Biomedical subjects

H Sakagami

Publications and source records attributed to H Sakagami.

At least 325 records · Page 18Linked to original sources

PubMedDate not supplied

Effect of metals and their antagonists on the radical intensity and cytotoxicity of ascorbates.

Five heavy metal antagonists were compared for their specificity of chelating action against copper (CuCl, CuCl2) and iron (FeCl2, FeCl3). ESR spectroscopy showed that both copper and iron significantly enhanced the radical intensity of ascorbate and sodium 5,6-benzylidene-L-ascorbate (SBA). Equimolar concentrations of dimercaprol efficiently chelated all these metals, thus significantly reducing their stimulation effects. On the other hand, the chelating action of penicillamine, ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid was limited to CuCl and CuCl2 whereas deferoxamine mesylate (DFO) was a specific iron chelator. The cytotoxic activity of sodium ascorbate was augmented by DFO, but diminished by FeCl3. The simultaneous addition of DFO and FeCl3 counteracted each other, thus neutralizing their individual effects. The cytotoxic activity of both sodium ascorbate and SBA was significantly enhanced by CuCl2 and this stimulation effect of CuCl2 was effectively chelated by DTPA. The present study demonstrates the specificity of the chelating action of these five antagonists, suggesting the possible application of these different types of antagonists for the prevention of the pathogenic diseases catalyzed by the corresponding metals.

Ascorbic Acid↗

PubMedDate not supplied

Relationship between biological activity and dipole moment in benzo[a]phenothiazines.

Relationship between the biological activity and two different dipole moments were investigated in 9 benzo[a]phenothiazines [1-8] by calculating the dipole moment with the PM3 method. 12H-Benzo[a]phenothiazine [1], 9-methyl-12H-benzo[a]phenothiazine [2], 10-methyl-12H-benzo[a]phenothiazine[3] and 11-methyl-12H-benzo[a]phenothiazine [4] induced monocytic differentiation of human myelogenous leukemic cell lines and displayed antitumor activity. These active compounds showed a significantly smaller value of calculated ground-state dipole moment (mu g) and larger value of first excited-state dipole moment (mu e). The mu e/mu g ratio of four active compounds [1-4] ranged from 3.25 to 4.38, whereas that of three inactive compounds [5,6,7] ranged from 1.77 to 2.72. These two different dipole moments might be useful parameters for estimation of the biological activity of benzo[a]phenothiazines [1-8].

Animals↗

PubMedDate not supplied

Rapid determination of ascorbate by ESR spectroscopy.

Optimal conditions for the determination of ascorbate, based on the detection of its radical by ESR spectroscopy, were established. The optimal pH for the measurement of the ascorbate radical was 10, whereas that for the gallate and caffeate radical was much higher. This was due to the liability of the ascorbate radical at higher pH. When the radical intensity of ascorbate vs. concentration was plotted double logarithmically, a linear correlation was established between these two parameters within the ascorbate concentration of 0.03-10 mM. ESR analysis of the homogenates under alkaline condition demonstrated that ascorbate is distributed in various mouse organs and that the ascorbate radical is unstable at neutral pH in the brain and liver, suggesting the presence of metabolizing substances. The present study suggests the applicability of the present technique for the study of ascorbate metabolism and identification of physiological factors which regulate the radical intensity of ascorbate.

Animals↗

PubMedDate not supplied

Modulating factors of radical intensity and cytotoxic activity of ascorbate (review).

Ascorbate acts both as an antioxidant and as an oxidant, depending upon the environment in which the molecule is present. We have reported that millimolar concentrations of ascorbate induced apoptotic cell death, characterized by cell shrinkage, nuclear fragmentation and internucleosomal DNA cleavage, in human myelogenous leukemic cell lines. Ascorbate derivatives, which can induce the apoptosis, produced the radical(s), elevated the oxidation potential and stimulated the methionine oxidation in the culture medium, whereas inactive derivatives did not. This suggests that the ascorbate induce the apoptosis by its prooxidant action. The effects of various factors, such as temperature, pH, metal, metal antagonist, redox agent, serum protein, polyphenol and (natural, chemically modified) polysaccharide on the radical intensity and apoptosis-inducing activity of ascorbate are reviewed. Gallate and benzo[a]phenothiazine derivatives, which can induce apoptosis or monocytic differentiation in human myelogenous leukemic cell lines, also produced radicals. These data suggest the significant role of radicals in the initiation of diverse biological activities.

Antineoplastic Agents↗

PubMedDate not supplied

Radical intensity and carcinogenic activity of benz[c]acridines.

