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In intensive agricultural watersheds, riverine particulate organic matter (POM) may be transported from many sources such as rice paddies, crop uplands, forests, and livestock farming areas during rainy seasons. However, the impacts of land-use and rainfall changes on the POM sources are not well understood. In this study, changes in the sources of riverine POM were investigated in an agricultural area of Korea between 2014 and 2020/21. During this period, land-use and rainfall patterns changed dramatically. The δ

Rice residue including root and straw are unique carbon (C) source in paddy soils. However, the potential changes in quantity and chemical composition of rice residue under co-elevated atmospheric CO2 concentration ([CO2]) and air temperature (Tair) and the legacy effect of the changed chemical composition on residue decomposition have not been investigated. This study was conducted to investigate biomass, chemical composition, and decomposability of rice root and straw produced under elevated [CO2] and Tair. Root and straw biomass increased by elevated [CO2] and elevated Tair, respectively, and the greatest biomass was achieved under co-elevated [CO2]-Tair for both root and straw. The concentration of lignin (recalcitrant) decreased while that of nonstructural carbohydrates (less recalcitrant) increased by co-elevated [CO2]-Tair. The ratio of lignin-to-nitrogen (lignin/N) decreased by co-elevated [CO2]-Tair compared to ambient [CO2]-Tair due to increased N and decreased lignin concentrations. Decomposability of root (lignin/N, 36.4) produced under co-elevated [CO2]-Tair was greater than that under ambient co-elevated [CO2]-Tair (lignin/N, 53.7); however, there was no difference in decomposability for straw, which had relatively narrow range of lignin/N (27.3–36.5) regardless of [CO2]-Tair conditions. The results of this study provide a novel insight into the changes in quantity and quality of rice residue under elevated [CO2]-Tair that are necessary to predict changes in paddy soil C sequestration under global warming.

The properties of secondary salt-affected soils developed from improper irrigation and drainage management and their effects on rice growth and yield are well documented. However, relevant informat...

Forest decline due to atmospheric pollution is a consequence of long-term chronic exposure, and thus chemical proxies that are sensitive to the pollution are helpful in estimating the impact of atmospheric pollution on forest health. In this study, we explored changes in the isotopic and elemental compositions of needles of red pine (Pinus densiflora) with varying precipitation pH and concentrations of NO2 and SO2 across 18 cities to identify isotopic and chemical signatures that are sensitive to acid deposition. The cities had different intensity of traffic and industrial activities, and thus were expected to have varying levels of atmospheric pollution. The pine needles were analyzed for carbon (δ13C) and nitrogen (δ15N) isotope ratios, N concentrations, C-to-N ratio (C/N), and calcium-to-aluminum ratio (Ca/Al). Analysis of variance, simple linear correlation, and redundancy analysis were used to investigate the variations in foliar chemistry with atmospheric variables. Neither NO2 nor SO2 concentration was correlated with foliar δ13C, δ15N, N concentration, and C/N; whereas precipitation pH was correlated with the foliar parameters, suggesting that foliar chemistry is more sensitive to total acidifying materials than to individual pollutant. The foliar δ13C decreased with lowered precipitation pH, reflecting the increased 13C-depleted CO2 that was co-emitted with acidifying materials from fossil fuel combustion. Foliar δ15N decreased and foliar N concentration increased with lowered precipitation pH, indicating tree uptake of 15N-depleted N from acid deposition. Accordingly, the C/N ratio also decreased with lowered precipitation pH. However, there was no relationship between foliar Ca/Al and precipitation pH; rather. Our result suggests that δ13C, δ15N, N concentration, and C/N of pine needle samples are associated with the level of precipitation pH and thus pine needles could be used as bio-indicators of the impacts of total acidifying pollutants on forest.

