Synthesis and evaluation of 2-phenylamino-1,4-naphthoquinones derivatives as potential hypoglycaemic agents

Abstract Due to the severe side effects revealed by most of the currently used antidiabetic medicines, search for finding new and safe drugs to manage diabetes is continued. Naphthoquinones possessing strong antioxidant properties have been employed as candidates for diabetes therapy. Present study is aimed at finding the antioxidant and hypoglycaemic potential of some novel derivatives of 2-phenylamino-1,4-naphthoquinones (PAN) including chloro, nitro, methyl and bromo (5a-d) derivatives synthesized by single pot experiment. Product crystals were purified by TLC and characterized by FT-IR. The antioxidant potential of the compounds was assayed through DPPH radical scavenging and reducing power activities noted as UV-vis. absorbance. The DPPH assay has showed the powerful antioxidant activity of nitro and bromo derivatives, while the nitro derivative showed the significant reduction potential towards FRAP assay. Hypoglycaemic potential of the compounds was studied in rat animal model. All synthesized compounds revealed better hypoglycaemic activity; however, the chloro-derivative exhibited the more potent hypoglycaemic activity showing about 43% reduction in the mean blood glucose levels of the treated animals. As the bioreduction of naphthoquinones may be influenced by changing its redox properties, it has been noticed that the e-donating resonance effect (+R) of chloro group has shown the significant effects on biological activity through stabalization of its imine form which limits the potential of generation of free radicals during bioreduction of quinones and thus has been proposed as the reason of its hypoglycaemic activity. Future studies employing the properties of e-donating groups of PAN may optimize the drug-receptor interaction for better drug designing and drug development strategies against diabetes and also for the clinical trials.

Resumo Em razão dos graves efeitos colaterais causados pela maioria dos medicamentos antidiabéticos atualmente utilizados, continua a busca por novos medicamentos seguros para o controle do diabetes. As naftoquinonas, que possuem fortes propriedades antioxidantes, têm sido empregadas como candidatas à terapia do diabetes. O presente estudo visa encontrar o potencial antioxidante e hipoglicemiante de alguns novos derivados de 2-fenilamino-1,4-naftoquinonas (PAN), incluindo derivados de cloro, nitro, metil e bromo (5a-d) sintetizados por experimento em pote único. Os cristais do produto foram purificados por TLC e caracterizados por FT-IR. O potencial antioxidante dos compostos foi testado por meio de atividades de sequestro de radicais DPPH e redução de energia observada como absorção no UV-vis. O ensaio DPPH mostrou a poderosa atividade antioxidante dos derivados nitro e bromo, enquanto o derivado nitro mostrou o potencial de redução significativo para o ensaio FRAP. O potencial hipoglicêmico dos compostos foi estudado em modelo animal de rato. Todos os compostos sintetizados revelaram melhor atividade hipoglicemiante; no entanto, o derivado cloro apresentou atividade hipoglicêmica mais potente, com redução de 43% nos níveis médios de glicose no sangue dos animais tratados. Como a biorredução de naftoquinonas pode ser influenciada pela alteração de suas propriedades redox, notou-se que o efeito da doação eletrônica por ressonância (+R) do grupo cloro tem sido significativo na atividade biológica por meio da estabilização de sua forma imina, que limita o potencial de geração de radicais livres durante a biorredução de quinonas, e, portanto, tem sido proposto como a razão de sua atividade hipoglicemiante. Estudos futuros empregando as propriedades de grupos de doação eletrônica de PAN podem otimizar a interação droga-receptor para melhor planejamento de medicamentos e estratégias de desenvolvimento de medicamentos contra o diabetes e também para os ensaios clínicos.

Synthesis and evaluation of 2-phenylamino-1, 4-naphthoquinones derivatives as potential hypoglycaemic agents / Síntese e avaliação de derivados de 2-fenilamino-1, 4-naftoquinonas como potenciais agentes hipoglicemiantes

Due to the severe side effects revealed by most of the currently used antidiabetic medicines, search for finding new and safe drugs to manage diabetes is continued. Naphthoquinones possessing strong antioxidant properties have been employed as candidates for diabetes therapy. Present study is aimed at finding the antioxidant and hypoglycaemic potential of some novel derivatives of 2-phenylamino-1,4-naphthoquinones (PAN) including chloro, nitro, methyl and bromo (5a-d) derivatives synthesized by single pot experiment. Product crystals were purified by TLC and characterized by FT-IR. The antioxidant potential of the compounds was assayed through DPPH radical scavenging and reducing power activities noted as UV-vis. absorbance. The DPPH assay has showed the powerful antioxidant activity of nitro and bromo derivatives, while the nitro derivative showed the significant reduction potential towards FRAP assay. Hypoglycaemic potential of the compounds was studied in rat animal model. All synthesized compounds revealed better hypoglycaemic activity; however, the chloro-derivative exhibited the more potent hypoglycaemic activity showing about 43% reduction in the mean blood glucose levels of the treated animals. As the bioreduction of naphthoquinones may be influenced by changing its redox properties, it has been noticed that the e-donating resonance effect (+R) of 'chloro' group has shown the significant effects on biological activity through stabalization of its imine form which limits the potential of generation of free radicals during bioreduction of quinones and thus has been proposed as the reason of its hypoglycaemic activity. Future studies employing the properties of e-donating groups of PAN may optimize the drug-receptor interaction for better drug designing and drug development strategies against diabetes and also for the clinical trials.

