Monitoring the oleuropein content of olive leaves and fruits using ultrasound‐ and salt‐assisted liquid–liquid extraction optimized by response surface methodology and high‐performance liquid chromatography

A novel and rapid ultrasound‐ and salt‐assisted liquid–liquid extraction coupled with high‐performance liquid chromatography has been optimized by response surface methodology for the determination of oleuropein from olive leaves. Box–Behnken design was used for optimizing the main parameters including ultrasound time (A), pH (B), salt concentration (C), and volume of miscible organic solvent (D). In this technique, a mixture of plant sample and extraction solvent was subjected to ultrasound waves. After ultrasound‐assisted extraction, phase separation was performed by the addition of salt to the liquid phase. The optimal conditions for the highest extraction yield of oleuropein were ultrasound time, 30 min; volume of organic solvent, 2.5 mL; salt concentration, 25% w/v; and sample pH, 4. Experimental data were fitted with a quadratic model. Analysis of variance results show that BC interaction, A², B², C², and D² are significant model terms. Unlike the conventional extraction methods for plant extracts, no evaporation and reconstitution operations were needed in the proposed technique.     

Structural modification on rupestonic acid leads to highly potent inhibitors against influenza virus

Molecular Diversity - Influenza viruses are responsible for seasonal epidemics and occasional pandemics, which cause significant morbidity and mortality. Although several drugs (adamantanes and...     

Non-equilibrium effects in chaperone-assisted translocation of a stiff polymer

Chaperone-assisted biopolymer translocation is the main model proposed for translocation in vivo. A dynamical Monte Carlo method is used to simulate the translocation of a stiff homopolymer through a nanopore driven by chaperones. Chaperones are proteins that bind to the polymer near the wall and prevent its backsliding through Cis side. The important parameters include binding energy, size and the local concentration of the chaperones. The profile of these local concentrations, build up the chaperones distribution. Here we investigate the effects of binding energy, size and the exponential distribution of chaperones in their equilibration in each step of the polymer translocation needed for stable translocation time. The simulation results show that in case of chaperones with the size of a monomer ($\lambda =1$) and/or positive effective binding energy and/or uniform distribution, the chaperones binding equilibration rate/frequency is less than 5 times per monomer. However, in some special cases in the exponential distribution of chaperones with size $\lambda >1$ and negative effective binding energy the equilibration rate will diverge to more than 20 times per monomer. We show that this non-equilibrium effect results in supper diffusion, seen before. Moreover, we confirm the equilibration process theoretically.     

Novel salep‐based chelating hydrogel for heavy metal removal from aqueous solutions

A novel optimized chelating hydrogel was synthesized via graft copolymerization of acrylamide and 2‐hydroxyethyl methacrylate (as two‐dentate chelating co‐monomer) onto salep (a multicomponent polysaccharide obtained from dried tubers of certain natural terrestrial orchids) using N,N′‐methylenebisacrylamide as a crosslinker and ammonium persulfate as an initiator. Reaction parameters (N,N′‐methylenebisacrylamide and ammonium persulfate amounts as well as acrylamide/2‐hydroxyethyl methacrylate weight ratio) affecting the water absorption of the chelating hydrogel were optimized using a systematic method to achieve a hydrogel with high swelling capacity as possible. Heavy metal ion adsorption capacity of the optimized hydrogel for metal ions [Cu (II), Pb (II), Cd (II), and Cr (III)] were investigated in aqueous media containing different concentrations of these ions (5–50 ppm). The results showed that the hydrogel have great potential for heavy metal removal from aqueous solutions. The hydrogel formation was confirmed by Fourier transform infrared spectroscopy, and surface morphology study of the hydrogel was performed by scanning electron microscope. Copyright © 2016 John Wiley & Sons, Ltd.     

Characterization and identification of chemical compositions in the extract of Artemisia rupestris L. by liquid chromatography coupled to quadrupole time-of-flight tandem mass spectrometry

Liquid chromatography coupled to negative electrospray ionization (ESI) tandem mass spectrometry (MS/MS) employing a time-of-flight tandem mass spectrometer was used in the structural determination of phenolic compounds and sesquiterpenoids occurring in the extract from Artemisia rupestris L. A total of 91 compounds including chlorogenic acid derivatives, flavonoids (aglycone, O-glycosyl, C-glycosyl and C,O-glycosyl), 2-phenoxychromones and guaiane sesquiterpenoids were identified by comparing the retention time and fragmentation behavior with reference standards or according to accurate mass measurement and the characteristic fragmentation at low and high collision energy. Most of these compounds were reported in Artemisia rupestris L. for the first time. Meanwhile, the proposed pathway and the major diagnostic fragmentation of 2-phenoxychromone and rupestonic acid were investigated to trace 2-phenoxychromone and rupestonic acid derivatives in crude plant extracts. According to these rules, we have successfully characterized five potential novel compounds including three 2-phenoxychromones (6-demethoxy-4'-O-methylcapillarisin-O-hexosylglucuronide, 6-demethoxy-4'-O-methylcapillarisin-O-pentosylhexoside and 6-demethoxy-4'-O-methylcapillarisin-O-deoxyhexosylhexoside) and two sesquiterpenoids (hexosyl-glycurinide-rupestonic acid and hexoside-rupestonic acid).     