Elevated atmospheric CO2 concentration ([CO2]) may change litter chemistry which affects litter decomposability. This study investigated respiration and microbial biomass of soils amended with litter of Pinus densiflora (a coniferous species; pine) and Quercus variabilis (a deciduous species; oak) that were grown under different atmospheric [CO2] and thus had different chemistry. Elevated [CO2] increased lignin/N through increased lignin concentration and decreased N concentration. The CO2 emission from the soils amended with litter produced under the same [CO2] regime was greater for oak than pine litter, confirming that broadleaf litter with lower lignin decomposes faster than needle leaf litter. Within each species, however, soils amended with high lignin/N litter grown under elevated [CO2] emitted more CO2 than those with low lignin/N litter grown under ambient [CO2]. Such contrasting effects of lignin/N on inter- and intra-species variations in litter decomposition should be ascribed to the effects of other litter chemistry variables including nonstructural carbohydrate, calcium and manganese as well as inhibitory effect of N on lignin decomposition. The microbial biomass was also higher in the soils amended with high lignin/N litter than those with low lignin/N litter probably due to low substrate use efficiency of lignin by microbes. Our study suggests that elevated [CO2] increases lignin/N for both species, but increased lignin/N does not always reduce soil respiration and microbial biomass. Further study investigating a variety of tree species is required for more comprehensive understanding of inter- and intra-species variations of litter decomposition under elevated [CO2].

The effects of increased nitrogen (N) availability through atmospheric deposition on the quantity and quality of tree leaf litter have been widely reported. However, such N effects under co-elevated CO2 concentration ([CO2]) and air temperature (Tair) have not been investigated. In this study, changes in biomass and chemistry of litter of Pinus densiflora S. et Z. (pine) and Quercus variabilis Blume (oak) saplings with two levels of each N × [CO2] × Tair were investigated for two growing seasons. The levels of N, [CO2], and Tair were 2 and 6-fold of ambient N deposition, ambient and ambient + 285 ppmv, and ambient and ambient + 2.2 °C, respectively, on average across the two seasons. The concentrations of N, minerals, and carbon (C) compounds such as non-structural carbohydrate (NSC) and lignin as well as stoichiometry such as the ratio of C to N (C/N) and lignin to N (lignin/N) of litter were analyzed to determine litter chemistry. In addition, the legacy effect of changed chemistry on microbial decomposability of the litters were also assessed by measuring CO2 emission in a 60-day lab incubation experiment. The effect of high N addition on increasing litter production was consistent regardless of [CO2] and Tair for oak; however, for pine, N-induced increases in litter production were negated under elevated [CO2] and/or Tair, probably due to efficient uptake and use of N by pine under elevated [CO2] as well as lowered N demand via warming-induced stress under elevated Tair. High N-induced decreases in C/N and lignin/N was consistent across [CO2]-Tair combination for both species though other chemical components such as NSC and minerals including phosphorous, calcium, aluminum, and manganese varied inconsistently. The CO2 emission from the soils amended with litters of different chemistry was not correlated with litter chemistry, suggesting that changed litter chemistry under different N level × [CO2] × Tair may not affect litter decomposability in the soils. This study enlarges our understanding of the effect of increased N availability on litter quantity, chemical composition, and microbial decomposability under different [CO2] and Tair. However, a study with mature trees in a natural forest stand should further improve our understanding.

To better predict forest productivity under rising atmospheric CO 2 concentration ([CO 2 ]), it is critical to understand how intrinsic water-use efficiency (WUE i ) and its relationship with tree growth are affected by the concomitant changes in environmental conditions such as precipitation, temperature, and air pollution that either enhance or undermine any potential CO 2 fertilization effect. We investigated changes in δ 13 C and WUE i in annual rings and basal area increment (BAI) of Pinus densiflora (from 1968 to 2007) and Quercus variabilis (from 1970 to 2007) trees in relation to precipitation, temperature, and air pollution in a humid temperate forest. The WUE i of P. densiflora increased by 39.9%, whereas that of Q. variabilis did not change over time in the study period. The WUE i was not affected by precipitation for both species but increased ( P P. densiflora and with SO 2 emissions for both species. Multiple regression models suggested that the effect of [CO 2 ] on tree growth was much higher than temperature; however, for the period (1998 to 2007) when SO 2 emissions data were available, SO 2 emission was the driver of changes in BAI and WUE i , and temperature effects became stronger than [CO 2 ]. Overall, BAI and WUE i were positively ( P P. densiflora , but not for Q. variabilis . We conclude that temperature and air pollution rather than precipitation were key determinants of WUE i at the study site and that the two species had contrasting responses to environmental changes.

