Flash Silica Research Articles

Novel metabolite madeirone and neomarinone extracted from Streptomyces aculeoletus as marine antibiofilm and antifouling agents.

Introduction: Biofouling poses a significant economic threat to various marine industries, leading to financial losses that can reach billions of euros annually. This study highlights the urgent need for effective alternatives to traditional antifouling agents, particularly following the global ban on organotin compounds. Material and methods: Streptomyces aculeolatus PTM-346 was isolated from sediment samples on the shores of the Madeira Archipelago, Portugal. The crude extract was fractionated using silica flash chromatography and preparative HPLC, resulting in two isolated marinone compounds: madeirone (1), a novel marinone derivative discovered in this study, and neomarinone (2). The antifouling activities of these compounds were tested against five marine bacterial species and the larvae of the mussel Mytilus galloprovincialis. Additionally, in silico and in vivo environmental toxicity evaluations of madeirone (1) and neomarinone (2) were conducted. Results: Madeirone (1) demonstrated significant antibiofilm efficacy, inhibiting Phaeobacter inhibens by up to 66%, Marinobacter hydrocarbonoclasticus by up to 60%, and Cobetia marina by up to 40%. Neomarinone (2) also exhibited substantial antibiofilm activity, with inhibition rates of up to 41% against P. inhibens, 40% against Pseudo-oceanicola batsensis, 56% against M. hydrocarbonoclasticus, 46% against C. marina, and 40% against Micrococcus luteus. The growth inhibition activity at the same concentrations of these compounds remained below 20% for the respective bacteria, highlighting their effectiveness as potent antibiofilm agents without significantly affecting bacterial viability. Additionally, both compounds showed potent effects against the settlement of Mytilus galloprovincialis larvae, with EC50 values of 1.76µg/mL and 0.12µg/mL for compounds (1) and (2), respectively, without impairing the viability of the targeted macrofouling species. In silico toxicity predictions and in vivo toxicity assays both support their potential for further development as antifouling agents. Conclusion: The newly discovered metabolite madeirone (1) and neomarinone (2) effectively inhibit both micro- and macrofouling. This distinct capability sets them apart from existing commercial antifouling agents and positions them as promising candidates for biofouling prevention. Consequently, these compounds represent a viable and environmentally friendly alternative for incorporation into paints, primers, varnishes, and sealants, offering significant advantages over traditional copper-based compounds.

Terpenoids from Myrrh and Their Cytotoxic Activity against HeLa Cells

The oleo-gum resin of Commiphora myrrha (Nees) Engl. has a long history of medicinal use, although many of its constituents are still unknown. In the present investigation, 34 secondary metabolites were isolated from myrrh resin using different chromatographic techniques (silica flash chromatography, CPC, and preparative HPLC) and their structures were elucidated with NMR spectroscopy, HRESIMS, CD spectroscopy, and ECD calculations. Among the isolated substances are seven sesquiterpenes (1-7), one disesquiterpene (8), and two triterpenes (23, 24), which were hitherto unknown, and numerous substances are described here for the first time for C. myrrha or the genus Commiphora. Furthermore, the effects of selected terpenes on cervix cancer cells (HeLa) were studied in an MTT-based in vitro assay. Three triterpenes were observed to be the most toxic with moderate IC50 values of 60.3 (29), 74.5 (33), and 78.9 µM (26). Due to the different activity of the structurally similar triterpenoids, the impact of different structural elements on the cytotoxic effect could be discussed and linked to the presence of a 1,2,3-trihydroxy substructure in the A ring. The influence on TNF-α dependent expression of the intercellular adhesion molecule 1 (ICAM-1) in human microvascular endothelial cells (HMEC-1) was also tested for 4-6, 9-11, 17, 18, 20, and 27 in vitro, but revealed less than 20% ICAM-1 reduction and, therefore, no significant anti-inflammatory activity.

