Mental health impact on healthcare workers from COVID-19 in Vietnam: Suggestions for a preventive program

The COVID-19 pandemic has had a negative impact on the mental health of healthcare workers participating in the prevention and control of the pandemic, thereby reducing their quality of life and affecting the quality of patient outcomes. This study aims to explore and deeply understand the mental health problems among healthcare workers participating in the prevention and control of COVID-19 in Ho Chi Minh City, Vietnam. A mixed methods study was undertaken with a descriptive cross-sectional survey of 2870 healthcare workers who have been participating in the prevention and control of COVID-19 in Ho Chi Minh City in 2021, followed by a qualitative descriptive phenomenological study comprised of in-depth interviews with a purposively sampled subset of 40 healthcare workers. Results showed that of the 2870 survey participants, the majority (60.6%) were female, and the average age was 35.1 (SD = 8.6). The prevalence of stress, anxiety and depression was 17.2%, 20.8%, and 17.6%, respectively. The findings from in-depth interviews revealed that the participants were under extreme mental health issues such as worries, stress, and negative emotions. The worrying was related to risk of infection, being shunned, stigmatised, or assaulted by the community. Stress was due to excessive pressure from work. Negative emotions were identified as sadness, self-pity, feelings of loneliness, entrusting fate, feelings of guilt, anxiety, confusion, obsession, disorientation, physical and mental exhaustion. Promoting mental health among healthcare workers who participated in the crisis is necessary and urgent.

Cytotoxic Activities and Fingerprint Analysis of Triterpenes by HPTLC Technique for Distinguishing Ganoderma Species from Vietnam and other Asian Countries

Ganoderma lucidum (Fr.) P. Karst. (Ganodermataceae), commonly called Linhzhi, is traditionally employed in the treatment of human diseases, including hepatitis, liver disorders, hypercholesterolemia, arthritis, bronchitis, and tumorigenic diseases. In this study, the fingerprint profiles of five different strains of G. lucidum originated from Japan, Korea, China, and Vietnam, five samples of G. lucidum growing on Erythrophloeum fordii Oliv. in Vietnam, and five related Linhzhi species (Ganoderma applanatum, Ganoderma australe, Ganoderma clossum, Ganoderma subresinosu, and Ganoderma sp.) were investigated for triterpene derivatives using high-pressure, thin-layer chromatography (HPTLC). The HPTLC fingerprint profiles demonstrated significant differences between G. lucidum and other related Linhzhi species in the presence of triterpene derivatives. Evaluation for the cytotoxicity of these samples against four cancer cell lines, including A549, MCF7, PC3, and HepG2, displayed various levels of cytotoxic effects, with IC₅₀ values of: 15.6-46.3 µg/mL on the A549 cancer cell line, of 18.4-43.6 µg/mL on the MCF7 cancer cell line, of 10.0-32.1 µg/mL on the PC3 cancer cell line, and of 10.6-27.6 µg/mL on the HepG2 cancer cell line. Conclusively, these data contributed to the literature on the cytotoxic activities and fingerprint analysis of triterpenes by the HPTLC technique for distinguishing Ganoderma species from Vietnam and other Asian countries.

Evaluating the performance of temporal and spatial early warning statistics of algal blooms

Regime shifts have large consequences for ecosystems and the services they provide. However, understanding the potential for, causes of, proximity to, and thresholds for regime shifts in nearly all settings is difficult. Generic statistical indicators of resilience have been proposed and studied in a wide range of ecosystems as a method to detect when regime shifts are becoming more likely without direct knowledge of underlying system dynamics or thresholds. These early warning statistics (EWS) have been studied separately but there have been few examples that directly compare temporal and spatial EWS in ecosystem-scale empirical data. To test these methods, we collected high-frequency time series and high-resolution spatial data during a whole-lake fertilization experiment while also monitoring an adjacent reference lake. We calculated two common EWS, standard deviation and autocorrelation, in both time series and spatial data to evaluate their performance prior to the resulting algal bloom. We also applied the quickest detection method to generate binary alarms of resilience change from temporal EWS. One temporal EWS, rolling window standard deviation, provided advanced warning in most variables prior to the bloom, showing trends and between-lake patterns consistent with theory. In contrast, temporal autocorrelation and both measures of spatial EWS (spatial SD, Moran's  I) provided little or no warning. By compiling time series data from this and past experiments with and without nutrient additions, we were able to evaluate temporal EWS performance for both constant and changing resilience conditions. True positive alarm rates were 2.5-8.3 times higher for rolling window standard deviation when a lake was being pushed towards a bloom than the rate of false positives when it was not. For rolling window autocorrelation, alarm rates were much lower and no variable had a higher true positive than false positive alarm rate. Our findings suggest temporal EWS provide advanced warning of algal blooms and that this approach could help managers prepare for and/or minimize negative bloom impacts.