Elevated CO2 concentration ([CO2]) and air temperature (Tair) as well as changed soil water availability (Wsoil) may affect quantity, chemistry, and microbial decomposability of tree leaf litter. However, our understanding is limited mainly to the effect of elevated [CO2]. This study investigated the effects of elevated [CO2] and Tair in combination with two Wsoil regimes on the quantity and chemistry including the ratio of lignin to nitrogen (lignin/N) of litter produced by Pinus densiflora and Quercus variabilis saplings, and microbial respiration of the soils amended with the litters. Either elevated [CO2] or high Wsoil alone increased litter production; meanwhile elevated Tair alone decreased litter production. However, co-elevation of [CO2] and Tair did not change litter production regardless of Wsoil regime for both species. Among litter chemistry, the lignin/N, which is a robust indicator of litter decomposability, of litter was changed in parallel with litter quantity (i.e., lignin/N ratio increased when litter quantity increased and vice versa) mainly due to dilution of N. Due to the opposite effect of warming and elevated [CO2] on litter quantity, lignin/N was not changed under co-elevated [CO2] and Tair at a given Wsoil regime for both species. Other litter chemistry including non-structural carbohydrates and minerals was also affected by [CO2], Tair, or Wsoil. However, changed litter chemistry did not change the CO2 emission from the soils amended with the litters; however, addition of litter with low lignin/N and high nutrients increased microbial biomass in the soil. This study enlarges our understanding of the effects of changed climatic variables on litter quantity, chemistry, and microbial decomposability and suggests that co-elevation of [CO2] and Tair may not cause a significant change in the litter parameters regardless of Wsoil. Study with mature trees at a natural forest should further improve our understanding.

Despite the ability of fly ash (FA) to remove phosphorus (P) from water via sorption and precipitation, its use as a bedding material for planted floats has never been evaluated. This study was conducted to investigate the effects of FA on P removal and chlorophyll-a (an indicator of algal growth) reduction in P-contaminated water. Six different FA rates (0, 2.5, 5, 10, 25, and 50 w/w%; codes are FA0, FA2.5, FA5, FA10, FA25, and FA50, respectively) and two rice (Oryza sativa L.) treatments (unplanted and planted) were investigated. The floats containing FA were placed on P-enriched (4 mg P L−1) baths. Water samples were collected periodically and analyzed for the concentrations of total P (TP), soluble P (SP), and chlorophyll-a. Both SP and TP decreased (P

Waterlogged paddy and water-unsaturated upland ecosystems have contrasting soil nitrogen (N) processes that affect the natural 15N abundance (15N/14N, expressed as δ15N) in different N pools. In this study, we investigated the δ15N patterns in soil and plant N pools of paddy and upland ecosystems. Samples were collected from 20 each of paddy and upland fields at the active growing season and analyzed for N concentration and δ15N. The higher (P

Understanding Spatial Variations of Water Quality Using Agricultural Nutrient Indices in Chonnam Province Byeong-Jun Jeon, Sang-Sun Lim, Kwang-Seung Lee, Se-In Lee, Jong-Hyun Ham, Sun-Ho Yoo, Kwang-Sik Yoon and Woo-Jung Choi (Department of Rural & Biosystems Engineering, Chonnam National University, Gwangju 500-757, Korea, Department of Agricultural Biotechnology, Seoul National University, Seoul 151-921, Korea)

Historical growth response of Quercus variabilis, which is the most important deciduous timber species in Korea, was investigated using the width and C isotope ratio (13C/12C denoted as δ13C) of the annual ring from 1975 to 2007. Tree disks were collected from three Q. variabilis trees with different growth statuses from a site in the Mt. Naejang area, and analyzed for annual ring width and δ13C. Basal area increment (BAI) of the annual ring was calculated from the width data, and carbon isotope discrimination (Δ) was calculated using δ13C. The intercorrelations among BAI, Δ, and environmental variables were explored. The BAI was positively (p

Only limited information is available in the research area on the effect of elevated CO2 concentration ([CO2]) and air temperature (Tair) on the fertilizer N uptake by rice. This study was conducted to investigate changes in rice uptake of N derived from fertilizer (NDFF) and soil (NDFS) as well as fertilizer N uptake efficiency (FUE) with elevated [CO2] and Tair in two soils with different fertility. Rice (Oryza sativa L.) plants were grown with 15N-urea for two growing seasons (2007 in the less fertile and 2008 in the more fertile soil) in temperature gradient chambers under two (ambient and elevated) levels of [CO2] and Tair regimes. At harvest, dry matter (DM) and N uptake amount of rice compartments (root, shoot, and grain) were determined. The DM of whole rice increased (P

