Modification of mortality and tumorigenesis by tocopherol-mono-glucoside (TMG) administered after X irradiation in mice and rats.

The effects of TMG [2-(alpha-d-glucopyranosyl) methyl-2,5,7,8-tetramethylchroman-6-ol], a water-soluble vitamin E derivative, administered after irradiation on the mortality of X-irradiated mice and on the development of tumors in the mammary and pituitary glands in rats were investigated. When TMG (650 mg/kg) was administered intraperitoneally (i.p.) to C3H mice immediately after whole-body exposure to 7 Gy radiation, the 30-day survival was significantly higher than that of the control mice. The i.p. administration of TMG at 4 h after irradiation significantly improved survival compared to that of the controls, but administration 8 h after irradiation did not have a significant effect. Subcutaneous administration of TMG immediately after irradiation also decreased mortality significantly. When dams of lactating Wister rats were exposed to 1.5 Gy of X rays at day 21 after parturition and were then treated with diethylstilbestrol as a tumor promoter, the incidence of mammary tumors and pituitary tumors was increased compared to that in the nonirradiated control group. The administration of TMG (600 mg/kg, i.p.) after irradiation significantly reduced the incidence of mammary tumors and pituitary tumors. The number of rats that were free of both mammary and pituitary gland tumors was enhanced fourfold by TMG. These results suggest that TMG is effective in preventing radiation-induced bone marrow death in mice and in reducing mammary and pituitary tumors in rats even when it is administered after irradiation.

Enhanced radical-scavenging activity of naturally-oriented artepillin C derivatives.

More than two-fold augmentation in the radical-scavenging activity of artepillin C could be achieved via altering the O-H bond dissociation enthalpy of artepillin C by means of structural modifications.

Modification of nitroxyl contrast agents with multiple spins and their proton T(1) relaxivity.

The purpose of this study is to test the performance of multispin nitroxyl contrast agents in improving the sensitivity of MR detection for nitroxyl contrast agents. The relation between T(1) relaxivity and the number of paramagnetic centers in a molecule was investigated. Compound 1 is a single molecule of methoxycarbonyl-PROXYL (MC-PROXYL). Two and three MC-PROXYL molecules were chemically coupled to obtain Compounds 2 and 3, which have two and three nitroxyl spins in the molecule, respectively. A good linear relation, the slope of which increased depending on the number of nitroxyl spins in the molecule, was obtained between T(1)-weighted (fast low-angle shot) MR image contrast enhancement at 7 T and the concentration of nitroxyl contrast agents. T(1)-weighted MR image contrast enhancement and T(1) relaxivity levels of nitroxyl contrast agents were increased depending on the number of nitroxyl spins in the molecule. Multicoupling nitroxyl molecules can enhance the T(1)-weighted contrast effect while maintaining the quantitative behavior of the molecule for up to three spins.

Heat-treated mineral-yeast as a potent post-irradiation radioprotector.

In vivo radioprotection of C3H mice by i.p. administration of Zn-, Mn-, Cu-, or Se-containing heat-treated Saccharomyces serevisiae yeast sample was examined. The 30-day survival of the group treated 30 min before 7.5 Gy whole-body X-irradiation with mineral-containing yeast powders suspended in 0.5% methylcellulose was significantly higher than that of control group. When mineral-yeast was administered immediately after irradiation, the survival rate was even higher and Zn- or Cu-yeast showed the highest rate (more than 90%). Although treatment with simple yeast showed a high survival rate (73%), it was significantly lower than that obtained by the Zn-yeast treatment. The effects of Zn-yeast were studied further. When the interval between irradiation and administration was varied, the protective activity of Zn-yeast decreased gradually by increasing the interval but was still significantly high for the administration at 10 h post-irradiation. The dose reduction factor of Zn-yeast (100 mg/kg, i.p. administration immediately after irradiation) was about 1.2. When the suspension of Zn-yeast was fractionated by centrifugation, the insoluble fraction showed a potent effect, while the soluble fraction had only a moderate effect. In conclusion, mineral-yeast, especially Zn-yeast, provides remarkable post-irradiation protection against lethal whole body X-irradiation. The activity is mainly attributable to the insoluble fraction, whereas some soluble components might contribute to the additional protective activity.

