Stereoselective Degradation and Microbial Epimerization of Triadimenol in Soils

Triadimenol is a widely used triazole fungicide and consists of four stereoisomers with 1R,2S, 1S,2R, 1R,2R, and 1S,2S configurations. The trans‐enantiomeric pair (1R,2S‐isomer and 1S,2R‐isomer) is also called triadimenol‐A and the cis‐enantiomeric pair (1R,2R‐isomer and 1S,2S‐isomer) triadimenol‐B. In this study, the stereoselective degradation and chiral stability of triadimenol in two soils were investigated in details. The dissipation of technical triadimenol, a 6:1 mixture of triadimenol‐A and triadimenol‐B, showed significant epimerization from triadimenol‐A to triadimenol‐B occurred along with the dissipation process. The degradation exhibited some stereoselectivity, resulting in a concentration order of 1S,2S > 1R,2R > 1R,2S > 1S,2R or 1S,2S > 1R,2R > 1S,2R > 1R,2S at the end of the 100 days incubation for Baoding soil or Wuhan soil, respectively. Further incubation of triadimenol‐B revealed no epimerization, i.e. triadimenol‐B was configurationally stable in soil, and 1R,2R‐triadimenol degraded slightly slower in the former part and slightly faster in the later part of the incubation than 1S,2S‐triadimenol. Moreover, by incubation of enantiopure 1S,2R‐triadimenol and 1R,2S‐triadimenol, the results documented the epimerization for each enantiomer occurred at both C‐1 and C‐2 positions. Finally, the present work also documented that the enantiomerization reaction for all the four stereoisomers was nearly negligible in the soils. Chirality 25:355‐360:, 2013. © 2013 Wiley Periodicals, Inc.     

Integration of metabolomics and in vitro metabolism assays for investigating the stereoselective transformation of triadimefon in rainbow trout

Triadimefon is a systemic agricultural fungicide of the triazole class whose major metabolite, triadimenol, also a commercial fungicide, provides the majority of the actual fungicidal activity, i.e., inhibition of steroid demethylation. Both chemicals are chiral: triadimefon has one chiral center with two enantiomers while its enzymatic reduction to triadimenol produces a second chiral center and two diastereomers with two enantiomers each. All six stereoisomers of the two fungicides were separated from each other using a chiral BGB‐172 column on a GC‐MS system so as to follow stereospecificity in metabolism by rainbow trout hepatic microsomes. In these microsomes the S‐(+) enantiomer of triadimefon was transformed to triadimenol 27% faster than the R‐(?) enantiomer, forming the four triadimenol stereoisomers at rates different from each other. The most fungi‐toxic stereoisomer (1S,2R) was produced at the slowest rate; it was detectable after 8 h, but below the level of method quantitation. The triadimenol stereoisomer ratio pattern produced by the trout microsomes was very different from that of the commercial triadimenol standard, in which the most rat‐toxic pair of enantiomers (known as “Diastereomer A”) is about 85% of the total stereoisomer composition. The trout microsomes produced only about 4% of “Diastereomer A”. Complementary metabolomic studies with NMR showed that exposure of the separate triadimefon enantiomers and the racemate to rainbow trout for 48 h resulted in different metabolic profiles in the trout liver extracts, i.e., different endogenous metabolite patterns that indicated differences in effects of the two enantiomers. Chirality, 2010. © 2009 Wiley‐Liss, Inc.     

Ecological risk assessment of heavy metal contamination in mangrove habitats,using biochemical markers and pollution indices: A case study of Avicennia marina L. in the Rabigh lagoon,Red Sea

Contamination of mangrove ecosystems, including those of the Red Sea area, has caused serious concern globally. Spatial distribution of heavy metals and their bioaccumulation in one of the common mangrove plants of Saudi Arabia, Avicennia marina L., was evaluated in 8 stations at the Rabigh lagoon to assess the ecological risks due to heavy metal contamination. Among all the heavy metals, Fe concentration was recorded highest (8939.38 ± 312.63 mg/kg) at station S4. Contamination factor (CF) values for all heavy metals determined in this study were recorded in ascending order as Cu < Cr < Mn < Zn < Fe < Ni < Pb < Cd, with the pollution load index pattern recorded in descending order as S6 > S4 > S3 > S5 > S7 > S1 > S8 > S2. Bio-concentration factor (BCF) was <1 for all the heavy metals and there was a positive correlation between the antioxidants and lead (Pb), which can be a result of the ability of A. marina to exclude or detoxify this metal by its mechanism of exclusion or detoxification. A significant correlation existed between the heavy metals concentration in sediment and A. marina leaves at one combination or the other, except for Cu and Cd, which do not correlate with any other metal concentration. The information provided in the present study can be used in the monitoring and measurement of heavy metal pollution in marine ecosystems or other aquatic environments, to prevent several ecological risks to the mangrove ecosystem.     

