Protective Effect of an Isoflavone, Tectorigenin, Against Oxidative Stress-induced Cell Death via Catalase Activation

BACKGROUND: Isoflavones are biologically active compounds that occur naturally in a variety of plants, with relatively high levels in soybean. Tectorigenin, an isoflavone, protects against hydrogen peroxide (H2O2)-induced cell damage. However, the underlying mechanism is unknown. METHODS: The MTT assay was performed to determine cell viability. Catalase activity was assessed by determining the amount of enzyme required to degrade 1 μM H2O2. Protein expression of catalase, phospho-extracellular signal-regulated kinase (ERK), IκB-α, and NF-κB were evaluated by Western blot analysis. A mobility shift assay was performed to assess the DNA-binding ability of NF-κB. Transient transfection and a NF-κB luciferase assay were performed to assess transcriptional activity. RESULTS: Tectorigenin reduced H2O2-induced death of Chinese hamster lung fibroblasts (V79-4). In addition, tectorigenin increased the activity and protein expression of catalase. Blockade of catalase activity attenuated the protective effect of tectorigenin against oxidative stress. Furthermore, tectorigenin enhanced phosphorylation of ERK and nuclear expression of NF-κB, while inhibition of ERK and NF-κB attenuated the protective effect of tectorigenin against oxidative stress. CONCLUSIONS: Tectorigenin protects cells against oxidative damage by activating catalase and modulating the ERK and NF-κB signaling pathway.

Hesperidin Attenuates Ultraviolet B-Induced Apoptosis by Mitigating Oxidative Stress in Human Keratinocytes

Human skin cells undergo pathophysiological processes via generation of reactive oxygen species (ROS) upon excessive exposure to ultraviolet B (UVB) radiation. This study investigated the ability of hesperidin (C28H34O15) to prevent apoptosis due to oxidative stress generated through UVB-induced ROS. Hesperidin significantly scavenged ROS generated by UVB radiation, attenuated the oxidation of cellular macromolecules, established mitochondrial membrane polarization, and prevented the release of cytochrome c into the cytosol. Hesperidin downregulated expression of caspase-9, caspase-3, and Bcl-2-associated X protein, and upregulated expression of B-cell lymphoma 2. Hesperidin absorbed wavelengths of light within the UVB range. In summary, hesperidin shielded human keratinocytes from UVB radiation-induced damage and apoptosis via its antioxidant and UVB absorption properties.

Hyperoside Induces Endogenous Antioxidant System to Alleviate Oxidative Stress

BACKGROUND: Hyperoside, a flavonoid which is mainly found in Hypericum perforatum L., has many biological effects. One of the most important effects is to prevent the oxidative stress induced by reactive oxygen species. However, the molecular mechanisms underlying its effect are not fully understood. Oxidative stress is implicated in the occurrence of various physical diseases. A wide array of enzymatic antioxidant defense systems include NADH: quinone oxidoreductase 1, superoxide dismutase, and heme oxygenase-1 (HO-1). In the present study, the protective effects of hyperoside against hydrogen peroxide-induced oxidative stress in human lens epithelial cells, HLE-B3, were investigated in terms of HO-1 induction. METHODS: The protein and mRNA expressions of HO-1 were examined by Western blotting and reverse transcriptase-PCR assays, respectively. To evaluate the ability of hyperoside to activate nuclear factor erythroid 2-related factor 2 (Nrf2), Western blotting and electrophoretic mobility shift assay were performed with nuclear extracts prepared from HLE-B3 cells treated with hyperoside. The activation of extracellular signal-regulated kinase (ERK), the upstream kinase of Nrf2 signaling, was monitored by Western blot analysis. The protective effect of hyperoside in HLE-B3 cells against hydrogen peroxide was performed by MTT assay. RESULTS: Hyperoside increased both the mRNA and protein expression of HO-1 in a time- and dose-dependent manner. In addition, hyperoside elevated the level of of Nrf2 and its antioxidant response element-binding activity, which was modulated by upstream of ERK. Moreover, it activated ERK and restored cell viability which was decreased by hydrogen peroxide. CONCLUSIONS: Hyperoside is an effective compound to protect cells against oxidative stress via HO-1 induction.

Baicalein Protects Human Skin Cells against Ultraviolet B-Induced Oxidative Stress

Baicalein (5,6,7-trihydroxy-2-phenyl-chromen-4-one) is a flavone, a type of flavonoid, originally isolated from the roots of Scutellaria baicalensis. This study evaluated the protective effects of baicalein against oxidative damage-mediated apoptosis induced by ultraviolet B (UVB) radiation in a human keratinocyte cell line (HaCaT). Baicalein absorbed light within the wavelength range of UVB. In addition, baicalein decreased the level of intracellular reactive oxygen species (ROS) in response to UVB radiation. Baicalein protected cells against UVB radiation-induced DNA breaks, 8-isoprostane generation and protein modification in HaCaT cells. Furthermore, baicalein suppressed the apoptotic cell death by UVB radiation. These findings suggest that baicalein protected HaCaT cells against UVB radiation-induced cell damage and apoptosis by absorbing UVB radiation and scavenging ROS.