Four new phenolic compounds from the fruit of Cornus officinalis (Cornaceae) and their anti-inflammatory activity in RAW 264.7 cells

Using various chromatographic methods, four new phenolics, coroffesters A-D (1 - 4) were isolated from the fruit of Cornus officinalis (Cornaceae). Their structures (1 - 4) were elucidated unambiguously by spectroscopic methods such as one- and two-dimensional nuclear magnetic resonance (1 D- and 2 D-NMR) spectroscopy and high-resolution electrospray ionization mass spectrometry (HR-ESI-MS). The anti-inflammatory activity of the isolated compounds was also evaluated. All compounds (1 - 4) showed moderate inhibitory activity against NO production in a dose-dependent manner in RAW 264.7 cells.

FACTORS INFLUENCING COMPETENCY DEVELOPMENT OF NURSES AS PERCEIVED BY STAKEHOLDERS IN VIETNAM

Background: Competency of nurses is vital to safe nursing practice as well as essential component to drive quality of nursing services. Competency development is a continuous process of improving knowledge, attitudes and skills, and is influenced by a numerous of factors.Purposes: This study aims to explore factors that influence the development of competencies of nurses working in clinical settings in Vietnam.Methods: A descriptive qualitative research was conducted in Ho Chi Minh City, Vietnam with a purposive sample of twenty-seven participants including nurses, nurse managers, administrators, nurse teachers, medical doctors, and other health care providers.  Data collection was by in-depth interviews and focus group discussions. Content analysis was used to analyze the data.Findings: The research participants described numerous of factors that influence the journey of developing nurses’ competencies. The identified factors were relevant to nursing education and training system in Vietnam; working environments of nurses; public image and values of nursing profession; characteristics of nurses themselves; Vietnamese nursing profession; sociocultural-economic and political aspects in Vietnam; and global contexts.Conclusion: The derived knowledge would greatly benefit clinical nurses, administrators, nursing educators, health care services managers, policy makers as well as other relevant health care stakeholders in proposing of solutions to promote nursing education, nursing workplace environments, and the appropriate regulations in order to enhance the nursing competency and quality of nursing services in Vietnam. 

Traphanoside GO1, a new triterpenoid saponin from the aerial parts of Glinus oppositifolius with the inhibitory effect on PGE2 production in LPS-induced HepG2 cells

A new saponin, 3-O-[α-ʟ-rhamnosyl-(1→3)-β-D-glucopyranosyl]-28-O-β-D-glucopyranosyl serjanic acid (Traphanoside GO1, 11) along with eleven compounds (1-10 and 12) were isolated from the aerial parts of Glinus oppositifolius. The structures of all isolates were elucidated by analyzing extensive 1 D- and 2 D-NMR and HR-ESI-MS, comparing with reported literature data. Compounds 7-8, 10-11, and 90% ethanol extract (GOE90) were evaluated for the inhibitory effect on PGE2 production from activated HepG2 cells. Among these, new compound 11 showed the most potent inhibitory activity by suppressing LPS-induced PGE2 production on the HepG2 cells.

Three New Constituents From the Parasitic Plant Balanophora laxiflora

Three new constituents (1-3) were isolated from the whole plant of Balanophora laxiflora. Their chemical structures were elucidated by extensive analysis of high-resolution electrospray ionization mass spectrometry and nuclear magnetic resonance spectroscopy. Absolute configurations of new compounds were determined by circular dichroism spectra and modified Mosher’s method. The isolated compounds weakly inhibited on both NO production and COX-2 mRNA expression in RAW264.7 macrophages.

Four New Compounds Isolated from the Aerial Part of Belamcanda chinensis (L.) and Their Effect on Vascular Smooth Muscle Cell (VSMC) Proliferation

Bio-guided fractionation of the 70% ethanol extract of Belamcanda chinensis (L.) DC. revealed four new compounds, including 6″-O-acetylembinin (5), 3″-O-acetylembinin (6), irigenin 3'-O-β-glucopyranoside (8), and 2'-acetyl-1,3-O-diferuloylsucrose (9), along with five known compounds (1-4, 7). Their chemical structures were determined using extensive NMR data, mass spectroscopy, and comparison with published literature. Among the isolates, compounds 1 and 4-7 achieved good regulation of the growth and proliferation of vascular smooth muscle cells.

Anti-inflammatory effect of oligostilbenoids from Vitis heyneana in LPS-stimulated RAW 264.7 macrophages via suppressing the NF-κB activation

Background

Vitis heyneana is widely distributed in the north of Vietnam, it has been used in Vietnamese traditional medicine as an agent for treatment of arthritis, bronchitis, carbuncles and inflammatory conditions, and menstrual irregularities. However, this plant has not been investigated in phytochemical constituents and biological effects, especially in the anti-inflammatory property.