In vitro dual activity of Aloe marlothii roots and its chemical constituents against Plasmodium falciparum asexual and sexual stage parasites

Ethnopharmacological relevanceAloe marlothii A.Berger (Xanthorrhoeaceae) is indigenous to southern African countries where its aqueous preparations are used in traditional medicine to treat several ailments including hypertension, respiratory infections, venereal diseases, chest pain, sore throat and malaria. Aim of the studyThe aims of this study were as follows: (i) isolate and identify the antiplasmodial active compounds in A. marlothii roots. As the water extract was previously inactive, the dichloromethane:methanol (DCM:MeOH) (1:1) was used, (ii) examine the activity of the isolated compounds against Plasmodium falciparum asexual blood stage (ABS) parasites as well as for transmission-blocking activity against gametocytes and gametes, and (iii) to use in silico tools to predict the target(s) of the active molecules. Materials and methodsThe crude DCM:MeOH (1:1) extract of A. marlothii roots was fractionated on a reverse phase C8 column, using a positive pressure solid-phase extraction (ppSPE) workstation to produce seven fractions. The resulting fractions and the crude DCM:MeOH extract were tested in vitro against P. falciparum (NF54) ABS parasites using the malaria SYBR Green I based-fluorescence assay. Flash silica chromatography and mass-directed preparative high-performance liquid chromatography were utilised to isolate the active compounds. The isolated compounds were evaluated in vitro against P. falciparum asexual (NF54 and K1 strains) and sexual (gametocytes and gametes) stage parasites. Molecular docking was then used for the in silico prediction of targets for the isolated active compounds in P. falciparum. ResultsThe crude extract and two SPE fractions displayed good antiplasmodial activity with >97% and 100% inhibition of ABS parasites proliferation at 10 and 20 μg/mL, respectively. Following UPLC-MS analysis of these active fractions, a targeted purification resulted in the isolation of six compounds identified as aloesaponol I (1), aloesaponarin I (2), aloesaponol IV (3), β-sorigenin-1-O-methylether (4), emodin (5), and chrysophanol (6). Aloesaponarin I (2) was the most bioactive, compared to other isolated constituents, against P. falciparum ABS parasites exhibiting equipotency against the drug-sensitive (NF54) (IC50 = 1.54 μg/mL (5 μM)) and multidrug-resistant (K1) (IC50 = 1.58 μg/mL (5 μM)) strains. Aloesaponol IV (3) showed pronounced activity against late-stage (>90% stage IV/V) gametocytes (IC50 = 6.53 μg/mL (22.6 μM)) demonstrating a 3-fold selective potency towards these sexual stages compared to asexual forms of the parasite (IC50 = 19.77 ± 6.835 μg/mL (68 μM)). Transmission-blocking potential of aloesaponol IV (3) was validated by in vitro inhibition of exflagellation of male gametes (94% inhibition at 20 μg/mL). In silico studies identified β-hematin and DNA topoisomerase II as potential biological targets of compounds 2 and 3, respectively. ConclusionThe findings from our study substantiate the traditional use of A. marlothii to treat malaria. To our knowledge, this study has provided the first report on the isolation and identification of antiplasmodial compounds from A. marlothii roots. Furthermore, our study has provided the first report on the transmission-blocking potential of one of the compounds from the genus Aloe, motivating for the investigation of other species within this genus for their potential P. falciparum transmission-blocking activity.

Development and evaluation of Pirkle-type chiral stationary phase for flash chromatography

Liquid chromatography is the most applied methodology for enantioseparation in preparative and semi-preparative scale; however, flash chromatography is seldom the first choice. This work proposes a new sustainable method to achieve pure enantiomers in mg scale. Herein, the functionalization of silica for flash chromatography columns with a suitable chiral selector, for subsequent quantitative enantioseparation of chiral compounds, is described. Accordingly, the Whelk-O®1 chiral selector was bonded to flash silica and packed into a reused solid phase extraction cartridge. For the evaluation of the enantioselective performance of the flash column, the enantiomers of a chiral derivative of xanthone were quantitatively enantioseparated with an average recovery of 70% and an enantiomer ratio (e.r.) of 99% and 97% for each enantiomer. Evaluation with the anti-inflammatory drug naproxen was also performed, resulting in an average recovery of 95% and 89% and 95% e.r. for each enantiomer. The flash column showed high stability and load ability, versatility, and good reproducibility.

Structure Elucidation of Triterpenoid Saponins Found in an Immunoadjuvant Preparation of Quillaja brasiliensis Using Mass Spectrometry and 1H and 13C NMR Spectroscopy.

