Evaluation of the conformity of intensity-modulated radiation therapy and volumetric modulated arc therapy using AAPM TG 119 protocol.

The aim of this work was to evaluate the conformity of intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT), and verify the accuracy of the planning and delivery system used in this work based on the AAPM TG-119 protocol. The Eclipse 13.6 treatment planning system (TPS) was used to plan the TG-119 test suite, which included four test cases: MultiTarget, Prostate, Head/Neck, and C-Shape for IMRT and VMAT techniques with 6 MV and 10 MV acceleration voltages. The results were assessed and discussed in terms of the TG-119 protocol and the results of previous studies. In addition, point dose and planar dose measurements were done using a semiflex ion chamber and an electronic portal imaging device (EPID), respectively. The planned doses of all test cases met the criteria of the TG-119 protocol, except those for the spinal cord of the C-Shape hard case. There were no significant differences between the treatment planning doses and the doses given in the TG-119 report, with p-values ranging from 0.974 to 1 (p > 0.05). Doses to the target volumes were similar in the IMRT and VMAT plans, but the organs at risk (OARs) doses were different depending on the test case. The planning results showed that IMRT is more conformal than VMAT in certain cases. For the point dose measurements, the confidence limit (CLpoint) of 0.030 and 0.021 were better than the corresponding values of 0.045 and 0.047 given in the TG-119 report for high-dose and low-dose areas, respectively. Regarding the planar dose measurements, the CLplanar value of 0.38 obtained in this work was lower than that given in the TG-119 report (12.4). It is concluded that the dosimetry measurements performed in this study showed better confidence limits than those provided in the TG 119 report. IMRT remains more conformal in certain circumstances than the more progressive VMAT. When selecting the method of delivering a dose to the patient, several factors must be considered, including the radiotherapy technique, energy, treatment site, and tumour geometry.

A Comprehensive Study of the Radical Scavenging Activity of Rosmarinic Acid.

Rosmarinic acid (RA) is reported in separate studies to be either an inducer or reliever of oxidative stress, and this contradiction has not been resolved. In this study, we present a comprehensive examination of the radical scavenging activity of RA using density functional theory calculations in comparison with experimental data. In model physiological media, RA exhibited strong HO• radical scavenging activity with overall rate constant values of 2.89 × 1010 and 3.86 × 109 M-1 s-1. RA is anticipated to exhibit excellent scavenging properties for HOO• in an aqueous environment (koverall = 3.18 × 108 M-1 s-1, ≈2446 times of Trolox) following the hydrogen transfer and single electron transfer pathways of the dianion state. The neutral form of the activity is equally noteworthy in a lipid environment (koverall = 3.16 × 104 M-1 s-1) by the formal hydrogen transfer mechanism of the O6(7,15,16)-H bonds. Chelation with RA may prevent Cu(II) from reduction by the ascorbic acid anion (AA-), hence blocking the OIL-1 pathway, suggesting that RA in an aqueous environment also serves as an OIL-1 antioxidant. The computational findings exhibit strong concurrence with the experimental observations, indicating that RA possesses a significant efficacy as a radical scavenger in physiological environments.

Study of the Mechanism and Kinetics of the Radical Scavenging Activity of 2-Mercaptoimidazole.

2-Mercaptoimidazole (2MI) is related to natural ovothiols that are recognized as powerful radical scavengers. Yet, despite early reports of its potent antioxidant properties, 2MI received little attention. Specifically, its radical scavenging activity against typical free radicals like HO• and HOO• has not yet been studied in terms of its mechanism and kinetics. In this project, density functional theory (DFT) simulations were used to assess the antiradical activity of 2MI. Calculations indicate that 2MI can demonstrate anti-HO• activity in both lipid and aqueous environments (koverall of 1.05 × 1010 and 2.07 × 1010 M-1 s-1, respectively). The calculated kinetics is extremely close to the experimental data in water (pH = 7.0), resulting in a kcalculated/kexperimental ratio of 1.73, validating the accuracy of the computational method and its usefulness for assessing radical scavenging activity in silico. In lipid media, the HOO• radical scavenging activity of 2MI is faster than that of common typical natural scavengers such as ascorbic acid, Trolox, and trans-resveratrol; hence, 2MI is a powerful radical scavenger in nonpolar media.