Despite the importance of dissolved organic N (DON) in wet precipitation, the N isotope ratio (δ 15 N) of DON has rarely been reported when compared to those of inorganic N (NH 4 + and NO 3 − ). This study was conducted to investigate seasonal variation of δ 15 N of DON in comparison with the δ 15 N of NH 4 + and NO 3 − during wet precipitation in a metropolis area that is surrounded by agricultural areas in southern Korea. For two years (2007 and 2008), all effective precipitation events (>5 mm) were collected and the δ 15 N of NH 4 + , NO 3 − , DON, and total N were analyzed, and the volume-weighted monthly mean N deposition and δ 15 N were calculated. The contribution of DON to total N deposition (41.0 and 37.3% in 2007 and 2008, respectively) was compatible to that of NH 4 + and two times higher than that of NO 3 − . The annual mean δ 15 N of DON (0.3 and 0.2‰ in 2007 and 2008, respectively) was higher than that of NH 4 + (−3.0 and −6.8‰, respectively) but similar to that of NO 3 − (1.5 and −0.5‰, respectively). The seasonal pattern of molar ratio of NH 4 + /NO 3 − in combination with δ 15 N of NH 4 + and NO 3 − indicated that there were multiple diffuse sources of N deposition presented and seasonal shifting of main sources of N deposition occurred in the study site. These sources included fertilized agricultural fields in the spring and early summer, livestock excrements in the middle summer and fall, and coal-fired boilers in the winter. The intimate relationship between DON and NH 4 + in terms of % portion in total N and their δ 15 N suggested that the source of DON was closely coupled with that of NH 4 + ; e.g. fertilizer and livestock excretion. A direct measurement of N species emitted from fertilized agricultural field and livestock manure is necessary to confirm the source of DON.

Fly ash can reduce CO2 emission from soils via biochemical (i.e., inhibition of microbial activity) and physicochemical (i.e., carbonation) mechanisms. This study investigated the effects of fly ash amendment on biochemical and physicochemical reduction in CO2 emission from normal and saline soils. The physicochemical mechanisms of reduction in CO2 emission by fly ash were estimated in a batch experiment with carbonate solution as a CO2 source by the scanning electron microscope (SEM) and inductively coupled plasma analyses. Biochemical mechanisms of reduction in CO2 emission by fly ash were investigated in a 3-day laboratory incubation experiment with normal and saline soils in the absence and presence of fly ash. Finally, the effects of fly ash amendment at a variety rate from 2 to 15 % (w/w) on CO2 emission from normal and saline soils in the presence of additional organic carbon source (glucose) were investigated through a 15-day laboratory incubation study. In the batch experiment with carbonate solution, both the SEM image of fly ash and changes in soluble Ca and Mg concentrations during reaction with carbonate suggested that the formation of CaCO3 and MgCO3 via carbonation was the principal physicochemical mechanism of carbonate removal by fly ash. In the 3-day incubation study conducted to examine biochemical mechanisms of reduction in CO2 emission by fly ash, microbial respiration of saline soil was inhibited (P

Soil acidification is known to be one of the constraints of tree growth; however, it is unclear how it affects tree growth at photosynthesis level (i.e., through affecting stomatal conductance vs. carboxylation rate) during the growth of trees. This paper studied the effects of soil acidification on Pinus densiflora foliar chemistry and tree ring C isotope ratio (13C/12C, expressed as δ13C) and their relationship with tree growth. Tree growth (diameter, annual growth ring area, and root biomass), soil chemistry (pH, mineral N, and exchangeable Ca and Al), foliage chemistry (N, Ca/Al, and δ13C), and tree ring δ13C in P. densiflora stands along a soil pH gradient (from 4.38 to 4.83, n = 9) in southern Korea were investigated. Overall, trees with relatively poor growth under more acidic soil conditions (low pH and Ca/Al) had lower values of foliar N concentration and δ13C and tree ring δ13C, suggesting that restricted N uptake under more acidic soil conditions caused N limitation for photosynthesis, leading to poor tree growth. In addition, relationships between mean annual area increment and carbon isotope discrimination of tree rings at five-yr intervals from 1968 to 2007 revealed that the impact of soil acidification on tree growth became severer during the last 15 yrs as negative correlations between them became significant after 1993. Reduced N uptake under acidic soil conditions resulted in lower radial growth of P. densiflora via non-stomatal limitation of photosynthesis.

