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Orlando Fatibellofilho - One of the best experts on this subject based on the ideXlab platform.
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spectrophotometric determination of Methyldopa and dopamine in pharmaceutical formulations using a crude extract of sweet potato root ipomoea batatas l lam as enzymatic source
Talanta, 1998Co-Authors: Iolanda Cruz Vieira, Orlando FatibellofilhoAbstract:A rapid, precise and low cost spectrophotometric method is proposed for the determination of Methyldopa and dopamine in pharmaceutical formulations. The crude extract of sweet potato root (Ipomoea batatas (L.) Lam.) was used as an enzymatic source of polyphenol oxidase (PPO; EC.1.14.18.1). This enzyme catalyses the oxidation of catecholamines to the corresponding Methyldopaquinone and dopaminequinone. Those compounds are converted by a rapid spontaneous auto-oxidation to Methyldopachrome and dopaminechrome which have a strong absorption at 480 or 470 nm, respectively. The calibration graphs are linear from 2.0 10 4 to 6.0 10 3 M. The results obtained by the proposed enzymatic method are in close agreement with those obtained using a Pharmacopoeia procedure and also with the label values. The detection limit (three times the signal blank:slope) was 3.4 10 5 and 3.0 10 5 M for Methyldopa and dopamine, respectively, the recovery of Methyldopa and dopamine from three samples ranged from 97.5 to 102.9% of the added amount. © 1998 Elsevier Science B.V. All rights reserved.
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spectrophotometric determination of Methyldopa and dopamine in pharmaceutical formulations using a crude extract of sweet potato root ipomoea batatas l lam as enzymatic source
Talanta, 1998Co-Authors: Iolanda Cruz Vieira, Orlando FatibellofilhoAbstract:A rapid, precise and low cost spectrophotometric method is proposed for the determination of Methyldopa and dopamine in pharmaceutical formulations. The crude extract of sweet potato root (Ipomoea batatas (L.) Lam.) was used as an enzymatic source of polyphenol oxidase (PPO; EC.1.14.18.1). This enzyme catalyses the oxidation of catecholamines to the corresponding Methyldopaquinone and dopaminequinone. Those compounds are converted by a rapid spontaneous auto-oxidation to Methyldopachrome and dopaminechrome which have a strong absorption at 480 or 470 nm, respectively. The calibration graphs are linear from 2.0 10 4 to 6.0 10 3 M. The results obtained by the proposed enzymatic method are in close agreement with those obtained using a Pharmacopoeia procedure and also with the label values. The detection limit (three times the signal blank:slope) was 3.4 10 5 and 3.0 10 5 M for Methyldopa and dopamine, respectively, the recovery of Methyldopa and dopamine from three samples ranged from 97.5 to 102.9% of the added amount. © 1998 Elsevier Science B.V. All rights reserved.
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spectrophotometric determination of Methyldopa and dopamine in pharmaceutical formulations using a crude extract of sweet potato root ipomoea batatas l lam as enzymatic source
Talanta, 1998Co-Authors: Iolanda Cruz Vieira, Orlando FatibellofilhoAbstract:A rapid, precise and low cost spectrophotometric method is proposed for the determination of Methyldopa and dopamine in pharmaceutical formulations. The crude extract of sweet potato root (Ipomoea batatas (L.) Lam.) was used as an enzymatic source of polyphenol oxidase (PPO; EC.1.14.18.1). This enzyme catalyses the oxidation of catecholamines to the corresponding Methyldopaquinone and dopaminequinone. Those compounds are converted by a rapid spontaneous auto-oxidation to Methyldopachrome and dopaminechrome which have a strong absorption at 480 or 470 nm, respectively. The calibration graphs are linear from 2.0x10(-4) to 6.0x10(-3) M. The results obtained by the proposed enzymatic method are in close agreement with those obtained using a Pharmacopoeia procedure and also with the label values. The detection limit (three times the signal blank/slope) was 3.4x10(-5) and 3.0x10(-5) M for Methyldopa and dopamine, respectively, the recovery of Methyldopa and dopamine from three samples ranged from 97.5 to 102.9% of the added amount.
Iolanda Cruz Vieira - One of the best experts on this subject based on the ideXlab platform.