Results

Bioassay-guided fractionation of the EtOAc soluble fraction from the aerial part of Vitis heyneana resulted in the isolation of a series of oligostilbenoids as piceid (1), 2-r-viniferin (2), betulifol A (3), vitisinol C (4), (-)-trans-ε-viniferin (5), α-viniferin (6), shoreaketon (7), amurensin B (8), vitisinol B (9), and cis-vitisin B (10). Compound 5 showed the most potent inhibitory activities by suppressing LPS-induced COX-2 expression and PGE2 production. This compound exhibited significantly reduced LPS-induced nitric oxide (NO) release in a dose-dependent manner. These effects are accompanied with the inhibition of transcription factor NF-κB activation.

Conclusion

The results suggested that trans-ε-viniferin exerts anti-inflammatory effects via suppression the NF-κB activation in RAW 264.7 cells.

An improved HPLC-DAD method for quantitative comparisons of triterpenes in Ganoderma lucidum and its five related species originating from Vietnam

An HPLC-DAD method for the quality control of wild and cultivated Ganoderma lucidum (Linhzhi) and related species samples was developed and validated. The quantitative determination of G. lucidum and its related species using 14 triterpene constituents, including nine ganoderma acids (compounds 4-12), four alcohols (compounds 13-16), and one sterol (ergosterol, 17) were reported. The standard curves were linear over the concentration range of 7.5-180 µg/mL. The LOD and LOQ values for the analyses varied from 0.34 to 1.41 µg/mL and from 1.01 to 4.23 µg/mL, respectively. The percentage recovery of each reference compound was found to be from 97.09% to 100.79%, and the RSD (%) was less than 2.35%. The precision and accuracy ranged from 0.81%-3.20% and 95.38%-102.19% for intra-day, and from 0.43%-3.67% and 96.63%-103.09% for inter-day, respectively. The study disclosed in detail significant differences between the quantities of analyzed compounds in different samples. The total triterpenes in wild Linhzhi samples were significantly higher than in cultivated ones. The total constituent contents of the five related Linhzhi samples were considerably lower than that in the G. lucidum specimens, except for G. australe as its constituent content outweighed wild Linhzhi's content by 4:1.

Dissociation pathways in the cysteine dication after site-selective core ionization

A photoelectron-ion-ion coincidence experiment has been carried out on the amino acid molecule cysteine after core-ionization of the O 1s, N 1s, C 1s, and S 2p orbitals. A number of different dissociation channels have been identified. Some of them show strong site-selective dependence that can be attributed to a combination of nuclear motion in the core-ionized state and Auger processes that populate different final electronic states in the dication.

Femtosecond X-ray-induced explosion of C60 at extreme intensity

Understanding molecular femtosecond dynamics under intense X-ray exposure is critical to progress in biomolecular imaging and matter under extreme conditions. Imaging viruses and proteins at an atomic spatial scale and on the time scale of atomic motion requires rigorous, quantitative understanding of dynamical effects of intense X-ray exposure. Here we present an experimental and theoretical study of C60 molecules interacting with intense X-ray pulses from a free-electron laser, revealing the influence of processes not previously reported. Our work illustrates the successful use of classical mechanics to describe all moving particles in C60, an approach that scales well to larger systems, for example, biomolecules. Comparisons of the model with experimental data on C60 ion fragmentation show excellent agreement under a variety of laser conditions. The results indicate that this modelling is applicable for X-ray interactions with any extended system, even at higher X-ray dose rates expected with future light sources.

In vitro and in vivo hepatoprotective effect of ganodermanontriol against t-BHP-induced oxidative stress

ETHNOPHARMACOLOGICAL RELEVANCE

Ganoderma lucidum (Fr.) Karst. (Ganodermataceae) is a mushroom which is used as a traditional remedy in the treatment of human diseases such as hepatitis, liver disorders, hypercholesterolemia, arthritis, bronchitis and tumorigenic diseases. This study targets the evaluation of hepatoprotective activity of ganodermanontriol, a sterol isolated from Ganoderma lucidum, and the investigation of its mechanism of action in Hepa1c1c7 and murine liver cells upon tert-butyl hydroperoxide (t-BHP)-induced inflammation. t-BHP was utilized to stimulate an anti-inflammatory reaction in the hepatic cell lines and murine hepatic tissue examined. Western blot and reverse transcription-quantitative polymerase chain reaction (RT-PCR) were used to estimate the expression of ganodermanontriol (GDT)-induced proteins, including heme oxidase-1 (HO-1) and mitogen-activated protein kinases (MAPKs) as well as the corresponding mRNA. Luciferase assays were conducted to evaluate the interaction between NF-E2-related factor-2 (Nrf-2), the antioxidant response element (ARE), and the promoter region of the HO-1 gene and subsequent gene expression. Biochemical markers for hepatotoxicity were monitored to assess whether GDT protected the cells from the t-BHP-mediated oxidative stimuli.

