Physiological and ecological responses to drought and heat stresses in Osmanthus fragrans ‘Boyejingui’

为了探讨植物对干旱、高温及协同胁迫的响应, 该研究以木犀(Osmanthus fragrans) ‘波叶金桂’为材料, 采用盆栽质量控水法模拟干旱胁迫(对照、轻度、中度和重度)和高温胁迫, 利用动态顶空气体循环吸附法和热脱附-气相色谱-质谱(TDS-GC-MS)联用技术对其挥发性有机化合物(VOCs)进行测定; 同时测定其非结构性碳(NSC)含量及次生代谢酶活性。结果表明: 干旱胁迫对‘波叶金桂’叶片NSC组分含量影响不显著; 可溶性糖和淀粉含量在高温胁迫下显著降低, 在协同胁迫后持续性下降, 重度协同胁迫下, 葡萄糖、果糖、蔗糖和淀粉分别比对照降低47.7%、46.4%、34.4%和38.2%。干旱胁迫和协同胁迫下3-羟基-3-甲基戊二酸单酰辅酶A还原酶(HMGR)、1-脱氧木酮糖-5-磷酸还原酶(DXR)活性表现出先上升后下降, 而脂氧合酶(LOX)活性表现出持续性上升趋势; 高温胁迫后, HMGR、DXR和LOX活性显著高于对照。干旱胁迫下萜烯类VOCs释放量表现出先上升后下降趋势, 中度干旱胁迫和高温胁迫下分别比对照高37.9%和32.3%; 协同胁迫下萜烯类释放量逐渐降低, 干旱、高温和协同胁迫诱导醛类释放量明显增加。上述结果表明: 干旱胁迫条件下, ‘波叶金桂’通过NSC进行自我渗透调节, 同时合成大量萜烯类化合物来提高抗旱性; ‘波叶金桂’调控萜烯类化合物合成以及绿叶挥发物(GLVs)的释放抵御高温胁迫; 协同胁迫下萜烯类化合物的合成途径受阻, ‘波叶金桂’提高GLVs合成与释放量抵御协同胁迫; 中度和重度协同胁迫导致‘波叶金桂’细胞膜严重受损, 自我调节能力降低。     

Levels of formaldehyde and TVOCs and influential factors of 100 underground station environments from 2013 to 2015

In this study, the environmental factors that affect airborne formaldehyde and total volatile organic compounds (TVOCs) were evaluated and the monthly variations in formaldehyde and TVOC levels in underground platforms of subway stations were compared. Formaldehyde level was determined from May 2013 to September 2015 for lines 1 to 4 of Seoul Metro. Samples for formaldehyde and TVOCs were collected at intervals of 30 min during a 60 min period, and then analyzed via high-performance liquid chromatography (HPLC) for formaldehyde and gas chromatography for TVOCs. Formaldehyde levels were correlated with depth of platform, whereas TVOC levels were negatively correlated with depth of platform. There were significant differences in levels of formaldehyde and TVOCs in 2013 and 2015 in the underground platforms. The highest levels of formaldehyde and TVOCs were in July from May to September, respectively (p < 0.05). Formaldehyde and TVOC levels varied greatly, depending on monthly variation and correlated with depth of platform. Therefore, Seoul Metro might need to manage the underground platforms at depth more carefully and further study the reasons behind the relatively high levels of formaldehyde and TVOC ranging from 12 to 22 m.     

Synthesis of novel Dy3+ activated Ba2CaZn2Si6O17 phosphors for white light‐emitting diodes

Dysprosium ion (Dy³⁺) activated Ba₂CaZn₂Si₆O₁₇ phosphors were synthesized using high temperature solid‐state reaction method. Powder X‐ray diffraction (PXRD) analysis confirmed the phase formation of the as‐prepared phosphors. Scanning electron microscopy (SEM) analysis disclosed an agglomeration of particles with an irregular morphology. Under 350 nm excitation, the emission spectrum of Dy³⁺ ions showed bands at 481 nm (blue), 577 nm (yellow) and 674 nm (red). The influence of the Dy³⁺ concentration on its emission intensity was investigated. The optimum concentration of Dy³⁺ ions in the Ba₂CaZn₂Si₆O₁₇:Dy³⁺ phosphors were found to be x = 0.06. The critical energy transfer distance was calculated. The fluorescence lifetime was also determined for Ba₂CaZn₂Si₆O₁₇:0.06Dy³⁺. The Commission International deI’Eclairage (CIE) chromaticity coordinates of the phosphor were calculated to be x = 0.304, y = 0.382. The activation energy for the thermal quenching was calculated to be 0.168 eV. These results indicated that the Ba₂CaZn₂Si₆O₁₇:Dy³⁺ phosphor might be a potential candidate for near ultraviolet (NUV)‐based white light‐emitting diodes.     

