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  • 1.
    Co, Michelle
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Analytisk kemi.
    Koskela, Pirjo
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Analytisk kemi.
    Eklund-Åkergren, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Analytisk kemi.
    Srinivas, Keerthi
    King, Jerry W.
    Sjöberg, Per J.R.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Analytisk kemi.
    Turner, Charlotta
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Analytisk kemi.
    Pressurized liquid extraction of betulin and antioxidants from birch bark2009Ingår i: Green Chemistry, ISSN 1463-9262, E-ISSN 1463-9270, Vol. 11, nr 5, s. 668-674Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Pressurized hot (subcritical) water and ethanol were used to extract betulin and antioxidants from birch bark. Betulin was found to be the major compound (around 26% (w/w)), which was able to be extracted with ethanol (120 degrees C, 50 bar, 15 minutes) but not with water at any of the temperatures tested (40-180 degrees C, 50 bar). The obtained extraction result for betulin is supported by theoretical solvation parameter calculations. Furthermore, high antioxidant activity of the extract was obtained using both ethanol and water as solvent. The antioxidant activity, as determined by a DPPH (2,2-diphenyl-1-picrylhydrazyl) assay, was found to be highest for the water extract of finely ground bark and it markedly increased with elevated extraction temperatures (90-180 degrees C). To elucidate if this was due to increased extraction efficiency or chemical reactions, a set of experiments was performed in which the samples were pre-treated with water at different temperatures before extraction. Results from liquid chromatography showed some differences in molecular composition between samples pre-treated at ambient and 180 degrees C, respectively. However, more detailed studies have to be performed to distinguish between hot-water extraction and reaction kinetics.

  • 2.
    Enquist, Per-Anders
    et al.
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för läkemedelskemi, Avdelningen för organisk farmaceutisk kemi.
    Lindh, Jonas
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för läkemedelskemi, Avdelningen för organisk farmaceutisk kemi.
    Nilsson, Peter
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för läkemedelskemi, Avdelningen för organisk farmaceutisk kemi.
    Larhed, Mats
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för läkemedelskemi, Avdelningen för organisk farmaceutisk kemi.
    Open-air oxidative Heck reactions at room temperature2006Ingår i: Green Chemistry, ISSN 1463-9262, E-ISSN 1463-9270, Vol. 8, nr 4, s. 338-343Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Palladium(II)-catalyzed oxidative Heck arylation reactions proceed at room temperature with atmospheric air as the sole reoxidant. Using arylboronic acids as arylating agents and inexpensive 2,9-dimethyl-1,10-phenanthroline as the supporting ligand, efficient vinylic substitution reactions were obtained both with electron-poor and electron-rich olefins on a 1–50 mmol scale.

  • 3.
    Fridén, Mikael E
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC.
    Jumaah, Firas
    Lund University, Department of Chemistry.
    Gustavsson, Christer
    Karlstad University, Department of Engineering and Chemical Sciences.
    Enmark, Martin
    Karlstad University, Department of Engineering and Chemical Sciences.
    Fornstedt, Torgny
    Karlstad University, Department of Engineering and Chemical Sciences.
    Turner, Charlotta
    Lund University, Department of Chemistry.
    Sjöberg, Per J R
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC.
    Samuelsson, Jörgen
    Karlstad University, Department of Engineering and Chemical Sciences.
    Evaluation and Analysis of Environmentally Sustainable Methodologies for Extraction of Betulin from Birch Bark with Focus on Industrial Feasibility2016Ingår i: Green Chemistry, ISSN 1463-9262, E-ISSN 1463-9270, Vol. 18, nr 2, s. 516-523Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Betulin from birch bark was extracted using two principally different extraction methodologies - classical Reflux Boiling (RB) and Pressurized Liquid Extraction (PLE). The extraction methods were analyzed based on both recovery and purity as well as for RB industrial feasibility. The purity and recovery for the different extraction methods were analyzed using High Performance Liquid Chromatography (HPLC) coupled with three different detection principles: Diode Array Detection (DAD), Mass Spectrometry (MS) and Charged Aerosol Detection (CAD). The chromatographic purity was determined by all detections whereas the DAD was used also for complementary gravimetric calculations of the purity of the extracts. The MS detection (in MS and MS/MS modes) was mainly used to characterize the impurities. Two steps to increase the purity of RB extracts were evaluated - pre-boiling the bark in water and precipitation by adding water to the extract. Finally, the methods were compared in terms of amounts of betulin produced and solvent consumed. The RB method including a precipitation step produced the highest purity of betulin. However, results indicate that PLE using three cycles with the precipitation step gives similar purities as for RB. The PLE method produced up to 1.6 times higher amount of extract compared to the RB method. However, the solvent consumption (liter solvent per gram product) for PLE was around 4.5 times higher as compared to the classical RB. PLE performed with only one extraction cycle gave results more similar to RB with 1.2 times higher yield and 1.4 times higher solvent consumption. The RB process was investigated on an industrial scale using a model approach and several important key-factors could be identified. The most energy demanding step was the recycling of extraction solvent which motivates that solvent consumption should be kept low and calculations show a great putative energy reduction by decreasing the ethanol concentration used in the RB process to lower than 90%.

