysed belonged to three different bacterial populations. The periods of study and the institutions the strains were isolated from correlated significantly with the resistance patterns shown by the strains. The most frequent resistance patterns found were the following: ACC (6')-I at the Hospital Infantil de México (Children's Hospital of México), and ANT (2') + AAC(6')-I at the Instituto Nacional de Pediatría (INPed or National Institute of Pediatrics) in Mexico City. Furthermore, the isolation frequency of aminoglycoside-sensitive strains decreased remarkably at the INPed over a 12-year period. These results suggest that there has been a selection of Serratia marcescens strains that are very resistant to aminoglycosides.