An immunoadjuvant preparation (named Fraction B) was obtained from the aqueous extract of Quillaja brasiliensis leaves, and further fractionated by consecutive separations with silica flash MPLC and reverse phase HPLC. Two compounds were isolated, and their structures elucidated using a combination of NMR spectroscopy and mass spectrometry. One of these compounds is a previously undescribed triterpene saponin (Qb1), which is an isomer of QS-21, the unique adjuvant saponin employed in human vaccines. The other compound is a triterpene saponin previously isolated from Quillaja saponaria bark, known as S13. The structure of Qb1 consists of a quillaic acid residue substituted with a β-d-Galp-(1→2)-[β-d-Xylp-(1→3)]-β-d-GlcpA trisaccharide at C3, and a β-d-Xylp-(1→4)-α-l-Rhap-(1→2)-[α-l-Arap-(1→3)]-β-d-Fucp moiety at C28. The oligosaccharide at C28 was further substituted at O4 of the fucosyl residue with an acyl group capped with a β-d-Xylp residue.

Sesquiterpenes from Myrrh and Their ICAM-1 Inhibitory Activity In Vitro.

By using various chromatographic steps (silica flash, CPC, preparative HPLC), 16 sesquiterpenes could be isolated from an ethanolic extract of myrrh resin. Their chemical structures were elucidated by 1D and 2D NMR spectroscopy and HRESIMS. Among them, six previously unknown compounds (1–6) and another four metabolites previously not described for the genus Commiphora (7, 10, 12, 13) could be identified. Sesquiterpenes 1 and 2 are novel 9,10-seco-eudesmanes and exhibited an unprecedented sesquiterpene carbon skeleton, which is described here for the first time. New compound 3 is an 9,10 seco-guaian and the only peroxide isolated from myrrh so far. Compounds 1, 2, 4, 7–9, 11, 13–16 were tested in an ICAM-1 in vitro assay. Compound 7, as well as the reference compound furanoeudesma-1,3-diene, acted as moderate inhibitors of this adhesion molecule ICAM-1 (IC50: 44.8 and 46.3 μM, respectively). These results give new hints on the activity of sesquiterpenes with regard to ICAM-1 inhibition and possible modes of action of myrrh in anti-inflammatory processes.

An Unconventional trans - exo -Selective Cyclization of Alkyne-Tethered Cyclohexadienones Initiated by Rhodium(III)-Catalyzed C–H Activation via Insertion Relay

Different from the established trans-endo-selective cyclization of alkyne-tethered electrophiles that involve an E/Z isomerization process, herein, the authors present a novel strategy to allow tra...

Arabian Sea associated bacterial strains a source of novel antibiotics against superbugs

One of the most severe health threats to both humans and animals is Antimicrobial resistance development in microorganisms AMR is a significant and growing challenge and to combat this issue new antimicrobials are urgently needed Fifteen microbial strains isolated from Arabian Sea were screened for their capacity to produce antimicrobial metabolites of pharmaceutical interest. These strains were associated to the brown seaweed Pelvetia canaliculata (Linnaeus) attached to the rocks of Sonmiani Beach (Karachi, Pakistan). Bacterial strains were isolated from sea weeds attached to rocks of Baluchistan coast line using marine agar 2216 and screened for antibacterial activity by agar well diffusion method and crude extract was made and antimicrobial metabolites were purified using silica gel column and structure of pure compound was elucidated using spectroscopic techniques. Crude extract filtrates from CMG 2180 strain, grew on ZMA medium, showed the most remarkable antimicrobial activity, and thus was chosen for further examination. The identification of CMG 2180 as a probable new type strain of the Actinobacterium Kocuria marina was based on phenotypic aspects and biochemical characteristics (e.g. halotolerant Gram-positive micrococcoid) as well as on the nucleotide sequence analysis of its full-length 16S rRNA gene showing the highest similarity with the type strain KMM 3905 (GenBank accession number EU073966). Interestingly, a unique UV-bioactive compound, for which the name of kocumarin was proposed, was isolated and purified from CMG 2180 strain’s crude extracts by flash silica gel column chromatography and TLC/HPTLC. Using routine methods, kocumarin demonstrated prominent and rapid activities against all tested fungi and pathogenic bacteria including MRSA. Its chemical structure was unraveled by 1D and 2D-NMR spectroscopy as 4-[(Z)−2 phenyl ethenyl] benzoic acid.

Toxic Indole Diterpenes from Endophyte-Infected Perennial Ryegrass Lolium perenne L.: Isolation and Stability.