The influence of microbial communities for triadimefon enantiomerization in soils with different pH values

Enantiomers of chiral molecules can undergo interconversion leading to markedly different toxicities, which can introduce significant uncertainty when evaluating biological and environmental fates. However, enantiomerization (the reversible conversion of one enantiomer into the other) related to soil microorganism is rarely understood. For better understanding, S‐triadimefon and R‐triadimefon enantiopure were incubated in different soils with different pH value. Both high‐performance liquid chromatography and high‐throughput sequencing technology were used to explore target analytes quantitatively and microbial taxa related to the conversion process. Results revealed a significant enantiomerization among the soils. The alkaline soil from Beijing had a faster conversion than neutral soil from Changchun, while acidic soil from Wuhan had no conversion. At the same results, analysis of bacteria community showed higher abundance of Arthrobacter and Halomonas genus in alkaline soil than neutral soil after treatments, but the acidic soil was lower. Moreover, Arthrobacter and Halomonas were responsible for converting S‐triadimefon to R‐triadimefon and R‐triadimefon to S‐triadimefon in alkaline and neutral soil, respectively. Thus, these genera may be one of the reasons to explain the enantiomerization in different soils observed in this study. Thus, research at microbial level is necessary for efficient ecological risk assessment of chiral fungicide.     

The association between algae organisms and environmental factors in Hai-tan Strait of Fujian,China

27 points were surveyed, and then algae and seawater samples were collected in Hai-tan Strait. The correlation on HAB (harmful algae blooms) species and environmental factors were studied. Water temperature (T) and salinity (S) ranging from 11.9 °C to 27.8 °C and 20.4 to 33.7 in the year, respectively. Dissolved inorganic nitrogen (DIN) in surface water ranged from 0.098 to 0.776 mg·L^?1, PO₄-P ranged from 0.0016 to 0.0729 mg·L^?1. And Eutrophication index (E) ranged from 0.03 to 13.8, varied different. 102 species of algae belonging to 4 classes and 52 genera were identified. The diversity was increasingly from winter to summer, decreasingly from summer to autumn, highest in summer. 49 species of red tide organisms were found in Hai-tan Strait, main two classes were Bacillariophyta and Pyrrophyta. Ceratium tripos and Noctiluca scintillans were dominant species in spring, Skeletonema costatum was common, and was also mainly HABs dominant species in summer, autumn and winter. Pearson correlation and Canonical correspondence analysis (CCA) showed that environment factors had significant correlation with dominance HABs species in different extent, and the ordination result was that S(Salinity) > T(Temperature) > pH > E(Eutrophication index) > DO(dissolved oxygen) > DIN > PO₄-P. Prorocentrum donghaiense, Skeletonema costatum, Noctiluca scintillans and Karenia mikimotoi caused many times red tide in 2011 to 2016. However, Prorocentrum donghaiense and Karenia mikimotoi cell density was low in survey year. North of the strait and east coast of the southern strait were sensitive sea area of red tide. The work highlights for the first time ecological characteristic of HAB was studied in Hai-tan Strait. Further, the data and results of this study will help us to improve efficiency for controlling HAB. Even, it is worthwhile to the management and response to the red tide disaster. Ordination result can also be a good indicator of ecological risk.     