RESULTS

GDT induced HO-1 expression via the activation of Nrf-2 nuclear translocation and the subsequent transcription of the HO-1 gene in vitro and in vivo, which seemed to be regulated by phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) and p38 signaling pathways. GDT exhibited in vitro and in vivo hepatoprotective activity as determined by the lowered levels of hepatic enzymes and malondialdehydes and the elevated glutathione levels.

CONCLUSIONS

This study validates the ethnopharmacological application of Ganoderma lucidum as a treatment for hepatic disorders. GDT induced in vitro and in vivo anti-inflammatory activity in t-BHP-damaged hepatic cells through the expression of HO-1, and in which PI3K/Akt and p38 kinases are involved. Our study motivates further research in the exploration of potent hepatoprotective agents from Ganoderma lucidum.

Xanthine oxidase inhibitory activity of constituents of Cinnamomum cassia twigs

A methanol extract of the twigs of Cinnamomum cassia was found to inhibit xanthine oxidase. Purification of the methanol extract afforded three new phenolic glycosides, cinnacasolide A-C (11-13), together with 10 known compounds (1-10). The structures of the three new compounds were determined by interpretation of spectroscopic data. Cinnamaldehyde derivatives 1-5 and 7 were significant inhibitors of xanthine oxidase, with IC(50) values ranging from 7.8 to 36.3 μg/mL. The results indicate that the acyl group of these cinnamaldehyde derivatives plays an important role in the inhibition of xanthine oxidase.

A new flavan-3-ol and the anti-inflammatory effect of flavonoids from the fruit peels of Wisteria floribunda

A new flavan-3-ol, (+)-afzelechin 5-O-β-d-glucopyranoside (2), together with 13 known flavonoids (1, 3-14), was isolated from the fruit peels of Wisteria floribunda. Their structures were assigned by detailed interpretation of NMR, MS, and CD spectroscopic data, as well as by comparing with published reports. The in vitro anti-inflammatory activity of the isolated compounds (1-14) was examined. Among them, compounds 3, 6, and 9 produced highest inhibitory effects on tumor necrosis factor alpha (TNF-α)-induced nuclear factor kappa-B activation in HepG2 cells with IC(50) values of 14.1, 16.5, and 11.9 μM, respectively. With the exception of compound 6, the compounds significantly inhibited the accumulation of pro-inflammatory inducible nitric oxide synthase and cyclooxygenase-2 proteins in TNF-α-stimulated HepG2 cells at a concentration as low as 0.1 μM.

WITHDRAWN: Anti-proliferative effects of compounds from the fruit peel of Wisteria floribunda on vascular smooth muscle cells

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Selected compounds derived from Moutan Cortex stimulated glucose uptake and glycogen synthesis via AMPK activation in human HepG2 cells

AIM OF THE STUDY

To evaluate the effect of selected compounds derived from Moutan Cortex on glucose uptake and glycogen synthesis associated with AMPK activation in insulin-resistant human HepG2 cell.

MATERIALS AND METHODS

The effect of isolated compounds (1-16) on glucose uptake and glycogen synthesis was performed using HepG2 cells. The western blot was used to determine the expression of AMPK and its downstream substrates, ACC, p-ACC, and p-GSK-3beta.

RESULTS

The effects of the 16 compounds from Moutan Cortex on glucose metabolism in HepG2 cells under high glucose conditions were evaluated. Compounds 2, 3, and 6 displayed highly potent effects on the stimulation of glucose uptake and glycogen synthesis in human HepG2 cells under high glucose conditions. Compounds 2, 3, and 6 phosphorylate AMPK (AMP-activated protein kinase), and resulted in increased phosphorylation of GSK-3beta and suppression of lipogenic expression (ACC and FAS) in a dose-dependent manner. Compounds 2, 3, and 6 also demonstrated interesting, strong eNOS phosphorylation in human umbilical vein endothelial cells (HUVECs). Compounds 1, 4, 5-12, and 14 displayed considerable effects on hepatic glucose production, AMPK activation, and phosphorylation of GSK-3beta in HepG2 cells under high glucose conditions.

CONCLUSIONS

These effects may indicate that the activation of AMPK by the active compounds from Moutan Cortex has considerable potential for reversing the metabolic abnormalities associated with type-2 diabetes.