Sucrose radical-production cross-section regarding heavy-ion irradiation.

We investigated the sucrose radical-production cross-section induced by heavy-ion irradiation. L-alanine was also used in order to compare radical yield and cross-section. The stable free radicals after irradiation were analyzed by electron paramagnetic resonance (EPR). The radical yield obtained by the irradiated samples had a logarithmic correlation with the LET (linear energy transfer). Quantitative EPR analyses showed that radical productions for sucrose and L-alanine vary both by different particle irradiation and the LET under the same absorbed dose. Furthermore, the cross-sections of radical productions for samples were calculated. Both cross-sections for C ions irradiation under LET 30 keV/microm at 50 Gy dose were approximately 3.0x10(-9) microm(2), taking account of the molecular areas of the samples. The values of the cross-sections imply that multiple ionizing particles involve producing stable radicals.

A long-lived o-semiquinone radical anion is formed from N-beta-alanyl-5-S-glutathionyl-3,4-dihydroxyphenylalanine (5-S-GAD), an insect-derived antibacterial substance.

N-beta-Alanyl-5-S-glutathionyl-3,4-dihydroxyphenylalanine (5-S-GAD), an insect-derived antibacterial peptide, generates hydrogen peroxide (H(2)O(2)) that exerts antitumour activity. We have investigated the precise mechanism of H(2)O(2) production from 5-S-GAD by autoxidation aiming to understand its action toward tumour cells. Using the electron spin resonance (ESR) technique, we detected a strong signal due to radical formation from 5-S-GAD. Surprisingly, the ESR signal of the radical derived from 5-S-GAD appeared after incubation for 30 min at 37 degrees C in the buffer at pH 7.4; the signal was persistently detected for 10 h in the absence of catalytic metal ions. The computer simulation of the observed ESR spectrum together with the theoretical calculation of the spin density of the radical species indicates that an o-semiquinone radical anion was formed from 5-S-GAD. We demonstrated that H(2)O(2) is produced via the formation of superoxide anion O2(.-) by the electron-transfer reduction of molecular oxygen by the 5-S-GAD anion, which is in equilibrium with 5-S-GAD in the aqueous solution. The radical formation and the subsequent H(2)O(2) production were inhibited by superoxide dismutase (SOD), when the antitumour activity of 5-S-GAD was inhibited by SOD. Thus, the formation of the o-semiquinone radical anion would be necessary for the antitumour activity of 5-S-GAD as an intermediate in the production of cytotoxic H(2)O(2).

Comparisons of EPR imaging and T1-weighted MRI for efficient imaging of nitroxyl contrast agents.

The resolution and signal to noise ratio of EPR imaging and T(1)-weighted MRI were compared using an identical phantom. Several solutions of nitroxyl contrast agents with different EPR spectral shapes were tested. The feasibility of T(1)-weighted MRI to detect nitroxyl contrast agents was described. T(1)-weighted MRI can detect nitroxyl contrast agents with a complicated EPR spectrum easier and quicker; however, T(1)-weighted MRI has less quantitative ability especially for lipophilic nitroxyl contrast agents, because T(1)-relaxivity, i.e. accessibility to water, is affected by the hydrophilic/hydrophobic micro-environment of a nitroxyl contrast agent. The less quantitative ability of T(1)-weighted MRI may not be a disadvantage of redox imaging, which obtains reduction rate of a nitroxyl contrast. Therefore, T(1)-weighted MRI has a great advantage to check the pharmacokinetics of newly modified and/or designed nitroxyl contrast agents.

