Isolation and Identification of Dihydrophenanthrene Derivatives from Dendrobium virgineum with Protective Effects against Hydrogen-Peroxide-Induced Oxidative Stress of Human Retinal Pigment Epithelium ARPE-19 Cells

Oxidative stress is a significant factor in the development of age-related macular degeneration (AMD), which results from cell damage, dysfunction, and death in the retinal pigmented epithelium (RPE). The use of natural compounds with antioxidant properties to protect RPE cells from oxidative stress has been explored in Dendrobium, a genus of orchid plants belonging to the family Orchidaceae. Two new compounds and seven known compounds from the MeOH extract of the whole plant of Dendrobium virgineum were successfully isolated and structurally characterized. Out of all the compounds isolated, 2-methoxy-9,10-dihydrophenanthrene-4,5-diol (3) showed the highest protective effect against hydrogen peroxide (H2O2)-induced oxidative stress in human retinal pigment epithelial (ARPE-19) cells. Therefore, it was selected to evaluate its protective effect and mechanism on oxidative-stress-induced ARPE-19 cells. Cells were pre-treated with compound 3 at 25, 50, and 100 µg/mL for 24 h and then induced with 400 µM H2O2 for 1 h. The results demonstrated that compound 3 significantly (p < 0.05) increased cell viability by 10–35%, decreased ROS production by 10–30%, and reduced phosphorylation of p38, ERK1/2, and SAPK/JNK by 20–70% in a dose-dependent manner without toxicity. Furthermore, compound 3 significantly (p < 0.05) modulated the expression of apoptosis pathway proteins (cytochrome c, Bax and Bcl-2) by 20–80%, and enhanced SOD, CAT, and GPX activities, and GSH levels in a dose-dependent manner. These results suggest that compound 3 protects ARPE-19 cells against oxidative stress through MAPKs and apoptosis pathways, including the antioxidant system. Thus, compound 3 could be considered as an antioxidant agent for preventing AMD development by protecting RPE cells from oxidative stress and maintaining the retina. These findings open up new possibilities for the use of natural compounds in the treatment of AMD and other oxidative-stress-related conditions

Physical activity and health related quality of life among the urban Thai elderly

This study investigated the association between types of physical activity and health related quality of nfe among the urban Thai elderly. A descriptive cross sectional design was guided by the Neuman Systems lVlodel A random sample of 350 elderly residing in the municipal area of Muang district, Chiang /v1ai Province, aged 60 years and over including men and women were recruited. Data were collected V'lith Physical Activity Scale for the Elderly (PASE) and Health Related Quality of Life Questionnaire then analyzed using multiple logistic regression analysis. IVlain findings demonstrated tha the high level of health related quality of life was associated with a high level of leisure time activity (aOR = 2.6, 95% CI = 1.3-4.9), a moderate level of leisure time activity (aOR = 2.1, 95%0 = 1.]-3.9), a high level of household activity (aOR =1.9, 95% Cf, 1.2-3.0)" and engaging in work related activity (except for work which involved mostly sitting and slight arm movement) (aOR = 1.9, 95% CI, 1.2-3.1) when controlling for the adequacy of income. The study suggests that household activity was an alternative strategy to enhance physical activity resulting the improvement health related quality of life among the urban Thai elderly

Atypical Pattern of Soil Carbon Stocks along the Slope Position in a Seasonally Dry Tropical Forest in Thailand

The pattern of soil carbon stock is atypical along the slope position in a seasonally dry tropical forest; the mean stock values increase from the lower, middle, to upper slopes, at 11.5, 13.2, and 15.5 kg m−2, respectively. In sloping landscapes, soil organic carbon tends to accumulate in lower slopes, but our previous soil respiration study suggested that soil carbon stock distribution along the slope position in seasonally dry tropical forests is atypical. The aims of this study were: (i) to examine whether the atypical pattern occurs widely in the watershed; and (ii) to examine the pattern of root development in the soil profile as a source of soil carbon. The density and stock of soil carbon in three soil layers (0⁻10, 10⁻30, and 30⁻100 cm) of 13 soil profiles were compared in different positions on the slope (upper, middle, and lower). Root biomass at each slope position was also determined. Soil carbon density in each layer increased significantly with an increase in the relative position of the slopes, particularly in the 10⁻30 cm soil layer. The density of medium root (3⁻10 mm in diameter) in the upper slopes was significantly higher than that in the middle and lower slopes, especially for 15⁻60 cm soil layers. The atypical pattern of soil carbon accumulation along the slope position occurred widely in the studied watershed and appeared to be caused by the development of root systems in deeply weathered soil under xeric soil conditions in the upper slopes. Roots of bamboo undergrowth may also contribute to soil carbon stabilization by reducing soil erosion in the surface soil