An Integrated Experimental and Computational Approach for Characterizing the Kinetics and Mechanism of Triadimefon Racemization

Enantiomers of chiral molecules commonly exhibit differing pharmacokinetics and toxicities, which can introduce significant uncertainty when evaluating biological and environmental fates and potential risks to humans and the environment. However, racemization (the irreversible transformation of one enantiomer into the racemic mixture) and enantiomerization (the reversible conversion of one enantiomer into the other) are poorly understood. To better understand these processes, we investigated the chiral fungicide, triadimefon, which undergoes racemization in soils, water, and organic solvents. Nuclear magnetic resonance (NMR) and gas chromatography / mass spectrometry (GC/MS) techniques were used to measure the rates of enantiomerization and racemization, deuterium isotope effects, and activation energies for triadimefon in H₂O and D₂O. From these results we were able to determine that: 1) the alpha‐carbonyl carbon of triadimefon is the reaction site; 2) cleavage of the C‐H (C‐D) bond is the rate‐determining step; 3) the reaction is base‐catalyzed; and 4) the reaction likely involves a symmetrical intermediate. The B3LYP/6–311 + G** level of theory was used to compute optimized geometries, harmonic vibrational frequencies, nature population analysis, and intrinsic reaction coordinates for triadimefon in water and three racemization pathways were hypothesized. This work provides an initial step in developing predictive, structure‐based models that are needed to identify compounds of concern that may undergo racemization. Chirality 28:633–641, 2016. © 2016 Wiley Periodicals, Inc.     

Lasiolactols A and B Produced by the Grapevine Fungal Pathogen Lasiodiplodia mediterranea

A strain of Lasiodiplodia mediterranea, a fungus associated with grapevine decline in Sicily, produced several metabolites in liquid medium. Two new dimeric γ‐lactols, lasiolactols A and B ( 1 and 2 ), were characterized as (2S*,3S*,4R*,5R*,2′S*,3′S*,4′R*,5′R*)‐ and (2R*,3S*,4R*,5R*,2′R*,3′S*,4′R*,5′R*)‐(5‐(4‐hydroxymethyl‐3,5‐dimethyl‐tetrahydro‐furan‐2‐yloxy)‐2,4‐dimethyl‐tetrahydro‐furan‐3‐yl]‐methanols by IR, 1D‐ and 2D‐NMR, and HR‐ESI‐MS. Other four metabolites were identified as botryosphaeriodiplodin, (5R)‐5‐hydroxylasiodiplodin, (–)‐(1R,2R)‐jasmonic acid, and (–)‐(3S,4R,5R)‐4‐hydroxymethyl‐3,5‐dimethyldihydro‐2‐furanone ( 3  –  6 , resp.). The absolute configuration (R) at hydroxylated secondary C‐atom C(7) was also established for compound 3 . The compounds 1  –  3 , 5, and 6 , tested for their phytotoxic activities to grapevine cv. Inzolia leaves at different concentrations (0.125, 0.25, 0.5, and 1 mg/ml) were phytotoxic and compound 5 showed the highest toxicity. All metabolites did not show in vitro antifungal activity against four plant pathogens.     

Impact of microorganisms,humidity, and temperature on the enantioselective degradation of imazethapyr in two soils

Imazethapyr (IM) is a chiral herbicide composed of an (−)‐R‐enantiomer and an (+)‐S‐enantiomer with differential herbicidal activity. In this study, the effects of microbial organisms, humidity, and temperature on the selective degradation of the (−)‐R‐ and (+)‐S‐enantiomers of IM were determined in silty loam (SL) and clay loam (CL) soil with different pH values. The (−)‐R‐enantiomer of IM was preferentially degraded in two soils under different microorganism, humidity, and temperature conditions. The average half‐lives of R‐IM ranged from 43 to 66.1 days and were significantly shorter (P <  0.05) than those of S‐IM, which ranged from 51.4 to 79.8 days. The enantiomer fraction (EF = (+)‐S‐enantiomer/((−)‐R‐enantiomer + (+)‐S‐enantiomer)) values were used to describe the enantioselectivity of degradation of IM were >0.5 (P <  0.05) in two unsterilized soils under different humidity and temperature conditions. The highest EF values were observed at unsterilized CL soil samples under 50% maximum water‐holding capacity (MWHC) and 25 °C environmental conditions. The EF values of the IM enantiomers were significantly higher (P <  0.05) in CL soils (higher pH = 5.81) and were 0.581 (unsterilized) and 0.575 (50% MWHC; 25 °C) compared with those recorded in SL soil (lower pH = 4.85). In addition, this study revealed that microbial organisms preferentially utilized the more herbicidal active IM enantiomer.     

