Heikki Vuorela | University of Helsinki (original) (raw)

Papers by Heikki Vuorela

Research paper thumbnail of Antimicrobial effects of Finnish plant extracts containing flavonoids and other phenolic compounds

Bookmarks Related papers MentionsView impact

Research paper thumbnail of High-performance liquid chromatographic determination of oligomeric procyanidins from dimers up to the hexamer in hawthorn

Journal of Chromatography A, 2002

An HPLC method using UV diode array detection was developed for analysing procyanidins qualitativ... more An HPLC method using UV diode array detection was developed for analysing procyanidins qualitatively and quantitatively up to the hexameric level in hawthorn samples. The analysed compounds included procyanidin dimers B-2, B-4 and B-5, procyanidin trimers C-1, epicatechin-(4β→8)-epicatechin-(4β→6)-epicatechin and epicatechin-(4β→6)-epicatechin-(4β→8)-epicatechin, a tetramer D-1 and a pentamer E-1 both consisting of (−)-epicatechin units linked through C-4β/C-8 bonds. The concentrations of two

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Tocopherols, tocotrienols and fatty acids as indicators of natural ageing in Pinus sylvestris seeds

Scandinavian Journal of Forest Research, 2005

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Choice of Solvent in the Extraction of Angelica archangelica Roots with Reference to Calcium Blocking Activity

Planta Medica, 1992

Twenty solvents were tested in the extraction of compounds from the roots of Angelica archangelic... more Twenty solvents were tested in the extraction of compounds from the roots of Angelica archangelica L. (Apiaceae), and the calcium-antagonistic activity of the extracts was investigated. Special attention was paid to the physical and chemical properties of the solvents and their extraction abilities. The calcium antagonistic effect of the extracts was investigated by measuring the inhibition of depolarization-induced Ca2+ uptake in rat pituitary GH4C1 cells. The criteria used in determining the best solvents for the extraction were the yield and the biological activity of the extract, as well as the amount of nonpolar compounds in the extract. The final criterion used in selecting the solvent was its usability with reference to boiling point, chemical interactions (e.g. methylation), etc. Chloroform was found to be the best solvent for the extraction of nonpolar, biologically active compounds from the roots of A. archangelica.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of A Bioassay Using Artemia salina for Detecting Phototoxicity of Plant Coumarins

Planta Medica, 1999

Artemia salina (brine shrimp) has been successfully used for toxicity testing, and a screening te... more Artemia salina (brine shrimp) has been successfully used for toxicity testing, and a screening test for phototoxicity has been developed based on this method. The ability of the method to test the phototoxic potential of seven known compounds was investigated. Athamantin (an angular furanocoumarin) and umbelliferone (a simple coumarin) showed no phototoxicity, while linear furanocoumarins exhibited phototoxic activity in the following order: psoralen > bergapten > peucedanin > xanthotoxin. The applicability of this method was also tested in screening the phototoxicity of plant material. Six plants from Apiaceae [Aegopodium podagraria L., Anethum graveolens L., Angelica archangelica L., Levisticum officinalis Koch, Petroselinum crispum (P. Mill) A. W. Hill., and Peucedanum palustre (L.) Moench] and one from Rutaceae (Ruta graveolens L.) were selected, all of them known to contain furanocoumarins. Extracts from leaves collected at different times during the growth period were used in the screening. Our results were in accordance with the furanocoumarin content of these plants and with the results of other phototoxicity tests. The Artemia salina method proved to be rapid, simple and inexpensive, and is therefore ideal in the initial biological screening of large numbers of samples for simultaneous detection of both toxicity and phototoxicity.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of A Furanocoumarin from Angelica archangelica

Planta Medica, 1992

Bookmarks Related papers MentionsView impact

Research paper thumbnail of The Structure-Dependent Chromatographic Behaviour of Amines Typical in Plant Materials

Planta Medica, 1991

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Impact of protein binding on thymoquinone's analytical detection

