In vivo and in vitro antimalarial activity of 4-nerolidylcatechol.

4-Nerolidylcatechol (4-NC) isolated from Piper peltatum L. (Piperaceae) was evaluated for in vitro antiplasmodial activity against Plasmodium falciparum (cultures of both standard CQR (K1) and CQS (3D7) strains and two Amazonian field isolates) and for in vivo antimalarial activity using the Plasmodium berghei-murine model. 4-NC exhibits significant in vitro and moderate in vivo antiplasmodial activity. 4-NC administered orally and subcutaneously at doses of 200, 400 and 600 mg/kg/day suppressed the growth of P. berghei by up to 63% after four daily treatments (days 1-4). Also, 4-NC exhibited important in vitro antiplasmodial activity against both standard and field P. falciparum strains in which 50% inhibition of parasite growth (IC(50) ) was produced at concentrations of 0.05-2.11 µg/mL and depended upon the parasite strain. Interestingly, healthy (non-infected) mice that received 4-NC orally presented (denatured) blood plasma which exhibited significant in vitro activity against P. falciparum. This is evidence that mouse metabolism allows 4-NC or active metabolites to enter the blood. Further chemical and pharmacological studies are necessary to confirm the potential of 4-NC as a new antimalarial prototype.

Bioactive dihydroxyfuranonaphthoquinones from the bark of Tabebuia incana A.H. Gentry (Bignoniaceae) and HPLC analysis of commercial pau d'arco and certified T.incana bark infusions

Tabebuia incana A.H. Gentry (Bignoniaceae) is a tree from the Brazilian Amazon having medicinal uses and is one several Tabebuia spp. known as pau d'arco or palo de arco in this region. Fractionation of the bark ethanolic extract afforded a mixture of 5 and 8-hydroxy-2-(1-hydroxyethyl)naphtho[2,3-b]furan-4,9-diones (1 and 2, respectively) identified on the basis of nuclear magnetic resonance (NMR), infrared (IR) and mass (MS) spectra, whose in vitro antimalarial and antitumor activity have been shown previously. This is the first study on T. incana bark, and 2 are described in this species for the first time. Also, high performance liquid chromatography (HPLC) analysis of T. incana bark tea revealed the presence of the 1 + 2 mixture peak corresponding to a concentration in the range 10-6-10-5 M. The chromatograms of teas prepared from commercial pau d' arco and T. incana bark were also studied and the presence of the 1 + 2 peak has potential for quality control of commercial plant materials.

Tabebuia incana A.H. Gentry (Bignoniaceae) é uma árvore da Amazônia brasileira com usos medicinais. É uma de várias espécies de Tabebuia conhecidas como pau d'arco ou palo de arco nesta região. O fracionamento do extrato etanólico das cascas resultou no isolamento da mistura de 5 e 8-hidróxi-2-(1-hidroxietil)nafto[2,3-b]furano-4,9-dionas (1 e 2, respectivamente), identificadas com base em seus espectros de ressonância magnética nuclear (RMN), infravermelho (IV) e massa (EM), e cujas atividades antimalárica e antitumoral in vitro foram mostradas previamente. Este é o primeiro estudo das cascas de T. incana e a primeira vez que o composto 2 é descrito nesta espécie. Análises por cromatografia liquida de alto empenho (CLAE) do chá das cascas de T. incana revelaram a presença de um pico correspondente à mistura de 1 + 2, permitindo inferir uma concentração na faixa de 10-6-10-5 M desses componentes no chá. Os cromatogramas de chás (infusões) preparados a partir das cascas de pau d' arco commercial and T. incana certificada também foram estudados. A verficação da presença do pico das substâncias 1 + 2 nos cromatogramas tem potencial contribuição para o controle de qualidade de material vegetal comercial.