We report the first example of chemical cross-linking of 5-formyl-2'-deoxyuridine containing oligonucleotides with oligopeptides through a Schiff base formation. Twenty amino acid residue peptides investigated here were derived from the DNA binding site of RecA protein. We have demonstrated that the lysine residue placed at the 6th or 8th position from the N-terminus of the peptide directly contacts with DNA.

Amino Acid Sequence↗

PubMedDate not supplied

Radical modulation activity of pine cone extracts of Pinus elliottii var. Elliottii.

The radical modulation activity of lignins prepared from the cone of Pinus elliottii var. Elliottii was investigated, using ESR spectroscopy. These lignins produced radical(s) under alkaline conditions, and the radical intensity was increased with increasing pH. Lower concentrations of lignins slightly reduced the radical intensity of sodium ascorbate, whereas higher concentrations of lignins enhanced both the radical intensity and cytotoxic activity of sodium ascorbate. Lignins effectively scavenged superoxide anion, produced by hypoxanthine-xanthine oxidase reaction. Elliottii lignins significantly inhibited the human immunodeficiency virus (HIV)-induced cytopathic effect, in similar fashions to other natural, commercial and synthetic lignins. Pretreatment of mice with lignins significantly protected them from the lethal infection with E. coli. Crude alkaline extracts of Elliottii pine cone displayed similar magnitude of activity with lignins. These data further supports the medicinal efficacy of plant extracts.

Animals↗

PubMedDate not supplied

Interaction between sodium 5,6-benzylidene-L-ascorbate and gallic acid.

The interaction between sodium 5,6-benzylidene-L-ascorbate (SBA) and gallic acid was investigated by two different parameters: radical intensity and cytotoxicity induction. These compounds produced ESR signals of radicals under alkaline conditions. The addition of increasing concentrations of SBA completely scavenged the gallate radical and replaced the latter with its ascorbate radical. On the other hand, gallic acid dose-dependently enhanced the radical intensity of SBA. Both of these two compounds dose-dependently reduced the viable cell number of human squamous carcinoma HSC-2 cells without inducing internucleosomal DNA cleavage. Electron micrographs of the dying cells demonstrate the irreversible degenerative changes especially in the cytoplasm of the cells. The cytotoxic activity of gallic acid was almost completely eliminated by catalase, whereas SBA was totally insensitive to catalase. When these two compounds were mixed together before adding to HSC-2 cells, the cytotoxic activity of gallic acid was significantly reduced by SBA, whereas that of SBA was not reduced by gallic acid. SBA dose-dependently reduced the gallate oxidation in the culture medium. The interaction between SBA and gallic acid may modify their individual biological activity.

Antineoplastic Agents↗

PubMedDate not supplied

Radical intensity and cytotoxicity of butylated hydroxyanisole and its orthobisphenol dimer.

The radical intensity of BHA (4-Hydroxy-3-t-butylanisole) and its dimer (3,3'-Di-t-butyl-5,5'-dimethoxy-1,1'-biphenyl-2,2'-diol, Bis-BHA) were compared with their cytotoxic activity. ESR spectroscopy showed that BHA produced characteristic five peaks of radicals under alkaline conditions (pH > 9.5). At higher pH, BHA radical rapidly disappeared, and progressively transformed into new radical species, as detected by the splitting of the ESR signal. BHA showed higher cytotoxic activity against salivary gland tumor cell line than against normal human gingival fibroblast. On the other hand, Bis-BHA did not produce any detectable amounts of radicals at wide ranges of pH, corresponding with its weaker cytotoxic activity as compared with BHA. BHA scavenged DPPH (1,1-Diphenyl-2-picrylhydrazyl) radical and superoxide anion, more efficiently than Bis-BHA. The present study demonstrated that BHA is more cytotoxic, produces higher amounts of radicals and more efficiently scavenges various radical species, as compared with Bis-BHA. This suggests the possible link between the cytotoxic activity and radical generation/scavenging activity in BHA-derived compounds.