Planta Medica, 2010

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Isolation and identification of oligomeric procyanidins from Crataegus leaves and flowers

Phytochemistry, 2002

Oligomeric procyanidins were isolated from the leaves and flowers of hawthorn (Crataegus laevigat... more Oligomeric procyanidins were isolated from the leaves and flowers of hawthorn (Crataegus laevigata). A trimer, epicatechin-(4 beta-->8)-epicatechin-(4 beta-->6)-epicatechin, and a pentamer consisting of (-)-epicatechin units linked through C-4 beta/C-8 bonds have been isolated from hawthorn for the first time, in addition to known procyanidins including dimers B-2, B-4 and B-5, trimers C-1 and epicatechin-(4 beta-->6)-epicatechin-(4 beta-->8)-epicatechin, and tetramer D-1. A fraction containing a hexamer was also found.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Application of centrifugal force to the extraction and separation of parasorboside and gerberin from Gerbera hybrida

Phytochemical Analysis, 2002

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Effects of Extracts of Commonly Consumed Food Supplements and Food Fractions on the Permeability of Drugs Across Caco-2 Cell Monolayers

Pharmaceutical Research, 2000

Extracts made from berries, herbs, and various plant materials, which might possess a range of ac... more Extracts made from berries, herbs, and various plant materials, which might possess a range of activities, are used as health promoting products. Because little is known about their effects on the absorption of co-administered drugs, the effects of some food supplements, Finnish berries, and herbs were studied on the permeability of some commonly used drugs. The permeabilities of verapamil, metoprolol, ketoprofen, paracetamol, and furosemide were studied across Caco-2 cell monolayers with contemporaneously administered extracts from flax seed, purple loosestrife, and Scots pine bark; bilberries, cowberries, and raspberries; oregano, rosemary, and sage. Toxicological tests were conducted to determine cellular damage. The effects of extracts on drug permeabilities were generally minor. Flax seed decreased the permeability of all drugs except verapamil. Purple loosestrife and pine decreased verapamil and metoprolol permeability. Changes caused by berries were mainly pH-related. Rosemary and oregano enhanced furosemide permeability. Ingestion of extracts of herbs and berries studied are not expected to markedly change the permeabilities of highly permeable drugs. Harmful effects at sites of or during absorption are unlikely. However, if high doses of extracts are administered with low permeable drugs in vitro, effects on drug permeabilities could not be excluded. Use of such extracts should therefore be evaluated during continuous medication.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Optimization of separation of (+)-catechin and (−)-epicatechin on cellulose TLC plates

JPC - Journal of Planar Chromatography - Modern TLC, 2002

ABSTRACT The separation of (+)-catechin and (-)-epicatechin on cellulose TLC plates with 1-butano... more ABSTRACT The separation of (+)-catechin and (-)-epicatechin on cellulose TLC plates with 1-butanol-water-acetic acid, 4 + 2 + 1 (v/v), has been studied under different development conditions on prewashed and untreated TLC plates. Plates were developed in horizontal chambers (tank and sandwich configuration) and in twin trough (unsaturated and saturated) developing chambers. Tank configurations were used with and without preconditioning. Prewashing of the TLC plates, preconditioning, and the type of development chamber used had a large effect on the chromatographic results. Without prewashing of the TLC plate unsatisfactory or misleading results were obtained. Anisaldehyde-sulfuric acid dipping reagent proved to be more selective than vanillin-phosphoric acid as detection reagent for the detection of flavan-3-ols in oak bark extract; the latter was, however, more sensitive.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Dehydration studies using a novel multichamber microscale fluid bed dryer with in-line near-infrared measurement

Journal of Pharmaceutical Sciences, 2003

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Effect of eluent on the ionization efficiency of flavonoids by ion spray, atmospheric pressure chemical ionization, and atmospheric pressure photoionization mass spectrometry

