Phenanthroline-Cu complex-mediated chemiluminescence of DNA and its potential use in antioxidation evaluation

Advances in Novel Biomaterial-Based Strategies for Spinal Cord Injury Treatment

Spinal cord injury (SCI) is a highly disabling neurological disorder. Its pathological process comprises an initial acute injury phase (primary injury) and a secondary injury phase (subsequent chronic injury). Although surgical, drug, and cell therapies have made some progress in treating SCI, there is no exact therapeutic strategy for treating SCI and promoting nerve regeneration due to the complexity of the pathological SCI process. The development of novel drug delivery systems to treat SCI is expected to significantly impact the individualized treatment of SCI due to its unique and excellent properties, such as active targeting and controlled release. In this review, we first describe the pathological progression of the SCI response, including primary and secondary injuries. Next, we provide a concise overview of newly developed nanoplatforms and their potential application in regulating and treating different pathological processes of SCI. Then, we introduce the existing potential problems and future clinical application perspectives of biomedical engineering-based therapies for SCI.

Critical review of the phytochemical profiles and health-promoting effects of the edible mushroom Armillaria mellea

Research on the nutritional and medicinal properties of wild edible mushrooms has witnessed a significant surge in recent years. Among these mushrooms, Armillaria mellea (AM) stands out due to its abundant biologically active components. The presence of biological compounds in AM, including carbohydrates, sterols, fatty acids, sesquiterpenes, non-hallucinogenic indole compounds and adenosine derivatives, has been demonstrated in previous studies. Notably, specific bioactive substances isolated from AM, such as armillarikin, have exhibited promising anticancer effects. In vitro studies have elucidated the mechanisms behind these effects, further emphasizing the potential of AM in cancer treatment. Consequently, the objective of this study is to provide a comprehensive overview of the phytochemical profiles of AM while thoroughly investigating its therapeutic benefits. Moreover, this research has uncovered novel and effective treatments, including the utilization of ultrasonic disruption extraction in food processing. These findings highlight the potential of AM as a functional food with possible medical applications. By exploring AM's phytochemical composition and therapeutic effects, this study aims to contribute to a deeper understanding of its potential as a valuable natural resource.

Antioxidant and DNA Damage Protecting Activity of Exopolysaccharides from the Endophytic Bacterium Bacillus cereus SZ1

An endophytic bacterium was isolated from the Chinese medicinal plant Artemisia annua L. The phylogenetic and physiological characterization indicated that the isolate, strain SZ-1, was Bacillus cereus. The endophyte could produce an exopolysaccharide (EPS) at 46 mg/L. The 1,1-diphenyl-2-picrylhydracyl (DPPH) radical scavenging activity of the EPS reached more than 50% at 3-5 mg/mL. The EPS was also effective in scavenging superoxide radical in a concentration dependent fashion with an EC50 value of 2.6 mg/mL. The corresponding EC50 for scavenging hydroxyl radical was 3.1 mg/mL. Moreover, phenanthroline-copper complex-mediated chemiluminescent emission of DNA damage was both inhibited and delayed by EPS. The EPS at 0.7-1.7 mg/mL also protected supercoiled DNA strands in plasmid pBR322 against scission induced by Fenton-mediated hydroxyl radical. The preincubation of PC12 cells with the EPS prior to H₂O₂ exposure increased the cell survival and glutathione (GSH) level and catalase (CAT) activities, and decreased the level of malondialdehyde (MDA) and lactate dehydrogenase (LDH) activity in a dose-dependent manner, suggesting a pronounced protective effect against H₂O₂-induced cytotoxicity. Our study indicated that the EPS could be useful for preventing oxidative DNA damage and cellular oxidation in pharmaceutical and food industries.

