Placoisoflavones A and B, two new cytotoxic isoflavonoids from Placolobium vietnamense N.D.Khôi & Yakovlev.

Two previously unreported isoflavonoids, placoisoflavones A and B (1 and 2), along with five known compounds, calopogonium isoflavone B (3), jamaicin (4), 6-methoxycalopogonium isoflavone A (5), vestitol (6), and caviunin (7) have been isolated from the stems of Placolobium vietnamense N.D.Khôi & Yakovlev. The structures of all isolated compounds were fully characterized using spectroscopic data and comparison with the previous literature. The cytotoxicity of all isolated compounds was evaluated against HepG2 cell line, and compound 1 showed the most potent cytotoxicity with an IC50 value of 8.0 µM.

Optimization and validation of an extraction method for the analysis of multi-class emerging contaminants in soil and sediment.

Analytical methods for the determination of multi-class emerging contaminants are limited for soil and sediment while they are essential to provide a more complete picture of their distribution in the environment and to understand their fate in different environmental compartments. In this paper, we present the development and optimization of an analytical strategy that combines reliable extraction, purification and the analysis using ultra-pressure liquid chromatography triple quadrupole mass spectrometry (UPLC-MS/MS) of 90 emerging organic contaminants including pesticides, pharmaceuticals and personal care products, flame retardants, per- and polyfluoroalkyl substances (PFASs) and plasticizers in soil and sediment. To extract a wide range of chemicals, the extraction strategy is based on the QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) approach. A number of different options were investigated (buffer, acidification, addition of EDTA, different types and combinations of dispersive SPE etc.) and the effectiveness of the chemical extraction procedure and the clean-up was assessed for two matrices: soil (organic matter content of 9%) and sediment (organic matter content of 1.9%). The method was fully validated for both matrices, in terms of accuracy, linearity, repeatability (intra-day), reproducibility (inter-day), method limits of detection and quantification (LODs and MLOQs, respectively). The final performance showed good accuracy and precision (mean recoveries were between 70 and 120% with relative standard deviations (RSD) less than 20% in most cases), low matrix effects, good linearity for the matrix-matched calibration curve (R2≥0.991) and MLOQs ranged from 0.25 and 10 µg/kg. To demonstrate the applicability and suitability of the validated method, soil and sediment samples from Vietnam, France, Sweden and Mexico were analyzed. The results showed that of the 90 target compounds, a total of 33 were quantified in the sediment and soil samples analyzed. In addition to multi-target analysis, this strategy could be suitable for non-target screening, to provide a more comprehensive view of the contaminants present in the samples.

Energy crop as an environmentally sustainable reclamation option for post-mining sites: a life cycle assessment of cassava planting in Vietnam.

Using post-mining areas for planting energy crops has emerged as a promising and sustainable reclamation solution due to its potential contributions to environmental protection, land restoration, and especially energy security. However, to ensure the sustainability of this reclamation solution, its environmental performance needs to be thoroughly assessed case by case. Located in Ha Thuong Commune, Dai Tu District, Thai Nguyen Province in northern Vietnam, Nui Phao is the world's largest tungsten mine. To restore post-mining sites at Nui Phao, cassava planting for ethanol production was one of the proposed measures. To support the decision-making, this study employs life cycle assessment to thoroughly evaluate the environmental performance and potential environmental benefits/costs of cassava-based reclamation system in terms of resource consumption and green house gas (GHG) emission. The results show that cassava-based reclamation might bring significant environmental benefits in terms of fossil fuel saving and GHGs reduction (i.e., reduce 50% fossil fuel consumption and 36% GHGs emission); however, it does not bring any benefit in terms of water and land resource consumption. Moreover, the results define cassava cultivation as the "hot spot" of the system, where innovations to enhance the yield and reduce water and fertilizer consumption are required to improve the environmental performance of the cassava-based reclamation system.

Phytoplankton characterization in a tropical tidal river impacted by a megacity: the case of the Saigon River (Southern Vietnam).

The spatiotemporal variation of phytoplankton and their relationship with environmental variables were analyzed in the Saigon River-a tropical river in Southern Vietnam. Two longitudinal profiles were conducted during dry and rainy season at 18 sampling sites covering more than 60 km long in the river. Besides, a bi-weekly monitoring conducted in the upstream, urban area (Ho Chi Minh City-HCMC), and downstream of Saigon River was organized from December 2016 to November 2017. The major phytoplankton were diatoms (e.g., Cyclotella cf. meneghiniana, Leptocylindrus danicus, Aulacoseira granulata), cyanobacteria (Microcystis spp., Raphidiopsis raciborskii, Pseudanabaena sp.), and euglenoids (Trachelomonas volvocina). Commonly freshwater phytoplankton species and sometimes brackish water species were dominant during the monitoring. Phytoplankton abundances in dry season were much higher than in rainy season (>100 times) which was explained by a shorter riverine water residence time and higher flushing capacity during the dry season. There was a clear separation of phytoplankton abundance between the urban area and the remaining area of Saigon River because of polluted urban emissions of HCMC. Redundancy analysis shows that the environmental variables (TOC, nitrogen, pH, salinity, Mo, Mn) were the driving factors related to the dominance of L. danicus and Cyclotella cf. meneghiniana in the upstream river and urban section of Saigon River. The dominance of cyanobacterium Microcystis spp. in the downstream of Saigon River was related to higher salinity, Mg, Cu concentrations, and lower concentrations of nutrients, Mn, Co, and Mo. The dominance of potentially toxic cyanobacteria in Saigon River possesses health risk to local residents especially upon the increasing temperature context and nutrient loading into the river in the next decades.