Em razão dos graves efeitos colaterais causados pela maioria dos medicamentos antidiabéticos atualmente utilizados, continua a busca por novos medicamentos seguros para o controle do diabetes. As naftoquinonas, que possuem fortes propriedades antioxidantes, têm sido empregadas como candidatas à terapia do diabetes. O presente estudo visa encontrar o potencial antioxidante e hipoglicemiante de alguns novos derivados de 2-fenilamino-1,4-naftoquinonas (PAN), incluindo derivados de cloro, nitro, metil e bromo (5a-d) sintetizados por experimento em pote único. Os cristais do produto foram purificados por TLC e caracterizados por FT-IR. O potencial antioxidante dos compostos foi testado por meio de atividades de sequestro de radicais DPPH e redução de energia observada como absorção no UV-vis. O ensaio DPPH mostrou a poderosa atividade antioxidante dos derivados nitro e bromo, enquanto o derivado nitro mostrou o potencial de redução significativo para o ensaio FRAP. O potencial hipoglicêmico dos compostos foi estudado em modelo animal de rato. Todos os compostos sintetizados revelaram melhor atividade hipoglicemiante; no entanto, o derivado cloro apresentou atividade hipoglicêmica mais potente, com redução de 43% nos níveis médios de glicose no sangue dos animais tratados. Como a biorredução de naftoquinonas pode ser influenciada pela alteração de suas propriedades redox, notou-se que o efeito da doação eletrônica por ressonância (+R) do grupo "cloro" tem sido significativo na atividade biológica por meio da estabilização de sua forma imina, que limita o potencial de geração de radicais livres durante a biorredução de quinonas, e, portanto, tem sido proposto como a razão de sua atividade hipoglicemiante. Estudos futuros empregando as propriedades de grupos de doação eletrônica de PAN podem otimizar a interação droga-receptor para melhor planejamento de medicamentos e estratégias de desenvolvimento de medicamentos contra o diabetes e também para os ensaios clínicos.

Epoxy-α-lapachone(2,2-Dimethyl-3,4-dihydro-spiro[2H-naphtho[2,3-b]pyran-10,2′-oxirane]-5(10H)-one): a promising molecule to control infections caused by protozoan parasites

ABSTRACT Natural products and their derivatives have been sources of search and research for new drugs for the treatment of neglected diseases. Naphthoquinones, a special group of quinones, are products of natural metabolites with a wide spectrum of biological activities and represent a group of interesting molecules for new therapeutic propositions. Among these compounds, lapachol stands out as a molecule from the heartwood of Tabebuia sp. whose structural changes resulted in compounds considered promising, such as epoxy-a-lapachone (ELAP). The biological activity of ELAP has been demonstrated, so far, for parasitic protozoa such as Leishmania spp., Trypanosoma cruzi and Plasmodium spp., species causing diseases needing new drug development and adequate health policy. This work gathers in vitro and in vivo studies on these parasites, as well as the toxicity profile, and the probable mechanisms of action elucidated until then. The potential of ELAP-based technology alternatives for a further drug is discussed here.

Biological activities of 1,4-naphthoquinones derivatives against T. cruzi and L. amazonensis

SUMMARY Introduction: Chagas disease and Leishmaniasis are neglected diseases caused by the Trypanosoma cruzi and kentoplastid parasites Leishmania spp. Parasitic diseases cause great impact on social and economic, affecting millions of people in the world and represent a major global health problem. In the search for new alternatives for the treatment of Leishmaniasis and Chagas disease, strategies have been used to discover new active molecules, because there is an urgent need for the development of new drugs. In this scenario, 1,4-naphthoquinones have shown notable activity in the context of neglected diseases. Aim: To synthesis of 1,4-naphthoquinones derivatives and evaluated these compounds against Trypanosoma cruzi epimastigotes, Leishmania promastigotes (Leishmania amazonensis) and cytotoxicity to LLCMK2 cells. Results: Nine 1,4-naphthoquinones derivatives were synthesized using 2-Bromo-1,4-naphthoquinone (1), 1,4-Naphthoquinone (5) and 2-Hydroxi-1,4-naphthoqui-none (9) as starting material. Derivative 6a exhibited excellent trypanocidal activity, IC50 of 0.25 ± 0.02 µM, superior potency compared with the reference drug Benznidazol. Besides, these compounds displayed low activity against promastigote from L. amazonensis. Conclusion: The results indicate that compound 6a may have potential for agent against Chagas disease.