  • 4.
    Krishna, Pilla Sankara
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Molekylär biomimetik. John Innes Ctr, Dept Mol Microbiol, Norwich NR4 7UH, Norfolk, England.
    Styring, Stenbjörn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Molekylär biomimetik.
    Mamedov, Fikret
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Molekylär biomimetik.
    Photosystem ratio imbalance promotes direct sustainable H-2 production in Chlamydomonas reinhardtii2019Ingår i: Green Chemistry, ISSN 1463-9262, E-ISSN 1463-9270, Vol. 21, nr 17, s. 4683-4690Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The green alga Chlamydomonas reinhardtii can photoproduce H-2 gas for only a few minutes under anaerobic conditions due to the inhibition of hydrogenase by O-2 produced by Photosystem II (PSII). A few days of sustained H-2 production can only be achieved when O-2 and H-2 production are temporally separated under two-stage processes such as sulfur deprivation. Under sulfur deprivation, H-2 production is initiated after the over-reduction of the plastoquinone pool and decreased PSII activity in the thylakoid membrane. As a result, activated hydrogenase consumes the excess of electrons produced by PSII [Volgusheva et al., Proc. Natl. Acad. Sci. U. S. A., 2013, 110, 7223]. Here, we report that similar conditions can be achieved by simply altering the ratio between photosystem I (PSI) and PSII. In the C3 mutant of C. reinhardtii, we found a lower PSI/PSII ratio than in the wild type, 0.33 vs. 0.85, respectively. This imbalance of photosystems resulted in the over-reduced state of the plastoquinone pool and activation of hydrogenase in the C3 mutant that allowed the photoproduction of H-2 continuously for 42 days. This is an unprecedented duration of H-2 production in green algae under standard growth conditions without any nutrient limitation. Photosynthetic electron flow from PSII to hydrogenase was closely regulated during this long-term H-2 production. The amount of PSII was decreased and the amount of PSI was increased reaching a PSI/PSII ratio of more than 5 as shown by EPR and fluorescence spectroscopy. This fine-tuning of photosystems allows to sustain the long-term production of H-2 in C. reinhardtii by a direct photosynthetic pathway.

  • 5.
    Kumaniaev, Ivan
    et al.
    Stockholm University, Department of Organic Chemistry.
    Subbotina, Elena
    Stockholm University, Department of Organic Chemistry.
    Sävmarker, Jonas
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för läkemedelskemi, Avdelningen för organisk farmaceutisk kemi. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    Larhed, Mats
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för läkemedelskemi, Avdelningen för organisk farmaceutisk kemi. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    Galkin, Maxim V.
    Stockholm University, Department of Organic Chemistry.
    Samec, Joseph S. M.
    Stockholm University, Department of Organic Chemistry.
    Lignin depolymerization to monophenolic compounds in a flow-through system2017Ingår i: Green Chemistry, ISSN 1463-9262, E-ISSN 1463-9270, Vol. 19, nr 24, s. 5767-5771Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A reductive lignocellulose fractionation in a flow-through system in which pulping and transfer hydrogenolysis steps were separated in time and space has been developed. Without the hydrogenolysis step or addition of trapping agents to the pulping, it is possible to obtain partially depolymerized lignin (21 wt% monophenolic compounds) that is prone to further processing. By applying a transfer hydrogenolysis step 37 wt% yield of lignin derived monophenolic compounds was obtained. Pulp generated in the process was enzymatically hydrolyzed to glucose in 87 wt% yield without prior purification.