Four New Stilbene Derivatives Isolated from Gnetum latifolium var. funiculare Markgr. and Their Inhibition of NO Production in LPS-activated RAW264.7 Cells.

Gnetum latifolium var. funiculare Markgr. is a medicinal plant and widely distributed in mountainous areas of Vietnam. Phytochemical investigation on the trunks of this plant afforded eight stilbene derivatives (1-8) including for new compounds (1-4). Their structures were determined based on extensive analyses of HR-ESI-MS, 1D and 2D NMR spectra. Among the isolates, compounds 1-3 showed moderate NO production inhibition in LPS-activated RAW264.7 cells with the IC50 values ranging from 46.81 to 68.10 µM, compounds 4 and 6 showed weak effects with the IC50 values of 96.57 and 79.46 µM, respectively, compared to that of the positive control compound, dexamethasone (IC50 14.20 µM).

Molecular analysis reveals a distinct subgenogroup of porcine epidemic diarrhea virus in northern Vietnam in 2018-2019.

The spike protein (S) of porcine epidemic diarrhea virus (PEDV), in particular, the C-terminal domain of the S1 subunit (S1-CTD), which contains the conserved CO-26K-equivalent (COE) region (aa 499-638), which is recognized by neutralizing antibodies, exhibits a high degree of genetic and antigenic diversity. We analyzed 61 PEDV S1-CTD sequences (630 nt), including 26 from samples collected from seven provinces in northern Vietnam from 2018 to 2019 and 35 other sequences, representing the G1a and 1b, G2a and 2b, and recombinant (G1c) genotypes and vaccines. The majority (73.1%) of the strains (19/26) belonged to subgroup G2b. In a phylogenetic analysis, seven strains were clustered into an independent, distinct subgenogroup named dsG with strong nodal support (98%), separate from both G1a and G1b as well as G2a, 2b, and G1c. Sequence analysis revealed distinct changes (513T>S, 520G>D, 527V>(L/M), 591L>F, 669A>(S/P), and 691V>I) in the COE and S1D regions that were only identified in these Vietnamese strains. This cluster is a new antigenic variant subgroup, and further studies are required to investigate the antigenicity of these variants. The results of this study demonstrated the continuous evolution in the S1 region of Vietnamese PEDV strains, which emphasizes the need for frequent updates of vaccines for effective protection.

Spectrum of HBB gene mutations among 696 ß-thalassemia patients and carriers in Southern Vietnam.

BACKGROUND: Thalassemias are common inherited blood disorders that have been extensively studied in Asia. Thus far, data on mutations of the HBB gene in Vietnamese patients with ß-thalassemia are limited to small studies. METHODS: We recruited 696 ß-thalassemia patients and carriers in southern Vietnam and analyzed for the HBB gene mutations using Sanger sequencing technology. RESULTS: We documented 27 types of known mutations and 10 types of novel variants on 737 alleles out of 1392 surveyed alleles. The three most common mutations, which account for more than ¾ of all mutant alleles, were c.79G > A (HbE), c.124_127delTTCT, and c.52A > T. The novel variants were mainly located in 5' untranslated region (c.-92delC and c.-67A > G) and 3' untranslated region (c.*4C > T, c.*116_*117insA, c.*142 T > C, c.*156G > C, c.*176_*177insA, and c.*247 T > C), except for one in intron 2 (c.316-99 T > G) and one in exon 3 (c.385delG). CONCLUSION: We provide here a comprehensive mutation spectrum of the HBB gene in Southern Vietnam, which is crucial for carrier screening and prenatal diagnosis in the future.

Separation of Rare-Earth Elements from Nitrate Solutions by Solvent Extraction Using Mixtures of Methyltri-n-octylammonium Nitrate and Tri-n-butyl Phosphate.