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spectrophotometric determination of Methyldopa and dopamine in pharmaceutical formulations using a crude extract of sweet potato root ipomoea batatas l lam as enzymatic source
Talanta, 1998Co-Authors: Iolanda Cruz Vieira, Orlando FatibellofilhoAbstract:A rapid, precise and low cost spectrophotometric method is proposed for the determination of Methyldopa and dopamine in pharmaceutical formulations. The crude extract of sweet potato root (Ipomoea batatas (L.) Lam.) was used as an enzymatic source of polyphenol oxidase (PPO; EC.1.14.18.1). This enzyme catalyses the oxidation of catecholamines to the corresponding Methyldopaquinone and dopaminequinone. Those compounds are converted by a rapid spontaneous auto-oxidation to Methyldopachrome and dopaminechrome which have a strong absorption at 480 or 470 nm, respectively. The calibration graphs are linear from 2.0 10 4 to 6.0 10 3 M. The results obtained by the proposed enzymatic method are in close agreement with those obtained using a Pharmacopoeia procedure and also with the label values. The detection limit (three times the signal blank:slope) was 3.4 10 5 and 3.0 10 5 M for Methyldopa and dopamine, respectively, the recovery of Methyldopa and dopamine from three samples ranged from 97.5 to 102.9% of the added amount. © 1998 Elsevier Science B.V. All rights reserved.
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spectrophotometric determination of Methyldopa and dopamine in pharmaceutical formulations using a crude extract of sweet potato root ipomoea batatas l lam as enzymatic source
Talanta, 1998Co-Authors: Iolanda Cruz Vieira, Orlando FatibellofilhoAbstract:A rapid, precise and low cost spectrophotometric method is proposed for the determination of Methyldopa and dopamine in pharmaceutical formulations. The crude extract of sweet potato root (Ipomoea batatas (L.) Lam.) was used as an enzymatic source of polyphenol oxidase (PPO; EC.1.14.18.1). This enzyme catalyses the oxidation of catecholamines to the corresponding Methyldopaquinone and dopaminequinone. Those compounds are converted by a rapid spontaneous auto-oxidation to Methyldopachrome and dopaminechrome which have a strong absorption at 480 or 470 nm, respectively. The calibration graphs are linear from 2.0 10 4 to 6.0 10 3 M. The results obtained by the proposed enzymatic method are in close agreement with those obtained using a Pharmacopoeia procedure and also with the label values. The detection limit (three times the signal blank:slope) was 3.4 10 5 and 3.0 10 5 M for Methyldopa and dopamine, respectively, the recovery of Methyldopa and dopamine from three samples ranged from 97.5 to 102.9% of the added amount. © 1998 Elsevier Science B.V. All rights reserved.
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spectrophotometric determination of Methyldopa and dopamine in pharmaceutical formulations using a crude extract of sweet potato root ipomoea batatas l lam as enzymatic source
Talanta, 1998Co-Authors: Iolanda Cruz Vieira, Orlando FatibellofilhoAbstract:A rapid, precise and low cost spectrophotometric method is proposed for the determination of Methyldopa and dopamine in pharmaceutical formulations. The crude extract of sweet potato root (Ipomoea batatas (L.) Lam.) was used as an enzymatic source of polyphenol oxidase (PPO; EC.1.14.18.1). This enzyme catalyses the oxidation of catecholamines to the corresponding Methyldopaquinone and dopaminequinone. Those compounds are converted by a rapid spontaneous auto-oxidation to Methyldopachrome and dopaminechrome which have a strong absorption at 480 or 470 nm, respectively. The calibration graphs are linear from 2.0x10(-4) to 6.0x10(-3) M. The results obtained by the proposed enzymatic method are in close agreement with those obtained using a Pharmacopoeia procedure and also with the label values. The detection limit (three times the signal blank/slope) was 3.4x10(-5) and 3.0x10(-5) M for Methyldopa and dopamine, respectively, the recovery of Methyldopa and dopamine from three samples ranged from 97.5 to 102.9% of the added amount.
Mohammad A Khalilzadeh - One of the best experts on this subject based on the ideXlab platform.