Preliminary results on the photoluminescence and optically stimulated luminescence in Cu‐doped and Ag‐doped ZnB2X4 (B = Li,Na, K: X = Cl,Br) compounds

Photoluminescence, and optically stimulated luminescence in ZnB₂X₄ (B; Li,Na,K: X; Cl,Br) compounds doped with Cu⁺ or Ag⁺ were studied. Double humped emission bands attributable to the activators were observed in all the samples. The observed photoluminescence of Cu⁺ and Ag⁺ could be identified with 3d⁹4s¹?3d¹⁰ and 4d⁹5s¹?5d¹⁰ transitions respectively. The longer wavelength band (400–500 nm range) could be attributed to the Cu⁺ or Ag⁺ ion replacing alkali ion at the octahedral alkali site whereas short wavelength band (340–400 nm range) is attributed to a Cu or Ag ion at tetrahedral zinc site. The short wavelength band was found to be intense compared with long wavelength and gave an indication that most of the Cu or Ag ions prefered a tetrahedral Zn site compared with the octahedral alkali site. All the samples exhibit optically stimulated luminescence (OSL). The sensitivity was found to be lattice dependent. The lowest sensitivity of about 1% compared with Al₂O₃:C was observed in lithium lattices whereas highest the sensitivity of about 290% was observed in the case of Cu‐doped ZnNa₂Br₄.     

Synthesis,nitric oxide release,and dipeptidyl peptidase-4 inhibition of sitagliptin derivatives as new multifunctional antidiabetic agents

Nitric oxide (NO) dysfunction has been found to be an important factor in both the development and progression of diabetic complications due to its many roles in the vascular system. Multifunctional compounds with hypoglycemic and endothelial protective action will be promising agents for the treatment of diabetes and its complications. In this study, a series of novel NO-donating sitagliptin derivatives and relevant metabolites were synthesized and evaluated as potential multifunctional hypoglycemic agents. All of synthetic compounds shown remarkable inhibitory activity against dipeptidyl peptidase IV (DPP-IV) in vitro and demonstrated excellent hypoglycemic activities in diabetic mice, similar to the activity of sitagliptin, and compounds T1-T4 shown different extents of NO-releasing abilities and potent antioxidant abilities in vivo. By screening in DPP-4, compound T4 was recognized as a potent DPP-4 inhibitor with the IC₅₀ value of 0.060?μM. Docking study revealed compound T4 has a favorable binding mode. Furthermore, compounds T1-T4 exhibited different extents of NO-releasing abilities and excellent anti-platelet aggregation in vitro. The overall results suggested that T4 could help to the amelioration of endothelial dysfunction by reducing blood glucose, lessening oxidative stress and raising NO levels as well as inhibiting platelet aggregation. Based on this research, compound T4 deserves further investigation as potential new multifunctional anti-diabetic agent with antioxidant, anti-platelet aggregation and endothelial protective properties.     

Monoterpene’s multiple free radical scavenging capacity as compared with the radioprotective agent cysteamine and amifostine

Monoterpenes are major active components of lavender, thyme, and mint. The X-ray radioprotective activity of pure monoterpenes is attributed to their scavenging ability against active species, but so far no firm evidence has been demonstrated. The objective of this study is to quantitatively determine antioxidant abilities of monoterpenes and collate it with radioprotective activity. Using multiple free-radical scavenging (MULTIS) method, we have determined the scavenging abilities of monoterpenes (linalool, thymol, and menthol) against six active species. A previous study has shown that the monoterpene linalool is a radioprotector for cellular systems, therefore, its scavenging ability was compared with known radioprotective agents such as cysteamine and amifostine. Results indicated that the monoterpene menthol but not linalool is a potent scavenger of reactive oxygen species and its scavenging magnitude is comparable to cysteamine and amifostine. This paper is first to show a correlation between ROS scavenging ability and radioprotective action.     

Cyclooxygenases and lipoxygenases are used by the fungus Podospora anserina to repel nematodes

Oxylipins are secondary messengers used universally in the living world for communication and defense. The paradigm is that they are produced enzymatically for the eicosanoids and non-enzymatically for the isoprostanoids. They are supposed to be degraded into volatile organic compounds (VOCs) and to participate in aroma production. Some such chemicals composed of eight carbons are also envisoned as alternatives to fossil fuels. In fungi, oxylipins have been mostly studied in Aspergilli and shown to be involved in signalling asexual versus sexual development, mycotoxin production and interaction with the host for pathogenic species. Through targeted gene deletions of genes encoding oxylipin-producing enzymes and chemical analysis of oxylipins and volatile organic compounds, we show that in the distantly-related ascomycete Podospora anserina, isoprostanoids are likely produced enzymatically. We show the disappearance in the mutants lacking lipoxygenases and cyclooxygenases of the production of 10-hydroxy-octadecadienoic acid and that of 1-octen-3-ol, a common volatile compound. Importantly, this was correlated with the inability of the mutants to repel nematodes as efficiently as the wild type. Overall, our data show that in this fungus, oxylipins are not involved in signalling development but may rather be used directly or as precursors in the production of odors against potential agressors.

Naturally occurring compounds in differentiation based therapy of cancer

Differentiation of cancer cells entails the reversion of phenotype from malignant to the original. The conversion to cell type characteristic for another tissue is named transdifferentiation. Differentiation/transdifferentiation of malignant cells in high grade tumor mass could serve as a nonaggressive approach that potentially limits tumor progression and augments chemosensitivity. While this therapeutic strategy is already being used for treatment of hematological cancers, its feasibility for solid malignancies is still debated. We will presently discuss the natural compounds that show these properties, with focus on anthraquinones from Aloe vera, Senna, Rheum sp. and hop derived prenylflavonoids.