The article presents data on the solvent extraction separation of rare-earth elements (REEs), such as La(III), Ce(III), Pr(III), and Nd(III), using synergic mixtures of methyltrioctylammonium nitrate (TOMANO3) with tri-n-butyl phosphate (TBP) from weakly acidic nitrate solutions. Specifically, experimental results on separation of REEs, for the pair Ce(III)/Pr(III) for quaternary mixtures of REEs (La(III), Ce(III), Pr(III), Nd(III)) and for the pair La(III)/Pr(III) for solutions containing La(III), Pr(III), and Nd(III), are presented. It was shown that effective separation for the pair Ce(III)/Pr(III) from a solution containing 219 g Ce(III)/L, 106 g La(III)/L, 20 g Pr(III)/L, 55 g Nd(III)/L, and 0.1 mol/L HNO3, was achieved using 56 steps of a multistage, counter-current solvent extraction cascade with scrubbing, at an organic-to-aqueous phase volume ratio (O/A) equal to 2/1 on the extraction section and O/A equal to 4/1 on the scrubbing section, using 3.3 mol/L solutions of the mixture TOMANO3-TBP with molar ratio 0.15:0.85 in dodecane. Separation for the pair La(III)/Pr(III) could be achieved using a solvent extraction cascade with scrubbing in 32 steps at O/A equal to 2/1 on the extraction section and O/A equal to 2.8/1 on the scrubbing section of the solvent extraction cascade from a solution containing 258 g La(III)/L, 58 g Pr(III)/L, 141 g Nd(III)/L, and 0.1 mol/L HNO3 with 3.0 mol/L solution of the mixture TOMANO3-TBP with molar ratio 0.2:0.8 in dodecane.

A persistent epidemic of porcine epidemic diarrhoea virus infection by serological survey of commercial pig farms in northern Vietnam.

BACKGROUND: Porcine epidemic diarrhoea (PED) is a highly contagious infectious disease with negative economic impacts on the swine industry. PED outbreaks were reported from 2009 to 2015, but sporadic infection has been observed until now in Vietnam. However, the seroprevalence of PEDV infection has not yet been reported for commercial pig farms in Vietnam. The aim of this study was to assess the seroprevalence of PEDV infection in Vietnamese pig farms to reveal the endemic status of PEDV in northern Vietnam. RESULTS: A serological survey of PEDV infection was carried out using indirect ELISA in commercial pig farms in Hai Duong, Hung Yen and Thai Binh provinces in northern Vietnam in 2019. Twenty sera were randomly collected from each of 10 commercial pig farms, from each province; none of the farms had vaccinated for PEDV. Serological evidence of natural PEDV infection, expressed as a high antibody titre, was observed in the pig farms in all 3 provinces. The OD values were significantly higher (p < 0.001) for pig sera from Thai Binh than from Hai Duong and Hung Yen. No significant differences (p > 0.05) were detected for seropositivity to PEDV based on locality, age, pig breed and farm size. CONCLUSIONS: This study indicates serological evidence of natural PEDV infection with high antibody titre in commercial pig farms. PEDV infection was widespread among the pig population in these 3 provinces and that good management and strict biosecurity are needed at these pig farms.

Concomitant Bacteremia in Adults With Severe Falciparum Malaria.