Bioaccumulation of heavy metals in the different tissues of Mackerel scad,Decapterus macarellus (Cuvier, 1833) collected from Karachi and Gwadar Coasts of Pakistan

IntroductionAmong other aquatic animals, fish can also accumulate a large number of toxic metals in their various body organs, which may enter in the human body and cause serious health issues. Therefore, the basic aim of this study was to observe the level of some heavy metals (i.e., Pb, Fe, Cu, Cd, Cr) found in the different tissues of Decapterus macarellus collected from the Karachi and Gwadar coasts of Pakistan.MethodsAbout 200 fish samples of five different size groups of Decapterus macarellus were collected from Gwadar and Karachi fish harbors during April to September 2020. Total 10 samples of each size group i.e., S1, S2, S3, S4 & S5 were collected from each coast. Heavy metals were analyzed in fish samples by using the atomic absorption spectrophotometer (AAS).ResultsThe overall results revealed that some metals like Cu, Pb, Cd & Cr contents were high in the stomach, while less in the muscles. Whereas, the concentration of Fe was found to be high in the liver, while low in skin of fish. The average values of bioaccumulation of these heavy metals (BAF) were found in decreasing order of Cu > Cd > Fe > Cr > Pb. In this study, except Cd and Cr, all metals were found within the permissible limits. Both sediment and water from the selected site areas were also analyzed to observe their pollution levels in the order of; sediment > water > fish tissues.ConclusionThus, it was concluded that the Karachi environment was much more polluted than the Gwadar environment because it is in an industrial unit and a busy sea site for trade. Moreover, consuming muscles from this species is safe for human health except for iron toxicity, but the use of the liver is not beneficial for all selected metals. Thus, the present work will also be helpful to monitor these toxic metals in a food chain and maintain a healthy life, and reduce all kinds of health risks associated with them.     

High‐Throughput Chiral LC–MS/MS Method Using Overlapping Injection Mode for the Determination of Pantoprazole Enantiomers in Human Plasma with Application to Pharmacokinetic Study

A sensitive and high‐throughput chiral liquid chromatography–tandem mass spectrometry method was developed and validated for the quantification of R‐pantoprazole and S‐pantoprazole in human plasma. Sample extraction was carried out by using ethyl acetate liquid–liquid extraction in 96‐well plate format. The separation of pantoprazole enantiomers was performed on a CHIRALCEL OJ‐RH column and an overlapping injection mode was used to achieve a run time of 5.0 min/sample. The mobile phase consisted of 1) 10 mM ammonium acetate in methanol: acetonitrile (1:1, v/v) and 2) 20 mM ammonium acetate in water. Isocratic elution was used with flow rate at 500 μL/min. The enantiomers were quantified on a triple‐quadrupole mass spectrometer under multiple reaction monitoring (MRM) mode with m/z 382.1/230.0 for pantoprazole and m/z 388.4/230.1 for pantoprazole‐d7. Linearity from 20.0 to 5000 ng/mL was established for each enantiomer (r² > 0.99). Extraction recovery ranged from 91.7% to 96.4% for R‐pantoprazole and from 92.5% to 96.5% for S‐pantoprazole and the IS‐normalized matrix factor was 0.98 to 1.07 for R‐pantoprazole and S‐pantoprazole, respectively. The method was demonstrated with acceptable accuracy, precision, selectivity, and stability and the method was applied to support a pharmacokinetic study of a phase I clinical trial of racemic pantoprazole in healthy Chinese subjects. Chirality 28:569–575, 2016. © 2016 Wiley Periodicals, Inc.     

Enantiomeric Separation and Simulation Studies of Pheniramine,Oxybutynin, Cetirizine,and Brinzolamide Chiral Drugs on Amylose‐Based Columns