  • 6.
    Lindahl, Sofia
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Analytisk kemi.
    Ekman, Anna
    Khan, Samiullah
    Wennerberg, Christina
    Börjesson, Pål
    Sjöberg, Per J.R.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Analytisk kemi.
    Nordberg Karlsson, Eva
    Turner, Charlotta
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Analytisk kemi.
    Exploring the possibility of using a thermostable mutant of β-glucosidase for rapid hydrolysis of quercetin glucosides in hot water2010Ingår i: Green Chemistry, ISSN 1463-9262, E-ISSN 1463-9270, Vol. 12, nr 1, s. 159-168Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The antioxidant quercetin was extracted from yellow onion waste and converted to its aglycone form by a combination of subcritical water extraction and enzymatic hydrolysis. The hydrolytic step was catalysed by a double residue (N221S, P342L) mutant of the thermostable beta-glucosidase (TnBgl1A), isolated from the thermophile Thermotoga neapolitana and cloned and produced in E. coli. The activity of wt TnBgl1A was shown to be dependent on the position of the glucosylation on the quercetin backbone, favouring hydrolysis of quercetin-4'-glucoside over quercetin-3-glucoside. The mutated variant of the enzyme harboured a mutation in the +2 sub-site (N221S) and showed increased catalytic efficiency in quercetin-3-glucoside hydrolysis and also to a certain extent hydrolysis of quercetin-4'-glucoside. The mutated enzyme was used directly in yellow onion extracts, prepared by subcritical water extraction, resulting in complete hydrolysis of the glucosylated flavonoids quercetin-3,4'-diglucoside, quercetin-4'-glucoside, quercetin-3-glucoside, isorhamnetin-4'-glucoside and isorhamnetin-3,4'-diglucoside. To complete hydrolysis within five minutes, 3 mg of TnBgl1A_N221S was used per gramme of onion (dry weight). A life cycle assessment was done to compare the environmental impact of the new method with a conventional solid-liquid extraction-and-hydrolysis method utilising aqueous methanol and hydrochloric acid. Comparison of the methods showed that the new method is preferable regarding primary energy consumption and global warming potential. Another advantage of this method is that handling of toxic chemicals (methanol and HCl) is avoided. This shows that combined subcritical water extraction/enzyme hydrolysis is both a fast and sustainable method to obtain quercetin from onion waste.

  • 7.
    Turner, Charlotta
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Analytisk kemi.
    Turner, Pernilla
    Department of Biotechnology, Lund University.
    Jacobson, Gunilla
    Department of Chemistry, Stanford university.
    Almgren, Knut
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Analytisk kemi.
    Waldebäck, Monica
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Analytisk kemi.
    Sjöberg, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Analytisk kemi.
    Karlsson, Eva Nordberg
    Department of Biotechnology, Lund University.
    Markides, Karin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Analytisk kemi.
    Subcritical water extraction and beta-glucosidase-catalyzed hydrolysis of quercetin glycosides in onion waste2006Ingår i: Green Chemistry, ISSN 1463-9262, E-ISSN 1463-9270, Vol. 8, nr 11, s. 949-959Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Onion waste is a renewable raw material, rich in different molecular species of the antioxidant quercetin. To utilize this resource, an environmentally sustainable procedure has been developed, using pressurized hot water to extract the quercetin species, followed by biocatalytic conversion of the quercetin glycosides to quercetin and carbohydrates. Two different recombinantly expressed thermostable beta-glucosidases, Thermotoga neapolitana beta-glucosidase A and B, were utilized as catalysts. These enzymes maintain activity at temperatures around 90 degrees C, and are therefore ideal to use in combination with hot water extraction. Our results, based on experimental design, showed that they converted quercetin glycosides to active quercetin in less than 10 min reaction time in water at 90 degrees C, pH 5.0. Experimental design showed that the optimal extraction conditions included three 5 min extraction cycles with water at 120 degrees C and 50 bars, giving a total extraction time of 15 min. Several different types of quercetin and isorhamnetin glycosides as well as kaempferol were detected in onion waste using LC-MS/MS analysis. After converting the different glycosidic compounds to their respective aglycones, the quercetin content was 10 to 50 mg g(-1) dry weight of onion waste (RSD 8%). In summary, our research demonstrates that subcritical water extraction followed by beta-glucosidase-catalyzed hydrolysis is a rapid method to determine the content of quercetin and isorhamnetin in onion samples, and is environmentally sustainable as it only uses water as solvent and enzymes as catalysts.

  • 8.
    Watile, Rahul
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Syntetisk organisk kemi.
    Biswas, Srijit
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Syntetisk organisk kemi.
    Samec, Joseph
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Syntetisk organisk kemi.
    An aqueous and recyclable copper(I)-catalyzed route to α-sulfenylated carbonyl compounds from propargylic alcohols and aryl thiols2013Ingår i: Green Chemistry, ISSN 1463-9262, E-ISSN 1463-9270, Vol. 15, nr 11, s. 3176-3179Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A highly efficient one-step copper(I)-catalyzed method for the synthesis of α-sulfenylated carbonyl compounds from propargylic alcohols and aryl thiols in aqueous media is described. A variety of α-sulfenylated carbonyl compounds can be synthesized in good to excellent yields. The catalyst has been successfully recycled up to 4 times without any loss of activity in an aqueous medium.

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