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liquid phase analysis of Methyldopa in the presence of tyrosine using electrocatalytic effect of a catechol derivative at a surface of nio nanoparticle modified carbon paste electrode
Journal of Molecular Liquids, 2017Co-Authors: Mohsen Keyvanfard, Mehdi Hatami, Vinod Kumar Gupta, Shilpi Agarwal, Hasan Sadeghifar, Mohammad A KhalilzadehAbstract:Abstract An electrocatalytic based sensor fabricated for square wave voltammetric determination of Methyldopa in the presence of tyrosine. For this goal, carbon paste electrode modified with NiO nanoparticle (NiO/NPs) and 2-(3,4-dihydroxyphenethyl)isoindoline-1,3-dione (DHPID) (CPE/DHPID/NiO/NPs) suggested as a highly selective sensor. The CPE/DHPID/NiO/NPs showed an excellent character for electrocatalytic oxidization of Methyldopa in aqueous solution. For the mixture containing Methyldopa and tyrosine, the oxidation peaks potential well separated from each other with differential potential ~ 500 mV. Methyldopa peak current increased linearly with its concentration at the ranges of 0.08–500 μM. The CPE/DHPID/NiO/NPs was successfully used for the analysis of Methyldopa in drug samples.
Debora Cristina Dalla Villa Batista - One of the best experts on this subject based on the ideXlab platform.
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Metodo cinetico para a determinação quantitativa de "alfa" - metildopa em preparações farmaceuticas
2017Co-Authors: Debora Cristina Dalla Villa BatistaAbstract:Resumo: A a-metildopa é um fármaco com propriedade anti-hipertensiva, bastante utilizado e de primeira escolha nos casos de hipertensão durante a gravidez. Sobre o seu mecanismo de ação no organismo, apesar de vários estudos, ainda não está comprovado. Sabe-se que a-metildopa é descarboxilada pela enzima dopadescarboxilase, e convertida até a- metilnoradrenalina, substituindo a noradrenalina, como um falso neuro-transmissor, impedindo a ação da noradrenalina e reduzindo a pressão sanguínea. No presente trabalho foi realizado um estudo sobre a farmacologia de a-metildopa e também sobre os processos de síntese com os mecanismos das reações envolvidas. A forma racêmica da a- metildopa foi sintetizada pela primeira vez por Pfister e colab., em 1955, o que exigiu que fossem desenvolvidos procedimentos para a resolução ótica da a-metildopa, pois somente o isômero levógero é farmacologicamente ativo. Na literatura há vários métodos para a determinação de a-metildopa em preparações farmacêuticas. Neste trabalho foi realizado um levanta- mento destes métodos e descrito o procedimento experimental para cada um. Também propõe-se um método cinético com detecção espectrofotométrica baseado na reação de a-metildopa com íons férricos, estes inicialmente complexados com ácido salicílico. A reação é monitorada num comprimento de onda de 525 nm. Para comparação foi utilizado um método espectrofotométrico de referência contido nas farmacopéias dos Estados Unidos (USP) e Brasileira.Abstract: a-Methyldopa is a substance with anti-hipertensive property wich is frequently used and is the first choice in the hipertension during pregnancy. Despite various studies, its mechanism of action in organisms has not been establishedyet. a-Methyldopa is known to be decarboxylated by the enzyme dopadecarboxylase, and converted to a-methylnoradrenaline, substituting noradrenaline, as a false neurotransmitter, which hinders the action of lhe noradrenaline and reduces blood pressure. In the present work a study on the pharmacology of a-Methyldopa and algo on lhe synthesis and the mechanisms of lhe reactions involved were carried aut. The racemic structure of a-Methyldopa was synthesized for first time by Pfister et al. in 1955. It was necessary to develop a procedure for the optical resolution of a-Methyldopa, because only lhe levogero isomer is pharmacologically active. Various methods for the determination of a- Methyldopa in pharmaceutics preparations are described in lhe literature. In this work, a survey of these methods together with the experimental procedure used for each method is presented. Also, a kinetic method based on spectrophotometric monitoring of the reaction of a-Methyldopa with iron (III), which is initially complexed with salicylic acid is proposed. The reaction is monitored at 525 nm. The method was compared with standard spectrophotometric method of the United States Pharmacopoeia (USP) and Brazilian Pharmacopoeia