The most potent of the indole diterpenes, lolitrem B, is found in perennial ryegrass (Lolium perenne L.) infected with the endophyte Epichloë festucae var. lolii (also termed LpTG-1). Ingestion causes a neurological syndrome in grazing livestock called ryegrass staggers disease. To enable the rapid development of new forage varieties, the toxicity of lolitrem B and its biosynthetic intermediates needs to be established. However, most of these indole diterpenes are not commercially available; thus, isolation of these compounds is paramount. A concentrated endophyte-infected perennial ryegrass seed extract was subjected to silica flash chromatography followed by preparative HPLC and purification by crystallization resulting in lolitrem B and the intermediate compounds lolitrem E, paspaline and terpendole B. The four-step isolation and purification method resulted in a 25% yield of lolitrem B. After isolation, lolitrem B readily degraded to its biosynthetic intermediate, lolitriol. We also found that lolitrem B can readily degrade depending on the solvent and storage conditions. The facile method which takes into consideration the associated instability of lolitrem B, led to the purification of indole diterpenes in quantities sufficient for use as analytical standards for identification in pastures, and/or for toxicity testing in pasture development programs.

A Multi-Step Chromatographic Approach to Purify Radically Generated Ferulate Oligomers Reveals Naturally Occurring 5-5/8-8(Cyclic)-, 8-8(Noncyclic)/8-O-4-, and 5-5/8-8(Noncyclic)-Coupled Dehydrotriferulic Acids.

Ferulate-mediated cross-linking of plant cell wall polymers has various implications on the quality of plant based food products, forage digestibility, and biomass utilization. Besides dehydrodiferulic acids (DFA), dehydrotriferulic acids (TriFA) gained increasing interest over the past two decades, because they potentially cross-link up to three polymers. Here, we describe a separation strategy to obtain several TriFA as analytical standard compounds from a reaction mixture after radical coupling of ethyl ferulate. By using silica flash chromatography, Sephadex LH-20 chromatography, and reversed phase HPLC, six known TriFA as well as three previously unidentified ferulic acid trimers were obtained, and their structures were characterized by mass spectrometry and NMR spectroscopy (1H, HSQC, COSY, HMBC, and NOESY). The novel trimers were identified as 5-5/8-8(cyclic)-, 8-8(noncyclic)/8-O-4-, and, tentatively, 5-5/8-8(noncyclic)-TriFA. Natural occurrence of these TriFA in plant cell walls was demonstrated by LC-MS/MS analyses of alkaline cell wall hydrolyzates.

Isolation, purification, structural elucidation and antimicrobial activities of kocumarin, a novel antibiotic isolated from actinobacterium Kocuria marina CMG S2 associated with the brown seaweed Pelvetia canaliculata

AimsScreening of seaweed-associated bacteria capable of producing antimicrobials. Methods and resultsFifteen microbial strains, associated to the brown seaweed Pelvetia canaliculata (Linnaeus) attached to the rocks of Sonmiani Beach (Karachi, Pakistan), were screened. Crude extract filtrates of CMG S2 strain grew on Zobell marine agar (ZMA) had the most remarkable antimicrobial activity. Based on its phenotypic aspects (e.g. Gram-positive, microccoid form), biochemical characteristics (e.g. halotolerance) and genetic analyses, CMG S2 is identified as a putatively new Kocuria marina type strain belonging to the actinobacteria’s class and micrococcaceae family. Thereby, the nucleotide sequence analysis of its full-length 16S ribosomal ribonucleic acid (rRNA) gene (GenBank accession number EU073966.1) displayed highest identity (i.e. 99%) and score (2630) with K. marina KMM 3905. Phylogenic trees analysis using the neighbor-joining method showed closest evolutionary distance of CMG S2 with KMM 3905 strain and K. carniphila (DC2201) specie. Interestingly, a unique ultraviolet (UV)-bioactive compound was purified from CMG S2 crude extracts by flash silica gel column and thin-layer chromatography (TLC) techniques. Its chemical structure was unraveled as 4-[(Z)-2 phenyl ethenyl] benzoic acid (PEBA, later named kocumarin) by nuclear magnetic resonance (NMR) spectroscopy techniques. Importantly, kocumarin demonstrated prominent and rapid growth inhibition against all tested fungi and pathogenic bacteria including methicillin-resistant Staphylococcus aureus (MRSA), with a minimal fungal inhibitory concentration (MFC) of 15–25μg/mL and a minimal (bacterial) inhibitory concentration (MIC) of 10–15μg/mL. Significance and impact of the studyKocumarin represents a new promising natural antibiotic for in vivo and environmental applications.