Purpose Since substrate quality can influence the C mineralization pattern of compost in soils, proper selection of compost is important in increasing soil organic carbon (SOC) levels. This study investigated the effect of substrate quality of livestock manure composts on compost C mineralization and retention in soils.

BACKGROUND: Soil acidification, which is known to be one of the reasons of forest decline, is associated with decreases in exchangeable Ca and increases in Al concentration, leading to low Ca/Al ratio in soil solution. As tree rings are datable archives of environmental changes, Ca/Al ratios of annual growth ring may show decreasing pattern in accordance with the progress of soil acidification. This study was conducted to investigate Ca/Al pattern of Pinus densiflora tree ring in an attempt to test its usefulness as an indicator of historical soil acidification. METHODS AND RESULTS: Three P. densiflora tree disks were collected from P. densiflora forests in Jeonnam province, and soil samples (0-10, 10-20, and 20-30 cm in depth) were also collected from the tree locations. Soils were analyzed for pH and exchangeable Ca and Al concentrations, and Ca/Al was calculated. Annual growth rings formed between 1969 and 2007 were separated and analyzed for Ca/Al. Soil Ca/Al was positively (P

BACKGROUND: Application of urea may increase CO2 emission from soils due both to CO2 generation from urea hydrolysis and fertilizer-induced decomposition of soil organic carbon (SOC). The objective of this study was to investigate the effects of increasing urea application on CO2 emission from soil and mineralization kinetics of indigenous SOC. METHODS AND RESULTS: Emission of CO2 from a soil amended with four different rates (0, 175, 350, and 700 mg N/kg soil) of urea was investigated in a laboratory incubation experiment for 110 days. Cumulative CO2 emission (Ccum) was linearly increased with urea application rate due primarily to the contribution of urea-C through hydrolysis to total CO2 emission. First-order kinetics parameters (C0, mineralizable SOC pool size; k, mineralization rate) became greater with increasing urea application rate; C0 increased from 665.1 to 780.3 mg C/kg and k from 0.024 to 0.069 day -1 , determinately showing fertilizer-induced SOC mineralization. The relationship of C0 (non-linear) and k (linear) with urea-N application rate revealed different responses of C0 and k to increasing rate of fertilizer N. CONCLUSION(s): The relationship of mineralizable SOC pool size and mineralization rate with urea-N application rate suggested that increasing N fertilization may accelerate decomposition of readily decomposable SOC; however, it may not always stimulate decomposition of non-readily decomposable SOC that is protected from microbial

A lipid-soluble ginseng extract possesses an anticancer activity against advanced human lung tumors in an established murine xenograft model without any sign of toxicity. The extract also shows a potent anti-proliferative activity against human cancer cell lines, leading to expansion of its preclinical applications to specific human tumor types.

The present investigation was conducted to evaluate the regulation of sleep architecture by the red ginseng water extract (RGE) in acutely and chronically restraint stressed rats. Adult rats were fitted with sleep-wake recording electrodes. Following post-surgical recovery, rats were extensively habituated for freely moving polygraphic recording conditions. Polygraphic signs of sleep-wake activities were recorded for 24 h after RGE administration and induction of stress and were analyzed to understand the regulation of sleep architecture. Acute stress decreased wakefulness and increased total sleep, non-rapid eye movement (NREM) sleep, and rapid eye movement (REM) sleep in both the daytime and nighttime recording. RGE shortened the daytime NREM and REM sleep, without changing the wakefulness and total sleep. RGE increased nighttime wakefulness, and decreased total, NREM and REM sleep. Chronic stress increased wakefulness and decreased total sleep in the daytime recording, and increased REM and decreased NREM sleep in both the day and night time recording. RGE ameliorated chronic stress and induced alterations of REM and NREM sleep in the day and night time sleep architecture. Acute and chronic stress could also induce alternations in cortex electroencephalogram (EEG) recording during NREM, REM sleep and wakefulness. These findings suggest that RGE may modulate the sleep behavior in acutely and chronically stressed rats and the ameliorating effect of RGE on the sleep architecture may involve in modulation of α-, θ- and δ- wave activities of the cortical EEG.