Multiple site tower flux and remote sensing comparisons of tropical forest dynamics in Monsoon Asia

The spatial and temporal dynamics of tropical forest functioning are poorly understood, partly attributed to a weak seasonality and high tree species diversity at the landscape scale. Recent neotropical rainforest studies with local tower flux measurements have revealed strong seasonal carbon fluxes that follow the availability of sunlight in intact forests, while in areas of forest disturbance, carbon fluxes more closely tracked seasonal water availability. These studies also showed a strong seasonal correspondence of satellite measures of greenness, using the Enhanced Vegetation Index (EVI) with ecosystem carbon fluxes in both intact and disturbed forests, which may enable larger scale extension of tower flux measurements. In this study, we investigated the seasonal patterns and relationships of local site tower flux measures of gross primary productivity (Pg) with independent Moderate Resolution Imaging Spectroradiometer (MODIS) satellite greenness measures across three Monsoon Asia tropical forest types, encompassing drought-deciduous, dry evergreen, and humid evergreen secondary tropical forests. In contrast to neotropical forests, the tropical forests of Monsoon Asia are more extensively degraded and heterogeneous due to intense land use pressures, and therefore, may exhibit unique seasonal patterns of ecosystem fluxes that are more likely water-limited and drought-susceptible. Our results show significant phenologic variability and response to moisture and light controls across the three tropical forest sites and at the regional scale. The drier tropical forests were primarily water-limited, while the wet evergreen secondary forest showed a slight positive trend with light availability. Satellite EVI greenness observations were generally synchronized and linearly related with seasonal and inter-annual tower flux Pg measurements at the multiple sites and provided better opportunities for tower extension of carbon fluxes than other satellite products, such as the MODIS Pg product. Satellite EVI-derived Pg images revealed strong seasonal variations in photosynthetic activity throughout the Monsoon Asia tropical region. © 2008 Elsevier B.V. All rights reserved

Multiple timescale variations and controls of soil respiration in a tropical dry dipterocarp forest, western Thailand

This study aims to improve our understanding of temporal variations and controlling factors of soil respiration (R-s) and its components (microbial respiration or R-m and root respiration or R-b) in an Asian tropical seasonal forest at diurnal, seasonal and annual timescales in relation to biotic and abiotic controls. R-s was studied by the trenching method in a seasonal dry diptercarp forest, western Thailand. An automated soil chamber system was used to produce hourly data of R-s during 2008-2011. Analysis of R-s in relation to both biotic and abiotic factors was carried out to understand its temporal variations at different timescales. R-m was the main contributor to overall magnitude and variability of R-s. Soil temperature alone was the main driver of diurnal variation, while the combination of soil moisture and soil temperature determined the seasonal variations. The amount of R-s was also related to the fine root (< 2 mm) and microbial biomass at seasonal timescales. Due to the small inter-annual variations in soil temperature and moisture, total soil respiration among the 4 years was not significantly different (p < 0.05). The annual totals for R-s during 2008-2011 were 3.20, 3.89, 3.52, 4.14 kgCO(2) m(-2) years(-1), respectively. The 4-year average ratio of R-m (trenched) to R-s (untrenched) was 66 +/- 4 %. R-m plays a crucial role in determining the magnitude (large ratio between R-m and R-s) and temporal variations of R-s. In this forest ecosystem, high seasonal variations in R-s were observed and were mainly attributed to the response of R-m to moisture