Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 296
Filtrar
1.
Chem Commun (Camb) ; 58(52): 7249-7252, 2022 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-35670109

RESUMO

Lower-rim Cinchona anchored calix[4]arene cationic catalysts were developed for asymmetric Michael addition of acetylacetone to ß-nitrostyrenes. The desired Michael adducts were formed with high yields and enantioselectivities. Density functional theory investigations throw light on the catalyst-substrate interaction and the reaction mechanism.


Assuntos
Calixarenos , Cinchona , Catálise , Estereoisomerismo
2.
Chirality ; 34(8): 1065-1077, 2022 08.
Artigo em Inglês | MEDLINE | ID: mdl-35596543

RESUMO

Chiral zwitterion ion exchangers represent efficient chiral stationary phases for stereoselective resolution of various analytes including chiral acids, bases, and zwitterions. In this contribution, we have focused on utilization of chiral zwitterionic sorbents, denoted as ZWIX (+A) and ZWIX (-A). These are analogical chiral systems to commercially available columns, Chiralpak ZWIX (+) and Chiralpak ZWIX (-), which are usually operated with buffered mobile phases. In this contribution, we have studied the enantiorecognition power of the ZWIX (+A) and ZWIX (-A) columns on a series of dipeptides operated under buffer-free reversed-phase conditions. Retention characteristics of zwitterionic dipeptides are discussed using an electrostatically driven adsorption model, which provides a good fit with both monotonous and U-shaped curves.


Assuntos
Alcaloides de Cinchona , Cinchona , Cromatografia Líquida de Alta Pressão , Dipeptídeos , Estereoisomerismo
3.
Hist Cienc Saude Manguinhos ; 29(1): 61-79, 2022.
Artigo em Inglês, Espanhol | MEDLINE | ID: mdl-35442279

RESUMO

This article examines the circulation of knowledge about Cinchona plants. Francisco José de Caldas and Alexander von Humboldt were interested in their taxonomy, distribution, trade, exploitation, production and conservation. The former's observations were better, but his contributions were silenced by Humboldt and other actors such as José Celestino Mutis. Caldas changed from a passive position of accepted subordination to one of self-advocacy, but his arguments were not widely publicized, in part because his results did not favor commercial interests and he lacked connections. Caldas used similar techniques to Humboldt to appropriate and systematize knowledge about cinchonas, silencing various sources.


El artículo reflexiona sobre la circulación de conocimiento en torno a las plantas de quina. Francisco José de Caldas y Alexander von Humboldt se interesaron por su taxonomía, distribución, comercio, explotación, producción y conservación. Las observaciones del primero fueron mejores, pero sus aportes fueron silenciados por el segundo y por otros actores como José Celestino Mutis. Caldas cambió desde una posición pasiva y de aceptada subalternidad, hasta una de reclamo, pero sus argumentos no tuvieron mayor difusión, en parte porque sus resultados no favorecían intereses comerciales y carecía de redes. Caldas usó dispositivos similares a los de Humboldt para apropiar y sistematizar conocimientos sobre las quinas, silenciando a varias fuentes.


Assuntos
Cinchona , Dissidências e Disputas
4.
J Chromatogr A ; 1670: 462974, 2022 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-35320750

RESUMO

The enantioselective separation of newly synthesized fluorine-substituted ß-phenylalanines has been performed utilizing Cinchona alkaloid-based ion-exchanger chiral stationary phases. Experiments were designed to study the effect of eluent composition, counterion content, and temperature on the chromatographic properties in a systematic manner. Mobile phase systems containing methanol or mixtures of methanol and acetonitrile together with acid and base additives ensured highly efficient enantioseparations. Zwitterionic phases [Chiralpak ZWIX (+) and ZWIX(-)] were found to provide superior performance compared to that by the anion-exchangers (Chiralpak QN-AX and QD-AX). A detailed thermodynamic characterization was also performed by employing van't Hoff analysis. Using typical liquid chromatographic experimental conditions, no marked effect of the flow rate could be observed on the calculated thermodynamic parameters. In contrast, a clear tendency has been revealed about the effect of the eluent composition on the thermodynamics for the zwitterionic phases.