The selected flavonol glycoside derived from Sophorae Flos improves glucose uptake and inhibits adipocyte differentiation via activation AMPK in 3T3-L1 cells

Among nine flavonols (1-9) obtained from Sophorae Flos, we first isolated compounds 4, 5, 8, and 9. These isolates (1-9) were evaluated for the phosphorylation of AMPK and ACC. Administered at 10 μM, 9 possessed high potent activity. Compound 9 displayed a dose-dependent stimulation of glucose uptake in 3T3-L1 cells, and this increase was obviously attenuated by compound C, an AMPK inhibitor. In addition, 9 also phosphorylated AMPK and its downstream substrate ACC in 3T3-L1 cells in a time- and dose-dependent manner. Moreover, we discovered that compound C inhibits 9-stimulated ACC phosphorylation and motivated the 9-inhibited C/EBPα and PPARγ, and FAS gene expression, significantly. These results revealed the role of the AMPK downstream signaling pathway in 9-improved glucose metabolism in 3T3-L1 cells and 9-inhibited adipocyte differentiation. Differentiation was investigated by Oil Red O staining activity after 9 administration (0-20 μM) in 6 days. Compound 9 decreased mean droplet size in a dose-dependent manner. The results revealed that 9 blocked adipogenic conversion in 3T3-L1 cells together with several significant downregulating adipocyte-specific transcription factors, including PPARγ, C/EBPα, and SREBP1. It also reduced FAS gene expression in a dose-dependent manner, which is crucial for adipogenesis in vitro.

The antimicrobial activity of compounds from the leaf and stem of Vitis amurensis against two oral pathogens

Nine compounds isolated from the leaf and stem of Vitis amurensis Rupr. (Vitaceae) were evaluated for their antimicrobial activity against two oral pathogens, Streptococcus mutans and Streptococcus sanguis, which are associated with caries and periodontal disease, respectively. The results of several antimicrobial tests, including MIC, MBC, and TBAI, showed that three compounds inhibited the growth of the test bacteria at concentrations ranging from 12.5 to 50 microg/mL. Among these compounds, compound 5, trans-epsilon-viniferin, displayed the strongest activity against S. mutans and S. sanguis with MIC values of 25 and 12.5 microg/mL, respectively. This is the first report on the antimicrobial activity of stilbenes and oligostilbenes isolated from the leaf and stem of V. amurensis. Thus, this result suggests that natural antimicrobial compounds derived from V. amurensis may benefit oral health as plaque-control agents for the prevention of dental caries and periodontal disease.

Antioxidant and lipoxygenase inhibitory activity of oligostilbenes from the leaf and stem of Vitis amurensis

ETHNOPHARMACOLOGICAL RELEVANCE

The root and stem of Vitis amurensis (Vitaceae) have popularly used as traditional medicine for treatment of cancer and various pains in Korea and Japan. Recent studies, its root and stem possess anti-inflammatory, anti-tumor activities, and protective effects against beta-amyloid-induced oxidative stress.

AIM OF THE STUDY

This study deals with the isolation, structural identification of the potent bioactive compounds from the leaf and stem, and their antioxidant capacity, as well as anti-inflammatory effect via lipoxygenase inhibitory assay.

MATERIALS AND METHODS

All isolated compounds yielded after using column chromatography were identified base on the physico-chemical properties and 1D, 2D NMR spectra. The scavenge ability against DPPH and ABTS(+) radicals, and to inhibit lipid peroxidation, as well as lipoxygenase type I inhibitory activity of all isolates were performed using in vitro assays.

RESULTS

Eleven resveratrol derivatives (1-11), including a new oligostilbene cis-amurensin B (9), whose structures were determined on the basis of extensively spectral analyses, were isolated from the leaf and stem of Vitis amurensis. The isolates (1-11) were examined for their antioxidant activities by evaluating scavenge ability against DPPH and ABTS(+) radicals, and to inhibit lipid peroxidation. Stilbenes 1 and 4, and oligostilbenes 5-10 displayed moderate anti-lipid peroxidation activities, but all the isolates exhibited strong ABTS(+) radical scavenging activity in the dose-dependent manner. In addition, the isolates showed stronger inhibitory capacity against soybean lipoxygenase type I than that of baicalein, a positive control. Of the isolates, r-2-viniferin (8) exhibited the strongest scavenging activity against ABTS(+) radical with TEAC value of 5.57, and the most potential inhibitory effect on soybean lipoxygenase with the IC(50) value of 6.39 microM.

CONCLUSION

This is the first report on the potential antioxidant and LOX-1 inhibitory effects of oligostilbenes isolated from the leaf and stem of Vitis amurensis. In addition, chemical compositions isolated from the leaf and stem are almost similar to those isolated from the root of Vitis amurensis. Therefore, the results may explain, in part, the uses of the leaf and stem, as well as the root of Vitis amurensis in the Korean traditional medicine.