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Metodo cinetico para a determinação quantitativa de "alfa" - metildopa em preparações farmaceuticas
Universidade Estadual de Campinas . Instituto de Quimica, 2004Co-Authors: Debora Cristina Dalla Villa BatistaAbstract:A a-metildopa é um fármaco com propriedade anti-hipertensiva, bastante utilizado e de primeira escolha nos casos de hipertensão durante a gravidez. Sobre o seu mecanismo de ação no organismo, apesar de vários estudos, ainda não está comprovado. Sabe-se que a-metildopa é descarboxilada pela enzima dopadescarboxilase, e convertida até a- metilnoradrenalina, substituindo a noradrenalina, como um falso neuro-transmissor, impedindo a ação da noradrenalina e reduzindo a pressão sanguínea. No presente trabalho foi realizado um estudo sobre a farmacologia de a-metildopa e também sobre os processos de síntese com os mecanismos das reações envolvidas. A forma racêmica da a- metildopa foi sintetizada pela primeira vez por Pfister e colab., em 1955, o que exigiu que fossem desenvolvidos procedimentos para a resolução ótica da a-metildopa, pois somente o isômero levógero é farmacologicamente ativo. Na literatura há vários métodos para a determinação de a-metildopa em preparações farmacêuticas. Neste trabalho foi realizado um levanta- mento destes métodos e descrito o procedimento experimental para cada um. Também propõe-se um método cinético com detecção espectrofotométrica baseado na reação de a-metildopa com íons férricos, estes inicialmente complexados com ácido salicílico. A reação é monitorada num comprimento de onda de 525 nm. Para comparação foi utilizado um método espectrofotométrico de referência contido nas farmacopéias dos Estados Unidos (USP) e Brasileira.a-Methyldopa is a substance with anti-hipertensive property wich is frequently used and is the first choice in the hipertension during pregnancy. Despite various studies, its mechanism of action in organisms has not been establishedyet. a-Methyldopa is known to be decarboxylated by the enzyme dopadecarboxylase, and converted to a-methylnoradrenaline, substituting noradrenaline, as a false neurotransmitter, which hinders the action of lhe noradrenaline and reduces blood pressure. In the present work a study on the pharmacology of a-Methyldopa and algo on lhe synthesis and the mechanisms of lhe reactions involved were carried aut. The racemic structure of a-Methyldopa was synthesized for first time by Pfister et al. in 1955. It was necessary to develop a procedure for the optical resolution of a-Methyldopa, because only lhe levogero isomer is pharmacologically active. Various methods for the determination of a- Methyldopa in pharmaceutics preparations are described in lhe literature. In this work, a survey of these methods together with the experimental procedure used for each method is presented. Also, a kinetic method based on spectrophotometric monitoring of the reaction of a-Methyldopa with iron (III), which is initially complexed with salicylic acid is proposed. The reaction is monitored at 525 nm. The method was compared with standard spectrophotometric method of the United States Pharmacopoeia (USP) and Brazilian Pharmacopoeia
Rahman Hosseinzadeh - One of the best experts on this subject based on the ideXlab platform.
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application of a nanostructured sensor based on graphene and ethyl 2 4 ferrocenyl 1 2 3 triazol 1 yl acetate modified carbon paste electrode for determination of Methyldopa in the presence of phenylephrine and guaifenesin
Applied Organometallic Chemistry, 2018Co-Authors: Hadi Beitollahi, Kaveh Movlaee, Mohammad Reza Ganjali, Parviz Norouzi, Rahman HosseinzadehAbstract:We introduce a new method to determine Methyldopa without the interference of phenylephrine and guaifenesin. For this purpose, a carbon paste electrode was modified with graphene and ethyl 2-(4-ferrocenyl[1,2,3]triazol-1-yl)acetate. According to electrochemical studies, oxidation current of Methyldopa on the surface of the modified electrode increased and shifted towards negative potentials. This modified electrode demonstrated two linear ranges of 0.4–30.0 μM and 30.0–500.0 μM with a detection limit of 0.08 μM. No change was observed in the sensitivity of the modified electrode towards Methyldopa in the presence of phenylephrine and guaifenesin, which enables the simultaneous or independent measurement of the three moieties. The efficiency of the proposed modified electrode was evaluated through the determination of these substances in real samples.
