Artemisa annua L. e Cinchona L. : os seus princípios ativos nas estratégias de combate à malária
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Data
2014
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A malária é a doença parasitária mais preocupante da atualidade, sendo um grave
problema de saúde pública, principalmente em África onde mata maioritariamente crianças
com idade inferior a 5 anos.
As estratégias farmacoterapêuticas de combate à malária, baseiam-se
principalmente nos fármacos derivados da artemisinina e em fármacos quinolínicos. A
artemisinina e a quinina são fármacos provenientes das espécies vegetais, Artemisia annua
L. e Cinchona L., respectivamente, e são conhecidos há muito tempo pela medicina
tradicional.
Estas substâncias são as que têm maior importância no tratamento da malária não
apresentando fármaco-resistências de larga escala, sendo que a quinina permanece eficaz,
apesar de algumas perdas de susceptibilidade por parte do Plasmodium, e as artemisininas,
nomeadamente os seus derivados semissintéticos artemeter, artesunato e
dihidroartemisinina, apenas apresentam resistência no sudeste asiático. Desta forma é
importante conhecer as características destes fármacos, de forma a perceber as vantagens
que apresentam, para além da sua eficácia contra o parasita, caracterizando os seus
mecanismos de acção, farmacodinâmica e cinética, posologia e toxicidade.
A perda de susceptibilidade e o aparecimento de fármaco-resistências constituem
um desafio, pelo que é muito importante implementar medidas para que estas não surjam em
grande escala, como o controlo do vector, bons métodos de diagnóstico, prevenção, uso
correto das terapêuticas e maneiras de incentivar a adopção de todas estas medidas de
forma eficaz pelos países.
Os princípios ativos antimaláricos da Cinchona L. e da Artemisia annua L. têm
características importantes que devem ser utilizadas na procura e síntese de novos fármacos
antimaláricos. A quinina permanece eficaz mesmo em estirpes de Plasmodium resistentes, e
têm sido desenvolvidos trabalhos de investigação de modo a justificar esta eficácia, já que
grande parte dos fármacos quinolínicos, como a cloroquina e a mefloquina, apresentam
fármaco-resistências. Esta eficácia da quinina poderá estar relacionada com o seu grupo
substituinte mais complexo, comparativamente ao grupo substituinte da cloroquina. As
artemisininas têm sido utilizadas como modelo no desenvolvimento de novos fármacos. A
sua ponte endoperóxida, considerada a grande responsável pelo efeito antimalárico, foi
utilizada como base na criação de potenciais fármacos, como o arterolano.
Malaria is the most worrying parasitic disease and represents a serious public health problem, especially in Africa where it kills mostly children under five years old. The pharmacotherapeutic strategies to prevent and treat malaria are mainly based on artemisinin derivatives and quinoline drugs. Both quinine and artemisinin are obtained from vegetal species, Artemisia annua L. and Cinchona L., and their use is known a long time ago by traditional medicine. These substances have major importance in the treatment of malaria because they don’t exhibit a long scale drug-resistance, as quinine remains effective despite some loss of sensitivity and artemisinins, including artemether, dihydroartemisinin and artesunate, only show resistance in Southeast Asia. Thus it is important to know the characteristics of these two agents in order to realize their advantages, beyond its anti-parasitic effect, realizing their mechanisms of action, pharmacodynamics and kinetics, toxicity and dosage. The loss of susceptibility and the emergence of drug-resistance in these drugs represent a challenge, so it is very important to be aware of the strategies to adopt in order to not arise them on a large scale. Some of these measures include vector controlling, good methods of diagnosis, prevention, correctly using therapeutics and encouragement to implement effectively all of these measures. The antimalarial drugs of Cinchona L. and Artemisia annua L. have important features that shall be used when searching and synthetizing new antimalarial drugs. Quinine remains effective even against resistant strains of Plasmodium, and has been researched in order to justify this, since much of quinoline drugs present drug-resistance. This efficacy can be related to its more complex substituent group, compared to the chloroquine’s one. Artemisinins have been used as a model for the development of new drugs. Its endoperoxide bridge, which is considered the main feature for its antimalarical effect, has been used in the creation of new potential drugs such as arterolane.
Malaria is the most worrying parasitic disease and represents a serious public health problem, especially in Africa where it kills mostly children under five years old. The pharmacotherapeutic strategies to prevent and treat malaria are mainly based on artemisinin derivatives and quinoline drugs. Both quinine and artemisinin are obtained from vegetal species, Artemisia annua L. and Cinchona L., and their use is known a long time ago by traditional medicine. These substances have major importance in the treatment of malaria because they don’t exhibit a long scale drug-resistance, as quinine remains effective despite some loss of sensitivity and artemisinins, including artemether, dihydroartemisinin and artesunate, only show resistance in Southeast Asia. Thus it is important to know the characteristics of these two agents in order to realize their advantages, beyond its anti-parasitic effect, realizing their mechanisms of action, pharmacodynamics and kinetics, toxicity and dosage. The loss of susceptibility and the emergence of drug-resistance in these drugs represent a challenge, so it is very important to be aware of the strategies to adopt in order to not arise them on a large scale. Some of these measures include vector controlling, good methods of diagnosis, prevention, correctly using therapeutics and encouragement to implement effectively all of these measures. The antimalarial drugs of Cinchona L. and Artemisia annua L. have important features that shall be used when searching and synthetizing new antimalarial drugs. Quinine remains effective even against resistant strains of Plasmodium, and has been researched in order to justify this, since much of quinoline drugs present drug-resistance. This efficacy can be related to its more complex substituent group, compared to the chloroquine’s one. Artemisinins have been used as a model for the development of new drugs. Its endoperoxide bridge, which is considered the main feature for its antimalarical effect, has been used in the creation of new potential drugs such as arterolane.
Descrição
Orientação : Amílcar Roberto
Palavras-chave
FARMACOLOGIA, MESTRADO INTEGRADO EM CIÊNCIAS FARMACÊUTICAS, MALÁRIA, MEDICAMENTOS, PHARMACOLOGY, MALARIA, DRUGS, PLANTAS MEDICINAIS, MEDICINAL PLANTS, CIÊNCIAS FARMACÊUTICAS, PHARMACEUTICAL SCIENCES