Bougainvinones NP, three new flavonoids from Bougainvillea spectabilis.

In an effort to identify natural bioactive compounds, three new flavonoids (1-3) and six known compounds (4-9) were isolated from the stem bark of Bougainvillea spectabilis. The structures of these compounds were accomplished using comprehensive spectroscopic methods, including 1D and 2D NMR spectra with references to the literatures, as well as high-resolution mass spectrometric analysis. Their cytotoxicity against KB and HeLa S-3 cell lines was also evaluated.

Nutrient dynamics and eutrophication assessment in the tropical river system of Saigon - Dongnai (southern Vietnam).

Saigon-Dongnai Rivers in Southern Vietnam is a complex lowland hydrological network of tributaries that is strongly influenced by the tidal cycles. The increasing economic, industrial and domestic developments in and around Ho Chi Minh City (HCMC) have led to serious impacts on water quality due to lack of appropriate wastewaters treatment. Drinking water production is impacted and the large aquaculture production areas may also be affected. We analyzed spatial and seasonal variability of nutrient concentrations (Phosphorus, Nitrogen and Silica) and eutrophication indicators (Organic Carbon, Chlorophyll-a and Dissolved Oxygen) based on bi-monthly monitoring during two hydrological cycles (July 2015-December 2017). Four monitoring sites were selected to assess the impact of HCMC: two upstream stations on the Saigon River and Dongnai River branches to provide the reference water quality status before reaching the urbanized area of HCMC; one monitoring station in the city center to highlight Saigon River water quality within the heart of the megacity; the fourth station downstream of the confluence to evaluate the impact of HCMC on the estuarine waters. This study points to excess nutrients in HCMC's water body with concentrations of NH4+ and PO43- averaging to 0.7 ±â€¯0.6 mgN L-1 and 0.07 ±â€¯0.06 mgP L-1, respectively in mean over the monitored period and rising up to 3 mgN L-1 and 0.2 mgP L-1, in extreme conditions. During the dry season, we evidenced that untreated domestic discharges leads to degradation of the Saigon River's water quality with extreme values of algal biomass (up 150 µChl-a L-1) and hypoxic conditions occurring episodically (DO < 2 mg L-1) in the heart of the megacity. Until now, eutrophication in the urban center has had no clear effect downstream because eutrophic water mass from the Saigon River is efficiently mixed with the Dongnai River and sea water masses during the successive semi-diurnal tidal cycles.

Cytotoxic Flavones from the Stem Bark of Bougainvillea spectabilis Willd.

Five new flavones possessing a fully substituted A-ring with C-6 and C-8 methyl groups, bougainvinones I - M (1: -5: ), along with three known congeners, 2'-hydroxydemethoxymatteucinol (6: ), 5,7,3',4'-tetrahydroxy-3-methoxy-6,8-dimethylflavone (7: ) and 5,7,4'-trihydroxy-3-methoxy-6,8-dimethylflavone (8: ), were isolated from the EtOAc extract of the stem bark of Bougainvillea spectabilis. Their structures were established by means of spectroscopic data (ultraviolet, infrared, high-resolution electrospray ionization mass spectrometry, and one-dimensional and two-dimensional nuclear magnetic resonance) and single-crystal X-ray crystallographic analysis. The in vitro cytotoxicity of all isolated compounds against five cancer cell lines (KB, HeLa S-3, MCF-7, HT-29, and HepG2) was evaluated. Compound 5: showed promising cytotoxic activity against the KB and HeLa S-3 cell lines, with IC50 values of 7.44 and 6.68 µM. The other compounds exhibited moderate cytotoxicity against the KB cell line.

Molecular Characterization of Resistance to Soybean Rust (Phakopsora pachyrhizi Syd. & Syd.) in Soybean Cultivar DT 2000 (PI 635999).

Resistance to soybean rust (SBR), caused by Phakopsora pachyrhizi Syd. & Syd., has been identified in many soybean germplasm accessions and is conferred by either dominant or recessive genes that have been mapped to six independent loci (Rpp1 -Rpp6), but No U.S. cultivars are resistant to SBR. The cultivar DT 2000 (PI 635999) has resistance to P. pachyrhizi isolates and field populations from the United States as well as Vietnam. A F6:7 recombinant inbred line (RIL) population derived from Williams 82 × DT 2000 was used to identify genomic regions associated with resistance to SBR in the field in Ha Noi, Vietnam, and in Quincy, Florida, in 2008. Bulked segregant analysis (BSA) was conducted using the soybean single nucleotide polymorphism (SNP) USLP 1.0 panel along with simple sequence repeat (SSR) markers to detect regions of the genome associated with resistance. BSA identified four BARC_SNP markers near the Rpp3 locus on chromosome (Chr.) 6. Genetic analysis identified an additional genomic region around the Rpp4 locus on Chr. 18 that was significantly associated with variation in the area under disease progress curve (AUDPC) values and sporulation in Vietnam. Molecular markers tightly linked to the DT 2000 resistance alleles on Chrs. 6 and 18 will be useful for marker-assisted selection and backcrossing in order to pyramid these genes with other available SBR resistance genes to develop new varieties with enhanced and durable resistance to SBR.