Antioxidants↗

PubMedDate not supplied

Interaction between sodium ascorbate and polyphenols.

The interaction between sodium ascorbate and polyphenols was investigated by two different parameters: radical intensity and cytotoxicity induction. ESR spectroscopy shows that sodium ascorbate, lignins (alkali-lignin, lignin sulfonate, pine cone-derived lignin) and tannins (gallic acid, epigallocatechin gallate (EGCg), tannic acid) all produced radicals with different intensities under alkaline conditions. All lignin samples significantly enhanced the radical intensity and cytotoxic activity of sodium ascorbate, whereas all tannin samples slightly reduced the radical intensity of sodium ascorbate. Sodium ascorbate efficiently scavenged the radical and cytotoxic activity of gallic acid, as expected by the ionization potential and heat of reaction by the PM3 semiempirical method. EGCg and tannic acid slightly reduced the cytotoxic activity of sodium ascorbate. The present study demonstrates that lignins and tannins modify the radical intensity and cytotoxic activity of sodium ascorbate in different manners, and suggests the applicability of ESR spectroscopy for the screening of drug to drug interaction.

Ascorbic Acid↗

PubMedDate not supplied

Interaction between antioxidants and hydroquinone/bisphenol.

We have investigated the stability of semiquinone radical (SQ .) produced from the mixture of hydroquinone (HQ) and bisphenol A (BPA) in the presence of various antioxidants, some of which induce apoptosis in tumor cell lines. BPA produced no detectable amount of ESR signal. The acceleration of HQ oxidation by BPA results in the production of SQ .. The BPA-enhanced SQ . production may occur through either SQ. regeneration by electron transfer from BPA working as an antioxidant or the O2- scavenging activity of BPA. SQ . intensity of HQ/BPA was reduced by lower concentrations of sodium ascorbate, epigallocatechin, gallate and quercetin, but significantly enhanced by gallic acid. The initial SQ . was replaced by the radicals of antioxidants except lignin and salicylic acid, at higher concentrations, due to their radical-radical coupling or dismutation process. Among these compounds, gallic acid enhanced the radical intensity of SQ . to the greatest extent. The results suggest that antioxidants from foods suppress the activity of xenobiotics such as HQ, however, they produce their own radical at higher concentrations, suggesting their bimodal actions. The present study demonstrates the usefulness of ESR spectroscopy for the interaction between HQ/BPA and antioxidants.

Antioxidants↗

PubMedDate not supplied

Antimicrobial and radical modulation activity of AV-07, a poly-herbal formula.

An extract of AV-07 was investigated for various biological activities. Pretreatment of mice with the AV-07 extract significantly protected them from lethal infection with E. coli. ESR spectroscopy showed that the extract produced radicals under alkaline conditions and enhanced the radical intensity of sodium ascorbate, suggesting its pro-oxidant action at higher concentrations. The extract effectively scavenged superoxide anion, produced by hypoxanthine-xanthine oxidase reaction and hydroxyl radical, produced by Fenton reaction. These data demonstrate that AV-07 extract contains various bioactive substances, suggesting its medicinal efficacy.

Animals↗

PubMedDate not supplied

Interaction between hydroquinone and ascorbic acid derivatives: quenching effect of organic solvents.

The interaction between hydroquinone (HQ) and ascorbic acid analogs was investigated. Semiquinone radicals (SQ.) generated by HQ were comparably scavenged by ascorbic acid, sodium ascorbate and ascorbate 6-palmitate, but much less efficiently by ascorbate 2,6-dipalmitate. Organic solvents, such as dimethysulfoxide (DMSO) or ethanol, which are utilized for solubilization of water-insoluble analogs, ascorbate 6-palmitate and ascorbate 2,6-dipalmitate, also scavenged SQ.. DMSO scavenged the SQ. more efficiently than ethanol. This suggests the importance of considering such a quenching effect of organic solvent in the study of the interaction between HQ and antioxidants. The involvement of the ascorbate radical for cytotoxicity induction is discussed.

Ascorbic Acid↗

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

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↗