Palbinone and triterpenes from Moutan Cortex (Paeonia suffruticosa, Paeoniaceae) stimulate glucose uptake and glycogen synthesis via activation of AMPK in insulin-resistant human HepG2 Cells

Moutan Cortex is a well-known herb in traditional Korean, Chinese, and Japanese anti-diabetic formulae. In the current study, we investigated the metabolic effects of isolated triterpenes (1-7) in HepG2 cells under high glucose conditions. These compounds remakably stimulated AMP-activated protein kinase (AMPK), GSK-3beta, and ACC phosphorylation. The compounds also increased glucose uptake and enhanced glycogen synthesis. Among these, compound 1 displayed the greatest potential anti-diabetic activity though the AMPK activation pathway. Compound 1 significantly increased the levels of phospho-AMPK, phospho-ACC, and phospho-GSK-3beta and stimulated glucose uptake and glycogen synthesis in a dose-dependent manner. In conclusion, our results suggest that these compounds, especially compound 1, may have beneficial roles in glucose metabolism via the AMPK pathway.

Inhibitors of aldose reductase and formation of advanced glycation end-products in moutan cortex (Paeonia suffruticosa)

The methanol extract of Moutan cortex (Paeonia suffruticosa) afforded two new compounds, 8-O-benzoylpaeonidanin (1) and 5-hydroxy-3S-hydroxymethyl-6-methyl-2,3-dihydrobenzofuran (2), in addition to 4-O-butylpaeoniflorin (3) as an artifact of the separation, seven monoterpene glycosides (4-10), two monoterpenes (11, 12), four acetophenones (13-16), and two triterpenes (17, 18). The structures of the compounds were determined by spectroscopic methods, and the compounds were evaluated for inhibitory effects against rat lens aldose reductase (RLAR) and advanced glycation end-product (AGEs) formation. Compounds 17 and 18 showed the most potent inhibitory activity against RLAR, with IC(50) values of 11.4 and 28.8 microM, respectively. Compounds 3 and 6 also inhibited RLAR with IC(50) values of 36.2 and 44.6 microM, respectively. The positive control, 3,3-tetramethyleneglutamic acid, had an IC(50) value of 31.8 microM. Compounds 3 and 6 inhibited AGE formation with IC(50) values of 10.8 and 11.3 microM, respectively. Compound 2 had an IC(50) value of 177.0 microM, whereas the positive control, aminoguanidine, had an IC(50) value of 1026.8 microM.

Tyrosinase-inhibitory constituents from the twigs of Cinnamomum cassia

A methanol extract of the twigs of Cinnamomum cassia was found to possess inhibitory activity against tyrosinase. Purification of the MeOH extract afforded four new phenolics, cassiferaldehyde (6), icariside DC (9), cinnacassinol (10), and dihydrocinnacasside (13), together with 10 known compounds (1-5, 7-12, and 14). The structures of the new compounds were determined by spectroscopic data interpretation. Compounds 1-6 and 8-13 showed strong inhibitory activity against tyrosinase, with IC(50) values ranging from 0.24 to 0.94 mM.

Biphenylquinolizidine alkaloids from Lagerstroemia indica

Two new biphenylquinolizidine alkaloids, 5-epi-dihydrolyfoline (1) and its stereoisomer, dihydrolyfoline (2), along with lagerine (3) were isolated from the aerial parts of Lagerstroemia indica. The structures of compounds 1-3 were elucidated by extensive spectroscopic techniques.

Inhibition of human low density lipoprotein and high density lipoprotein oxidation by oligostilbenes from rhubarb

The objective of the present study was to elucidate the beneficial properties of ampelopsine B (1) and epsilon-Viniferin (2), two oligostilbenes isolated from rhubarb, toward cardiovascular disease by protecting human lipoproteins against lipid peroxidation. In low density lipoprotein (LDL) oxidation, both 1 and 2 exert an inhibitory activity against Cu(2+)-, 2,2'-azobis-(2-amidinopropane) hydrochloride (AAPH)-induced, as exhibited by prolongation of lag time from 52 to 118 and 136 min, respectively, and also increasing the lag time 38 to 105 and 128 min in high density lipoprotein (HDL) oxidation for 1 and 2, respectively, at the concentration of 3.0 microM. In generation of thiobarbituric acid reactive substances (TBARS), compounds 1 and 2 inhibited LDL oxidation mediated by either catalytic Cu(2+) or thermo-labile radical initiator (AAPH) in a dose-dependent manner with IC(50) values of 3.6 and 6.0 microM for 1, and 1.7 and 3.2 microM for 2, respectively. In addition, compounds 1-2 also showed strong ability to protect HDL oxidation induced by both Cu(2+) and AAPH with low IC(50) values. The results suggest that oligostilbenes 1-2 may have a role in preventing lipoprotein oxidation.