Copper-Catalyzed Benzylic sp3C-H Amination Reaction of Amidines: Synthesis of Quinazoline Derivatives

Quinazoline motif is an important heterocyclic framework, which widely exists in many biologically active molecules and natural products. Although numerous synthetic efforts have been made for the preparation of quinazoline de- rivatives in recent years, it is still highly desirable to search for a more convenient and efficient approach. As part of our ongoing interest in transition-metal-catalyzed C—H functionalization, herein, we report a novel copper-catalyzed synthesis of quinazoline derivatives from amidines. During these transformations, the selectivity of benzylic sp 3 C—H over aryl sp 2 C—H bond was efficiently realized. Various 2-arylquinazoline derivatives were obtained in moderate to good yields. A representa- tive procedure for the copper-catalyzed construction of quinazolines from amidines is as following: N-(o-tolyl)benzimidamide (1a, 0.4 mmol, 89.7 mg), Cu(OTf)2 (0.04 mmol, 13.8 mg) and Ag2CO3 (0.8 mmol, 219 mg) were added to a 25 mL sealed tube, followed by addition of DMF (2 mL). The mixture was stirred at 140 ℃ for 10 h. After cool- ing to room temperature, the mixture was poured into ice-water and extracted with CH2Cl2 (15 mL×3). The combined or- ganic layers were dried (Na2SO4), filtered over Celite, evaporated in vacuo. The residue was purified by a shot flash silica gel column chromatography (petroleum ether/ethyl acetate, V∶V=15∶1) to afford the product 2a (71%, 62.4 mg). Keywords copper; N-arylamidines; C—N bond formation; quinazoline derivatives

Determination of Oxidized Triacylglycerol Polymers by Preparative Flash Chromatography and High-Performance Size-Exclusion Chromatography

An simple operation and high sensitivity method without internal standard was developed for the quantitative analysis of oxidized triacylglycerol polymers(TGP).Polar compounds(PC) were obtained from 1 g oil sample by preparative flash chromatography(PFC)(flash silica column,20 g,particle size:40-60 μm,pore size:6 nm) and subsequently separated by a high-performance size-exclusion chromatography(GPC column,Φ7.8 mm×300 mm,particle size:5 μm,pore size:10 nm) into oxidized triacylglycerol polymers(TGP),oxidized triacylglycerol dimers(TGD),oxidized triacylglycerol monomers(ox-TGM),diacylglycerols(DG) and free fatty acids(FFA).By quantitation of PC in oil through gravimetric determination and TGP in PC through area normalization method,TGP content in oil was calculated.The results showed that the calibration curves for TGO and TGD were linear in the concentration ranges of 28-1 800 mg/L and 11-2800 mg/L,respectively,with correlation coefficients(r2) more than 0.99.Their LODs were 28 mg/L and 11 mg/L,respectively,and LOQs were 113 mg/L and 44 mg/L,respectively,which was equivalent to 0.01% for LOQ of TGP in oil.The RSDs of TGP in oil detected by PFC-HPSEC were less than 10%.The recoveries at spiked levels of 2.27%,8.47% and 30.94% ranged from 95% to 98% with RSDs less than 4%.In detecting TGP in oil,PFC-HPSEC matched traditional silica column well with RE of 0-8.9%.The method could be used in the determination of TGP in all kinds of oil samples,including used cooking oil and unused edible oil,especially for virgin oil and refined oils and fats with low levels of TGP.

Consecutive Online Separation and Determination of Polybrominated Diphenyl Ethers, Phthalate Esters and Bisphenol A in Human Serum by Gas Chromatography-Mass Spectrometry