Assuntos
Alcaloides de Cinchona , Cinchona , Cromatografia Líquida de Alta Pressão/métodos , Cinchona/química , Alcaloides de Cinchona/química , Metanol , Fenilalanina , Estereoisomerismo , Termodinâmica
5.
Org Biomol Chem ; 20(4): 824-830, 2022 01 26.
Artigo em Inglês | MEDLINE | ID: mdl-35015015

RESUMO

Selenium-containing amino acids are valuable targets but methods for the stereoselective α-selenation of simple amino acid precursors are rare. We herein report the enantioselective electrophilic α-selenation of azlactones (masked α-amino acid derivatives) and isoxazolidin-5-ones (masked ß-amino acids) using Cinchona alkaloids as easily accessible organocatalysts. A variety of differently substituted derivatives was accessed with reasonable levels of enantioselectivities and further studies concerning the stability and suitability of these compounds for further manipulations have been carried out as well.


Assuntos
Alcaloides/química , Aminoácidos/síntese química , Cinchona/química , Aminoácidos/química , Catálise , Estrutura Molecular , Estereoisomerismo
6.
Clin Dermatol ; 39(5): 900-903, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34785019

RESUMO

Quinine and its D-isomer quinidine have been used medically in Europe since the 1600s. They were originally found within the bark of the cinchona tree in the jungle of the Andes. They were recognized to have multiple beneficial medical properties, ranging from a combined antipyretic and analgesic effect to the first effective treatment for malaria and later atrial fibrillation. With the development of other medications and the recognition of the potential life-threatening toxic reactions to these drugs, their medical use declined. Quinine is available without a prescription in many countries and is present in tonic water. Quinine has an extensive following of users who believe it is salutary and harmless, considering it a food supplement. In the past, dermatologists were frequently the first to recognize disease caused by these drugs owing to early findings of dermatitis or petechiae. Even though the medical use of these drugs has markedly decreased, drug eruptions may still be due to quinine, and patients may even be unaware they are taking this medication.


Assuntos
Cinchona , Dermatologia , Erupção por Droga , Humanos , Extratos Vegetais , Quinina/efeitos adversos
7.
Chem Commun (Camb) ; 57(79): 10116-10124, 2021 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-34522921

RESUMO

Organocatalysis has unique modes of activation, mild reaction conditions, and good catalyst structural amenability. The integration of green techniques such as catalyst recovery and one-pot reactions makes organocatalysis more efficient and attractive. Presented in this article are the recyclable cinchona alkaloid-catalyzed reactions including fluorination and Michael addition-initiated cascade reactions in asymmetric synthesis of functionalized compounds of biological interest.


Assuntos
Cinchona/química , Compostos Orgânicos/síntese química , Catálise , Halogenação , Estrutura Molecular , Compostos Orgânicos/química
8.
Pharmazie ; 76(8): 396-402, 2021 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-34412740

RESUMO

This paper examines the contribution of three Portuguese scientists to Cinchona cultivation in the former Portuguese colonies in the second half of the 19th century, while discussing the importance of their studies in Germany to their professional lives. Portuguese pharmaceutical, medical, and botanical literature from the 19 th and 20 th century was reviewed, as well as books and articles regarding the history of pharmacy and medicine in Portugal. Cinchona bark, source of the antimalarial alkaloid quinine, is obtained from a South American plant, and was an important commodity in the 19th century. Many European nations (including Portugal) tried to acclimatize and cultivate Cinchona plants in their colonies. Pharmacist Joaquim dos Santos e Silva (1842-1906) performed chemical analysis of Cinchona bark samples from the Portuguese colonies in Africa. Forester Bernardino Barros Gomes (1839-1910) wrote a book with practical instructions for Cinchona cultivation and chronicled the history of Cinchona plantations in the British and Dutch colonies. In that work he also encouraged private planters to cultivate Cinchona. Forester Adolpho Frederico Möller (1842-1920), as inspector of the Botanical Garden of Coimbra, managed Cinchona plants' cultivation in the garden's nurseries, which were later sent to the colonies, and answered queries from Cinchona planters. Silva's chemistry studies in Germany were crucial to his career and the work of the three scientists was influenced and guided by their knowledge of German science and scientific culture.