Marinobacter aquaeolei sp. nov., a halophilic bacterium isolated from a Vietnamese oil-producing well

Several strains of moderately halophilic and mesophilic bacteria were isolated at the head of an oil-producing well on an offshore platform in southern Vietnam. Cells were Gram-negative, non-spore-forming, rod-shaped and motile by means of a polar flagellum. Growth occurred at NaCl concentrations between 0 and 20%; the optimum was 5% NaCl. One strain, which was designated VT8T, could degrade n-hexadecane, pristane and some crude oil components. It grew anaerobically in the presence of nitrate on succinate, citrate or acetate, but not on glucose. Several organic acids and amino acids were utilized as sole carbon and energy sources. The major components of its cellular fatty acids were C12:0 3-OH, C16:1, omega 9c, C16:0 and C18:1 omega 9c. The DNA G + C content was 55.7 mol%. 16S rDNA sequence analysis indicated that strain VT8T was closely related to Marinobacter sp. strain CAB (99.8% similarity) and Marinobaster hydrocarbonoclasticus (99.4% similarity). Its antibiotic resistance, isoprenoid quinones and fatty acids were similar to those of Marinobacter hydrocarbonoclasticus and Pseudomonas nautica. However, the whole-cell protein pattern of VT8T differed from that of other halophilic marine isolates, including P. nautica. DNA-DNA hybridization indicated that the level of relatedness to Marinobacter hydrocarbonoclasticus was 65% and that to P. nautica was 75%. Further differences were apparent in Fourier-transformed IR spectra of cells and lipopolysaccharide composition. It is proposed that VT8T should be the type strain of a new species and should be named Marinobacter aquaeolei. P. nautica may have been misclassified, as suggested previously, and may also belong to the genus Marinobacter.

Characterization of petroleum-degrading bacteria from oil-contaminated sites in Vietnam

Four petroleum-degrading bacterial strains, 2TN-NB, 6TBX-CL, MVK2-5, and XCK, were isolated from various oil-contaminated sites in Vietnam. Determination of the nucleotide sequence of the gene encoding 16S rRNA allowed 2TN-NB to be identified as Acinetobacter sp. and the other three stains as Pseudomonas sp. Among the four isolates, 2TN-NB was most effective in degrading crude oil: in 1 d, it degraded 95% of the crude oil in the culture medium (5%, v/v). The isolated strains could also degrade a sulfur-containing aromatic hydrocarbon, dibenzothiophene (DBT), with low efficiency. Except for MVK2-5, which degraded crude oil least efficiently, the isolates produced biosurfactants in amounts sufficient for structural analysis. FT-IR measurement suggested that strains 6TBX-CL and XCK produced glycolipid-type biosurfactants while that produced by 2TN-NB was of the polysaccharide type.

Developmental and cell cycle regulation of alfalfa nucMs1, a plant homolog of the yeast Nsr1 and mammalian nucleolin

We report here the isolation and characterization of the nucMs1 alfalfa cDNA, whose predicted amino acid sequence structurally resembles the yeast Nsr1 protein and animal nucleolins. These proteins consist of an N-terminal acidic domain, centrally located RNA recognition motifs (RRMs), and a C-terminal glycine- and arginine-rich domain. In comparison with animal nucleolins that contain four RRMs, NucMs1 more closely resembles the yeast Nsr1 protein, which contains only two RRMs. A NucMs1 C-terminal peptide antibody specifically recognized a 95-kD nucleolar protein in alfalfa cells that changed its localization in a cell cycle-dependent manner. The nucMs1 transcript and p95nucMs1 protein levels correlated with cell proliferation, and nucMs1 gene expression was found to be induced in the G1 phase upon mitogenic stimulation of G0-arrested leaf cells. In situ hybridization analysis of different alfalfa organs during various developmental stages showed that nucMs1 gene expression is highest in root meristematic cells, but it is also found in other meristematic cells of the plant body. nucMs1 expression is tightly linked to cell proliferation but does not depend on a particular cell cycle phase. No nucMs1 expression was observed in cells that had exited the cell cycle and were undergoing differentiation or polar growth, indicating that nucMs1 may not be necessary for processes other than cell proliferation.

The D-type alfalfa cyclin gene cycMs4 complements G1 cyclin-deficient yeast and is induced in the G1 phase of the cell cycle