Comparison of stable nitroxide, 3-substituted 2,2,5,5-tetramethylpyrrolidine-N-oxyls, with respect to protection from radiation, prevention of DNA damage, and distribution in mice.

We compared three 3-substituted 2,2,5,5-tetramethylpyrrolidine-N-oxyls (PROXYLs): carbamoyl-, methoxycarbonyl-, and hydroxymethyl-PROXYL (CM-, MC-, and HM-PROXYL, respectively) with respect to radioprotection, prevention of DNA damage, and in vivo distribution in mice. The PROXYLs provided protection to C3H mice against lethal X-irradiation (8 Gy) with the following order of magnitude, HM- > CM- approximately MC-PROXYL. In contrast, radioprotection at the cellular level assessed by the colony formation of leukemia cell line L5178Y showed no difference among them. The degree of protection from X ray-induced oxidation of DNA bases measured by the formation of 8-hydroxydeoxyguanosine in salmon DNA and the cleavage of DNA measured by electrophoresis of plasmid pBR322 DNA did not differ among the PROXYLs. Redox potentials were also similar for each. However, the blood concentration of the PROXYLs injected ip into the mice showed different maximum concentrations (HM- > CM- approximately MC-PROXYL), although all reached a maximum at around 5-10 min and gradually decreased thereafter. Their concentration in bone marrow showed a similar pattern, suggesting that the difference in in vivo radioprotection among the three PROXYLs is due to the difference in their distribution to bone marrow. In general, the radioprotection provided by stable nitroxides is affected not only by redox potential and reactivity in vitro but also by pharmacokinetics.

Drastic effect of several caffeic acid derivatives on the induction of heme oxygenase-1 expression revealed by quantitative real-time RT-PCR.

Among antioxidative polyphenols, caffeic acid esters such as caffeic acid phenethyl ester (CAPE) and chlorogenic acid are contained in propolis, vegetables and coffee. In this study, we compared the efficacy of some polyphenols on the activation level of a cytoprotective heme oxygenase-1 (HO-1) gene in RAW264.7 mouse macrophage cells using quantitative real-time RT-PCR. The quantitative study revealed a variety of activation level of HO-1 gene by the chemicals. CAPE and caffeic acid ethyl ester (CAEE) at the final concentration of 2 muM drastically activated the HO-1 gene to 39.2-fold and 20.1-fold, respectively. Curcumin, structurally related with caffeic acid and an element of turmeric, induced the HO-1 gene to 5.8-fold. In contrast, no activation was observed by other caffeic acid esters such as chlorogenic acid and rosmarinic acid. Higher concentrations were necessary for the activation by an antioxidant cysteamine and the electrophile diethyl maleate. Although the inducible activities of CAPE and chlorogenic acid were distinctly different, they showed similar reductive capacities when determined by cyclic voltammetry. These results show that the drastic activation of HO-1 gene by CAPE and CAEE is dependent upon their chemical structures, rather than the reductive activity of polyphenols, possibly reflecting the physiological effects of the nutritional elements.

N-[18F] fluoroethylpiperidin-4ylmethyl acetate, a novel lipophilic acetylcholine analogue for PET measurement of brain acetylcholinesterase activity.

The reduction of acetylcholinesterase (AChE) activity in the brain has been measured in dementia disorders such as Alzheimer's disease and dementia with Lewy bodies using (11)C-labeled acetylcholine analogues, N-[(11)C]methylpiperidin-4-yl acetate and propionate, and positron emission tomography (PET). Our aim was to develop an (18)F-labeled acetylcholine analogue useful for brain AChE mapping with PET, since (18)F, with a longer half-life, has advantages over (11)C. In a preliminary study, a series of N-[(14)C]ethylpiperidin-3-yl or -4-ylmethanol esters (acetyl and propionyl esters) were newly designed and evaluated in vitro regarding the reactivity with and specificity to AChE using purified human enzymes, leading to a novel (18)F-labeled acetylcholine analogue, N-[(18)F]fluoroethylpiperidin-4-ylmethyl acetate. In rat experiments, the (18)F-labeled candidate showed desirable properties for PET AChE measurement: high brain uptake of the authentic ester, high AChE specificity, a moderate hydrolysis rate, and low membrane permeability (metabolic trapping) of the metabolite.