A new chromone from seeds of <Emphasis Type="Italic">Cydonia oblonga</Emphasis>

The new chromone 5,7-dihydroxy-2-n-pentacosanylchromen-4-one (1) in addition to the three known compounds ursolic acid (2), tormentic acid (3), and β-daucosterol (4) were isolated from seeds of Cydonia oblonga. Their structures were determined based on their 1D and 2D NMR and HR-ESI-MS spectral data.     

The Antiproliferative and Apoptosis-Inducing Effects of the Red Macroalgae Gelidium latifolium Extract against Melanoma Cells

The red macroalga Gelidium latifolium is widely distributed in the coastal areas of Indonesia. However, current knowledge on its potential biological activities is still limited. In this study, we investigated the potential bioactive compounds in Gelidium latifolium ethanol extract (GLE), and its cytotoxic effects against the murine B16-F10 melanoma cell line. GLE shows high total phenolic content (107.06 ± 17.42 mg GAE/g) and total flavonoid content (151.77 ± 3.45 mg QE/g), which potentially contribute to its potential antioxidant activity (DPPH = 650.42 ± 2.01 µg/mL; ABTS = 557.01 ± 1.94 µg/mL). ESI-HR-TOF-MS analysis revealed large absorption in the [M-H]^- of 327.2339 m/z, corresponding to the monoisotopic molecular mass of brassicolene. The presence of this compound potentially contributes to GLE’s cytotoxic activity (IC₅₀ = 84.29 ± 1.93 µg/mL). Furthermore, GLE significantly increased the number of apoptotic cells (66.83 ± 3.06%) compared to controls (18.83 ± 3.76%). Apoptosis was also confirmed by changes in the expression levels of apoptosis-related genes (i.e., p53, Bax, Bak, and Bcl2). Downregulated expression of Bcl2 indicates an intrinsic apoptotic pathway. Current results suggest that components of Gelidium latifolium should be further investigated as possible sources of novel antitumor drugs.     

红景天苷分子结构与光谱的密度泛函理论分析

随着科学技术不断发展，中药质量控制和质量评价出现了越来越多的新技术。在中药标准化过程中，现代药学研究已经取得了许多令人瞩目的成果，检测方法和技术取得了很大的进展，由过去单一指标检测发展到多指标检测，但由于中草药成分复杂，作用机制不明等因素制约了中药的发展。红景天是一种少数民族药，是中医药发展不可或缺的组成部分。红景天苷是红景天中的主要有效成分之一，其提取、分离和纯化等方法报道甚多，但其分子键长键角二面角、前线轨道分布、表面静电势等分子参数却鲜有报道，这些都是决定其化学性质和反应机理的重要因素。采用Gaussian09W化学计算软件的密度泛函理论DFT/B3LYP方法和6-31(d)基组优化红景天苷分子，得到其稳定结构的键长、键角和二面角参数。在此稳定构型的基础上，计算其表面静电势（ESP）、最低空轨道（LUMO）、最高占据轨道（HOMO）、红外光谱（IR）和核磁共振波谱数据（NMR）。分别对IR和NMR峰位置进行了归属并与文献报道数据进行了对比，结果表明：计算结果的红外吸收频率没有出现虚频说明该优化结果是合理可靠的，最高占据轨道能量E=-5.82 eV，最低空轨道能量E=-0.000 42 eV，二者差值为5.81 eV。通过绘制了轨道的电子云分布图可以看出HOMO轨道主要分布于苯环，为π电子的成键轨道有一个节面；LUMO轨道也主要分布在苯环上，为π电子的反键轨道有两个节面。表面静电势的绘制可以直观地反映出分子中哪部分易发生亲核取代、哪部分易发生亲电取代反应。通过绘制第一激发态和基态电子差值，可以直观地得到电子的迁移方向。对红景天苷分子计算理论研究可以为进一步探索其化学反应机理、结构修饰和活性位点的确认等提供重要的参考依据和新思路。     

Total Synthesis of 3 (R)-Panaxynol

Panaxynol1,asacommonconstituentofmanyplantparts',wasfirstdescribedbyTakahashietal.2in1964asaconstituentofPanaxyginseng.C.A.MeyershowedinhisBioassayshowedthatpanaxynolhadselectiveinvitrocytotoxicityagainstL-1210',MKI,B-16,andL-929cancercelllinescomparedtonormalcellcultures4.TheabsoluteconfigurationhadbeenestablishedbyLarsenetal.5tobe3R.Hereinwereportthefirsttotalstereoselectivesynthesisofpanaxynol(l).C'-CIafragmentofpanaxynol1wasobtainedaccordingtothefollowingsequencefReagentsandconditio…