Lipid-soluble ginseng extract was prepared by n-hexane extraction of red ginseng. BALB/c-nu mice were inoculated with human lung cancer (NCI-H460) cells to establish a human tumor xenograft model in nude mice, and the lipid-soluble ginseng extract was orally administered. The tumor inhibitory rates of the lipid-soluble ginseng extract at doses of 0.1, 0.3, and 1.0 g/kg/day were 18.9% (P

Two types of sequential extraction process (SEP) for the recovery of bioactive components from Korean red ginseng were examined. As a SEP (normal SEP, nSEP), Korean red ginseng was sequentially treated using hot water and n-hexane for the successive extraction of water-soluble and lipid-soluble components. Also by changing the sequential order of solvents, an alternative SEP (reverse SEP, rSEP) in which n-hexane extraction was followed by hot water extraction, was proposed. Regardless of the sequential order of solvents, the recovery yield of acidic polysaccharide (AP) and crude saponin (CS) showed no significant change. On the other hand, in the rSEP, the lipid-soluble fraction was obtained from red ginseng with an enhanced recovery yield, four times higher than that in nSEP. Additionally, from dose-response assays to assess the effects of lipid-soluble components on the proliferation of human hepatoma (HepG2) and breast (MCF-7) cancer cell lines, it was found that hexane extract of red ginseng (HER) in rSEP has higher efficacy than the hexane extract of red ginseng marc (HERM) obtained in nSEP. This strongly suggested that rSEP would be a more attractive industrial process in terms of the efficacy of lipid-soluble extract as well as the recovery yield.

An orifice type of aerodynamic lens is generally used to focus nanoparticles. However, it is impossible to focus particles smaller than 10nm in air due to flow instability of fluid in a lens. In this study, we propose a new converging-diverging type of the aerodynamic lens capable of focusing particles of 5-50nm in air. Designing factors of the lens configurations is also extracted and explained in detail through a numerical simulation. It was demonstrated that the aerosols are delivered from the entrance to the downstream of the lens system with 90% transmission efficiency. The final beam diameters are shown to be more or less 1mm in the range of particle size.

Despite lack of scientific evidences to support its therapeutic efficacy, the use of herbal supplements has significantly increased. The purpose of this study was to evaluate the effects of traditional anti-diabetic herbs on the progress of diabetes in db/db mice, a typical non-insulin-dependent model. Five different experimental diets were as follows: control diet, 0.5% mulberry leaf water extract diet, 0.5% Korean red ginseng diet, 0.5% banaba leaf water extract diet, and 0.5% combination diet (mulberry leaf water extract/Korean red ginseng/banaba leaf water extract, 1:1:1). Blood levels of glucose, insulin, HbA1c, and triglyceride were measured every 2 weeks. At 12 weeks of age, animals were sacrificed, and tissue mRNA levels of PPAR-alpha, PPAR-gamma, and LPL were determined. Results indicated that mulberry leaf water extract, Korean red ginseng, banaba leaf water extract, and the combination of above herbs effectively reduced blood glucose, insulin, TG, and percent HbA1c in study animals (p

The growth temperature dependence of strain in ZnSe epilayers on (1 0 0) GaAs substrates was investigated. The strain effect was confirmed using high-resolution X-ray diffraction, Raman scattering and photoluminescence. With the increasing growth temperature, the lattice constant decreased and the Raman frequency red-shifted. Also, the near band-edge emission peak energy decreased and the energy difference between the heavy hole- and the light hole-free exciton peak increased a little. This is well explained by the thermal tensile strain remaining in the epilayer.