Solid phase extraction ( SPE)‐chiral separation of the important drugs pheniramine, oxybutynin, cetirizine, and brinzolamide was achieved on the C₁₈ cartridge and AmyCoat (150 x 46 mm) and Chiralpak AD (25 cm x 0.46 cm id) chiral columns in human plasma. Pheniramine, oxybutynin, cetirizine, and brinzolamide were resolved using n‐hexane‐2‐PrOH‐DEA (85:15:0.1, v/v), n‐hexane‐2‐PrOH‐DEA (80:20:0.1, v/v), n‐hexane‐2‐PrOH‐DEA (70:30:0.2, v/v), and n‐hexane‐2‐propanol (90:10, v/v) as mobile phases. The separation was carried out at 25 ± 1 ºC temperature with detection at 225 nm for cetirizine and oxybutynin and 220 nm for pheniramine and brinzolamide. The flow rates of the mobile phases were 0.5 mLmin^‐1. The retention factors of pheniramine, oxybutynin, cetirizine and brinzolamide were 3.25 and 4.34, 4.76 and 5.64, 6.10 and 6.60, and 1.64 and 2.01, respectively. The separation factors of these drugs were 1.33, 1.18, 1.09 and 1.20 while their resolutions factors were 1.09, 1.45, 1.63 and 1.25, and 1.15, respectively. The absolute configurations of the eluted enantiomers of the reported drugs were determined by simulation studies. It was observed that the order of enantiomers elution of the reported drugs was S‐pheniramine > R‐pheniramine; R‐oxybutynin > S‐oxybutynin; S‐cetirizine > R‐cetirizine; and S‐brinzolamide > R‐brinzolamide. The mechanism of separation was also determined at the supramolecular level by considering interactions and modeling results. The reported SPE‐chiral high‐performance liquid chromatography ( HPLC) methods are suitable for the enantiomeric analyses of these drugs in any biological sample. In addition, simulation studies may be used to determine the absolute configuration of the first and second eluted enantiomers. Chirality 26:136–143, 2014. © 2014 Wiley Periodicals, Inc.     

Supramolecular solvent‐based vortex‐mixed microextraction: Determination of chiral triazole fungicide in beer samples

A supramolecular solvent composed of decanol in tetrahydrofuran/water was utilized for the simultaneous microextraction of chiral triadimefon and triadimenol in beer samples. Supramolecular solvents are nanostructured amphiphilic liquids that contain aqueous cavities, and the size of those cavities can be adjusted by the ratio of decanol, tetrahydrofuran, and water. The target analytes were mixed into the matrix sample and extracted in the supramolecular solvent phase, which was followed by separation and quantification by chiral liquid chromatography‐mass spectrometry. The influences of some analytical parameters and matrix components were all examined. Under the optimized conditions, the method detection limits were in the range of 0.24 to 0.98 μg L^?1 (at a signal/noise of 3), with relative standard deviations between 1.6 and 5.7%. The linearities of the calibration plots were between 0.5 to 50 (triadimenol) and 1.0 to 100 μg L^?1 (triadimefon). When this method was applied to a spiked beer sample, the recoveries ranged from 84 to 100%.     

Structure-activity relationship analysis of dammarane-type natural products as muscle-type creatine kinase activators

Muscle-type creatine kinase (CK-MM) is the target protein of ginsenosides in skeletal muscle. 20(S)-protopanaxadiol [20(S)-PPD] is an activator of CK-MM and exerts an anti-fatigue effect. In this study, twelve dammarane-type compounds were used for structure-activity relationship analysis in terms of enzyme activity, intermolecular interaction, and molecular docking. Enzyme activity analysis showed that 20(S)-PPD, 20(R)-PPD, 20(S)-protopanaxatriol [20(S)-PPT], 25-OH-PPD, 24-COOH-PPD, panaxadiol (PD), and ginsenoside Rh2 significantly increased CK-MM activity. Panaxatriol (PT), ocotillol, ginsenoside Rg1, and ginsenoside Rd had no significant influence on CK-MM activity, while jujubogenin inhibited its activity. Biolayer Interferometry (BLI) assay produced the same results as those on enzyme activity. The interaction intensity between dammarane-type compounds and CK-MM was linearly related to the compounds’ maximum increment rate of enzyme activity. Molecular docking showed the following sequence of docking scores: Rd > Rg1 > Rh2 > 24-COOH-PPD > 20(S)-PPD > 20(S)-PPT > 25-OH-PPD > 20(R)-PPD > ocotillol > PT > PD > jujubogenin. We demonstrated that 20(S)-PPD was the best activator of CK-MM among the 12 dammarane-type compounds. The cyclization of the dammarane side chain, the hydroxyl group at position C⁶, and the glycosylation of C³, C⁶, and C²⁰ reduced the ability to activate CK-MM. These findings can help in the development of enhanced CK-MM activators through structural modification.     