BACKGROUND: Approximately 6% of children hospitalized with severe falciparum malaria in Africa are also bacteremic. It is therefore recommended that all children with severe malaria should receive broad-spectrum antibiotics in addition to parenteral artesunate. Empirical antibiotics are not recommended currently for adults with severe malaria. METHODS: Blood cultures were performed on sequential prospectively studied adult patients with strictly defined severe falciparum malaria admitted to a single referral center in Vietnam between 1991 and 2003. RESULTS: In 845 Vietnamese adults with severe falciparum malaria admission blood cultures were positive in 9 (1.07%: 95% confidence interval [CI], .37-1.76%); Staphylococcus aureus in 2, Streptococcus pyogenes in 1, Salmonella Typhi in 3, Non-typhoid Salmonella in 1, Klebsiella pneumoniae in 1, and Haemophilus influenzae type b in 1. Bacteremic patients presented usually with a combination of jaundice, acute renal failure, and high malaria parasitemia. Four bacteremic patients died compared with 108 (12.9%) of 836 nonbacteremic severe malaria patients (risk ratio, 3.44; 95% CI, 1.62-7.29). In patients with >20% parasitemia the prevalence of concomitant bacteremia was 5.2% (4/76; 95% CI, .2-10.3%) compared with 0.65% (5/769; 0.08-1.2%) in patients with <20% parasitemia, a risk ratio of 8.1 (2.2-29.5). CONCLUSIONS: In contrast to children, the prevalence of concomitant bacteremia in adults with severe malaria is low. Administration of empirical antibiotics, in addition to artesunate, is warranted in the small subgroup of patients with very high parasitemias, emphasizing the importance of quantitative blood smear microscopy assessment, but it is not indicated in most adults with severe falciparum malaria.

Theoretical and Experimental Studies of the Antioxidant and Antinitrosant Activity of Syringic Acid.

Syringic acid (SA) is a natural phenolic acid found in vegetables, fruits, and other plant-based foods. A range of biological activities were proposed for this compound including anticancer, antimicrobial, anti-inflammation, and anti-diabetic activities, as well as antioxidant and antinitrosant properties. In this study, the focus is on the latter two. The HO•, HOO•, NO, and NO2 scavenging activities of SA were evaluated in physiological environments by kinetic and thermodynamic calculations. The computed rate constants of the HO• radical scavenging of SA were 4.63 × 109 and 9.77 × 107 M-1 s-1 in polar and nonpolar solvents, respectively. A comparison with the experimentally determined rate constant in aqueous solution yields a kcalculated/kexperimental ratio of 0.3, thus the computed kinetic data are reasonably accurate. SA exhibited excellent HOO• and NO2 scavenging activity in water (koverall(HOO•) = 1.53 × 108 M-1 s-1 and koverall(NO2) = 1.98 × 108 M-1 s-1), whereas it did not show NO scavenging activity in any of the studied environments. In lipid medium, SA exhibited weak activity. Thus, in polar environments, the HOO• radical scavenging of SA is 1.53 times higher than that of ascorbic acid. Consistently, SA is a promising antioxidant and antinitrosant agent in polar environments.

Investigation of the gut microbiome of Apis cerana honeybees from Vietnam.

OBJECTIVES: In this study, the gut microbiome of healthy adult honeybees, Apis cerana, was investigated by sequencing the V3 - V4 region in 16S rRNA gene using Illumina Miseq platform. RESULTS: The total of 37,853 reads for 16S rRNA gene were obtained and 30,121 (79.6%) reads were valid with 25,291 (84.0%) reads that were classified into 116 species belonging to four major phyla. The relative abundances of the bacterial isolates in honeybee samples were phylum Proteobacteria (70.7%), Actinobacteria (10.7%), Firmicutes (10.3%), and Bacteroidetes (8.4%), respectively. Lactic acid bacteria comprised 18.95% with 10 groups including Bifidobacterium asteroides, B. indicum, Fructobacillus fructosus, Lactobacillus apinorum, L. apis, L. helsingborgensis, L. kimbladii, L. kullabergensis, and L. kunkeei. CONCLUSIONS: The presence of beneficial bacteria in the gut highlighted their role in the honeybee and suggested that they can be promising candidates for the development of probiotics for health improvement, infection control and disease management of honeybees.

Comparison of Novel, Bach Mai Boston Tool (BBT) and the Patient-Generated Subjective Global Assessment (PG-SGA) for Oncology Inpatients.