Zn 1 x Mn x Te epilayers have been grown on GaAs (1 0 0) substrates by hot-wall epitaxy. The structure of the epilayers was found to be zincblende over the whole range of the composition. The lattice parameters and the compositions were determined with double crystal rocking curves. Exciton-related near-edge emissions were observed in the 10 K photoluminescence spectrum without an external magnetic field. The peak energy of the edge emission increased linearly with increasing Mn composition up to 60%. The intra-ion transition emissions were observed in high Mn composition epilayers and the transition energy did not depend on the Mn composition.

Fractionation of a ginseng source to produce differences in the ginsenoside profile might influence its effect on postprandial glycemia. To explore this possibility and identify an efficacious ginseng for a longterm study, we conducted a preparation-finding study of different Korean red ginseng (KRG) root fractions followed by a dose-finding study of the most efficacious fraction.A double-blind, randomized, within-subject design was used in both studies. In the preparation-finding study, 7 healthy subjects (sex: 3m:4f, age: 32 +/- 4 y, BMI: 24 +/- 2 kg/m2) received 6 g placebo and KRG-rootlets, -body, and -H2O extract 40 min before a 50 g-OGTT with finger-prick blood samples at -40-, 0-, 15-, 30-, 45-, 60-, 90-, 120-min. In the dose-finding study, 12 healthy subjects (sex: 9M,3F, age: 29 +/- 3 y, BMI: 22.5 +/- 1 kg/m2) received 0 g (placebo), 2 g, 4 g, and 6 g of the most efficacious root fraction following the same protocol. Ginsenosides were analyzed using HPLC-UV.In the preparation-finding study, a wide variation in the ginsenoside profiles was achieved across the 3 KRG fractions. This variation coincided with differential effects. The main effects of KRG-rootlets (p = 0.050) and time (p0.001) and their interaction (p0.1) were significant. This was reflected in a 29% reduction in area under the curve (AUC) by KRG-rootlets compared with placebo (p = 0.052). Conversely, neither KRG-H2O extract nor KRG-body affected glycemia. Stepwise-multiple regression models identified Rg1 as the sole predictor of mean- and AUC postprandial blood glucose. In the dose-finding study, KRG-rootlets were tested as the most efficacious fraction. A significant effect of KRG-rootlets treatment (mean of 3 doses) but not dose was found. The mean of 3 doses decreased AUC by 17% compared with placebo (p = 0.057).Together the studies indicate 2 g KRG-rootlets is sufficient to achieve reproducible reductions in postprandial glycemia. But the longterm sustainability of KRG selected using this approach remains to be tested.

Background and aim To address the paucity of randomized clinical studies assessing ginseng on long-term outcomes in type 2 diabetes, we assessed the clinical antidiabetic efficacy and safety of 12weeks of supplementation with a Korean red ginseng (KRG) preparation, dose, and mode of administration, selected from an acute, clinical, screening model. Methods and results Nineteen participants with well-controlled type 2 diabetes (sex: 11 M:8 F, age: 64±2years, BMI: 28.9±1.4kg/m 2 , HbA 1c : 6.5%) completed the study. Using a double-blind, randomized, crossover design, each participant received the selected KRG preparation (rootlets) and placebo at the selected dose (2g/meal=6g/day) and mode of administration (preprandial oral agent [−40min]) for 12weeks as an adjunct to their usual anti-diabetic therapy (diet and/or medications). Outcomes included measures of efficacy (HbA 1c and fasting- and 75-g oral glucose tolerance test [OGTT]-plasma glucose [PG], plasma insulin [PI], and insulin sensitivity index [ISI] indices); safety (liver, kidney, haemostatic, and blood-pressure function); and compliance (returned capsules, diet-records, and body-weight). There was no change in the primary endpoint, HbA 1c . The participants, however, remained well-controlled (HbA 1c =6.5%) throughout. The selected KRG treatment also decreased 75g-OGTT-PG indices by 8–11% and fasting-PI and 75g-OGTT-PI indices by 33–38% and increased fasting-ISI (homeostasis model assessment [HOMA]) and 75g-OGTT-ISI by 33%, compared with placebo ( P Conclusions Although clinical efficacy, as assessed by HbA 1c , was not demonstrated, 12weeks of supplementation with the selected KRG treatment maintained good glycemic control and improved PG and PI regulation safely beyond usual therapy in people with well-controlled type 2 diabetes. Further investigation with similarly selected KRG treatments may yield clinical efficacy.