Introducción: La enfermedad de Chagas y la leishmaniasis son enfermedades desatendidas causadas por los parásitos Trypanosoma cruzi y kentoplastid Leishmania spp. Las enfermedades parasitarias tienen un gran impacto social y económico, afectan a millones de personas en el mundo y representan un importante problema de salud mundial. En la búsqueda de nuevas alternativas para el tratamiento de la leishmaniasis y la enfermedad de Chagas, se han utilizado estrategias para descubrir nuevas moléculas activas, porque existe una necesidad urgente de desarrollo de nuevos fármacos. En este escenario, las 1,4-naftoquinonas han mostrado una notable actividad en el contexto de enfermedades desatendidas. Objetivo: Sintetizar derivados de 1,4-naftoquinonas y evaluación de estos compuestos frente a epimastigotes de Trypanosoma cruzi, promastigotes de Leishmania (Leishmania amazonensis) y citotoxicidad a células LLCMK2. Resultados: Se sintetizaron nueve derivados de 1,4-naftoquinonas usando 2-bromo-1,4-naftoquinona (1), 1,4-naftoquinona (5) y 2-hidroxi-1,4-naftoquinona (9) como material de partida. El derivado 6a exhibió una excelente actividad tripanocida, CI50 de 0,25 ± 0,02 µM, potencia superior en comparación con el fármaco de referencia Benznidazol. Además, estos compuestos mostraron una baja actividad contra el promastigote de L. amazonensis. Conclusión: Los resultados indican que el compuesto 6a puede tener potencial como agente contra la enfermedad de Chagas.

Introdução: A doença de Chagas e a leishmaniose são doenças negligenciadas causadas pelos parasitas Trypanosoma cruzi e kentoplastídeos Leishmania spp. As doenças parasitárias causam grande impacto social e econômico, afetando milhões de pessoas no mundo e representam um dos maiores problemas de saúde global. Na busca por novas alternativas para o tratamento da Leishmaniose e da doença de Chagas, estratégias têm sido utilizadas para descobrir novas moléculas ativas, porque há urgência no desenvolvimento de novos fármacos. Nesse cenário, as 1,4-nafto-quinonas têm mostrado notável atividade no contexto das doenças negligenciadas. Objetivos: Sintetizar derivados de 1,4-naftoquinonas e avaliar esses compostos contra epimastigotas de Trypanosoma cruzi, promastigotas de Leishmania (Leishmania amazonensis) e citotoxicidade para células LLCMK2. Resultados: Nove derivados de 1,4-naftoquinonas foram sintetizados usando 2-Bromo-1,4-naftoquinona (1), 1,4-Naftoquinona (5) e 2-Hidroxi-1,4-naftoquinona (9) como material de partida. O derivado 6a exibiu excelente atividade tripanocida, IC50 de 0,25 ± 0,02 µM, potência superior em comparação com o medicamento de referência Benzonidazol. Além disso, esses compostos apresentaram baixa atividade contra a forma promasti-gota de L. amazonensis. Conclusão: Os resultados indicam que o composto 6a pode ter potencial para agente contra a doença de Chagas.

Antiproliferation activity of a naphthoquinone derivative against vascular smooth muscle cells / 中国药理学通报

Aim: To explore the effect of a synthetic naphthoquinone derivative on the proliferation of rat aortic vascular smooth muscle cells(RAVSMCs) stimulated by platelet-derived growth factor BB (PDGF-BB) and to clarify its mechanism underlying the anti-proliferative effect. Methods: The influence of the synthetic naphthoquinone derivative on cell cycle progression and main signal transduction pathway of cell cycle induced by PDGF-BB were investigated by cell proliferation assay, [3H] thymidine incorporation test, cell cycle process analysis and immunoblotting assay. Results: S phase cell percentage in the cell cycle was reduced, while G0/G1 phase cell percentage was increased by the synthetic naphthoquinone in a dose-dependent (0. 1, 0. 5, 1 μmol · L-1) manner. Moreover, DNA synthesis also decreased. The inhibitory rate of PDGF-BB-induced RAVSMCs proliferation achieved the maximum of 44. 4% after 24 h pre-treatment by the synthetic naphthoquinone derivative at the concentration of 1 μmol · L-1. The phosphorylation of extracellular regulated kinase l/2(ERKl/2), Akt, phospholipase C (PLC) γ1 and PDGF receptor β(PDGFRβ) induced by PDGF-BB was significantly decreased (P < 0. 01) by addtion of 1 μmol · L-1 synthetic naphthoquinone derivative. Conclusions: The synthetic naphthoquinone derivative exhibits anti-proliferation activity against RAVSMCs induced by PDGF-BB via blocking the transformation of G0/G1 phase cell into S-phase cell in the cell cycle. The mechanisms might be related to its down-regulatory effect on phosporalation level of ERK1/2, Akt, PLCγ1 and PDGFRβ.