Oncology inpatients are at high risk of malnutrition. Identification of at risk patients by nutrition screening requires a practical and easy to use tool. The aim of this study was to determine the validity of the Bach Mai Boston Tool (BBT) compared to a 'gold standard' full nutrition assessment using the Patient-Generated Subjective Global Assessment (PG-SGA). A cross-sectional study was conducted on 270 oncology inpatients from January to December 2016. Cohen's Kappa, sensitivity, specificity and ROC analyses were performed. 270 inpatients were included in this study with a mean age of 56.3 ± 12.1 years old. Of these patients, 51.8% were male, and 74.1% had gastrointestinal cancer. The mean body mass index of patients was 20.6 ± 3.0 kg/m2. The PG-SGA tool identified 146 (54.1%) malnourished patients, while the BBT identified 105 (39.9%) malnourished patients. The BBT had a medium consistency, with a Kappa value of 0.6. Using a cut-off point of ≥ 4, the BBT had a sensitivity of 87.7% and a specificity of 72.6%. On the other hand, a BBT with a cut-off point ≥ 5 resulted in a sensitivity of 67.1%, a specificity of 94.4%, and an AUC of 0.81. The BBT is a practical, informative and valid tool for detecting malnutrition in hospitalized oncology patients. We recommend using a cut-off point of 4 for screening the risk of malnutrition for oncology inpatients.

Patient experiences of primary care quality amongst different types of health care facilities in central Vietnam.

BACKGROUND: Patient experience with primary health care services can vary markedly between different types of health care facilities, even within the same country setting. Given known benefits of high quality primary health care, the performance of these facilities may significantly impact population health. The aim of this study was to compare the quality of primary care in different types of health facilities as experienced by Vietnamese consumers. METHODS: 1662 people who utilized primary health care services at least once over the past two years in various types of facilities in central Vietnam were surveyed in a cross-sectional study using the Vietnamese version of the Primary Care Assessment Tool (VN PCAT-AE) to assess overall primary care quality as well as several different domains of high quality primary care services. RESULTS: Commune health centers were associated with the highest overall primary care quality (PCAT expanded score 21.07, p < 0.001) as well as high scores in nearly all individual domains of primary care quality experienced by consumers compared with other types of facilities. Conversely, private facilities such as private clinics and pharmacies were rated lowest overall (PCAT expanded score 18.45, p < 0.05 and 16.90, p < 0.001 respectively). District hospitals and other government hospitals (PCAT expanded score 20.10 and 19.72 respectively) were reported as the best quality in comprehensiveness of available services (p < 0.001). Polyclinics performed quite well in comprehensiveness of services available (3.11) and first contact-access (2.79) but less so in other domains, especially in cultural competency (1.87). CONCLUSIONS: The high quality of primary care services experienced by consumers in commune health centers compared with other facilities gives Vietnam ample reason to promote greater use of these community-based primary care facilities. Populations may benefit most from building and strengthening grassroots networks of such community-based health centers as an effective solution for overcrowding at hospitals while simultaneously providing better overall health outcomes.

Polylactic Acid/Chitosan Nanoparticles Loading Nifedipine: Characterization Findings and In Vivo Investigation in Animal.

This paper presents the results of zeta potential, water contact angle, atomic force microscopy image, in vitro solubility, and content of heavy metals in polylactic acid (PLA)/chitosan (CS) nanoparticles loading nifedipine. In addition, the In Vivo test of the PLA/CS nanoparticles loading nifedipine in the mice is also one of highlights of this work. The Zeta potential result shows that the charged surface of the PLA/CS nanoparticles loading nifedipine is neutral, negative or complex depending on nifedipine content. Nifedipine plays a role in increase of hydrophobic property, swelling degree and regular surface as well as decrease of surface rough of the nanoparticles. The PLA/CS/nifedipine nanoparticles are dissolved in the solutions with pH 6.8, pH 4.5 and pH 1.2. The In Vivo test of PLA/CS nanoparticles loading nifedipine on mice was evaluated by the change in diastolic pressure, systolic pressure, arterial pressure and heart rate. The obtained results confirm that the PLA/CS nanoparticles loading nifedipine is suitable to apply in the treatment of hypertension patients lately.

Long-term outcome in survivors of neonatal tetanus following specialist intensive care in Vietnam.