Among 13 benz[c]acridines, six 7-methyl-substituted compounds (7-methylbenz[c]acridine, 7,9-dimethylbenz[c]acridine, 7,10-dimethylbenz[c]acridine, 7,11-dimethylbenz[c]acridine, 7,9,10-trimethylbenz[c]acridine, 7,9,11-trimethylbenz[c]acridine) were carcinogenic, while the other seven compounds (benz[c] acridine, 8-methylbenz[c]acridine, 9-methylbenz[c]acridine, 10-methylbenz[c]acridine, 11-methylbenz[c]acridine, 5,7-dimethylbenz[c]acridine, cis-5,6-dihydroxy-5,6-dihydrobenz[c]acridine) were inactive. Using both McLachlan-Hückel molecular orbital (McLachlan-HMO) and HMO methods, all the carcinogenic compounds were shown to have the elevated pi-spin density at 12th nitrogen atom of their molecules, as compared with noncarcinogenic compounds. Electron spin resonance (ESR) spectroscopy, however, revealed that both carcinogenic and noncarcinogenic compounds produced no detectable amounts of radical. This is in contrast to ascorbates, gallates and benzo[a]phenothiazines, which induced apoptosis by radical mediated mechanism(s). Amino acid analysis demonstrated that methionine oxidation is not involved in the induction of carcinogenic activity by benz[c]acridines.

Acridines↗

PubMedDate not supplied

Chelating effect of human serum proteins on metal-catalyzed ascorbate radical generation.

Purified human serum albumin and immunoglobulin G (IgG) were investigated for their metal-chelating activity, using ESR spectroscopy. Both copper (Cu2+) and iron ions (Fe3+) enhanced the radical intensity of both sodium ascorbate and sodium 5,6-benzylidene-L-ascorbate (SBA). Albumin significantly reduced the stimulation effect of copper, but not that of iron. On the other hand, IgG effectively reduced the radical intensity of iron, without affecting that of copper. The present study demonstrates the specific chelating action of these serum proteins, suggesting their possible preventive effects on metal-catalyzed pathogenic diseases.

Adult↗

PubMedDate not supplied

Correlation between structure and diverse biological activities of "half-mustard type" phenothiazines.

The structure and activity relationship of fifteen "half-mustard type" phenothiazines and related compounds were investigated. These compounds did not show any direct bactericidal activity, possibly due to the lack of radical generation activity. Pretreatment with phenothiazines significantly reduced the lethality of Escherichia coli GN2411 infection, possibly due to activation of the host defense mechanism. Higher concentrations of these compounds showed cytotoxic activity against several cultured tumor cell lines. However, no clear-cut relationship was established between biological activity and two dipole moments (mu g, mu e).

Anti-Bacterial Agents↗

PubMedDate not supplied

Comparative study of the antitumor action between sodium 5,6-benzylidene-L-ascorbate and sodium ascorbate (minireview).

This review summarizes our comparative study of the antitumor action of sodium 5,6-benzylidene-L-ascorbate (SBA) and sodium ascorbate. Both SBA and ascorbate produced ascorbate radicals during decomposition, elevated oxidation potential and oxidized methionine to methionine sulfoxide, in the regular culture medium. They induced apoptotic cell death (characterized by internucleosomal DNA fragmentation) in human myelogenous leukemic cell lines, but killed most of other tumor cell lines by necrosis without induction of internucleosomal DNA fragmentation. The cytotoxic activity of SBA and ascorbate was significantly enhanced in the presence of copper and the stimulation effect of copper was reduced by a heavy metal antagonist. However, the cytotoxic activity of SBA was only slightly modified by iron, cysteine analog or catalase, in contrast to ascorbate, which was highly sensitive to all these agents. Furthermore, intravenous administration of SBA induced degeneration in chemically-induced hepatocellular carcinoma whereas ascorbate was inactive. These data suggest the differential mode of antitumor action between these two compounds.

Animals↗

PubMedDate not supplied

Enhancement of cytotoxic activity of ascorbate by Acer nikoense Maxim. Extracts.

Millimolar concentrations of ascorbic acid or sodium ascorbate induced cytotoxicity against human glioblastoma T98G cells. Addition of hot water and sodium hydroxide extracts of the bark of Acer nikoense Maxim. synergistically enhanced the cytotoxic activity of ascorbate. Human peripheral blood lymphocytes and polymorphonuclear cells were relatively resistant to ascorbate, the Acer nikoense Maxim. extract, or a combination of them. The extracts stimulated the degradation of ascorbates via ascorbyl radical production, in parallel with their ability to stimulate the cytotoxic activity of ascorbate. The results suggest the medicinal efficacy of the Acer nikoense Maxim. extracts.