Journal of Mass Spectrometry, 2001

The effect of nine different eluent compositions on the ionization efficiency of five flavonoids ... more The effect of nine different eluent compositions on the ionization efficiency of five flavonoids was studied using ion spray (IS), atmospheric pressure chemical ionization (APCI), and the novel atmospheric pressure photoionization (APPI), in positive and negative ion modes. The eluent composition had a great effect on the ionization efficiency, and the optimal ionization conditions were achieved in positive ion IS and APCI using 0.4% formic acid (pH 2.3) as a buffer, and in negative ion IS and APCI using ammonium acetate buffer adjusted to pH 4.0. For APPI work, the eluent of choice appeared to be a mixture of organic solvent and 5 mM aqueous ammonium acetate. The limits of detection (LODs) were determined in scan mode for the analytes by liquid chromatography/mass spectrometry using IS, APCI and APPI interfaces. The results show that negative ion IS with an eluent system consisting of acidic ammonium acetate buffer provides the best conditions for detection of flavonoids in mass spectrometry mode, their LODs being between 0.8 and 13 microM for an injection volume of 20 microl.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Antimicrobial activity of some coumarin containing herbal plants growing in Finland

Journal of Ethnopharmacology, 2000

Antimicrobial screening against selected Gram-positive and Gram-negative bacteria, yeasts, mold, ... more Antimicrobial screening against selected Gram-positive and Gram-negative bacteria, yeasts, mold, as well as plant pathogenic fungi, with emphasis on method optimization was carried out on methanol extracts prepared from seven plants grown in Finland. Sensitivity to the extracts was found to vary considerably among the micro-organisms, the extract from Petroselinum crispum and Ruta graveolens showing the highest toxicity against Rhizoctonia solani. The growth of Heterobasidium annosum was inhibited, whereas that of Phytophtora (cactorum) was promoted by all the extracts. The antibacterial and antifungal activities of six natural coumarin compounds were weak, except for the inhibitory effect against Fusarium culmorum.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Optimized separation of pharmacologically active flavonoids from Epimedium species by capillary electrophoresis

Journal of Chromatography A, 1996

Sixteen pharmacologically active flavonoids and one phenylethanoid glucoside isolated from Epimed... more Sixteen pharmacologically active flavonoids and one phenylethanoid glucoside isolated from Epimedium species were analyzed by capillary electrophoresis in different buffer systems of AMPSO, CAPS, phosphate and borate. The borate system proved to be the best. After optimization and studies of the effect of borate and SDS concentrations, organic modifier, voltage and effective capillary length on migration of the analytes, 14

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Fractionation of polyphenols in hawthorn into polymeric procyanidins, phenolic acids and flavonoids prior to high-performance liquid chromatographic analysis

Journal of Chromatography A, 2006

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Separation of eight selected flavan-3-ols on cellulose thin-layer chromatographic plates

Journal of Chromatography A, 2005

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Rotation planar extraction and rotation planar chromatography of oak (Quercus robur L.) bark

Journal of Chromatography A, 2003

The versatile novel instrument for rotation planar extraction and rotation planar chromatography ... more The versatile novel instrument for rotation planar extraction and rotation planar chromatography was exploited for the investigation of oak bark (Quercus robur L.). The same instrument enabled extraction of the bark, analytical proof of (+)-catechin directly in the crude extract and also its fractionation. Additionally, epimeric flavan-3-ols, (+)-catechin and (-)-epicatechin were separated by analytical ultra-micro rotation planar chromatography on cellulose plates with pure water as developing solvent. A comparison of the extraction of oak bark with 80% aqueous methanol by rotation planar extraction and medium pressure solid-liquid extraction was carried out and both techniques were shown to be suitable for the efficient extraction of oak bark. The raw extracts and fractions on thin-layer chromatography showed many compounds that possessed antioxidant activity after spraying with 1,1-diphenyl-2-picrylhydrazyl. Rotation planar fractionation of 840 mg of crude oak bark extract on silica gel gave 6.7 mg of pure (+)-catechin in one run.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Impact of protein binding on the analytical detectability and anticancer activity of thymoquinone

