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Tea (Camellia sinensis) and herbal tea have been recognized as rich sources of bioactive constituents with the ability to exert antioxidant actions. The aims of this study were to analyze phenolic, carotenoid and saccharide contents in a set of Vietnamese tea and herbal tea and compare the results with those of green and black teas marketed in the U.S. In total, 27 phenolics, six carotenoids and chlorophylls, and three saccharides were quantitatively identified. Catechins, quercetin glycosides and chlorogenic acid were the predominating phenolics in the teas, with the concentrations following the order: jasmine/green teas > oolong tea > black tea. Lutein was the dominant carotenoid in the teas and its concentrations were generally found to be higher in the jasmine and green teas than in the oolong and black teas. The study showed that the green teas originating in Vietnam had much higher levels of phenolics and carotenoids than their counterparts stemming from another country. The application of partial least squares discriminant analysis (PLS-DA) as a chemometric tool was able to differentiate phenolic profiles between methanolic extracts and tea infusions. Through principal component analysis (PCA), the similarities and dissimilarities among the jasmine, green, oolong, black teas and herbal teas were depicted.

Since the first case of COVID-19 was announced on January 23, there have been only 123 infected cases with zero death confirmed [1,2]. [...]we write this letter to shed more light about epidemiological maps of cases in Vietnam and also provide helpful information for epidemiologists and policy makers to address specific measures in response to the pandemic. While the infection rates of COVID-19 in countries like China and Italy are significantly higher among the elderly, the most cases (79 out of 123) reported in Vietnam have been observed for the young (aged 11 – 40) (Fig. 2).3 The Vietnam response Although Vietnam is not one of the countries with the highest number of confirmed cases, the novel coronavirus outbreak in Vietnam is considered complex and unpredictable. [...]Vietnamese government, personally the Deputy Prime Minister Vu Duc Dam, directed and deployed prevention and control measures rapidly from the early stage in Vinh Phuc province to current situations of the overall national epidemic. To further prevent the spread from overseas, the Vietnamese government has been imposing a series of rigorous measures, including a temporary suspension of entry of all foreigners who have come from or transited through the COVID-19 affected areas, and a new mandatory regulation that all incoming travelers to Vietnam have to be quarantined at centralized facilities for 14 days [4].4 Suggestions for COVID-19 infection control In regard to the 14-day mandatory quarantine, we speculate that this implementation might sooner or later lead to shortage of space for quarantine, especially in the two metropolitan areas, Hanoi and Ho Chi Minh City. [...]the Vietnamese government may consider a combination of strict self-quarantine in the community and use of new technology, such as application of big data and artificial intelligence to improve contact tracing and the management of potentially infected patients.

Plant perception of insect feeding involves integration of the multiple signals involved: wounding, oral secretions, and substrate borne feeding vibrations. Although plant responses to wounding and oral secretions have been studied, little is known about how signals from the rapidly transmitted vibrations caused by chewing insect feeding are integrated to produce effects on plant defenses. In this study, we examined whether 24 h of insect feeding vibrations caused changes in levels of phytohormones and volatile organic compounds (VOCs) produced by leaves of when they were subjected to just feeding vibrations or feeding vibrations and wounding + methyl jasmonate (MeJA), compared to their respective controls of silent sham or wounding + MeJA. We showed that feeding vibrations alone caused a decrease in the concentrations of most phytohormones, compared to those found in control plants receiving no vibrations. When feeding vibrations were combined with wounding and application of MeJA, the results were more complex. For hormones whose levels were induced by wounding and MeJA (jasmonic acid, indole-3-butyric acid), the addition of feeding vibrations caused an even larger response. If the level of hormone was unchanged by wounding and MeJA compared with controls, then the addition of feeding vibrations had little effect. The levels of some VOCs were influenced by the treatments. Feeding vibrations alone caused an increase in β-ionone and decrease in methyl salicylate, and wounding + MeJA alone caused a decrease in benzaldehyde and methyl salicylate. When feeding vibrations were combined with wounding + MeJA, the effects on β-ionone and methyl salicylate were similar to those seen with feeding vibrations alone, and levels of benzaldehyde remained low as seen with wounding + MeJA alone. The widespread downregulation of plant hormones observed in this study is also seen in plant responses to cold, suggesting that membrane fluidity changes and/or downstream signaling may be common to both phenomena.