Beta Lapachone blocks the cell cycle and induces apoptosis in canine osteosarcoma cells / Beta Lapachona bloqueia o ciclo celular e induz apoptose em células de osteossarcoma canino

Osteosarcoma is a malignant tumor of primitive bone cells with a high incidence in dogs and humans. The need for more effective drugs with less adverse consequences has pushed the development of chemotherapeutic agents from plants and other natural sources. The aim of this study was to verify the cytotoxic effects of beta-lapachone, a compound present in the sawdust of Tabebuia sp. (popularly known as ipê) wood, on canine osteosarcoma cells subcultured and treated in different concentrations (0.1µm, 0.3µm e 1.0µm) and exposure times (24h, 48h e 72h). Results were obtained through Trypan blue dye exclusion, tetrazolium reducing method, cell survival assay, Annexin V-FITC and Propidium Iodine labeling, JC-1 dye labeling and cell cycle kinetics e analysis. The group treated with 0.3µm beta-lapachone presented higher decrease in cell viability (80.27%, 24h, 47.41%, 48h and 35.19%, 72h) and greater progression of cytotoxicity (19.73%, 24h, 52.59%, 48h and 64.81%, 72h). The lower IC50 (0.180µm) was verified in the group treated for 72 hours. Cell growth after treatment decreased as concentration and time of exposure increased, with 0.50% survival fraction at the concentration of 1.0µm. Initial apoptosis was the most frequent type of cell death in all groups, reaching bottom in the 24-hour group treated with 0.1µm (4.26%) and peaking in the 72-hour group treated with 1.0µm (85.89%). Mitochondrial depolarization demonstrated a dose-dependent phenomenon, indicating the intrinsic apoptosis. Cell growth inhibition by blocking cell cycle in the G0/G1 phase related to the exposure the time. β-lapachone is cytotoxic for canine osteosarcoma cells, induces apoptosis and promotes cell cycle arrest in G0/G1 phase.(AU)

O osteossarcoma é o tumor maligno das células ósseas primitivas, com alta incidência em cães e humanos. A necessidade de medicamentos mais efetivos, com menor consequência adversa, tem gerado esforços para o desenvolvimento de agentes quimioterápicos compostos por plantas e outras fontes naturais. O objetivo deste estudo foi verificar os efeitos citotóxicos da beta lapachona, um composto presente na serragem da madeira do ipê, sobre células de osteossarcoma canino subcultivadas e submetidas ao tratamento, de acordo com as diferentes concentrações (0.1µm, 0.3µm e 1.0µm) e tempo de exposição (24h, 48h e 72h). Os resultados foram obtidos por meio dos métodos de exclusão do corante azul de Tripan e de redução do tetrazólio, além dos ensaios de sobrevivência celular, de dupla marcação com Anexina V-FITC e Iodeto de Propídio, de marcação com o corante JC-1 e pela análise da cinética do ciclo celular. O grupo tratado com 0.3µm de beta lapachona apresentou melhor regressão da viabilidade celular (80,27%, 24h; 47,41%, 48h e 35,19%, 72h) e maior progressão da citotoxicidade (19,73%, 24h; 52,59%, 48h e 64,81%, 72h). O menor IC50 (0.180µm) ocorreu no grupo tratado por 72 horas. O crescimento celular após o tratamento foi menor, de acordo com o aumento da concentração e tempo de exposição, apresentando 0,50% de fração de sobrevivência na concentração de 1.0µm. A apoptose inicial foi o tipo de morte celular mais frequente em todos os grupos, menor no grupo de 24 horas tratado com 0.1µm (4,26%) e maior no grupo de 72 horas tratado com 1.0µm (85,89%). A despolarização mitocondrial ocorreu de maneira dose dependente, indicando a ocorrência de apoptose intrínseca. A β lapachona possui efeitos citotóxicos em células de osteossarcoma canino, induz apoptose e promove o bloqueio do ciclo celular na fase G0/G1.(AU)

Identification and characterization of chemical constituents in Cortex Juglandis Mandshuricae based on UPLC-Q-TOF/MS / 中草药

Objective: To identify the major chemical constituents in Cortex Juglandis Mandshuricae by ultra performance liquid chromatography coupled with time-of-flight mass spectrometry (UPLC-Q-TOF/MS). Methods: The separation was performed on Waters Acquity UPLC BEH C18 column (100 mm×2.1 mm, 1.7 μm), with a mobile phase using water with 0.1% formic acid (A) and acetonitrile with 0.1% formic acid (B) for gradient elution; Q-TOF/MS and electrospray ion (ESI) source was applied for the analysis under the positive and negative ion modes; Target search and non-target search were performed by Peakview 2.0/masterview1.0 or Markerview 1.2.1 software. Then the formulas of compounds were determined by accurate mass and isotopic abundance ratio from target screening function of software. Their structures were determined by analysis of MS/MS fragment or comparison with standard substances and references. Results: Forty-four major chemical compounds including 13 naphthalene quinones, 3 diarylheptanoids, 15 flavonoids, and 13 other compounds were identified or inferred in Cortex Juglandis Mandshuricae. Conclusion: UPLC-Q-TOF/MS method which develops a new strategy can identify the main chemical constituents from Cortex Juglandis Mandshuricae rapidly and accurately, main chemical constituents can be used for quality evaluation and pharmacological research.