Journal of Chemical Biology, 2011

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Antimicrobial effects of Finnish plant extracts containing flavonoids and other phenolic compounds

Bookmarks Related papers MentionsView impact

Research paper thumbnail of High-performance liquid chromatographic determination of oligomeric procyanidins from dimers up to the hexamer in hawthorn

Journal of Chromatography A, 2002

An HPLC method using UV diode array detection was developed for analysing procyanidins qualitativ... more An HPLC method using UV diode array detection was developed for analysing procyanidins qualitatively and quantitatively up to the hexameric level in hawthorn samples. The analysed compounds included procyanidin dimers B-2, B-4 and B-5, procyanidin trimers C-1, epicatechin-(4β→8)-epicatechin-(4β→6)-epicatechin and epicatechin-(4β→6)-epicatechin-(4β→8)-epicatechin, a tetramer D-1 and a pentamer E-1 both consisting of (−)-epicatechin units linked through C-4β/C-8 bonds. The concentrations of two

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Tocopherols, tocotrienols and fatty acids as indicators of natural ageing in Pinus sylvestris seeds

Scandinavian Journal of Forest Research, 2005

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Choice of Solvent in the Extraction of Angelica archangelica Roots with Reference to Calcium Blocking Activity

Planta Medica, 1992

Twenty solvents were tested in the extraction of compounds from the roots of Angelica archangelic... more Twenty solvents were tested in the extraction of compounds from the roots of Angelica archangelica L. (Apiaceae), and the calcium-antagonistic activity of the extracts was investigated. Special attention was paid to the physical and chemical properties of the solvents and their extraction abilities. The calcium antagonistic effect of the extracts was investigated by measuring the inhibition of depolarization-induced Ca2+ uptake in rat pituitary GH4C1 cells. The criteria used in determining the best solvents for the extraction were the yield and the biological activity of the extract, as well as the amount of nonpolar compounds in the extract. The final criterion used in selecting the solvent was its usability with reference to boiling point, chemical interactions (e.g. methylation), etc. Chloroform was found to be the best solvent for the extraction of nonpolar, biologically active compounds from the roots of A. archangelica.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of A Bioassay Using Artemia salina for Detecting Phototoxicity of Plant Coumarins

Planta Medica, 1999

Artemia salina (brine shrimp) has been successfully used for toxicity testing, and a screening te... more Artemia salina (brine shrimp) has been successfully used for toxicity testing, and a screening test for phototoxicity has been developed based on this method. The ability of the method to test the phototoxic potential of seven known compounds was investigated. Athamantin (an angular furanocoumarin) and umbelliferone (a simple coumarin) showed no phototoxicity, while linear furanocoumarins exhibited phototoxic activity in the following order: psoralen > bergapten > peucedanin > xanthotoxin. The applicability of this method was also tested in screening the phototoxicity of plant material. Six plants from Apiaceae [Aegopodium podagraria L., Anethum graveolens L., Angelica archangelica L., Levisticum officinalis Koch, Petroselinum crispum (P. Mill) A. W. Hill., and Peucedanum palustre (L.) Moench] and one from Rutaceae (Ruta graveolens L.) were selected, all of them known to contain furanocoumarins. Extracts from leaves collected at different times during the growth period were used in the screening. Our results were in accordance with the furanocoumarin content of these plants and with the results of other phototoxicity tests. The Artemia salina method proved to be rapid, simple and inexpensive, and is therefore ideal in the initial biological screening of large numbers of samples for simultaneous detection of both toxicity and phototoxicity.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of A Furanocoumarin from Angelica archangelica

Planta Medica, 1992

Bookmarks Related papers MentionsView impact

Research paper thumbnail of The Structure-Dependent Chromatographic Behaviour of Amines Typical in Plant Materials

Planta Medica, 1991

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Impact of protein binding on thymoquinone's analytical detection

Planta Medica, 2010

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Isolation and identification of oligomeric procyanidins from Crataegus leaves and flowers