In-vivo PET imaging of inducible D2R reporter transgene expression using [11C]FLB 457 as reporter probe in living rats.

BACKGROUND: Increasing interest is being shown in a variety of methods for the in-vivo monitoring of gene expression. Of these, the reporter assay using positron emission tomography (PET) has been studied most extensively. METHODS: We evaluated tetracycline-induced gene expression using a PET reporter method employing the dopamine type 2 receptor (D2R) gene as a reporter gene and [(11)C]FLB 457 as a reporter probe. We constructed a plasmid containing the D2R gene, whose expression was under the control of the tetracycline-responsive element, and transfected it into HeLa-Tet-On cells. D2R messenger RNA (mRNA) expression was measured by reverse transcription-polymerase chain reaction (RT-PCR) and D2R binding in the cultured cells was measured by a binding assay using methoxy-[(3)H]raclopride as a ligand. The tetracycline analogue, doxycycline, was used to regulate D2R expression. RESULTS: Doxycycline dose- and exposure time-dependent D2R transgene expression was observed in the mRNA measurements and receptor binding in the cells. The stably transfected cells were inoculated into nude rats and D2R expression in xenograft tumours was monitored by in-vivo receptor binding using PET. Doxycycline-dependent D2R expression was also observed in this in-vivo system. The correlation between the magnitude of the [(11)C]FLB 457 PET signal and the D2R-expressing cell fraction in the tumours showed the usefulness of the D2R-FLB 457 reporter gene-reporter probe system with PET for the quantitative evaluation of inducible in-vivo gene expression. CONCLUSION: The D2R-FLB 457 reporter gene-reporter probe system should be considered as a useful technique for measuring inducible in-vivo gene expression.

Assessment of oxidative stress in the spontaneously hypertensive rat brain using electron spin resonance (ESR) imaging and in vivo L-Band ESR.

This study examined the blood brain barrier (BBB)-permeable nitroxyl compound, 3-methoxycarbonyl-2,2,5,5-tetramethylpyrrolidine-1-oxyl (MC-PROXYL), as a spin probe for the assessment of oxidative stress in the brain by electron spin resonance (ESR) imaging and in vivo L-band ESR. Preliminary comparisons were made by ESR imaging of MC-PROXYL in the isolated brains of normal Wistar-Kyoto rats (WKY), spontaneously hypertensive rats (SHR), and stroke prone SHR (SHRSP). The decay of the ESR images of MC-PROXYL in the isolated brains was faster in SHR than in normal WKY, but was only moderate in SHRSP. In addition, the decay rate of MC-PROXYL in the heads of live rats, as measured noninvasively by L-band ESR, was faster in SHR than in WKY, and was slower in SHR than in SHRSP. Taken together, our data suggest that the oxidative stress of SHR is not as high as that in high oxidative stress animal models such as SHRSP. This is the first study to present reconstructed 3D images of the distribution of MC-PROXYL in the isolated SHR brain. The ESR technique employed herein appears to be a powerful tool for evaluating oxidative stress and for detecting the region of oxidative stress in the brain of SHR.

In vivo radioprotection of mice by 3-methyl-1-phenyl-2-pyrazolin-5-one (edaravone; Radicut), a clinical drug.

Edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one; Radicut) is a brain-protecting agent used clinically to treat acute ischemic stroke with a reaction mechanism of free radical scavenging. Since the initial stage of radiation damage involves the formation of free radicals, edaravone is expected to be effective in preventing lethal damage from ionizing radiation. In the present study, we used mice to examine in vivo the radioprotective effect of edaravone on whole body X-ray irradiation. A solution of edaravone was administered intraperitoneally to C3H mice (male, 10 weeks old), and they were irradiated with a total dose of 8.0 Gy. Edaravone exhibited dose-dependent and injection time-dependent radioprotection. When injected 30 min before the X-ray irradiation, it had the greatest radioprotective effect, whereas an injection after the irradiation showed no protective effect. The LD(50/30) was about 8.8 Gy for edaravone-injected mice and 6.6 Gy for control mice, yielding a DRF for edaravone (450 mg/kg bw) of 1.3. Edaravone decreased the body temperature transiently about 3-6C, but this did not seem to be responsible for the radioprotection. Since the radioprotection was observed only when the reagent was administered before the irradiation, the primary action of edaravone might be the quenching of free radicals with a short lifetime generated by the irradiation.

Radioprotective effect of chitosan in sub-lethally X-ray irradiated mice.

The radioprotective effect of chitosan was studied in mice following whole-body X-ray irradiation. C3H/He mice were exposed to 7 Gy, and their survival rates were examined. The survival rates of chitosan-diet mice were about 20% higher than those of mice on a standard diet, and the rates dropped sharply to a plateau at day 10 after X-ray irradiation. The chitosan-diet mice had an increased weight ratio of spleen to body within the experimental period. The leukocyte, thrombocyte, and erythrocyte counts as well as the hematocrit and hemoglobin levels were recovered significantly and more rapidly in the chitosan-diet mice than the standard-diet mice at day 14 after irradiation. The scavenging abilities of chitosan were evaluated by the ESR spin-trapping method. These observations suggested that chitosan led to hematopoetic activation and leukocytogenesis in mice after sub-lethal dose irradiation, and that the biological response might be caused by radical trapping or scavenging.

Reactive oxygen species scavenging ability of a new compound derived from weathered coal.

The scavenging activity of three fulvic acids (named XWCS-1, XWCS-4, and XWCS-8 according to time taken for ozonolysis) obtained by ozonolysis of humic acid extracted from Xinjiang (China) weathered coal and a fulvic acid (named XWCFA) extracted from the same coal towards reactive oxygen species such as superoxide radical (O(2)(.)(-)) and hydroxyl radical ((.)OH) was investigated with an electron spin resonance (ESR)-spin trapping method using 5,5-dimethyl-1-pyrroline N-oxide (DMPO) as a spin trap. O(2)(.)(-) was generated with a hypoxanthine-xanthine oxidase system. (.)OH was generated by three different methods; (i) FeSO(4)-hydrogen peroxide (H(2)O(2)) system, (ii) Cu(en)(2)-H(2)O(2) system, and (iii) UVB photolysis of H(2)O(2). At physiological pH, XWCS-1 had the greatest O(2)(.)(-) scavenging activity, followed by XWCS-4, XWCS-8 and XWCFA. XWCFA had the greatest ?OH scavenging activity among the four fulvic acids, whereas XWCS-1 and XWCS-4 enhanced the production of (.)OH from a metal-catalyzed hydroxyl radical generating system, suggesting that these molecules act as prooxidants in the presence of metal ion.

[Stereoselective synthesis of polyhydroxylated amines using (S)-pyroglutamic acid derivatives].

