Synthesis,antimicrobial and anti-biofilm activities of novel Schiff base analogues derived from methyl-12-aminooctadec-9-enoate

A novel library of Schiff base analogues (5a–q) were synthesized by the condensation of methyl-12-aminooctadec-9-enoate and different substituted aromatic aldehydes. The synthesized compounds were thoroughly characterized by spectroscopic techniques (FT-IR, ¹H NMR, ¹³C NMR, ESI-MS and HRMS). The Schiff base analogues with different substitutions were screened for in vitro antibacterial activity against 7 different bacterial strains. Among these, the compounds with electron withdrawing substituent, namely chlorine (5a) and electron donating substituents, namely hydroxy (5n) and methoxy (5o), were found to exhibit excellent to good antimicrobial activities (MIC value 9–18 μM) against Staphylococcus aureus MTCC 96, Staphylococcus aureus MLS-16 MTCC 2940 and Bacillus subtilis MTCC 121. The products were also screened for anti-biofilm and MBC (Minimum Bactericidal Concentration) activities which exhibited promising activities.     

中国樟科非粮生物柴油能源植物资源的初步评价与筛选

通过调查我国现有樟科油脂植物资源,本研究对74份(9属47种)樟科油脂植物样品的含油率、脂肪酸甲酯组成、碘值及其油酸甲酯的理化性质进行了分析,并根据非粮生物柴油能源植物的评价标准,初步筛选出了19份(5属18种)具有开发利用价值的樟科非粮生物柴油能源植物,为樟科油脂植物资源的评价与筛选、深度开发与综合利用等提供参考依据。     

Comparative proteomic analysis of methyl jasmonate‐induced defense responses in different rice cultivars

Jasmonate is an important endogenous chemical signal that plays a role in modulation of plant defense responses. To understand its mechanisms in regulation of rice resistance against the fungal pathogen Magnaporthe oryzae, comparative phenotype and proteomic analyses were undertaken using two near‐isogenic cultivars with different levels of disease resistance. Methyl‐jasmonate (MeJA) treatment significantly enhanced the resistance against M. oryzae in both cultivars but the treated resistant cultivar maintained a higher level of resistance than the same treated susceptible cultivars. Proteomic analysis revealed 26 and 16 MeJA‐modulated proteins in resistant and susceptible cultivars, respectively, and both cultivars shared a common set of 13 proteins. Cumulatively, a total of 29 unique MeJA‐influenced proteins were identified with many of them known to be associated with plant defense response and ROS accumulation. Consistent with the findings of proteomic analysis, MeJA treatment increased ROS accumulation in both cultivars with the resistant cultivar showing higher levels of ROS production and cell membrane damage than the susceptible cultivar. Taken together, our data add a new insight into the mechanisms of overall MeJA‐induced rice defense response and provide a molecular basis of using MeJA to enhance fungal disease resistance in resistant and susceptible rice cultivars.     

紫杉醇合成中甲基茉莉酮酸作用位点与配伍特性研究

以简化的紫杉醇事成途径基础上,提出了一种拟稳态转移模型。模型从诱导子作用在力改变的角度,成功地解释了诱导了作用下紫杉烷含量的变化,并给出了不同位为酶活力的提高与各代谢产物浓度转移模式间的关系,提供了一种从中间代谢产物稳态的转移模式确定诱导子的作用位点的方法。在适宜浓度甲基茉莉酮酸（ＭＪ）诱导下１０去乙酰基巴卡享Ⅲ（１０－ＤＡＢ）与巴卡Ⅲ（ＢａｃｃａｔｉｎⅢ）含量下降而紫梆醇含量上升,确定ＭＪ在紫杉     

石灰菌代谢产物的化学研究(Ⅰ)

从石灰菌(Lactarius hysginus Fr.)提取物的中性部分,分离得到六个化合物,经物理常数和光谱分析,鉴定为麦角甾醇(A)、硬脂酸甲脂(B)、N-苯基-2-萘胺(C)、24E-麦角甾7,22-二烯-6-酮一3β,5α-二醇(D)、庚酰胺(E)、24E-麦角甾-7.22-二烯-3β,5α,6β-三醇(F),其中化合物D作为天然产物尚未见文献报道。     

Role of base excision repair in maintaining the genetic and epigenetic integrity of CpG sites

Cytosine methylation at CpG dinucleotides is a central component of epigenetic regulation in vertebrates, and the base excision repair (BER) pathway is important for maintaining both the genetic stability and the methylation status of CpG sites. This perspective focuses on two enzymes that are of particular importance for the genetic and epigenetic integrity of CpG sites, methyl binding domain 4 (MBD4) and thymine DNA glycosylase (TDG). We discuss their capacity for countering C to T mutations at CpG sites, by initiating base excision repair of G·T mismatches generated by deamination of 5-methylcytosine (5mC). We also consider their role in active DNA demethylation, including pathways that are initiated by oxidation and/or deamination of 5mC.     

Setting the stage for evolution of a new enzyme

The evolution of novel enzymes has fueled the diversification of life on earth for billions of years. Insights into events that set the stage for the evolution of a new enzyme can be obtained from ancestral reconstruction and laboratory evolution. Ancestral reconstruction can reveal the emergence of a promiscuous activity in a pre-existing protein and the impact of subsequent mutations that enhance a new activity. Laboratory evolution provides a more holistic view by revealing mutations elsewhere in the genome that indirectly enhance the level of a newly important enzymatic activity. This review will highlight recent studies that probe the early stages of the evolution of a new enzyme from these complementary points of view.     

Synthesis and radical-scavenging activity of C-methylated fisetin analogues

The radical-scavenging reaction of fisetin, a natural antioxidant found in strawberries, is known to proceed via hydrogen transfer to produce a fisetin radical intermediate. Thus, introduction of an electron-donating group into the fisetin molecule is expected to stabilize the radical, leading to enhanced radical-scavenging activity. In this study, fisetin derivatives in which methyl substituents were introduced at the ortho positions relative to the catechol hydroxyl groups were synthesized and their radical scavenging activities were evaluated and compared with that of the parent fisetin molecule. Among the methyl derivatives, 5′-methyl fisetin, in which the inherent planar structure of fisetin was retained, exhibited the strongest radical scavenging activity. Introduction of methyl substituents may be effective for the enhancement of various biological activities of antioxidants, particularly radical-scavenging activity.     

Methyl-containing pharmaceuticals: Methylation in drug design

The importance of methyl groups in modulating biological activity, selectivity, solubility, metabolism and pharmacokinetic/pharmacodynamic properties of biologically active molecules is highlighted. The information compiled from selected beneficial cases, focuses mostly on marketed drugs and clinical candidates, and indicates that the methylation strategy has been successful in drug design.