Antineoplastic Agents↗

PubMedDate not supplied

Effect of physiological fluids on radical intensity of sodium ascorbate and sodium 5,6-benzylidene-L-ascorbate.

The effect of various physiological fluids on the radical intensity of sodium ascorbate and sodium 5,6-benzylidene-L-ascorbate (SBA) was investigated using ESR spectroscopy. Blood from various animals did not significantly affect the radical intensity of both ascorbates, whereas the corresponding plasma fractions significantly enhanced the radical intensity. This suggests that some populations of blood cells might modify the interaction between plasma components and ascorbates. Saliva contained labile substance(s) which effectively reduced the ascorbate radical intensity. HPLC demonstrated the presence of endogenous ascorbate in rat liver and brain homogenates. When sodium ascorbate or SBA was incubated with any of these homogenates, their radical intensity was synergistically enhanced, but abruptly declined without any apparent ascorbate degradation. Incubation with homogenates elevated the radical intensity of SBA up to the level significantly higher than that of sodium ascorbate. The present data suggest that antitumor action of SBA might be mediated via the accelerated production of ascorbate radical in the target organ.

Animals↗

PubMedDate not supplied

Biological activity of 6,12-dihydro-1-benzopyrano[3,4-b][1,4]benzothiazin-6-ones.

Ten 6,12-dihydro-1-benzopyrano[3,4-b][1,4]benzothiazin-6-ones (Coumarins)[1-7] and related coumarins [8-10] were compared for their cytotoxic activity and radical intensity. Among these compounds, compound 7 showed highest cytotoxic activity against human promyelocytic leukemic HL-60 cells. Compound 7 produced radicals under alkaline conditions, and showed the lowest pi-spin density at S-atom of the molecule, suggesting the delocalization of pi-spin density. These data suggest the possible relation between radical intensity and biological activity.

Antineoplastic Agents↗

PubMedDate not supplied

Interaction between eugenol-related compounds and radicals.

The radical modulating activity of 2-methoxy-4-(2-propenyl)phenol (eugenol), 2-t-butyl-4-methoxy-phenol (BHA), and their dimers (bis-eugenol, bis-BHA) was investigated, using ESR spectroscopy. Eugenol produced radicals in alkaline solutions, and enhanced the radical intensity of both sodium-L-ascorbate and sodium 5,6-benzylidene-L-ascorbate. BHA has similar, but slightly lower activity, and their dimers were inactive. Their ability to scavenge the superoxide anion (O2-), generated by hypoxanthine and xanthine oxidase reaction, was in the order of eugenol > bis-eugenol > BHA > bis-BHA. The relative radical intensity among these compounds was paralleled by their cytotoxic activity. The present study demonstrates that eugenol and BHA were very reactive with radicals and their reactivity was considerably reduced by dimerization. The applicability of the dimerized eugenol in dentistry was discussed.

Ascorbic Acid↗

PubMedDate not supplied

Radical scavenging activity of Acer nikoense Maxim. extract.

The effect of hot water and alkaline extracts of Acer nikoense Maxim. on the radical intensity of sodium ascorbate, superoxide anion (O2-)(produced by hypoxanthine-xanthine oxidase reaction) and hydroxyl radical (-OH)(generated by Fenton reaction) was investigated using ESR spectroscopy. All these extracts produced radical(s) under alkaline conditions and enhanced the radical intensity of sodium ascorbate. Among these fractions, Fr. I showed the highest stimulation effect, which coincided with its higher degradation rate and capacity to enhance the cytotoxic activity of ascorbate. These fractions also dose-dependently reduced the radical intensity of O2- and -OH. The present study demonstrates that Acer nikoense Maxim. extracts potentiate both radical intensity and apoptosis-inducing activity of ascorbate.

Dose-Response Relationship, Drug↗

PubMedDate not supplied

Relationship between radical intensity and cytotoxic activity of dopamine-related compounds.

Millimolar concentrations of dopamine (DA), norepinephrine (NE), and 3,4-dihydroxyphenylacetic acid (DOPAC) were cytotoxic to human promyelocytic leukemiC HL-60 cells. However, their metabolites (3,4-dihydroxymandelic acid (DOMA), 3-methoxytyramine (MT), normetanephrine (NMN)) and six synthetic derivatives (which have two OCH3 groups replacing two OH groups on catechol backbone) displayed much lower cytotoxic activity. Three active compounds, but not other less potent compounds, produced radicals under alkaline conditions. All active compounds significantly enhanced the decay of ascorbic acid endogenously present in rat brain homogenate, whereas all synthetic derivatives were inactive. Ascorbic acid induced apoptotic cell death in HL-60 cells and the apoptosis induction was significantly reduced by simultaneous addition of (DA). The cytotoxic activity of (DA) was also neutralized by ascorbic acid. These data suggest the possible interaction between (DA) and ascorbic acid.