Role of reactive oxygen species in ultra-weak photon emission in biological systems

Ultra-weak photon emission originates from the relaxation of electronically excited species formed in the biological systems such as microorganisms, plants and animals including humans. Electronically excited species are formed during the oxidative metabolic processes and the oxidative stress reactions that are associated with the production of reactive oxygen species (ROS). The review attempts to overview experimental evidence on the involvement of superoxide anion radical, hydrogen peroxide, hydroxyl radical and singlet oxygen in both the spontaneous and the stress-induced ultra-weak photon emission. The oxidation of biomolecules comprising either the hydrogen abstraction by superoxide anion and hydroxyl radicals or the cycloaddition of singlet oxygen initiate a cascade of oxidative reactions that lead to the formation of electronically excited species such as triplet excited carbonyl, excited pigments and singlet oxygen. The photon emission of these electronically excited species is in the following regions of the spectrum (1) triplet excited carbonyl in the near UVA and blue-green areas (350-550nm), (2) singlet and triplet excited pigments in the green-red (550-750nm) and red-near IR (750-1000nm) areas, respectively and (3) singlet oxygen in the red (634 and 703nm) and near IR (1270nm) areas. The understanding of the role of ROS in photon emission allows us to use the spontaneous and stress-induced ultra-weak photon emission as a non-invasive tool for monitoring of the oxidative metabolic processes and the oxidative stress reactions in biological systems in vivo, respectively.

Chemiluminescence evaluation of antioxidant activity and prevention of DNA damage effect of peptides isolated from soluble eggshell membrane protein hydrolysate

A new kind of soluble eggshell membrane protein (SEP) was prepared from eggshell membrane (ESM). The extraction rate of SEP could rise to 90% by two times, basically accomplishing the complete utilization of the whole ESM. Five proteases were employed as hydrolytic enzyme for the preparation of antioxidative peptides from SEP, and the antioxidative activities of the hydrolysates were investigated using a chemiluminescence method. Among the hydrolysates, alcalase hydrolysates with the highest free radical scavenging activity were further separated into three fractions using Sephadex G-25 gel filtration chromatography of the 4 h hydrolysate (SP1, SP2, and SP3). Among these three fractions, SP2 with an average molecular weight of 618.86 Da possessed the strongest fraction of scavenging activity. The IC50 values of the superoxide radicals, hydroxyl scavenging activities, and protective effect on DNA damage caused by hydroxyl radicals generated were 0.10, 0.18, and 0.95 mg/mL, respectively. These results demonstrate that inexpensive ESM waste could be a new alternative in the production of antioxidative peptides.

Binding to the minor groove of the double-strand, tau protein prevents DNA from damage by peroxidation

Tau, an important microtubule associated protein, has been found to bind to DNA, and to be localized in the nuclei of both neurons and some non-neuronal cells. Here, using electrophoretic mobility shifting assay (EMSA) in the presence of DNA with different chain-lengths, we observed that tau protein favored binding to a 13 bp or a longer polynucleotide. The results from atomic force microscopy also showed that tau protein preferred a 13 bp polynucleotide to a 12 bp or shorter polynucleotide. In a competitive assay, a minor groove binder distamycin A was able to replace the bound tau from the DNA double helix, indicating that tau protein binds to the minor groove. Tau protein was able to protect the double-strand from digestion in the presence of DNase I that was bound to the minor groove. On the other hand, a major groove binder methyl green as a negative competitor exhibited little effect on the retardation of tau-DNA complex in EMSA. This further indicates the DNA minor groove as the binding site for tau protein. EMSA with truncated tau proteins showed that both the proline-rich domain (PRD) and the microtubule-binding domain (MTBD) contributed to the interaction with DNA; that is to say, both PRD and MTBD bound to the minor groove of DNA and bent the double-strand, as observed by electron microscopy. To investigate whether tau protein is able to prevent DNA from the impairment by hydroxyl free radical, the chemiluminescence emitted by the phen-Cu/H₂O₂/ascorbate was measured. The emission intensity of the luminescence was markedly decreased when tau protein was present, suggesting a significant protection of DNA from the damage in the presence of hydroxyl free radical.

