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In this study, we investigated the effects of gamma irradiation on the antioxidant activity and metabolite profiles of Euphorbia maculata calli (PC3012). Gamma irradiation at various doses (0, 0.05, 0.5, and 10 kGy) significantly enhanced the 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS+) radical scavenging activities of the callus extracts of PC3012 in a dose-dependent manner. High-performance liquid chromatography (HPLC) and ultra-performance liquid chromatography-quadrupole time-of-flight/mass spectrometry (UPLC-Q-TOF/MS) analyses revealed that irradiation increased the lysophospholipid content, although no new antioxidant compounds were formed. Furthermore, a PLS-DA analysis revealed evident metabolic differences between non-irradiated and irradiated samples, which were further verified by statistical validation. These findings suggest that gamma irradiation induces specific biochemical modifications that enhance the bioactive properties of PC3012 calli. This technology exhibits potential for utilization in the natural product and food sectors, particularly in the development of functional foods and nutraceuticals with improved health benefits. [ABSTRACT FROM AUTHOR]

Deinococcus radiodurans R1 is extremely resistant to ionizing radiation and oxidative stress. In this study, we characterized DR0846, a candidate peroxiredoxin in D. radiodurans. DR0846 is a peroxiredoxin Q containing two conserved cysteine residues. DR0846 exists mainly in monomeric form with an intramolecular disulfide bond between the two cysteine residues. We found that DR0846 functions as a molecular chaperone as well as a peroxidase. A mutational analysis indicates that the two cysteine residues are essential for enzymatic activity. A double‐deletion mutant lacking DR0846 and catalase DR1998 exhibits decreased oxidative and heat shock stress tolerance with respect to the single mutants or the wild‐type cells. These results suggest that DR0846 contributes to resistance against oxidative and heat stresses in D. radiodurans. [ABSTRACT FROM AUTHOR]

Photodissociation of n-alkyl iodides and CF3I has been studied using state-selective ionization and pulsed-field time-of-flight (TOF) mass spectrometry. The (2+1) resonance-enhanced multiphoton ionization cross-section ratio of I(2P1/2) and I(2P3/2) is measured from I2 photodissociation in the 304 nm region. Using this ratio, the relative populations of I(2P1/2) and I(2P3/2) by a pure parallel excitation to the 3Q0 state of n-alkyl iodides and CF3I are obtained. This method can exclude the effects of clusters and spectrum overlap in different dissociation paths from branching ratio calculations. The product quantum yield of I(2P3/2) obtained from branching ratio reveals the 3Q0–1Q1 curve crossing probability—which increases from 0.70 for CH3I to 0.86 for n-C4H9I (with recoil velocity decrease of fragments at the curve crossing point). The potential energies at the crossing point and the Landau–Zener parameters ζ, calculated from our modified model, are 385 kJ/mol and 1100 m/s for n-alkyl iodides, and 391 kJ/mol and 177 m/s for CF3I, respectively. © 1996 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The photodissociation dynamics of IBr has been studied at 304 nm by state-selective photofragment translational spectroscopy. Velocity distributions, anisotropy parameters, and relative quantum yields are obtained for the ground I(2P3/2) and spin–orbit excited state I*(2P1/2) iodine atoms, which are produced from photodissociation of IBr at this wavelength. Two sharp velocity distributions observed for the I channel suggest the two dissociation pathways that correlate with ground-state iodine formation. Based on the expected translational energy release and the energy separation between the peaks, the two distributions have been assigned to dissociation of IBr to form I(2P3/2)+Br(2P3/2) and I(2P3/2)+Br*(2P1/2) with the former channel appearing at higher translational energy. The I* distribution shows one strong peak indicating that there is one dominant channel for formation of I* atoms at this wavelength which has been assigned to dissociation of IBr to form I*(2P1/2)+Br(2P3/2) with a quantum yield of 0.1. The I* signal formed from the I*(2P1/2)+Br*(2P1/2) dissociation channel is observed very weakly.The observed anisotropy parameter indicates that the I+Br* product (β=-0.7) is formed mainly from the perpendicular 1Π1(2341)←X transition while the I*+Br channel (β=1.8) is formed predominantly from the parallel 3Π0+(2341)←X transition followed by curve crossing to the 3Σ0+-(2422) state. The recoil energy dependence of the anisotropy parameter in the I atom produced in the I+Br channel shows a positive β value above maximum of the peak recoil energy and a negative value below the peak maximum of the recoil energy distribution. These results are interpreted in terms of the presence of more than one path for the formation of I+Br photoproduct with opposite polarization for their absorbing transitions, most likely the 3Π0+(2341)←X and the 3Π1(2341)←X transitions. The possible excited state... [ABSTRACT FROM AUTHOR]