BACKGROUND: Neonatal tetanus continues to occur in many resource-limited settings but there are few data regarding long-term neurological outcome from the disease, especially in settings with critical care facilities. METHODS: We assessed long-term outcome following neonatal tetanus in infants treated in a pediatric intensive care unit in southern Vietnam. Neurological and neurodevelopmental testing was performed in 17 survivors of neonatal tetanus and 18 control children from the same communities using tools previously validated in Vietnamese children. RESULTS: The median age of children assessed was 36 months. Eight neonatal tetanus survivors and 9 community control cases aged < 42 months were tested using the Bayley III Scales of Infant and Toddler Development (Bayley III-VN) and 8 neonatal tetanus survivors and 9 community controls aged ≥42 months were tested using the Movement Assessment Battery for Children. No significant reductions in growth indices or neurodevelopmental scores were shown in survivors of neonatal tetanus compared to controls although there was a trend towards lower scores in neonatal tetanus survivors. Neurological examination was normal in all children except for two neonatal tetanus survivors with perceptive deafness and one child with mild gross motor abnormality. Neonatal tetanus survivors who had expienced severe disease (Ablett grade ≥ 3) had lower total Bayley III-VN scores than those with mild disease (15 (IQR 14-18) vs 24 (IQR 19-27), p = 0.05) with a significantly lower cognitive domain score (3 (IQR 2-6) severe disease vs 7 (IQR 7-8) mild disease, p = 0.02). CONCLUSIONS: Neonatal tetanus is associated with long-term sequelae in those with severe disease. In view of these findings, prevention of neonatal tetanus should remain a priority.

PCR-based assays for validation of single nucleotide polymorphism markers in rice and mungbean.

BACKGROUND: Single nucleotide polymorphism (SNP) markers are the method of choice for genetic analyses including diversity and quantitative trait loci (QTL) studies. Marker validation is essential for QTL studies, but the cost and workload are considerable when large numbers of markers need to be verified. Marker systems with low development costs would be most suitable for this task. RESULTS: We have tested allele specific polymerase chain reaction (PCR), tetra markers and a genotyping tool based on the single strand specific nuclease CEL-I to verify randomly selected SNP markers identified previously either with a SNP array or by genotyping by sequencing in rice and mungbean, respectively. The genotyping capacity of allele-specific PCR and tetra markers was affected by the sequence context surrounding the SNP; SNPs located in repeated sequences and in GC-rich stretches could not be correctly identified. In contrast, CEL-I digestion of mixed fragments produced from test and reference DNA reliably pinpointed the correct genotypes, yet scoring of the genotypes became complicated when multiple SNPs were present in the PCR fragments. A cost analysis showed that as long the sample number remains small, CEL-I genotyping is more cost-effective than tetra markers. CONCLUSIONS: CEL-I genotyping performed better in terms of genotyping accuracy and costs than tetra markers. The method is highly useful for validating SNPs in small to medium size germplasm panels.

The radical scavenging activity of monocaffeoylquinic acids: the role of neighboring hydroxyl groups and pH levels.

Caffeoylquinic acids (CQAs) are well-known antioxidants. However, a key aspect of their radical scavenging activity - the mechanism of action - has not been addressed in detail thus far. Here we report on a computational study of the mechanism of activity of CQAs in scavenging hydroperoxyl radicals. In water at physiological pH, the CQAs demonstrated ≈ 104 times higher HOO˙ antiradical activity than in lipid medium (k(lipid) ≈ 104 M-1 s-1). The activity in the aqueous solution was determined by the hydrogen transfer mechanism of the adjacent hydroxyl group (O6'-H) of the dianion states (Γ = 93.2-95.2%), while the single electron transfer reaction of these species contributed 4.8-6.8% to the total rate constants. The kinetics estimated by the calculations are consistent with experimental findings in water (pH = 7.5), yielding a kcalculated/kexperimental = 2.4, reinforcing the reliability and precision of the computational method and demonstrating its utility for evaluating radical reactions in silico. The results also revealed the pH dependence of the HOO˙ scavenging activity of the CQAs; activity was comparable for all compounds below pH 3, however at higher pH values 5CQA reacted with the HOO˙ with lower activity than 3CQA or 4CQA. It was also found that CQAs are less active than Trolox below pH 4.7, however over pH 5.0 they showed higher activity than the reference. The CQAs had the best HOO˙ antiradical activity at pH values between 5.0 and 8.6. Therefore, in the physiological environment, the hydroperoxyl antiradical capacity of CQAs exhibits similarity to renowned natural antioxidants including resveratrol, ascorbic acid, and Trolox.