A chiral,porous, organic cage‐based,enantioselective potentiometric sensor for 2‐aminobutanol

A new enantioselective potentiometric sensor containing R‐type chiral porous organic cage CC9 as the chiral selector was designed for the assay of 2‐aminobutanol. Optimized membrane electrodes displayed a linear dynamic range from 10⁻³ ~ 10⁻¹ mol·L⁻¹ with a detection limit of 2.5 × 10⁻⁴ mol·L⁻¹ and a Nernstian response of 27 ± 0.5mV·decade⁻¹ toward S‐2‐aminobutanol within the pH range 7.0–10.0. The potentiometric enantioselectivity coefficient ( ) of this sensor was −1.333, indicating that the porous organic cage‐based electrode exhibited good discrimination toward S‐2‐aminobutanol over R‐2‐aminobutanol.     

Stereoselective interaction of an azole antifungal agent with its target, lanosterol 14 alpha-demethylase (cytochrome P-45014DM): a model study with stereoisomers of triadimenol and purified cytochrome P-45014DM from yeast

The effect of the four triadimenol stereoisomers on the purified yeast lanosterol 14 alpha-demethylase (cytochrome P-45014DM), the primary target of azole antifungal agents, was studied. (1S,2R)-Triadimenol was the most potent demethylase inhibitor and bound quantitatively to the enzyme below 0.05 microM. This isomer also interfered with the chemical reduction of cytochrome P-45014DM and the binding of CO to the cytochrome. The other isomers showed a lower inhibitory effect on the enzyme, and the order of activity was (1R,2R) greater than (1R,2S) greater than or equal to (1S,2S). Based on these findings and the reported preferred conformations for the triadimenol stereoisomers (Anderson, N.H. et al., Pestic. Sci. 15:310-316, 1984), it is predicted that orientation of the hydrophobic tert-butyl and p-chlorophenyl groups relative to the azole nitrogen is important to fit the antifungal agent in the active site of the demethylase.     

水环境中药物和个人护理品(PPCPs)的污染现状及对藻类的毒性研究进展

药物和个人护理品(PPCPs)因持续排放到水环境且对水生态环境和人类健康造成潜在威胁而受到广泛关注.藻类作为水体重要的初级生产者,对水体的生态平衡和稳定起着重要的作用.本文围绕地表水PPCPs污染,介绍了不同国家和地区地表水体中PPCPs的浓度分布和污染特征,并从毒性效应、生物累积及潜在的生态风险等方面,综述了PPCPs对藻类的污染生态学研究进展,阐述PPCPs对藻类的毒性效应及机制,PPCPs在藻类中的生物累积,以及地表水体PPCPs的生态风险,为地表水体PPCPs的相关标准制定和修订,以及水体生态环境健康风险评价提供参考.     

Assessment of the bioaccumulation pattern of Pb,Cd, Cr and Hg in edible fishes of East kolkata Wetlands,India

Waste water fed pisciculture is nowadays a common feature in aquaculture belts across the globe. East Kolkata Wetlands (EKW) a nature’s wonder where waste water fed natural aquaculture beltis is active for more than 70 years now and is efficiently operating as a natural waste management system. The peri urban wetland is also a site of international importance and is listed in Ramsar. Field and lab-based investigations were carried out using three commonly edible carp variety of fishes such as Rohu (Labeorohita), Catla (Catlacatla) and Nile Tilapia (Oreochromisniloticus) collected from ponds (bheries) of the wetland located on the eastern fringes of Kolkata, India. The lab-based analysis revealed the presence of toxic metals such as Cr, Pb, Cd and Hg in the samples with the seasonal order of accumulation being monsoon > post-monsoon > winter > pre-monsoon in the successive years of 2016, 2017 and 2018. Bio-accumulation of toxic heavy metals in fishes follows the order Tilapia > Rohu > Catla where as the bioaccumulation pattern of toxic metals shows the trend Pb > Cd > Cr > Hg across all the seasons and years. The ambient media was also investigated to understand in detail the bioaccumulation pattern at different trophic levels of the ecosystem. Water and sediments were analyzed to evaluate the contamination of toxic heavy metals from point and non-point sources. Current study shows the observed bioaccumulation pattern of the toxic heavy metals in one of the fragile ecosystems that raises an important question of environmental safety in the food we intake on daily basis.     