Assuntos
Alcaloides , Antimaláricos , Cinchona , História do Século XIX , História do Século XX , Portugal , Quinina/história
9.
J Evid Based Integr Med ; 26: 2515690X211026193, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34225463

RESUMO

OBJECTIVES AND SETTING.: As the lethal COVID-19 pandemic enters its second year, the need for effective modalities of alleviation remains urgent. This includes modalities that can readily be used by the public to reduce disease spread and severity. Such preventive measures and early-stage treatments may temper the immediacy of demand for advanced anti-COVID measures (drugs, antibodies, vaccines) and help relieve strain also on other health system resources. DESIGN AND PARTICIPANTS.: We present results of a clinical study with a multi-component OTC "core formulation" regimen used in a multiply exposed adult population. Analysis of clinical outcome data from our sample of over 100 subjects - comprised of roughly equal sized regimen-compliant (test) and non-compliant (control) groups meeting equivalent inclusion criteria - demonstrates a strong statistical significance in favor of use of the core formulations. RESULTS.: While both groups were moderate in size, the difference between them in outcomes over the 20-week study period was large and stark: Just under 4% of the compliant test group presented flu-like symptoms, but none of the test group was COVID-positive; whereas 20% of the non-compliant control group presented flu-like symptoms, three-quarters of whom (15% overall of the control group) were COVID-positive. CONCLUSIONS.: Offering a low cost, readily implemented anti-viral approach, the study regimen may serve, at the least, as a stopgap modality and, perhaps, as a useful tool in combatting the pandemic.


Assuntos
Antivirais/uso terapêutico , COVID-19/tratamento farmacológico , Controle de Doenças Transmissíveis , Suplementos Nutricionais , Pandemias , Adulto , COVID-19/virologia , Cinchona , Feminino , Humanos , Ionóforos/uso terapêutico , Lisina/uso terapêutico , Masculino , Pessoa de Meia-Idade , Medicamentos sem Prescrição , Quercetina/uso terapêutico , SARS-CoV-2 , Índice de Gravidade de Doença , Resultado do Tratamento , Vitaminas/uso terapêutico , Zinco/uso terapêutico
10.
Chem Commun (Camb) ; 57(55): 6816-6819, 2021 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-34151341

RESUMO

Dual cinchona quinuclidinium salts with a diphenyl ether linker were synthesized and used as powerful asymmetric phase transfer catalysts in the α-alkylation of imines of glycine and alanine ester with 0.01-0.1 mol% loading (17 examples, 92-99% ee). Skewed conformers of dual quinuclidiniums at TS were proposed to rationalize their high efficiency via DFT calculations.


Assuntos
Cinchona/química , Glicina/química , Iminas/química , Sais/química , Alquilação , Catálise , Teoria da Densidade Funcional , Ésteres/química , Modelos Moleculares , Conformação Molecular , Estereoisomerismo
11.
J Chromatogr A ; 1648: 462212, 2021 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-33992991