Synthesis and computational evaluation of the antioxidant activity of pyrrolo[2,3-b]quinoxaline derivatives.

Pyrrolo[2,3-b]quinoxaline derivatives are known to possess antioxidant, anticancer, and antibacterial properties. Here we report the successful synthesis of five derivatives of 3-hydroxy-3-pyrroline-2-one through substitution. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay was employed to evaluate the antioxidant activity of the compounds. Out of these, ethyl 1,2-diphenyl-1H-pyrrolo[2,3-b]quinoxaline-3-carboxylate (3a) demonstrated the greatest potential as a radical scavenger. Thermodynamic and kinetic calculations of the radical scavenging activity indicated that 3a exhibited HO˙ radical scavenging activity with the overall rate constant of 8.56 × 108 M-1 s-1 in pentyl ethanoate; however, it was incapable of scavenging hydroperoxyl radicals in nonpolar media. In non-polar environments, the hydroxyl radical scavenging capability of 3a is fairly similar to that of reference antioxidants such as Trolox, melatonin, indole-3-carbinol, and gallic acid. Hence, in the physiological lipid environment, 3a holds promise as a scavenger of HO˙ radicals.

Reaction of methylene blue with OH radicals in the aqueous environment: mechanism, kinetics, products and risk assessment.

Methylene Blue (MB) is an industrial chemical used in a broad range of applications, and hence its discharge is a concern. Yet, the environmental effects of its degradation by HO˙ radicals have not been fully studied yet. This study employs quantum chemical calculations to investigate the two-step degradation of MB by HO˙ radicals in aqueous environments. It was found that MB undergoes a rapid reaction with the HO˙ radical, with an overall rate constant of 5.51 × 109 to 2.38 × 1010 M-1 s-1 and has a rather broad lifetime range of 11.66 hours to 5.76 years in water at 273-383 K. The calculated rate constants are in good agreement with the experimental values (k calculation/k experimental = 2.62, pH > 2, 298 K) attesting to the accuracy of the calculation method. The HO˙ + MB reaction in water followed the formal hydrogen transfer and radical adduct formation mechanisms, yielding various intermediates and products. Based on standard tests these intermediates and some of the products can pose a threat to aquatic organisms, including fish, daphnia, and green algae, they have poor biodegradability and have the potential to induce developmental toxicity. Hence MB in the environment is of moderate concern depending on the ratio of safe to harmful breakdown products.

Identification and nitric oxide production inhibitory activity of phenolic derivatives from the trunks of Gnetum latifolium.

Phytochemical investigation of the trunks from Gnetum latifolium led to the isolation of a novel phenolic glucoside, 2E-2,4-di-(3,4-dihydroxyphenyl)but-2-en-1-yl-O-ß-D-glucopyranoside (1), along with five known stilbene derivatives (2-6). Their structures were determined mainly using high-resolution electrospray ionisation mass spectrometry and nuclear magnetic resonance spectroscopic analyses, followed by comparisons of observed spectral data with reported values. The novel compound 1 in G. latifolium was found to be useful as a chemotaxonomic marker. Biological evaluation revealed that compound 6 had remarkable inhibitory effects on nitric oxide production, with a half-maximal inhibitory concentration (IC50) value of 4.85 ± 0.20 µM, which was much higher than that of the positive control dexamethasone (IC50 = 14.20 ± 0.54 µM).