Combined treatment of rituximab,idarubicin, dexamethasone,cytarabine, methotrexate with radiotherapy for primary central nervous system lymphoma

The overall response rates and long‐term survival of primary central nervous system lymphoma (PCNSL) are still significantly inferior to the results achieved in similar subtypes of extranodal non‐Hodgkin's lymphoma. It is clearly necessary to investigate new therapeutic methods on PCNSL. We encountered three patients histologically documented PCNSL as diffuse large B‐cell lymphoma (DLBCL). They were treated with R‐IDARAM which comprised rituximab, idarubicin, dexamethasone, cytarabine and methotrexate. Patient 1 received stereotactic brachytherapy (SBT) prior to chemotherapy performed with iodine‐125 seeds (cumulative therapeutic dose 50 Gy). After six cycles of R‐IDARAM at 3‐weekly intervals, radiotherapy was applied at a dosage of 2000–4000 cGy in conventional schedule (180 or 200 cGy/day) to whole brain or spinal cord in all patients. Complete remission (CR) was achieved after first two cycles of R‐IDARAM in all patients. All three patients remained in CR at the time of this report with a median duration of follow‐up of 23 months (ranging from 13 to 41 months). Three patients have been alive for 41, 13, 16 months respectively until now. The patient with the longest survival time was the one given SBT prior to chemotherapy. This study suggests that R‐IDARAM combining with radiotherapy maybe a high effective regimen in PCNSL patients especially those with primary central nervous system DLBCL. A comprehensive treatment combining internal radiotherapy by SBT, modified R‐IDARAM and followed reduced external radiotherapy may be a new treatment concept for PCNSL with higher efficiency and lower toxicity.     

Examination of the structures of several glycerolipids from marine macroalgae by NMR and GC‐MS

Several classes of glycerolipids were isolated from the total lipids of the algae Saccharina cichorioides, Eualaria fistulosa, Fucus evanescens, Sargassum pallidum, Silvetia babingtonii (Ochrophyta, Phaeophyceae), Tichocarpus crinitus, and Neorhodomela larix (Rhodophyta, Florideophyceae). The structures of these lipids were examined by nuclear magnetic resonance (NMR) spectroscopy, including 1D (¹H and ¹³C) and 2D (COSY, HSQC and HMBC) experiments. All of the investigated algae included common galactolipids and sulfonoglycolipids as the major glycolipids. Minor glycolipids isolated from S. cichorioides, T. crinitus, and N. laris were identified as lyso‐galactolipids with a polar group consisted of the galactose. Comparison of the ¹H NMR data of minor nonpolar lipids isolated from the extracts of the brown algae S. pallidum and F. evanescens with the ¹H NMR data of other lipids allowed them to be identified as diacylglycerols. The structures of betaine lipids isolated from brown algae were confirmed by NMR for the first time. The fatty acid compositions of the isolated lipids were determined by gas chromatography‐mass spectrometry.     

Mass spectrometry analysis of human P2X1 receptors; insight into phosphorylation,modelling and conformational changes

Recombinant FlagHis₆ tagged Human P2X1 receptors expressed in HEK293 cells were purified, digested with trypsin and analysed by mass spectroscopy (96% coverage following de‐glycosylation and reduction). The receptor was basally phosphorylated at residues S387, S388 and T389 in the carboxyl terminus, a triple alanine mutant of these residues had a modest ~ 25% increase in current amplitude and recovery from desensitization. Chemical modification showed that intracellular lysine residues close to the transmembrane domains and the membrane stabilization motif are accessible to the aqueous environment. The membrane‐impermeant cross‐linking reagent 3,3′‐Dithiobis (sulfosuccinimidylpropionate) (DTSSP) reduced agonist binding and P2X1 receptor currents by > 90%, and modified lysine residues were identified by mass spectroscopy. Mutation to remove reactive lysine residues around the ATP‐binding pocket had no effect on inhibtion of agonist evoked currents following DTSSP. However, agonist evoked currents were ~ 10‐fold higher than for wild type following DTSSP treatment for mutants K199R, K221R and K199R‐K221R. These mutations remove reactive residues distant from the agonist binding pocket that are close enough to cross‐link adjacent subunits. These results suggest that conformational change in the P2X1 receptor is required for co‐ordination of ATP action.