Limited information about exposure to volatile organic compounds (VOCs) in primary schools in Vietnam is available. In this study, we aimed to characterize indoor VOCs in four primary schools situated in Ho Chi Minh City, a metropolis in the south of Vietnam and assess health risks linked to the students’ exposure to VOCs. Indoor and outdoor air samples were collected in the schools and analyzed for volatile composition using gas chromatography coupled with mass spectrometry. Different classes of VOCs, including aromatic hydrocarbons, alkanes, aldehydes, esters, cyclic terpenes, and chlorinated hydrocarbons, were identified and quantified in classrooms of the schools. The results showed that the concentrations of the VOCs differed significantly among the schools and between ground-floor and first floor classrooms. In addition, VOC profiles differed considerably between air-conditioned and non-air-conditioned classrooms. Limonene, a compound associated with fragrance products, was the most abundant VOC, with the median (range) concentration of 26.12 (10.29, 50.08) μg/m3. The concentrations of the compounds examined in the study were in general found to be higher indoors compared with outdoors, signifying indoor emission sources. Potential harmful effects are expected as a result of exposure to benzene, ethylbenzene, naphthalene, 1,4-dichlorobenzene and tetrachloroethylene in the investigated schools. Further research is needed to fully assess the health risks to students, teachers, and staff in these educational environments.

Monofloral honey samples (Coffea robusta) from Vietnam were determined for their chemical compositions. This is the first report on the chemical composition and antioxidant activity of coffee honey from Vietnam. These samples were characterized by their high contents of total and reducing sugars, total phenolic contents, and total flavonoid contents. The contents of seven phenolic acids (PAs) were quantified by high performance liquid chromatography (HPLC) and analyzed with the assistance of principle component analysis (PCA) to differentiate the honey samples into groups. The hydroxymethylfurfural (HMF) (0.048–2.933 mg/kg) and free acid contents (20.326–31.163 meq/kg) of coffee honey were lower in Nepal, which reflected the freshness of the honey when conducting this survey. The coffee honey had total sugar and reducing sugar contents 831.711 g/kg and 697.903 g/kg, respectively. The high level of total phenolic (0.642 mg GAE/g) and flavonoid (0.0341 mg GE/g) contents of coffee honey contributed to their antioxidant activity of this honey sample. Among the coffee honey tested, the IC50 of DPPH radical-scavenging activities value was 1.134–17.031 mg/mL, while the IC50 of ABTS radical-scavenging activities value was 115.381–213.769 mg/mL. The phenolic acids composition analysis displayed that gallic acid appeared in high concentrations in all studied honey samples, ranging from 0.037–1.015 mg/kg, and ferulic acid content ranged from 0.193 to 0.276 mg/kg. The content of trigonelline and caffeine in coffee honey samples ranged from 0.314–2.399 mg/kg and 8.946–37.977 mg/kg. The data in this article highlight the relevance of coffee honey as a healthy substance.

Black walnut ( Juglans nigra L.) is an excellent source of health-promoting compounds. Consumption of black walnuts has been linked to many health benefits (e.g., anti-inflammatory) stemming from its phytochemical composition and medicinal properties, but these effects have not been systematically studied or characterized. In this study, potential anti-inflammatory compounds found in kernel extracts of 10 black walnut cultivars were putatively identified using a metabolomic profiling analysis, revealing differences in potential anti-inflammatory capacities among examined cultivars. Five cultivars were examined for activities in the human promonocytic cell line U-937 by evaluating the effects of the extracts on the expression of six human inflammatory cytokines/chemokines using a bead-based, flow cytometric multiplex assay. The methanolic extracts of these cultivars were added at four concentrations (0.1, 0.3, 1, and 10 mg/ml) either before and after the addition of lipopolysaccharide (LPS) to human U-937 cells to examine their effect on cytokine production. Results from cytotoxicity and viability assays revealed that the kernel extracts had no toxic effect on the U-937 cells. Of the 13 cytokines [interleukin (IL)-1β, tumor necrosis factor alpha (TNF-α), monocyte chemoattractant protein (MCP)-1, IL-6, IL-8, IL-10, IL-12, IL-17, IL-18, IL-23, IL-33, interferon (IFN)-α, IFN-γ] measured, only six were detected under the culture conditions. The production of the six detected cytokines by phorbol 12-myristate 13-acetate (PMA)-differentiated, LPS-stimulated U-937 was significantly inhibited by the kernel extracts from two cultivars Surprise and Sparrow when the extracts were added before the addition of LPS. Other cultivars (Daniel, Mystry, and Sparks) showed weak or no significant effects on cytokine production. In contrast, no inhibitory effect was observed on the production of cytokines by PMA-differentiated, LPS-stimulated U-937 when the kernel extracts were added after the addition of LPS. The findings suggest that the extracts from certain black walnut cultivars, such as Sparrow and Surprise, are promising biological candidates for potentially decreasing the severity of inflammatory disease.