Naturally occurring polyhydroxylated amines such as (+)-1-deoxynojirimycin, polyoxamic acid, anisomycin, (-)swainsonine, and alexine stereoisomers, which have interesting biological activities including glucosidase- and mannosidase-inhibitory activity, immunoregulatory activity, and antibacterial effects, were synthesized stereoselectively starting from (S)-pyroglutamic acid derivatives. α,ß-Unsaturated lactams ((S)-5-hydroxymethyl-2-oxo-3-pyrroline derivatives), α,ß-unsaturated δ-lactone ((S)-4-amino-2-penten-5-olide derivative), and E-olefin ((S,E)-methyl-4-amino-5-hydroxypent-2-enoate derivative) from (S)-pyroglutamic acid derivatives were dihydroxylated using OsO4 in the presence of N-methyl morpholine N-oxide (NMO) to afford various chiral building blocks with different configurations. The stereoselectivity of cis-dihydroxylation for α,ß-unsaturated lactams and α,ß-unsaturated δ-lactone was very high, while the stereoselectivity was low for E-olefin. Therefore, the double asymmetric induction of E-olefin using K2OsO4 with chiral ligands was successively applied to yield high stereoselectivity. (2R,3S)-2-Hydroxymethyl-3-hydroxypyrrolidine and Gaissman-Weiss lactone, important intermediates for the preparation of pyrrolizidine alkaloids, were synthesized from a (3R,4R,5R)-3,4-dihydroxy-5-hydroxymethyl-2-pyrrolidinone derivative derived from α,ß-unsatulated lactam. (+)-1-Deoxynojirimycin was synthesized from a (2S,3R,4R)-methyl 4-amino-2,3,5-trihydroxypentanoate derivative of E-olefin. (-)-Swainsonine and its stereoisomers were synthesized from (2R,3S,4R)- or (2R,3R,4R)-2-hydroxymethyl-3,4-dihydroxypyrrolidine derivatives of α,ß-unsaturated δ-lactone or α,ß-unsaturated lactam. The key reaction was diastereoselective allylation of the aldehyde derived from the corresponding 2-hydroxymethylpyrrolidine derivatives with various allylation reagents. The high diastereoselectivity could be explained by cyclic chelate formation between metals and the α-aminocarbonyl group or ß-alkoxycarbonyl group, in which the nucleophile approaches from the less hindered face. Four alexine stereoisomers were synthesized from (2R,3R,4S,5R)- and (2R,3R,4S,5S)-2,3-dihydroxymethyl-3,4-dihydroxyl pyrrolidine derivatives of α,ß-unsaturated lactam.

Gamma-tocopherol-N,N-dimethylglycine ester as a potent post-irradiation mitigator against whole body X-irradiation-induced bone marrow death in mice.

We examined the radioprotective and mitigative effects of gamma-tocopherol-N,N-dimethylglycine ester (GTDMG), a novel water-soluble gamma-tocopherol derivative, against X-irradiation-induced bone marrow death in mice. Mice (C3H, 10 weeks, male) were injected intraperitoneally with GTDMG suspended in a 0.5% methyl cellulose solution before or after receiving of 7.5-Gy whole body X-irradiation. GTDMG significantly enhanced the 30-day survival rate when given 30 min before or immediately after the irradiation. Its mitigative activity (administered after exposure) was examined further in detail. The optimal concentration of GTDMG given immediately after irradiation was around 100 mg/kg body weight (bw) and the 30-day survival rate was 97.6 ± 2.4%. When GTDMG was administered 1, 10 and 24 h post-irradiation, the survival rate was 85.7 ± 7.6, 75.0 ± 9.7 and 36.7 ± 8.8%, respectively, showing significant mitigation even at 24 h after irradiation (P < 0.05). The value of the dose reduction factor (100 mg/kg bw, given intraperitoneally (i.p.) immediately after irradiation) was 1.25. GTDMG enhanced the recovery of red blood cell-, white blood cell-, and platelet-counts after irradiation and significantly increased the number of endogenous spleen colonies (P < 0.05). Subcutaneous (s.c.) administration also had mitigative effects. In conclusion, GTDMG is a potent radiation mitigator.

Vascular homeostasis regulators, Edn1 and Agpt2, are upregulated as a protective effect of heat-treated zinc yeast in irradiated murine bone marrow.