Green tea ameliorates recognition memory defects in acute radiation syndrome caused by gamma irradiation / 동물의과학연구지

An evidence suggests that even low-dose irradiation can lead to progressive cognitive decline as well as memory deficits in both humans and experimental animals in part due to hippocampal dysfunction. To determine whether or not green tea (GT) and epigallocatechin gallate (EGCG) could attenuate memory impairment as well as suppress hippocampal neurogenesis, passive avoidance and object recognition memory test as well as TUNEL assay and immunohistochemical detection with markers of neurogenesis (Ki-67 and doublecortin (DCX)) were performed using adult mice treated with relatively low-dose gamma irradiation (2.0 Gy). GT was administered intraperitonially at a dosage of 50 mg/kg of body weight at 36 and 12 hr preirradiation and at 30 minutes post-irradiation, or orally at a dosage of 250 mg/kg of body weight/day for 7 days before autopsy. EGCG (25 mg/kg of body weight) was administered intraperitonially at 36 and 12 hr pre-irradiation and at 30 minutes post-irradiation. In the passive avoidance and object recognition memory test, mice trained for 1 day after acute irradiation (2 Gy) showed significant memory deficits compared with sham controls. The number of TUNEL-positive apoptotic nuclei in the dentate gyrus increased by 12 h after irradiation. In addition, the numbers of Ki-67- and DCX-positive cells significantly decreased. GT treatment prior to irradiation attenuated memory defects, blocked apoptotic death, as well as reduced the number of DCX-positive cells. Therefore, GT may attenuate memory defects in adult mice exposed to a relatively low dose of radiation possibly by inhibiting the detrimental effects of irradiation on hippocampal neurogenesis.

Evaluation of effect of red ginseng on ovariectomy-induced bone loss in C3H/HeN mice / 동물의과학연구지

Panax ginseng, also known as Korean ginseng, has long been used as a broad tonic in Oriental medicine to augment vitality, health, and longevity, particularly in older people. This study investigated the effects of Korean red ginseng (RG) on bone loss in ovariectomized (OVX) mice. C3H/HeN mice (10-weeks-old) were divided into sham and OVX groups. OVX mice were treated with vehicle, 17beta-estradiol (E2), RG (oral administration, 250 mg/kg/day), or RG (intraperitoneal administration, 50 mg/kg/every other day) for 6 weeks. Serum E2 concentration and alkaline phosphatase (ALP) activity were measured. Tibiae were analyzed using microcomputed tomography. Biomechanical properties and osteoclast surface level were measured. There was no significant difference in the degree of grip strength, body weight, uterine weight, mechanical property, tibiae length, or tibiae weight between the OVX and RG-treated groups. Compared with the OVX group, the serum ALP level was significantly lower in the RG-treated groups. Serum E2 levels and osteoclast surface levels did not change between the OVX and RG-treated groups. RG could not preserve trabecular bone volume, trabecular bone number, trabecular separation, trabecular thickness, structure model index, or bone mineral density of the proximal tibiae metaphysic. In conclusion, there was no definite effect of RG on OVX-induced bone loss in C3H/HeN mice.

Prolonged expression of senescence markers in mice exposed to gamma-irradiation

Although ionizing radiation is known to induce cellular senescence in vitro and in vivo, its long-term in vivo effects are not well defined. In this study, we examined the prolonged expression of senescence markers in mice irradiated with single or fractionated doses. C57BL/6 female mice were exposed to 5 Gy of gamma-rays in single or 5, 10, 25 fractions. At 2, 4, and 6 months after irradiation, senescence markers including mitochondrial DNA (mtDNA) common deletion, p21, and senescence-associated beta-galactosidase (SA beta-gal) were monitored in the lung, liver, and kidney. Increases of mtDNA deletion were detected in the lung, liver, and kidney of irradiated groups. p21 expression and SA beta-gal staining were also increased in the irradiated groups compared to the non-irradiated control group. Increases of senescence markers persisted up to 6 months after irradiation. Additionally, the extent of mtDNA deletion and the numbers of SA beta-gal positive cells were greater as the number of radiation fractions increased. In conclusion, our results showed that ionizing radiation, especially that delivered in fractions, can cause the persistent upregulation of senescence marker expression in vivo. This should be considered when dealing with chronic normal tissue injuries caused by radiation therapy or radiation accidents.

Morphometric Analysis of Tibial Bone in Three Strains of Mice Using Micro-computed Tomography / 한국실험동물학회지

This study investigated the trabecular and cortical bone microarchitecture of tibia in 14-week-old C3H/HeN, C57BL/6J and ICR mice using micro-computed tomography (micro-CT). Defined volumes of interest were scanned at a resolution of 17 micrometer (isotropic). The X-ray tube was set at photon energy of 50 kV, current of 200 microA, exposure time 1.2 sec, and a 0.5 mm-thick aluminium filter. For quantification of bone mineral density (BMD), the bone samples were scanned by micro-CT together with 2 calibration phantoms. The image slices were reconstructed using 3-dimensional CT analyzer software. C3H/HeN mice showed significantly higher levels of bone volume fraction, trabecular number and BMD, and lower levels of trabecular separation, structure model index and degree of anisotropy compared to C57BL/6J or ICR mice in trabecular bone area. So the C3H/HeN mouse appeared to be a good model animal for the study on the changes of trabecular bone with high trabecular bone mass.

Morphometric Analysis of Tibial Bone in Three Strains of Mice Using Micro-computed Tomography / 한국실험동물학회지

This study investigated the trabecular and cortical bone microarchitecture of tibia in 14-week-old C3H/HeN, C57BL/6J and ICR mice using micro-computed tomography (micro-CT). Defined volumes of interest were scanned at a resolution of 17 micrometer (isotropic). The X-ray tube was set at photon energy of 50 kV, current of 200 microA, exposure time 1.2 sec, and a 0.5 mm-thick aluminium filter. For quantification of bone mineral density (BMD), the bone samples were scanned by micro-CT together with 2 calibration phantoms. The image slices were reconstructed using 3-dimensional CT analyzer software. C3H/HeN mice showed significantly higher levels of bone volume fraction, trabecular number and BMD, and lower levels of trabecular separation, structure model index and degree of anisotropy compared to C57BL/6J or ICR mice in trabecular bone area. So the C3H/HeN mouse appeared to be a good model animal for the study on the changes of trabecular bone with high trabecular bone mass.