Research progress on Rubiae Radix et Rhizoma / 中草药

Rubiae Radix et Rhizoma is one of the Chinese materia medica in common use, which has the effect of promoting circulation of blood, hemostasis, activating collaterals, and so on. The chemical constituents of Rubiae Radix et Rhizoma are plentiful which mainly contain anthraquinones and naphthoquinones and cyclic hexapeptides, terpenoids, polysaccharides, and microelement are also included. The pharmacological activities are various which have the effects of hemostasis, antitumor, anti-oxidant, anti-inflammatory, anti-microbial, rising white blood cell and immunoregulation. The clinical applications are also extensive which have the prominent curative effect for gynecological diseases such as metrorrhagia and metrostaxis, abnormal uterine bleeding, primary dysmenorrhea and other diseases such as anaphylactoid purpura, and renal hematuria. Rubiae Radix et Rhizoma has the very important research values. This paper summarized the research progress on Rubiae Radix et Rhizoma in recent years from the aspects of chemical component, pharmacological action, processing and clinical application so as to provide references to further researches and applications of Rubiae Radix et Rhizoma.

Analysis on major chemical compounds in exocarp of Juglans mandshurica based on UPLC-Q-TOF/MS / 中草药

Objective: To identify the major chemical compounds in 78 batches of the exocarp of Juglans mandshurica from different origins by ultra performance liquid chromatography coupled with time-of-fight mass spectrometry (UFLC-Q-TOF/MS) and determine the major active chemical components. Methods: The separation was performed on Waters Acquity UPLC BEH C18 column (100 mm × 2.1 mm, 1.7 μm), with a mobile phase using water with 0.1% formic acid (A) and acetonitrile with 0.1% formic acid (B) for gradient elution; Q-TOF/MS and electrospray ion (ESI) source were applied for the analysis under the positive ion mode; One thousand ions were extracted through Markerview 1.2.1 software from 78 batches. And common ions (compounds) were selected according to the following principles: One ion can be detected in all samples, and the relative strength is greater than the e4. Then the formula of common ions were determined by accurate mass and isotopic abundance ratio from target screening function of Peakview 2.0/masterview1.0 software. Their structures were determined by analysis of MS/MS fragment or comparison with standard substances and references. Results: Thirty-one major chemical compounds including eleven naphthalene quinones, three diarylheptanoids, three flavonoids, eight triterpenes, and six other compounds were identified or inferred in the exocarp of J. mandshurica. Conclusion: UPLC-Q-TOF/MS method which develops a new strategy can identify the main chemical constituents from the exocarp of J. mandshurica rapidly and accurately, main chemical constituents can be used for the quality evaluation and efficacy material research.

Dynamic variation of major effective components in fresh rejuvenated fruit of Juglans mandshurica based on UPLC-Q-TOF-MS / 中国中药杂志

The changes in effective components of Juglans mandshurica at different harvest periods were analyzed by UPLC-Q-TOF-MS/MS. Eighteen batch samples of J. mandshurica from six harvest periods were assessed by multivariate statistical analysis with Markerview software. The formula of different compounds were determined by accurate mass and isotopic abundance ratio from target screening function of Peakview 2.0/Masterview1.0 software. Then their structure were determined by analysis of MS/MS fragment or comparison with standard substances and references. Naphthoquinone are the major markers in samples of Juglans mandshurica from different harvest periods. Thirty-eight of naphthalenequinones were identified or inferred in J. mandshurica and contents decline gradually. UPLC-Q-TOF-MS method which develops a new strategy can identify and analyze chemical constituents from J. mandshurica rapidly and accurately, main chemical constituents can be used for quality evaluation and efficacy material research. The dynamic changes in the metabolite accumulation of J. mandshurica the basic data for harvesting medicinal plants at different times.

2-Methoxy-1,4-Naphthoquinone (MNQ) Suppresses Protein Kinase C βI, δ, and ζ Expression in Raji Cells.