Animals↗

PubMedDate not supplied

Effect of antioxidants on radical intensity and cytotoxic activity of eugenol.

The effect of antioxidants on the radical intensity of 2-methoxy-4-(2-propenyl)phenol (eugenol) was investigated, using ESR spectroscopy. Eugenol produced radicals in alkaline solutions, with an optimum pH of 9.5. The intensity of eugenol radical was a positive function of its concentration, reaching a plateau level at 100 mM. The eugenol radical was rapidly diminished under alkaline conditions. Water-soluble antioxidants, such as cysteine, N-acetyl-L-cysteine, glutathione and sodium ascorbate, completely scavenged the eugenol radical. Gallic acid at lower doses significantly, but not completely, scavenged the eugenol radical. Among water-insoluble antioxidants, terpenes (beta-carotene, retinol, lycopene) effectively scavenged the eugenol radical, whereas phenolic compounds (alpha-tocopherol, Trolox) were inactive. Millimolar concentrations of eugenol were cytotoxic against human salivary gland and oral squamous carcinoma cell lines. Addition of sodium ascorbate or beta-carotene reproducibly reduced the cytotoxic activity of eugenol. The applicability of the antioxidants in dentistry was discussed.

Acetylcysteine↗

PubMedDate not supplied

Role of hydrogen peroxide for cell death induction by sodium 5,6-benzylidene-L-ascorbate.

The role of hydrogen peroxide in the induction of cell death in human promyelocytic leukemic HL-60 cells by sodium 5,6-benzylidene-L-ascorbate (SBA) and its degradation product, ascorbic acid, was investigated. Millimolar concentrations of these compounds induced cell death, characterized by cell shrinkage, nuclear and internucleosomal DNA fragmentation, disappearance of microvilli and condensation of chromatin near the nuclear membrane. Catalase significantly reduced the cytotoxic activity of these compounds, whereas superoxide dismutase, nitric oxide (NO) generator, NO scavenger and NO synthase inhibitor were inactive, suggesting the possible role of H2O2. Determination of H2O2 with the peroxyoxalate chemiluminescence demonstrated that sodium ascorbate and SBA produced H2O2 in amounts necessary for cell death induction.

Antineoplastic Agents↗

PubMedDate not supplied

Re-evaluation of the culture condition of polymorphonuclear cells for the study of apoptosis induction.

The culture conditions of human peripheral blood polymorphonuclear leukocytes (PMN) in the study of apoptosis induction were re-evaluated. The changes in the relative viable cell number of PMNs after tumor necrosis factor (TNF) treatment were colorimetrically investigated using a cell counting kit. The relative potency of PMNs to produce the superoxide anion (O2-) was measured as the reduction of color intensity by addition of superoxide dismutase (SOD). When the PMNs were cultured in conventional RPMI1640 medium supplemented with 10% fetal bovine serum (FBS), the stimulation effect of TNF on O2- generation by PMNs was observed only for the first 6 hours. When FBS was replaced with human serum, the effect of TNF was maintained for longer incubation periods. Prolonged incubation of PMNs spontaneously produced large DNA fragments, and the extent of DNA fragmentation was relatively smaller in human serum-containing medium. TNF, LPS, hyperthermia or potassium thiocyanate slightly accelerated the production of large DNA fragments, as well as the induction of trace amounts of internucleosomal DNA cleavage in PMNs, which became detectable only after concentration by fractional isopropanol precipitation. The present study suggests the importance of the use of human serum rather than conventional FBS for the study of apoptosis induction in PMNs.

Animals↗

PubMedDate not supplied

Calcium mobilization during nicotine-induced cell death in human glioma and glioblastoma cell lines.

Nicotine dose-dependently induced cytotoxicity in human glioma (KG-1-C) and glioblastoma (GBS-1, T98G) cell lines, but could not induce internucleosomal DNA cleavage, in contrast to apoptosing human myelogenous leukemic cell lines. Human glioma/glioblastoma cell lines thus might have a chromatin structure resistant to endonuclease digestion. Nicotine induced a rapid increase in the intracellular calcium concentration. Confocal experiments with Fluo-3 fluorescence revealed that nicotine elevated the free Ca2+ concentration in both nuclear and cytoplasmic regions of the cells, and the elevation of Ca2+ in the nuclear region was more pronounced than that of the cytoplasmic region. The present study suggests that nuclear accumulation of Ca2+ is an important initial step for cell death induction by nicotine.

Apoptosis↗