Extracting allelochemicals from rice (Oryza sativa) straw and use for weed management is more sustainable than burning and reduces herbicide dependence. Water soluble compounds were extracted from shoots and roots of OM 5930, generating both a crystallized by-product and liquid extract. Crystallized product was applied to soil with pre-germinated barnyardgrass (Echinochloa crus-galli L. Beauv), red sprangletop (Leptochloa chinensis L. Nees), and grass-like fimbry (Fimbristylis miliacea L. Vahl) seeds. As little as 9.4 g per pot (1 ton ha−1 biomass) reduced survival of all species, with the order of sensitivity barnyardgrass (BG) < red sprangletop (RS) < grasslike-fimbry (GF). Increased rates or time of exposure (3 to 42 days after treatment; DAT) resulted in a stepwise reduction in seed survival. Using liquid extract, 5.33 g pot−1 (3 tons ha−1 biomass) reduced BG survival by 49.8%, while 2.67 g pot−1 reduced survival of RS and GF by 49.7 and 54.3%, respectively at 42 DAT. A rate of 8 g pot−1 reduced survival of BG seedlings by 78.3% but was lethal to RS and GF seedlings. The most abundant allelochemicals present were ergosterol peroxide, p-coumaric acid, and salicylic acid. OM 5930 rice is a promising variety for extraction of allelopathic compounds and application for extended herbicidal activity.

The methanol extracts of nine popular cultivated Vietnamese rice cultivars (Oryza sativa L.cv. OM 2395, 5451, 6976, 380, 5930, 4498, 3536, N406, and 7347) were used to explore their allelopathic potential on barnyardgrass (Echinochola crus-galli L.). At 0.1 g mL−1, OM 5930, OM 4498, and OM 6976 correlatively possessed greatest phytotoxicity on barnyardgrass shoot (98.77%, 90.75%, and 87.17%) and root (99.39%, 92.83%, and 86.56%) growth. The following study aimed to detect previously-known allelochemicals in those rice using XCMS online cloud-based metabolomics platform. Twenty allelochemicals were semi-quantified and seven of them were detected predominantly and five was putatively confirmed in OM 5930 (mg/ 100g fresh rice) as salicylic acid (5.0076), vanillic acid (0.1246), p-coumaric acid (0.1590), 2,4-dimethoxybenzoic acid (0.1045), and cinnamic acid (3.3230). These compounds were active at concentrations greater than 0.5 mM and the average EC50 were 1.24 mM. The results indicated that OM 5930 may use as promising candidates in weed biological control for rice production.

The aim of the present study was to determine the phenolics, carotenoids, B-vitamins, and antioxidant activity of nuts and seeds grown in Vietnam. The concentrations of carotenoids and B-vitamins may vary among the nuts and seeds. Watermelon seed contained the highest level of lutein while pumpkin seed was the β-carotene richest sample. Sachi inchi and sunflower seed comprised considerable levels of vitamin B1, B6, and B9. The phenolic analysis revealed that cashew contained the highest total amount of flavonoids (466.04 μg/g), with catechin, epicatechin, and procyanidin B2 predominating over the other flavonoids. Likewise, chlorogenic and neochlorogenic acids made up the highest total amount of phenolic acids in sunflower seed (1870.41 μg/g). Walnut appeared to possess the highest antioxidant activity evaluated by DPPH, ABTS, FRAP, and reducing power assays. The correlation analysis indicated strong positive correlations between total phenolic content with DPPH and FRAP values. Principal component analysis graphically showed the distant positioning of cashew and sunflower seed, highlighting their significantly higher levels of phenolics. The findings of the study would be useful to improve nutrient database contents for flavonoids and phenolic acids as well as to promote the consumption of nut and seed products in Vietnam.

Very recently, we have reported that more than 60% of the infected cases occurring in a public hospital in Hanoi, the capital of Vietnam, are linked to food delivery of mildly ill or presymptomatic nonclinical staff working at the hospital cafeteria. 2 This has raised a concern that food delivery has a great potential of contributing to the spread of the disease. 3 While more and more people adhere to the shelter-in-place order, delivery workers are fulfilling customer orders. Evidence has shown that presymptomatic or asymptomatic transmission is 1 of the major routes by which the novel coronavirus spreads. 5 Furthermore, 1 study indicates that presymptomatic transmission accounts for 6.4% of 157 locally acquired cases of COVID-19 in Singapore. 6 FIGURE 1 Potential spread of COVID-19 through food delivery service (a), food delivery workers at a takeout restaurant (b), and close contact with a customer (c). Delivery workers should wear new face masks and gloves, and frequently apply hand sanitizers to minimize contamination with the novel coronavirus. 3.