RESUMO

Chiral ion exchangers based on quinine (QN) and quinidine (QD), namely Chiralpak QN-AX and QD-AX as anionic and ZWIX(+) and ZWIX(-) as zwitterionic ion exchanger chiral stationary phases (CSPs) have been investigated with respect to their retention and chiral resolution characteristics. For the evaluation of the effects of the composition of the polar organic bulk solvents of the mobile phase (MP) and those of the organic acid and base additives acting as displacers necessary for a liquid chromatographic ion-exchange process, racemic N-(3,5-dinitrobenzoyl)leucine and other related analytes were applied. The main aim was to evaluate the impact of the MP variations on the observed, and thus the apparent enantioselectivity (αapp), and the retention factor. Significant differences were found using either polar protic methanol (MeOH) or polar non-protic acetonitrile (MeCN) solvents in combination with the acid and base additives as counter- and co-ions. It became clear, that the charged sites of both the chiral selectors of the CSPs and the analytes get specifically solvated, accompanied by the adsorption of all MP components on the CSP, thereby building a stagnant "stationary phase layer" with a composition different from the bulk MP. Via a systematic change of the MP composition, trends of resulting αapp and retention factors have been identified and discussed. In a detailed set of experiments, the effect of the concentration of the acid component in the MP containing MeOH or MeCN was specifically investigated, with the acid considered to be a displacer in anion-exchange type chromatographic systems. Surprisingly, all four chiral columns retained and resolved the tested N-acyl-Leu analytes with αapp values up to 21 within a retention factor window of 0.03 and 10 with pure MeOH as eluent. However, using pure MeCN as eluent, an almost infinite-long retention of the acidic analyte was noticed in all cases. We suggest that the rather different thickness of the solvation shells generated by MeOH or MeCN around the charged/chargeable sites of the chiral selector determines eventually the strength of the electrostatic selector-selectand interactions. As a control experiment we included the non-chiral N-acylglycine derivatives as analyte in all cases to support the interpretations with respect to the contribution of the enantioselective and non-enantioselective retention factor increments as a part of the observed αapp.


Assuntos
Cinchona/química , Leucina/química , Solventes/química , Cromatografia Líquida de Alta Pressão/métodos , Cromatografia por Troca Iônica/métodos , Troca Iônica , Quinidina/química , Quinina/química , Estereoisomerismo
12.
J Sep Sci ; 44(14): 2735-2743, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33999502

RESUMO

Enantiomers of cationic compounds of pharmaceutical relevance, namely tetrahydro-ß-carboline and 1,2,3,4-tetrahydroisoquinoline analogs, were separated by high-performance liquid chromatography. Separations were performed on Cinchona-alkaloid-based zwitterionic ion exchanger type chiral stationary phases applied as cation exchangers using mixtures of methanol and acetonitrile or tetrahydrofuran as bulk solvent components containing triethylammonium acetate or ammonium acetate as organic salt additives. On the zwitterionic ZWIX(+) and ZWIX(-) columns investigated, retention and enantioseparation of the studied basic analytes were influenced by the nature and concentration of the organic components of the mobile phase. The effect of organic salt additives on the retention behavior of the studied analytes can be described by the stoichiometric displacement model related to the counterion concentration. Investigations on the structure-retention relationships were performed applying different mobile phase systems for the two types of cationic analytes. For the thermodynamic characterization, parameters such as changes in standard enthalpy (Δ(ΔH°)), entropy (Δ(ΔS°)), and free energy (Δ(ΔG°)) were calculated on the basis of van't Hoff plots derived from the ln α versus 1/T curves. In most cases, enthalpy-driven enantioseparations were observed, with a consistent dependence of the calculated thermodynamic parameters on the mobile phase composition. Elution sequences of the studied compounds were determined in all cases.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Alcaloides de Cinchona , Cinchona/química , Cátions/isolamento & purificação , Alcaloides de Cinchona/análise , Alcaloides de Cinchona/química , Preparações Farmacêuticas/isolamento & purificação
13.
Org Lett ; 23(6): 2227-2231, 2021 03 19.
Artigo em Inglês | MEDLINE | ID: mdl-33656901

RESUMO

A new and crucial synthon of 3-((diphenylmethylene)-amino)-oxindole was designed and synthesized, for which an organocatalytic and enantioselective Michael/cyclization reaction with a terminal vinyl ketone catalyzed by a cinchona base was disclosed. A wide variety (28 examples) of almost all new chiral spiro[oxindol-3,2'-pyrrols] were prepared in excellent yields (up to 99%) with excellent enantioselectivities (95-99% ee), of which a typical chiral spiro product was further reduced to chiral spiro[oxindole-3,2'-pyrrolidine].