Cyclins are key regulators of the cell cycle in all eukaryotes. In alfalfa, we have previously isolated three B-type cyclins. The closely related cycMs1 and cycMs2 genes are expressed primarily during the G2 and M phases and are most likely mitotic cyclins; expression of the cycMs3 gene is induced in the G0-to-G1 transition, when cells reenter the cell cycle. By complementation of G1 cyclin-deficient yeast cells, a novel alfalfa cyclin, designated cycMs4, was isolated. The predicted amino acid sequence of the cycMs4 gene is most similar to that of the Arabidopsis cyclin delta 3 gene. CycMs4 and cyclin delta 3 belong to the class of D-type cyclins and contain PEST-rich regions and a retinoblastoma binding motif. When comparing expression levels in different organs, cycMs4 transcripts were present predominantly in roots. Whereas expression of the cycMs4 gene was cell cycle-regulated in suspension-cultured cells, transcription in roots was observed to depend also on the positional context of the cell. When differentiated G0-arrested leaf cells were induced to resume cell division by treatment with plant hormones, cycMs4 transcription was induced before the onset of DNA synthesis. Whereas this induction was preceded by that of the cycMs3 gene, cycMs2 expression occurred later and at the same time as mitotic activity. These data suggest that cycMs4 plays a role in the G1-to-S transition and provide a model to investigate the plant cell cycle at the molecular level.

cycMs3, a novel B-type alfalfa cyclin gene, is induced in the G0-to-G1 transition of the cell cycle

Cyclins are key regulators of the cell cycle in all eukaryotes. We have previously isolated two B-type cyclin genes, cycMs1 and cycMs2, from alfalfa that are primarily expressed during the G2-to-M phase transition and are most likely mitotic cyclin genes. Here, we report the isolation of a novel alfalfa cyclin gene, termed cycMs3 (for cyclin Medicago sativa), by selecting for mating type alpha-pheromone-induced cell cycle arrest suppression in yeast. The central region of the predicted amino acid sequence of the cycMs3 gene is most similar to the cyclin box of yeast B-type and mammalian A- and B-type cyclins. In situ hybridization showed that cycMs3 mRNA can be detected only in proliferating cells and not in differentiated alfalfa cells. When differentiated G0-arrested cells were induced to reenter the cell cycle in the G1 phase and resume cell division by treatment with plant hormones, cycMs3 transcript levels increased long before the onset of DNA synthesis. In contrast, histone H3-1 mRNA and cycMs2 transcripts were not observed before DNA replication and mitosis, respectively. In addition, cycMs3 mRNA was found in all stages of the cell cycle in synchronously dividing cells, whereas the cycMs2 and histone H3-1 genes showed a G2-to-M phase- or S phase-specific transcription pattern, respectively. These data suggest that the role of cyclin CycMs3 differs from that of CycMs1 and CycMs2. We propose that CycMs3 helps control reentry of quiescent G0-arrested cells into the G1 phase of the cell cycle.

Rhizobium meliloti lipopolysaccharide and exopolysaccharide can have the same function in the plant-bacterium interaction

A fix region of Rhizobium meliloti 41 involved both in symbiotic nodule development and in the adsorption of bacteriophage 16-3 was delimited by directed Tn5 mutagenesis. Mutations in this DNA region were assigned to four complementation units and were mapped close to the pyr-2 and pyr-29 chromosomal markers. Phage inactivation studies with bacterial cell envelope preparations and crude lipopolysaccharides (LPS) as well as preliminary characterization of LPS in the mutants indicated that these genes are involved in the synthesis of a strain-specific LPS. Mutations in this DNA region resulted in a Fix- phenotype in AK631, an exopolysaccharide (EPS)-deficient derivative of R. meliloti 41; however, they did not influence the symbiotic efficiency of the parent strain. An exo region able to restore the EPS production of AK631 was isolated and shown to be homologous to the exoB region of R. meliloti SU47. By generating double mutants, we demonstrated that exo and lps genes determine similar functions in the course of nodule development, suggesting that EPS and LPS may provide equivalent information for the host plant.

Rhizobium fix genes mediate at least two communication steps in symbiotic nodule development

To identify bacterial genes involved in symbiotic nodule development, ineffective nodules of alfalfa (Medicago sativa) induced by 64 different Fix-mutants of Rhizobium meliloti were characterized by assaying for symbiotic gene expression and by morphological studies. The expression of leghemoglobin and nodulin-25 genes from alfalfa and of the nifHD genes from R. meliloti were monitored by hybridizing the appropriate DNA probes to RNA samples prepared from nodules. The mutants were accordingly divided into three groups. In group I none of the genes were expressed, in group II only the plant genes were expressed and in group III all three genes were transcribed. Light and electron microscopical analysis of nodules revealed that nodule development was halted at different stages in nodules induced by different group I mutants. In most cases nodules were empty lacking infection threads and bacteroids or nodules contained infection threads and a few released bacteroids. In nodules induced by a third mutant class bacteria were released into the host cells, however the formation of the peribacteroid membrane was not normal. On this basis we suggest that peribacteroid membrane formation precedes leghemoglobin and nodulin-25 induction, moreover, after induction of nodulation by the nod genes at least two communication steps between the bacteria and the host plants are necessary for the development of the mature nodule. By complementing each mutant of group I with a genomic R. meliloti library made in pLAFRl, four new fix loci were identified, indicating that several bacterial genes are involved in late nodule development.