Galangin Activates the ERK/AKT-Driven Nrf2 Signaling Pathway to Increase the Level of Reduced Glutathione in Human Keratinocytes

Previously, we demonstrated that galangin (3,5,7-trihydroxyflavone) protects human keratinocytes against ultraviolet B (UVB)-induced oxidative damage. In this study, we investigated the effect of galangin on induction of antioxidant enzymes involved in synthesis of reduced glutathione (GSH), and investigated the associated upstream signaling cascades. By activating nuclear factor-erythroid 2-related factor (Nrf2), galangin treatment significantly increased expression of glutamate-cysteine ligase catalytic subunit (GCLC) and glutathione synthetase (GSS). This activation of Nrf2 depended on extracellular signal-regulated kinases (ERKs) and protein kinase B (AKT) signaling. Inhibition of GSH in galangin-treated cells attenuated the protective effect of galangin against the deleterious effects of UVB. Our results reveal that galangin protects human keratinocytes by activating ERK/AKT-Nrf2, leading to elevated expression of GSH-synthesizing enzymes.

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.

Effects of Galantamine Treatment on Attention, Activities of Daily Living, and Neuropsychiatric Symptoms between the Patients with Pure Alzheimer's Disease and Mixed Dementia

OBJECTIVES: The purpose of this study was to compare the efficacy of galantamine treatment, especially attention ability between patients with pure Alzheimer's disease (AD) and Mixed dementia (MD) during a 24-week trial. METHODS: A total of 40 patients were recruited for this 24-week study. The effect of galantamine on attention was measured using Seoul Computerized NeuroCognitive Function Test (SCNT) and frontal functions test of Seoul Neuropsychological Screening Battery (SNSB). Patients'activities of daily living using the Seoul-Activities of Daily Living (S-ADL) and the Seoul-Instrumental Activities of Daily Living (S-IADL) ; behavioral symptoms using the Korean version Neuropsychiatric Inventory (K-NPI) were measured at baseline and 24-week. RESULTS: 17 pure AD patients and 23 MD patients were analyzed in this study. Attention as measured by SCNT was not significantly different from baseline after 24 weeks of treatment in both groups. There was no significant difference between two groups in mean change from baseline in the SCNT, S-ADL, S-IADL and K-NPI scores at 24-week. CONCLUSION: Galantamine showed a therapeutic effect on cognition, activities of daily living, neuropsychiatric symptoms in pure AD and MD. Furthermore, Galantamine may specifically help to maintain attention and it may have positive effects on other cognitive and functional abilities.

Comparative Assessment of Clinical Efficacy after 12-Month Clinical Trial of Donepezil between the Patients with Pure Alzheimer's Disease and Mixed Dementia

OBJECTIVES: The purpose of this study was to compare the efficacy of donepezil treatment between patients with pure Alzheimer's disease (AD) and Mixed dementia (MD) during a 12-month trial. METHODS: A total of 139 patients were recruited for this 52-week study. The effect of donepezil on cognitive function was measured using Alzheimer's Disease Assessment Scale-cognitive subscale-preliminary Korean version (ADAS-cog-K). Patients' activities of daily living using the Seoul-Instrumental Activities of Daily Living (S-IADL) and Seoul-Activities of Daily Living (S-ADL);behavioral symptoms using the Korean version Neuropsychiatric Inventory (K-NPI) were measured at baseline, 13-weeks, 26-weeks, 39-weeks and 52-weeks. We defined the responsive patients to donepezil at those who showed a cognitive improvement or no change during the first six-month clinical trial. RESULTS: 84 pure AD patients and 34 MD patients were available for intent-to-treat (ITT) last observation carried forward (LOCF) analysis. There was no significant difference between two groups in mean change from baseline in the total ADAS-cog-k, S-ADL, S-IADL and K-NPI scores at 52-week. Based on the operational criteria, 60.7% of pure AD patients and 58.8% of MD patients were responders to donepezil. CONCLUSION: MD patients had similar levels of efficacy with pure AD patients and donepezil was well tolerated in both groups. These results suggest that donepezil is an effective and well-tolerated treatment for MD patients as well as for pure AD patients.

Comparative Assessment of Clinical Efficacy after 12-Month Clinical Trial of Donepezil between the Patients with Pure Alzheimer's Disease and Mixed Dementia

OBJECTIVES: The purpose of this study was to compare the efficacy of donepezil treatment between patients with pure Alzheimer's disease (AD) and Mixed dementia (MD) during a 12-month trial. METHODS: A total of 139 patients were recruited for this 52-week study. The effect of donepezil on cognitive function was measured using Alzheimer's Disease Assessment Scale-cognitive subscale-preliminary Korean version (ADAS-cog-K). Patients' activities of daily living using the Seoul-Instrumental Activities of Daily Living (S-IADL) and Seoul-Activities of Daily Living (S-ADL);behavioral symptoms using the Korean version Neuropsychiatric Inventory (K-NPI) were measured at baseline, 13-weeks, 26-weeks, 39-weeks and 52-weeks. We defined the responsive patients to donepezil at those who showed a cognitive improvement or no change during the first six-month clinical trial. RESULTS: 84 pure AD patients and 34 MD patients were available for intent-to-treat (ITT) last observation carried forward (LOCF) analysis. There was no significant difference between two groups in mean change from baseline in the total ADAS-cog-k, S-ADL, S-IADL and K-NPI scores at 52-week. Based on the operational criteria, 60.7% of pure AD patients and 58.8% of MD patients were responders to donepezil. CONCLUSION: MD patients had similar levels of efficacy with pure AD patients and donepezil was well tolerated in both groups. These results suggest that donepezil is an effective and well-tolerated treatment for MD patients as well as for pure AD patients.

Comparative Assessment of Clinical Efficacy between the Naive and the Switching Group to Donepezil: 12 Months Prospective Study

OBJECTIVES: The purpose of this study was to compare the efficacy between switching patients with Alzheimer's disease (AD) from galantamine or rivastigmine to donepezil because they were not responding adequately, and naive patients with AD who initiated therapy with donepezil. METHODS: A total of 108 patients were recruited for this 52-week study. The effect of donepezil on cognitive function was measured using Alzheimer's Disease Assessment Scale-cognitive subscale-preliminary Korean version (ADAS-cog-K). Patients' activities of daily living using Seoul-Activities of Daily Living (S-ADL) and the Seoul-Instrumental Activities of Daily Living (S-IADL);behavioral symptoms using the Korean version Neuropsychiatric Inventory (K-NPI) were measured at baseline, 13-weeks, 26-weeks, 39-weeks and 52-weeks. We defined the responsive patients to donepezil at those who showed a cognitive improvement or no change during the first six-month clinical trial. RESULTS: 86 naive patients and 22 switching patients were enrolled in the study. 74 patients completed the study and 34 discontinued their treatment before week 52. There was no significant difference between two patient groups in demographic data, baseline characteristics and dementia severity except duration of illness. The total ADAS-cog-K scores were not significantly different from baseline after 52 weeks of treatment in both groups. Both groups demonstrated deterioration of S-ADL and S-IADL at 52 weeks. The NPI scores did not significantly change in both groups. Based on the operational criteria, 61.6% of the naive group and 54.5% of the switching group were responders to donepezil. CONCLUSION: The switching group had similar levels of efficacy with the naive group who initiated therapy with donepezil. These results suggest that patients not responding adequately to rivastigmine or galantamine may improve or stabilize after switching to donepezil and prior medication does not effect donepezil's efficacy.