PURPOSE: To elucidate the mechanism underlying the in vivo radioprotection activity by Zn-containing, heat-treated Saccharomyces cerevisiae yeast (Zn-yeast). MATERIALS AND METHODS: Zn-yeast suspension was administered into C3H/He mice immediately after whole body irradiation (WBI) at 7.5 Gy. Bone marrow was extracted from the mice 6 hours after irradiation and analyzed on a microarray. Expression changes in the candidate responsive genes differentially expressed in treated mice were re-examined by qRT-PCR. The bone marrow was also examined pathologically at 6 h, 3, 7, and 14 days postirradiation. RESULTS: Thirty-six genes, including Edn1 and Agpt2, were identified as candidate responsive genes in irradiated mouse bone marrow treated with Zn-yeast by showing a greater than three-fold change compared with control (no irradiation and no Zn-yeast) mice. The expressions of Cdkn1a, Bax, and Ccng, which are well known as radioresponsive genes, were upregulated in WBI mice and Zn-yeast treated WBI mice. Pathological examination showed the newly formed microvessels lined with endothelial cells, and small round hematopoietic cells around vessels in bone marrow matrix of mice administered with Zn-yeast after WBI, while whole-body irradiated mice developed fatty bone marrow within 2 weeks after irradiation. CONCLUSION: This study identified a possible mechanism for the postirradiation protection conferred by Zn-yeast. The protective effect of Zn-yeast against WBI is related to maintaining the bone marrow microenvironment, including targeting endothelial cells and cytokine release.

Heterogeneity of regional redox status and relation of the redox status to oxygenation in a tumor model, evaluated using electron paramagnetic resonance imaging.

It is widely accepted that redox status, along with the partial pressure of oxygen (pO(2)), determines the efficacy of some therapeutic methods applied to treat tumors, including radiation. Redox status, evaluated by the reduction of a nitroxyl probe, was reportedly heterogeneous in a mouse tumor model. However, neither variation of heterogeneity of the redox status among mice nor the relation of the redox status to pO(2) in tumors has been characterized sufficiently. In this study, the regional reduction status in a mouse radiation-induced fibrosarcoma tumor model was evaluated using sequential three-dimensional electron paramagnetic resonance (EPR) imaging after i.v. injection of a tissue-permeable nitroxyl probe, HM-PROXYL. The regional decay of HM-PROXYL signal obeyed first-order kinetics, and the amplitude of the reduction rate and extent of its heterogeneity in a tumor varied among six mice. The tissue pO(2) was measured using EPR oximetry with lithium phthalocyanine (LiPc) microcrystals implanted within the tumor. The location of LiPc was determined with EPR imaging. A sequential image was obtained following the injection of HM-PROXYL, even after LiPc implantation, by choosing an HM-PROXYL signal peak which does not overlap with the signal of LiPc. The relationship between pO(2) and the reduction rate at the region of pO(2) measurement was found to be low (r = 0.357) in 13 tumor-bearing mice, indicating that the extent of oxygenation does not necessarily affect the redox status under air-breathing conditions. The results strongly indicate the necessity of measurements of both redox status and oxygenation in every tumor to characterize tumor physiology.

Effect of methyl substitution on the antioxidative property and genotoxicity of resveratrol.

Resveratrol ( trans-3,4',5-trihydroxystilbene) is a natural phytoalexin with various biological activities including inhibition of lipid peroxidation and free radical scavenging properties. In addition to its beneficial effects, resveratrol also has significant genotoxicity that leads to a high frequency of chromosome aberration together with micronucleus and sister chromatid exchanges. To enhance the radical scavenging activities and to reduce the genotoxicity of resveratrol, we designed 4'-methyl resveratrol analogues where a methyl group was introduced at the ortho position relative to the 4'-hydroxy group, which is responsible for both antioxidative activities and genotoxicity of resveratrol. These synthesized methyl analogues of resveratrol showed increased antioxidative activities against galvinoxyl radical as an oxyl radical species. Furthermore, the methyl analogues also surprisingly showed reduced in vitro genotoxicities, suggesting that methyl substitution may improve resveratrol efficacy.