Antioxidant properties of two gallotannins isolated from the leaves of Pistacia weinmannifolia

Pistacia weinmannifolia J. Poisson ex Franch (Anacardiaceae) is a shrub or arbor widely found in Yunnan province of China and its leaves are used as traditional Chinese medicine by herbalists. The leaves of P. weinmannifolia are rich in phenolic compounds, among which two novel gallotannins, Pistafolin A and Pistafolin B, are identified. In the present investigation, the antioxidant efficiency of Pistafolin A and Pistafolin B in preventing lipid, protein and DNA from reactive oxygen species-mediated damage was studied. Both Pistafolin A and Pistafolin B inhibited the peroxyl-radical induced lipid peroxidation of l-alpha-phosphatidylcholine liposomes dose-dependently and prevented the bovine serum albumin from peroxyl-induced oxidative damage. Pistafolin A and Pistafolin B also inhibited copper (II)-1,10-phenanthroline complex-induced DNA oxidative damage. Both Pistafolin A and Pistafolin B scavenged the hydrophilic 2,2'-azinobis(3-ethylbenzothiozoline-6-sulphonic acid) diammonium salt-free radicals and the hydrophobic 1,1-dipheny-2-picrylhydrazyl radicals effectively, suggesting they may act as hydrogen donating antioxidants. The protective effects of the two gallotannins against oxidative damage of biomacromolecules were due to their strong free radical scavenging ability. Pistafolin A with three galloyl moieties showed stronger antioxidant ability than Pistafolin B with two galloyl moieties.

Chemiluminescence evaluation of oxidative damage to biomolecules induced by singlet oxygen and the protective effects of antioxidants

A chemiluminescence (CL) method was developed for the evaluation of oxidative damage to biomolecules induced by singlet oxygen ((1)O(2)) and for the evaluation of the protective effects of antioxidants. The (1)O(2) was generated from the reaction of H(2)O(2)+OCl(-). Results showed that the CL signal from the reaction of H(2)O(2)+OCl(-) was weak, however, it was enhanced dose-dependently with the addition of DNA and unsaturated fatty acid, respectively. Spectra analysis indicated that the enhanced CL could be ascribed to the decay of triplet-excited carbonyl compounds, which were generated from the reaction of (1)O(2) plus the biomolecules. On the other hand, the enhanced CL produced in the above systems could be effectively inhibited by lycopene, beta-carotene, VC, and VE, but could not be inhibited by mannitol, SOD, and NaN(3). The mechanism therein was discussed.

Tau could protect DNA double helix structure

The hyperchromic effect has been used to detect the effect of tau on the transition of double-stranded DNA to single-stranded DNA. It was shown that tau increased the melting temperature of calf thymus DNA from 67 to 81 degrees C and that of plasmid from 75 to 85 degrees C. Kinetically, rates of increase in absorbance at 260 nm of DNA incubated with tau were markedly slower than those of DNA and DNA/bovine serum albumin used as controls during thermal denaturation. In contrast, rates of decrease in the DNA absorbance with tau were faster than those of controls when samples were immediately transferred from thermal conditions to room temperature. It revealed that tau prevented DNA from thermal denaturation, and improved renaturation of DNA. Circular dichroic spectra results indicated that there were little detectable conformational changes in DNA double helix when tau was added. Furthermore, tau showed its ability to protect DNA from hydroxyl radical (.OH) attacking in vitro, implying that tau functions as a DNA-protecting molecule to the radical.

The involvement of singlet oxygen in copper-phenanthroline/H2O2-induced DNA base damage: a chemiluminescent study

Copper in the presence of excess 1,10-phenanthroline, a reducing agent, and H2O2 causes DNA base damage as well as strand breakage. We have reported in previous work that a strong chemiluminescence was followed by DNA base damage in this system, which is characteristic of guanine. In the present work, the mechanism of the chemiluminescence was studied. Results show that the luminescence was inhibited by all three classes of reactive oxygen species (*OH, O2-, (1)O2) scavengers to different degrees. Singlet oxygen scavengers showed the most powerful inhibition while the other two classes of scavengers were relatively weaker. The emission intensity in D2O was 3-fold that in H2O. Comparing the effect of scavengers on the luminescence of DNA with that of dGMP, the ratio of inhibition was similar. On the other hand, DNA breakage analysis showed that inhibition by the singlet oxygen scavenger NaN3 of strand breakage was strong and comparable to that of the scavengers of the two oxygen radicals. The results suggest that singlet oxygen may be a major factor for the chemiluminescence of guanine, while DNA strand breakage may be caused by many active species.