Phytochemistry, 2002

Oligomeric procyanidins were isolated from the leaves and flowers of hawthorn (Crataegus laevigat... more Oligomeric procyanidins were isolated from the leaves and flowers of hawthorn (Crataegus laevigata). A trimer, epicatechin-(4 beta-->8)-epicatechin-(4 beta-->6)-epicatechin, and a pentamer consisting of (-)-epicatechin units linked through C-4 beta/C-8 bonds have been isolated from hawthorn for the first time, in addition to known procyanidins including dimers B-2, B-4 and B-5, trimers C-1 and epicatechin-(4 beta-->6)-epicatechin-(4 beta-->8)-epicatechin, and tetramer D-1. A fraction containing a hexamer was also found.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Application of centrifugal force to the extraction and separation of parasorboside and gerberin from Gerbera hybrida

Phytochemical Analysis, 2002

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Effects of Extracts of Commonly Consumed Food Supplements and Food Fractions on the Permeability of Drugs Across Caco-2 Cell Monolayers

Pharmaceutical Research, 2000

Extracts made from berries, herbs, and various plant materials, which might possess a range of ac... more Extracts made from berries, herbs, and various plant materials, which might possess a range of activities, are used as health promoting products. Because little is known about their effects on the absorption of co-administered drugs, the effects of some food supplements, Finnish berries, and herbs were studied on the permeability of some commonly used drugs. The permeabilities of verapamil, metoprolol, ketoprofen, paracetamol, and furosemide were studied across Caco-2 cell monolayers with contemporaneously administered extracts from flax seed, purple loosestrife, and Scots pine bark; bilberries, cowberries, and raspberries; oregano, rosemary, and sage. Toxicological tests were conducted to determine cellular damage. The effects of extracts on drug permeabilities were generally minor. Flax seed decreased the permeability of all drugs except verapamil. Purple loosestrife and pine decreased verapamil and metoprolol permeability. Changes caused by berries were mainly pH-related. Rosemary and oregano enhanced furosemide permeability. Ingestion of extracts of herbs and berries studied are not expected to markedly change the permeabilities of highly permeable drugs. Harmful effects at sites of or during absorption are unlikely. However, if high doses of extracts are administered with low permeable drugs in vitro, effects on drug permeabilities could not be excluded. Use of such extracts should therefore be evaluated during continuous medication.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Optimization of separation of (+)-catechin and (−)-epicatechin on cellulose TLC plates

JPC - Journal of Planar Chromatography - Modern TLC, 2002

ABSTRACT The separation of (+)-catechin and (-)-epicatechin on cellulose TLC plates with 1-butano... more ABSTRACT The separation of (+)-catechin and (-)-epicatechin on cellulose TLC plates with 1-butanol-water-acetic acid, 4 + 2 + 1 (v/v), has been studied under different development conditions on prewashed and untreated TLC plates. Plates were developed in horizontal chambers (tank and sandwich configuration) and in twin trough (unsaturated and saturated) developing chambers. Tank configurations were used with and without preconditioning. Prewashing of the TLC plates, preconditioning, and the type of development chamber used had a large effect on the chromatographic results. Without prewashing of the TLC plate unsatisfactory or misleading results were obtained. Anisaldehyde-sulfuric acid dipping reagent proved to be more selective than vanillin-phosphoric acid as detection reagent for the detection of flavan-3-ols in oak bark extract; the latter was, however, more sensitive.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Dehydration studies using a novel multichamber microscale fluid bed dryer with in-line near-infrared measurement

Journal of Pharmaceutical Sciences, 2003

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Effect of eluent on the ionization efficiency of flavonoids by ion spray, atmospheric pressure chemical ionization, and atmospheric pressure photoionization mass spectrometry