Assuntos
Cinchona/química , Oxindóis/química , Bases de Schiff/química , Compostos de Espiro/química , Ciclização , Cetonas/química , Estrutura Molecular , Estereoisomerismo
14.
Actas Dermosifiliogr (Engl Ed) ; 112(2): 118-126, 2021 Feb.
Artigo em Inglês, Espanhol | MEDLINE | ID: mdl-33045209

RESUMO

Researchers the world over are working to find the treatments needed to reduce the negative effects of coronavirus disease 2019 (COVID-19) and improve the current prognosis of patients. Several drugs that are often used in dermatology are among the potentially useful treatments: ivermectin, antiandrogenic agents, melatonin, and the antimalarial drugs chloroquine and hydroxychloroquine. These and other agents, some of which have proven controversial, are being scrutinized by the scientific community. We briefly review the aforementioned dermatologic drugs and describe the most recent findings relevant to their use against COVID-19.


Assuntos
COVID-19/tratamento farmacológico , SARS-CoV-2 , Antagonistas de Androgênios/farmacologia , Antagonistas de Androgênios/uso terapêutico , Antimaláricos/farmacologia , Antimaláricos/uso terapêutico , Antioxidantes/farmacologia , Antioxidantes/uso terapêutico , Antiparasitários/farmacologia , Antiparasitários/uso terapêutico , COVID-19/mortalidade , Cloroquina/farmacologia , Cloroquina/uso terapêutico , Cinchona/química , Humanos , Hidroxicloroquina/farmacologia , Hidroxicloroquina/uso terapêutico , Ivermectina/farmacologia , Ivermectina/uso terapêutico , Melatonina/farmacologia , Melatonina/uso terapêutico , Internalização do Vírus/efeitos dos fármacos
15.
J Pharm Biomed Anal ; 193: 113724, 2021 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-33197835

RESUMO

In this study, we present results obtained on the diastereo- and enantioseparation of some basic natural and synthetic Cinchona alkaloid analogs by applying liquid chromatographic (LC) and subcritical fluid chromatographic (SFC) modalities on amylose and cellulose tris-(phenylcarbamate)-based stationary phases using n-hexane/alcohol/DEA or CO2/alcohol/DEA mobile phase systems. Seven chiral stationary phases in their immobilized form were employed to explore their stereoselectivity for a series of closely related group of analytes. The most important characteristics of LC and SFC systems were evaluated through the variation of the applied chromatographic conditions (e.g., the nature and content of the alcohol modifier, the concentration of additives, temperature). The columns Chiralpak IC and IG turned out to be the best in both LC and SFC modalities. Temperature-dependence study indicated enthalpy-controlled separation in most cases; however, separation controlled by entropy was also registered.


Assuntos
Alcaloides de Cinchona , Cinchona , Cromatografia Líquida de Alta Pressão , Polissacarídeos , Estereoisomerismo
16.
Probl Sotsialnoi Gig Zdravookhranenniiai Istor Med ; 28(Special Issue): 1118-1122, 2020 Oct.
Artigo em Russo | MEDLINE | ID: mdl-33219768

RESUMO

The article presents a review of the historical facts related to the discovery and introduction of chloroquine and hydroxychloroquine. The history of studying aminoquinoline preparations is associated with the discovery of the antimalarial action of the bark of the quinine tree, the isolation of quinine from other active substances - alkaloids and the determination of their structure. The structural similarity of quinine and one of the first chemically synthesized dyes - methylene blue-was an important factor at the beginning of the synthesis of molecules with antimalarial activity in the 1930s in Germany. Pamaquin (plasmoquin, plasmoсid), quinacrine (quinacrine, Atebrin, Mepacrine), sontoquine (sontochin), chloroquine, primaquine, hydroxychloroquine, and mefloquine (Lariam) were consistently introduced in medical practice. Many of these medications are no longer widely used. However, chloroquine and hydroxychloroquine have not lost their relevance. The scope of their use has been expanded.