Protein Kinase C (PKC) is widely documented to be involved in the regulation of cancer cell growth, proliferation, survival, inflammation and apoptosis. This study evaluates the capability of 2-Methoxy-1,4- Naphthoquinone (MNQ) in regulating PMA-induced PKC expression in human Burkitt’s lymphoma cell line (Raji cells). MNQ exhibited stronger anti-tumour-promoting activity than genistein based on the inhibitory assay of Epstein-Barr virus (EBV) activation. The IC50 values attained were 2.92 and 7.40 μM, respectively. The suppressive effects of MNQ on PKC expression was determined by using the PepTag® non-radioactive detection of PKC assay. The IC50 values achieved for staurosporine and rottlerin (standard control), and MNQ were 0.01, 6.38, and 13.13 μM, respectively. These preliminary results indicate that MNQ specifically suppressed the expression of PKC βI, δ, and ζ in a concentration-dependent manner in Raji cells.

A novel 96-microwell-based high-throughput spectrophotometric assay for pharmaceutical quality control of crizotinib, a novel potent drug for the treatment of non-small cell lung cancer / Um ensaio espectrofotométrico de alto rendimento à base de novo de 96 micropoços para o controlo de qualidade farmacêutica crizotinibe, um novo potente fármaco para o tratamento de cancro do pulmão de células não-pequenas

This study describes the development and validation of a novel 96-microwell-based high throughput spectrophotometric assay for pharmaceutical quality control of crizotinib (CZT), a novel drug for the treatment of non-small cell lung cancer. We examined the reaction between CZT and 1,2-naphthoquinone-4-sulphonate, a chromogenic reagent. A red-colored product showing a maximum absorption peak (λ_max) at 490 nm was produced in an alkaline medium (pH 9). We examined stoichiometry of the reaction and postulated the reaction mechanism. To our knowledge, this is the first study to describe a color-developing reaction for the proposed assay. The reaction was performed in a 96-microwell plate, and the absorbance of the colored product was measured using an absorbance reader at 490 nm. Under optimized reaction conditions, Beer's law, which shows a correlation between absorbance and CZT concentration, was obeyed in the range of 4-50 µg/well with an appropriate correlation coefficient (0.999). The limits of detection and quantification were 1.73 and 5.23 µg/well, respectively. The assay showed high precision and accuracy. The proposed assay was applied successfully for the determination of CZT in capsules. Thus, the assay proposed in this study is practical and valuable for routine application in pharmaceutical quality control laboratories...

Este estudo descreve o desenvolvimento e a validação de um novo ensaio espectrofotométrico em larga escala em 96 micropoços para o controle farmacêutico de crizotinibe (CZT), novo fármaco para o tratamento de câncer de pulmão de células não pequenas. Examinamos a reação entre o CZT e o 4-sulfonato de 1,2-naftoquinona, um reagente cromogênico. Obteve-se, em meio alcalino (pH 9), produto vermelho, com absorção máxima (λ_max) em 490 nm. Examinamos a estequiometria da reação e propusemos mecanismo de reação. Este, segundo nosso conhecimento, é o primeiro estudo para descrever reação de desenvolvimento de cor para o ensaio proposto. A reação foi realizada em placas de 96 micropoços e mediu-se a absorbância do produto colorido utilizando-se leitor de absorbância a 490 nm. Sob condições otimizadas de reação, a lei de Beer, que mostra a correlação entre a absorbância e a concentração de CZT, foi obedecida na faixa de 4-50 µg/poço, com coeficiente de correlação apropriado (0,999). Os limites de detecção e de quantificação foram, respectivamente, 1,73 e 5,23 µg/poço. O ensaio mostrou alta precisão e exatidão. O ensaio proposto foi aplicado com sucesso para a determinação de CZT em cápsulas e é prático e válido para a aplicação de rotina em laboratórios de controle farmacêutico...

Effect of Plumbago zeylanica administration on brain neurotransmitter level in Wistar albino rats.

According to WHO about 80% of the world’s population relies on traditional medicine for their primary health care. Plumbago zeylanica L. is a medicinal plant, belong to the family of Plumbaginaceae and the root of P. zeylanica contains several bioactive constituent like L-dopa, Plumbagin (naphthoquinone), droseron, chitranone, triterpenoid, anthraquinone. This study is designed to evaluate the effect of P. zeylanica and naphthoquinone on the level of various amine neurotransmitters namely epinephrine, norepinephrine, serotonin, 5-hydroxyindole 3- acetic acid (5-HIAA), and dopamine on the discrete regions of the brain tissues. Wistar male albino rats were treated separately with ethanoloic extract of P. zeylannica (root) and the commercially purchased phytochemical naphthoquinone at the dose of 2mg/kg b. wt with different experimental groups. The brain tissue homogenates (cerebral cortex, cerebellum, hypothalamus, pons-medulla, midbrain, and corpus striatum) were analyzed to quantify the aforementioned neurotransmitters by high performance liquid chromatography (HPLC). The results showed that, administration of P. zeylanica and NQ does not alter the many of the studied neurotransmitter at significant level; however, there is a change in the neurotransmitter profile in few specific regions of Wistar rat brain and striatum was found to be affected more.