Abstract A method was developed for the consecutive online separation of several environmental estrogens, polybrominated diphenyl ethers (PBDEs), phthalate esters (PAEs) and bisphenol A (BPA), in human serum by gas chromatography-mass spectrometry (GC-MS). After denaturation of protein by concentrated hydrochloride acid, extraction by ether, separation by silica flash chromatograph, several group components including PBDEs, PAEs and BPA in human serum were separated and purified. Then these group components were detected by GC-MS in selected ion monitoring mode. The standard calibration curves of PBDEs, PAEs and BPA were linear over the assayed range with correlation coefficients equal or higher than 0.99. The detection limitations of the targeted compounds ranged from 0.005 to 0.048 μg L−1 for PBDEs, 0.103-0.833 μg L−1 for PAEs, and 0.035 μg L−1 for BPA. In standard duplicated samples, the relative standard deviations were 2.8%-10.9% for PBDEs, 5.6%−9.9% for PAEs, and 3.0% for BPA. The surrogate recoveries in these 7 samples ranged from 74.8% to 88.5% for PCB-209 (polychloride diphenyl ether 209) in PBDEs, from 78.7% to 97.0% for DBP-D4 (dibutyl phthalate-deutorium 4) in PAEs, and from 76.3 % to 93.1% for BPA-D16 (Bisphenol A-Deutorium 16) in BPA, respectively. This method for detecting multiple environmental estrogens in human serum is sensitive, high reproducible with satisfied recoveries.

Analysis of commercial Acid Black 194 and related dyes by micellar electrokinetic chromatography

The commercial dye C.I. Acid Black 194 was analyzed by reversed-phase HPLC, Capillary Zone Electrophoresis and Micellar ElectroKinetic Chromatography under different operative conditions, with the scope to detect the impurity distribution typical of any production processes and synthetic batch. The three chrome(III) complexes deriving from the industrial synthesis of C.I. Acid Black 194, and one of the main impurities were isolated by silica flash chromatography and identified by mass spectrometry and NMR. More than twelve compounds present in the commercial mixture, but undetectable by the analytical protocols known in literature, were fully separated by the MECK mode capillary electrophoresis with low % Relative Standard Deviation of the main electrophoretic parameters. Two of them were identified by isolation from the commercial mixture. As additional examples two other commercial metal-based dyes, C.I. Acid Brown 432 and C.I. Acid Brown 434, were analyzed by the same protocol with very good results.

Antitumor activity of two gelsemine metabolites in rat liver microsomes

Gelsemine is one of the major alkaloids from Gelsemium elegans Benth., which has been used as an antitumor remedy in clinic. In this paper, metabolism of gelsemine has been investigated in vitro in phenobarbital-treated rat liver microsomes. The metabolites of gelsemine were separated and evaluated using the flash silica gel column, preparative HPLC, using NMR and MS methods. According to the spectral data, two metabolites, M1 and M2, were identified as 4-N-demethylgelsemine and 21-oxogelsemine, respectively. By the MTT method in vitro, the antitumor activities between gelsemine and its metabolites were compared in the HepG2 and HeLa cell lines. Moreover, the main metabolic pathway was further proposed.

6]-Dehydroshogaol, a minor component in ginger rhizome, exhibits quinone reductase inducing and anti-inflammatory activities that rival those of curcumin

Quinone reductase (QR) inducing activity, a biomarker for Phase II enzyme induction, was detected in a crude ginger rhizome ethanolic extract using a murine hepatoma cell (Hepa 1c1c7) bioassay. An ethyl acetate-partitioned fraction became enriched in QR inducing activity with a CD value (concentration required to double QR specific activity) of 7 μg/ml and was further separated by silica flash chromatography. The four major fractions recovered exhibited CD values ranging 10–20 μg/mL for QR inducing activity. 1H NMR analysis revealed an abundance of gingerols in the first 3 fractions, and this led to a comparative assessment of QR inducing and anti-inflammatory activities among [6]-gingerol and structurally related vanilloids from ginger and other spices. [6]-Dehydroshogaol (DHSG), a minor component of fresh ginger, had QR inducing activity (CD = 8.4 μM) of comparable potency to the well known cancer preventive agent, curcumin (CD = 4.3 μM). In contrast, [6]-gingerol the major pungent component of ginger showed less potent QR inducing activity (CD = 55 μM) and capsaicin exhibited the weakest inducing activity (CD = 103 μM). [6]-Shogaol, [6]-DHSG and curcumin were also potent inhibitors of nitric oxide (NO) synthesis, inhibiting 50% NO evolution in activated macrophages at levels of 10–12 μM (IC 50 values). Comparatively, IC 50 values for [6]-gingerol and capsaicin were about an order of magnitude greater (less potent) at 90 μM and 169 μM, respectively. This appears to be the first report of biological activities of [6]-DHSG, and Phase II enzyme-inducing ability of shogoal and gingerol.