Journal of Mass Spectrometry, 2001

The effect of nine different eluent compositions on the ionization efficiency of five flavonoids ... more The effect of nine different eluent compositions on the ionization efficiency of five flavonoids was studied using ion spray (IS), atmospheric pressure chemical ionization (APCI), and the novel atmospheric pressure photoionization (APPI), in positive and negative ion modes. The eluent composition had a great effect on the ionization efficiency, and the optimal ionization conditions were achieved in positive ion IS and APCI using 0.4% formic acid (pH 2.3) as a buffer, and in negative ion IS and APCI using ammonium acetate buffer adjusted to pH 4.0. For APPI work, the eluent of choice appeared to be a mixture of organic solvent and 5 mM aqueous ammonium acetate. The limits of detection (LODs) were determined in scan mode for the analytes by liquid chromatography/mass spectrometry using IS, APCI and APPI interfaces. The results show that negative ion IS with an eluent system consisting of acidic ammonium acetate buffer provides the best conditions for detection of flavonoids in mass spectrometry mode, their LODs being between 0.8 and 13 microM for an injection volume of 20 microl.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Antimicrobial activity of some coumarin containing herbal plants growing in Finland

Journal of Ethnopharmacology, 2000

Antimicrobial screening against selected Gram-positive and Gram-negative bacteria, yeasts, mold, ... more Antimicrobial screening against selected Gram-positive and Gram-negative bacteria, yeasts, mold, as well as plant pathogenic fungi, with emphasis on method optimization was carried out on methanol extracts prepared from seven plants grown in Finland. Sensitivity to the extracts was found to vary considerably among the micro-organisms, the extract from Petroselinum crispum and Ruta graveolens showing the highest toxicity against Rhizoctonia solani. The growth of Heterobasidium annosum was inhibited, whereas that of Phytophtora (cactorum) was promoted by all the extracts. The antibacterial and antifungal activities of six natural coumarin compounds were weak, except for the inhibitory effect against Fusarium culmorum.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Optimized separation of pharmacologically active flavonoids from Epimedium species by capillary electrophoresis

Journal of Chromatography A, 1996

Sixteen pharmacologically active flavonoids and one phenylethanoid glucoside isolated from Epimed... more Sixteen pharmacologically active flavonoids and one phenylethanoid glucoside isolated from Epimedium species were analyzed by capillary electrophoresis in different buffer systems of AMPSO, CAPS, phosphate and borate. The borate system proved to be the best. After optimization and studies of the effect of borate and SDS concentrations, organic modifier, voltage and effective capillary length on migration of the analytes, 14

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Fractionation of polyphenols in hawthorn into polymeric procyanidins, phenolic acids and flavonoids prior to high-performance liquid chromatographic analysis

Journal of Chromatography A, 2006

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Separation of eight selected flavan-3-ols on cellulose thin-layer chromatographic plates

Journal of Chromatography A, 2005

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Rotation planar extraction and rotation planar chromatography of oak (Quercus robur L.) bark

Journal of Chromatography A, 2003

The versatile novel instrument for rotation planar extraction and rotation planar chromatography ... more The versatile novel instrument for rotation planar extraction and rotation planar chromatography was exploited for the investigation of oak bark (Quercus robur L.). The same instrument enabled extraction of the bark, analytical proof of (+)-catechin directly in the crude extract and also its fractionation. Additionally, epimeric flavan-3-ols, (+)-catechin and (-)-epicatechin were separated by analytical ultra-micro rotation planar chromatography on cellulose plates with pure water as developing solvent. A comparison of the extraction of oak bark with 80% aqueous methanol by rotation planar extraction and medium pressure solid-liquid extraction was carried out and both techniques were shown to be suitable for the efficient extraction of oak bark. The raw extracts and fractions on thin-layer chromatography showed many compounds that possessed antioxidant activity after spraying with 1,1-diphenyl-2-picrylhydrazyl. Rotation planar fractionation of 840 mg of crude oak bark extract on silica gel gave 6.7 mg of pure (+)-catechin in one run.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Impact of protein binding on the analytical detectability and anticancer activity of thymoquinone

Journal of Chemical Biology, 2011

Bookmarks Related papers MentionsView impact