Study on chemical constituents from green husk of Juglans sigillata / 中草药

Objective: To investigate the chemical constituents in the green husk of Juglans sigillate. Methods: The chemical constituents were isolated by silica gel, RP-18, MCI column chromatographies and so on. The structures were identified on the basis of spectroscopic analysis (MS, 13C-NMR, 1H-NMR). Results: Eleven compounds were isolated from the extract of green husk of J. sigillate. And their structures were characterized as: sinapaldehyde (1), (Z)-10-eicosenoic acid (2), 5α, 8α-epidioxyergosta-6, 22E-diene-3β-ol (3), 5, 8-dihydroxy-4-methoxy-α-tetralone (4), regiolone (5), 4, 5-dihydroxy-α-tetralone (6), 4, 5, 8-trihydroxy-α-tetralone (7), 5-hydroxy-4-methoxy-α-tetralone (8), 5-hydroxy-2-methoxy-1, 4-naphthoquinone (9), naringenin (10), and β-sitosterol (11). Conclusion: Compounds 1-2 are isolated from the plants of Juglans Linn. for the first time.

The molecular docking of 1,4-naphthoquinone derivatives as inhibitors of Polo-like kinase 1 using Molegro Virtual Docker.

Polo-like kinase 1 (Plk1) is over expressed in many types of human cancers, and has been implicated as an adverse prognostic marker for cancer patients. Plk1 is localized to its intracellular anchoring sites via its polo-box domain (PBD). The PBD of Plk1 has a crucial role in proper subcellular localization and mitotic functions of Plk1. Plk1 is the preferential target for inhibition of the mitotic processing therefore it can be chosen as drug target for the treatment of cancer. The aim of the study is to find plk1 inhibitor potential from naphthoquinone derivatives through binding free energy analysis into plk1 using molecular docking. We conducted docking simulation to naphthoquinone derivatives as ligands into plk1 as receptor. The 3D structure of plk1 was downloaded from PDB (Code ID:3THB). The structure of ligands and protein were prepared using ChemBioDrawUltra 12.0. Docking process, the interaction and binding of ligands – protein were done and visualized using software Molegro Virtual Docking.(MVD). The results showed no hydrogen bonding and electrostatic interaction between compound NO11(modified naphthoquinone) with Plk1, but this compound have more steric interaction with Phe 133, Asp 194, Glu 101, Lys 82, Cys 133 and Glu 140 of Plk1. Moldock scores of compound NO11, is -134.73 kcal/mol. It is predicted that compound NO11 has potency as lead compound to find a new anticancer candidates for possible therapeutic agents.

Naphthoquinones: biological properties and synthesis of lawsone and derivatives- a structured review / Naftoquinonas: propiedades biológicas y síntesis de lawsona y derivados ­ una revisión estructurada

Background: Naphthoquinones are natural pigments that are widely distributed in nature and have important biological activities. Lawsone (2-hydroxy-1,4-naphthoquinone) and its synthetic derivatives, and especially those containing nitrogen, have promising potential for the treatment of different diseases due to their antibacterial, antifungal, antiviral, antitumor and antiparasitic effects, and for pest control via their molluscicidal and insecticidal activities. Their pharmacological activities and mechanisms of action are related to their oxide/reduction and acid/base properties, and can be modulated by directly adding a substituted to the 1,4-naphthoquinone ring. Due to this, naphthoquinones and their derivatives are at the center of multiple areas of research. In this manuscript, we present a structured review of lawsone, a hydroxyl derivative of naphthoquinone, and discuss relevant reports about the chemistry and synthesis of derivatives. Finally, we present the pharmacological activities and mechanism of action reported. Objective: The purpose of this review is to present recent reports from the literature about the chemistry, synthesis and pharmacological properties of lawsone and its amine derivatives. Methods: This structured review presents a discussion about lawsone literature over the last ten years. The most representative studies including those about the chemistry of lawsone, the synthesis of its derivatives, and pharmacological properties were identified and selected. The information has been compiled, organized and presented into logical topics in order to provide a current review for the field of lawsone chemistry. Results: A general overview of the principal aspects of lawsone chemistry, the synthesis of its derivatives and their pharmacological activities and mechanism of action has been obtained. This provides researchers in the area with a framework from which to investigate further. Conclusions: Lawsone and its derivatives have promising potential for treating several diseases due to their antibacterial, antifungal, antiviral, antitumor and antiparasitic effects and have the potential to control pests via their molluscicidal and insecticidal properties. For this reason, it would be of interest to evaluate the synthetic derivatives of this compound for their pharmacologic actions; in the future, synthetic derivatives of lawsone could potentially be used to treat disease and be used as pesticides.