A New Arylsulfate Sulfotransferase Involved in Liponucleoside Antibiotic Biosynthesis in Streptomycetes

Sulfotransferases are involved in a variety of physiological processes and typically use 3'-phosphoadenosine 5'-phosphosulfate (PAPS) as the sulfate donor substrate. In contrast, microbial arylsulfate sulfotransferases (ASSTs) are PAPS-independent and utilize arylsulfates as sulfate donors. Yet, their genuine acceptor substrates are unknown. In this study we demonstrate that Cpz4 from Streptomyces sp. MK730-62F2 is an ASST-type sulfotransferase responsible for the formation of sulfated liponucleoside antibiotics. Gene deletion mutants showed that cpz4 is required for the production of sulfated caprazamycin derivatives. Cloning, overproduction, and purification of Cpz4 resulted in a 58-kDa soluble protein. The enzyme catalyzed the transfer of a sulfate group from p-nitrophenol sulfate (K(m) 48.1 microM, k(cat) 0.14 s(-1)) and methyl umbelliferone sulfate (K(m) 34.5 microM, k(cat) 0.15 s(-1)) onto phenol (K(m) 25.9 and 29.7 mM, respectively). The Cpz4 reaction proceeds by a ping pong bi-bi mechanism. Several structural analogs of intermediates of the caprazamycin biosynthetic pathway were synthesized and tested as substrates of Cpz4. Des-N-methyl-acyl-caprazol was converted with highest efficiency 100 times faster than phenol. The fatty acyl side chain and the uridyl moiety seem to be important for substrate recognition by Cpz4. Liponucleosides, partially purified from various mutant strains, were readily sulfated by Cpz4 using p-nitrophenol sulfate. No product formation could be observed with PAPS as the donor substrate. Sequence homology of Cpz4 to the previously examined ASSTs is low. However, numerous orthologs are encoded in microbial genomes and represent interesting subjects for future investigations.

Synthesis of Silica Particles Grafted with Well-Defined Living Polymeric Chains by Combination of RAFT Polymerization and Coupling Reaction

A combinatorial approach based on reversible addition−fragmentation chain transfer (RAFT) polymerization and coupling reaction was used to prepare well-defined silica−polymer hybrids. Chain-end-functionalized homopolymers were synthesized by RAFT polymerization of vinyl monomers such as methyl acrylate, butyl acrylate, N,N-dimethylacrylamide, N-isopropylacrylamide, N-acrylomorpholine, methyl methacrylate, and styrene mediated by S-methoxycarbonylphenylmethyl S′-trimethoxysilylpropyltrithiocarbonate in toluene or dioxane at 60 °C, and di-, tri-, and tetrablock copolymers were further synthesized by successive chain extension polymerization. These polymers comprising a trimethoxysilane functionality in the chain end were then grafted to the surface of flash silica by coupling reaction between trimethoxysilane and hydroxyl groups. IR and thermogravimetric analyses results indicated the grafting ratios of polymeric chains on the surface of silica were relatively high. The grafted polymeric chains were cleaved...

Botrytis cinerea로부터 분리한 두 개의 새로운 phytotoxin의 구조 결정 및 생물활성

We discovered two novel phytotoxins produced by the pathogenic fungus, Botrytis cinerea. Among the twenty-five B. cinerea isolates, which were obtained from various host plants in 1994 and 1996, twenty-two showed strong or moderate pathogenicity on five plants such as cucumber, tomato, red pepper, tobacco and Chinese cabbage. The culture filtrate of the B. cinerea 2-16 strain showed the most potent phytotoxic activity in a tobacco leaf-wounding assay. Two novel phytotoxins were isolated from the liquid cultures of B. cinerea 2-16 by ethyl acetate extraction, flash silica gel column chromatography, silica gel column chromatography, Sephadex LH-20 column chromatography, preparative TLC and subsequently preparative HPLC. Their chemical structures were determined to be 3-O-acetyl botcinol and 3-O-acetyl botcinolide, respectively, by mass and NMR spectral analyses. These two phytotoxins caused leaf necrosis in a leaf-wounding bioassay, and significant electrolyte leakage from leaf tissues of tobacco. In the two bioassays tested, 3-O-acetyl botcinol exhibited stronger phytotoxic activity than 3-O-acetyl botcinolide. This is the first report on the production of both 3-O-acetyl botcinol and 3-O-acetyl botcinolide from B. cinerea.