Assuntos
Antimaláricos , Cinchona , Cloroquina , Casca de Planta , Quinina
17.
Anal Bioanal Chem ; 412(27): 7405-7416, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32851457

RESUMO

Alkaloids represent a major group of natural products (NPs), derived from highly diverse organisms. These structurally varied specialized metabolites are widely used for medicinal purposes and also known as toxic contaminants in agriculture and dietary supplements. While the detection of alkaloids is generally facilitated by GC- or LC-MS, these techniques do require considerable efforts in sample preparation and method optimization. Bypassing these limitations and also reducing experimental time, matrix-free laser desorption ionization (LDI) and related methods may provide an interesting alternative. As many alkaloids show close structural similarities to matrices used in matrix-assisted laser desorption ionization (MALDI), they should ionize upon simple laser irradiation without matrix support. With this in mind, the current work presents a systematic evaluation of LDI properties of a wide range of structurally diverse alkaloids. Facilitating a direct comparison between LDI and ESI-MS fragmentation, all tested compounds were further studied by electrospray ionization (ESI). Moreover, crude plant extracts of Atropa belladonna, Cinchona succirubra, and Colchicum autumnale were analyzed by LDI in order to evaluate direct alkaloid detection and dereplication from complex mixtures. Finally, dose-dependent evaluation of MALDI and LDI detection using an extract of Rosmarinus officinalis spiked with atropine, colchicine, or quinine was conducted. Overall, present results suggest that LDI provides a versatile analytical tool for analyzing structurally diverse alkaloids as single compounds and from complex mixtures. It may further serve various potential applications ranging from quality control to the screening for toxic compounds as well as the build up of MS databases. Graphical abstract.


Assuntos
Alcaloides/análise , Atropa belladonna/química , Cinchona/química , Colchicum/química , Extratos Vegetais/química , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodos
18.
Sci Rep ; 10(1): 4558, 2020 03 12.
Artigo em Inglês | MEDLINE | ID: mdl-32165694

RESUMO

In this works, a simple, efficient and repeatable protocol was developed for in vitro regeneration via callus-mediated organogenesis of Neolamarkia Cadamba using cotyledonary petioles and hypocotyls. Effects of basal medium, plant growth regulators, the types and age of explant on the formation of adventitious buds/shoots were studied. Meanwhile, histological analysis for early ontogenic stages and genetic stability assessment by flow cytometry were investigated. Our investigation demonstrated that, compared with 6-benzyladenine (BA), N6-(2-isopentenyl) adenine (2-ip), Thidiazuron (TDZ) was the optimal cytokinin for buds/shoots induction on cotyledon and hypocotyl explants. Douglas-fir and sugar pine medium (DCR) supplemented with 22.7 µM TDZ and 0.27 µM α-naphthalene acetic acid (NAA) was most effective on bud induction, with the highest bud-induction rate and numbers of buds on cotyledon and hypocotyl explants. The available shoot per explant hit 35.2 when the induced callus sub-cultured to a medium without TDZ. It was found that TDZ could promote induction of the callus and the buds, however, continuous exposure beyond 4 weeks of supplemented high concentration (exceed 11.35 µM), TDZ was harmful to the proliferation and growth of buds/shoots. DCR appeared more efficiency than Murashige and Skoog medium (MS), Woody Plant medium (WPM), anther culture of cereal crops medium (N6) on bud induction. Age of cotyledon and hypocotyl explants in 20-day to 25-day was most beneficial to adventitious buds/shoots formation. Histological investigation confirmed that the buds originated from the wounded incisions of cotyledonary petiole and hypocotyl fragments, with callus formation. The regeneration plantlets were successfully acclimatized in greenhouse, yielded above 95% survival rate in field, exhibited normal morphology and growth characteristics. The analysis of flow cytometry on N. cadamba indicated no variation in the ploidy levels between the regenerated plantlets and the donor trees. The developed procedure can be used for mass production, germplasm exchange and transgenic studies to improve the resistance of the species via Agrobacterium-mediated.


Assuntos
Técnicas de Cultura de Células/métodos , Cinchona/crescimento & desenvolvimento , Cotilédone/citologia , Meios de Cultura/química , Hipocótilo/citologia , Compostos de Benzil/farmacologia , Cinchona/citologia , Cinchona/genética , Cotilédone/efeitos dos fármacos , Cotilédone/genética , Citocininas/farmacologia , Citometria de Fluxo , Hipocótilo/efeitos dos fármacos , Hipocótilo/genética , Ácidos Naftalenoacéticos/química , Organogênese Vegetal , Compostos de Fenilureia/farmacologia , Reguladores de Crescimento de Plantas/farmacologia , Ploidias , Purinas/farmacologia , Tiadiazóis/farmacologia , Clima Tropical
19.
Phytother Res ; 34(7): 1556-1569, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32022345