2-Bromo-1,4-naphthoquinone: a potentially improved substitute of menadione in Apatone™ therapy

Apatone™, a combination of menadione (2-methyl-1,4-naphthoquinone, VK3) and ascorbic acid (vitamin C, VC) is a new strategy for cancer treatment. Part of its effect on tumor cells is related to the cellular pro-oxidative imbalance provoked by the generation of hydrogen peroxide (H2O2) through naphthoquinone redox cycling. In this study, we attempted to find new naphthoquinone derivatives that would increase the efficiency of H2O2 production, thereby potentially increasing its efficacy for cancer treatment. The presence of an electron-withdrawing group in the naphthoquinone moiety had a direct effect on the efficiency of H2O2 production. The compound 2-bromo-1,4-naphthoquinone (BrQ), in which the bromine atom substituted the methyl group in VK3, was approximately 10- and 19-fold more efficient than VK3 in terms of oxygen consumption and H2O2 production, respectively. The ratio [H2O2]produced / [naphthoquinone]consumed was 68 ± 11 and 5.8 ± 0.2 (µM/µM) for BrQ and VK3, respectively, indicating a higher efficacy of BrQ as a catalyst for the autoxidation of ascorbic acid. Both VK3 and BrQ reacted with glutathione (GSH), but BrQ was the more effective substrate. Part of GSH was incorporated into the naphthoquinone, producing a nucleophilic substitution product (Q-SG). The depletion of BrQ by GSH did not prevent its redox capacity since Q-SG was also able to catalyze the production of reactive oxygen species. VK3/VC has already been submitted to clinical trials for the treatment of prostate cancer and has demonstrated promising results. However, replacement of VK3 with BrQ will open new lines of investigation regarding this approach to cancer treatment.

Antitumor and immunomodulatory effects of the naphthoquinone 5-methoxy-3,4-dehydroxanthomegnin

Large number of quinones has been associated with antitumor, antibacterial, antimalarial and antifungal activities. In this work we describe the effect of the naphthoquinone, 5-methoxy-3,4-dehydroxanthomegnin, on murine tumor cells (LP07 and LM2) and its immunomodulatory effect on nitric oxide (NO) production on LPS-stimulated macrophages. The results have shown that 5-methoxy-3,4-dehydroxanthomegnin was a significant inhibitor of LPS-stimulated NO generation from macrophage (inhibition percentage ranged from 97.4 to 98.9 percent) and a strong cytotoxic agent against both tumor cells LP07 and LM2 (CI50 6.2±0.36 µM and 74.6±1.9 µM, respectively). These results indicate that the 5-methoxy-3,4-dehydroxanthomegnin may show promising activity in the treatment of murine breast and lung cancer by immunomodulatory and antiproliferative activities.

Larvicidal activity of extracts from three Plumbago spp against Anopheles gambiae

Three Plumbago spp have been tested for mosquito larvicidal activity. The crude extracts exhibiting the highest larvicidal activity against Anopheles gambiae were hexane (LC50 = 6.4 μg/mL) and chloroform (LC50 = 6.7 μg/mL) extracts from Plumbago zeylanica Linn, chloroform (LC50 = 6.7 ug/mL) extract from Plumbago stenophylla Bull and ethyl acetate (LC50 = 4.1 μg/mL) extract from Plumbago dawei Rolfe. These LC50 values were within 95 percent confidence limits. 5-hydroxy-2-methyl-1,4-naphthoquinone (plumbagin) 1 (LC50 = 1.9 μg/mL) and β-sitosterol 2 were characterised from ethyl acetate extract of root bark of P. dawei, a native medicinal plant growing in Kenya, based on spectral analysis and comparisons with data in literature.

Molluscicidal activity of 2-hydroxy-[1, 4]naphthoquinone and derivatives

The toxic profile of lawsone (2-hydroxy-[1,4]naphthoquinone) and a series of [1,4]naphthoquinone derivatives was evaluated against the brine shrimp Artemia salina and against the mollusk Biomphalaria glabrata, the main transmitting vector of schistosomiasis in Brazil. Of the seventeen compounds tested nine fell below the threshold of 100 µg/mL set for potential molluscicidal activity by the World Health Organization. As a general rule derivatives with non-polar substituents presented the highest molluscicidal activities. These substances showed significant toxicity in A. salina lethality bioassay.

A toxicidade da lausona (2-hidroxi-1,4)-naftoquinona e de diversos derivados foi avaliada frente à Artemia salina e ao molusco Biomphalaria glabrata, o principal vetor de transmissão da esquistossomose no Brasil. Entre os dezessete compostos testados, nove apresentaram um perfil de toxicidade menor que 100 µg/mL, sendo potenciais agentes moluscicidas de acordo com as designações da Organização Mundial da Saúde. No presente estudo, os compostos contendo substituintes apolares exibiram as maiores atividades. Estes compostos também se mostraram significantemente tóxicos frente à A. salina.