RESUMO

Malaria is one of the life-threatening parasitic diseases that is endemic in tropical areas. The increased prevalence of malaria due to drug resistance leads to a high incidence of mortality. Drug discovery based on natural products and secondary metabolites is considered as alternative approaches for antimalarial therapy. Herbal medicines have advantages over modern medicines, including fewer side effects, cost-effectiveness, and affordability encouraging the herbal-based drug discovery. Several naturally occurring, semisynthetic, and synthetic antimalarial medications are on the market. For example, chloroquine is a synthetic medication for antimalarial therapy derived from quinine. Moreover, artemisinin, and its derivative, artesunate with sesquiterpene lactone backbone, is an antimalarial agent originated from Artemisia annua L. A. annua traditionally has been used to detoxify blood and eliminate fever in China. Although the artemisinin-based combination therapy against malaria has shown exceptional responses, the limited medicinal options demand novel therapeutics. Furthermore, drug resistance is the cause in most cases, and new medications are proposed to overcome the resistance. In addition to conventional therapeutics, this review covers some important genera in this area, including Artemisia, Cinchona, Cryptolepis, and Tabebuia, whose antimalarial activities are finely verified.


Assuntos
Antimaláricos/uso terapêutico , Artemisia/química , Cinchona/química , Cryptolepis/química , Malária/tratamento farmacológico , Plantas Medicinais/química , Tabebuia/química , Antimaláricos/farmacologia , Humanos
20.
J Ethnopharmacol ; 249: 112375, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31698039

RESUMO

ETHNOPHARMACOLOGICAL RELEVANCE: Species of the genus Cinchona (Rubiaceae) have been used in traditional medicine, and as a source for quinine since its discovery as an effective medicine against malaria in the 17th century. Despite being the sole cure of malaria for almost 350 years, little is known about the chemical diversity between and within species of the antimalarial alkaloids found in the bark. Extensive historical Cinchona bark collections housed at the Royal Botanic Gardens, Kew, UK, and in other museums may shed new light on the alkaloid chemistry of the Cinchona genus and the history of the quest for the most effective Cinchona barks. AIM OF THE STUDY: We used High-Pressure Liquid Chromatography (HPLC) coupled with fluorescence detection (FLD) to reanalyze a set of Cinchona barks originally annotated for the four major quinine alkaloids by John Eliot Howard and others more than 150 years ago. MATERIALS AND METHODS: We performed an archival search on the Cinchona bark collections in the Economic Botany Collection housed in Kew, focusing on those with historical alkaloid content information. Then, we performed HPLC analysis of the bark samples to separate and quantify the four major quinine alkaloids and the total alkaloid content using fluorescence detection. Correlations between historic and current annotations were calculated using Spearman's rank correlation coefficient, before paired comparisons were performed using Wilcox rank sum tests. The effects of source were explored using generalized linear modelling (GLM), before the significance of each parameter in predicting alkaloid concentrations were assessed using chi-square tests as likelihood ratio testing (LRT) models. RESULTS: The total alkaloid content estimation obtained by our HPLC analysis was comparatively similar to the historical chemical annotations made by Howard. Additionally, the quantity of two of the major alkaloids, quinine and cinchonine, and the total content of the four alkaloids obtained were significantly similar between the historical and current day analysis using linear regression. CONCLUSIONS: This study demonstrates that the historical chemical analysis by Howard and current day HPLC alkaloid content estimations are comparable. Current day HPLC analysis thus provide a realistic estimate of the alkaloid contents in the historical bark samples at the time of sampling more than 150 years ago. Museum collections provide a powerful but underused source of material for understanding early use and collecting history as well as for comparative analyses with current day samples.


Assuntos
Cinchona/química , Casca de Planta/química , Alcaloides/química , Cromatografia Líquida de Alta Pressão/métodos , Alcaloides de Cinchona/química , Extratos Vegetais/química , Quinina/química
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...