Chemical Investigation and in vitro Antimalarial Activity of Tabebuia ochracea ssp. neochrysantha

Abstract

A study of Tabebuia ochracea ssp. neochrysantha, a plant traditionally used in the Amazon against malaria, was pursued. Bioactivity was tested in vitro against Plasmodium berghei and Plasmodium falciparum (FcB2 chloroquine-resistant strain). Inhibitory activity was determined by measuring parasite 3 H-hypoxanthine incorporation. Fractionation of the chloroformic extract of P. ochracea (inner stem bark) afforded five furanonaphthoquinones. The highest antimalarial activity against P. berghei was given by a mixture of two compounds which could not be separated, but the isomeric structures of 5-and 8-hydroxy-2-(1'-hydroxy)-ethylnaphtho-[2,3-b]-furan-4,9-dione ( 1 and 2) were determined from spectroscopic data. The 50% inhibitory concentration (IC 50 ) values obtained with the mixture of compounds 1 and 2 were 1.67 ϫ 10 -7 M for P. berghei and 6.77 ϫ 10 -7 for the FcB2 chloroquineresistant strain of P. falciparum. For the former parasite, the IC 50 value for chloroquine was 5 ϫ 10 -8 M. That for P. falciparum was 1.1 ϫ 10 -7 M. These results indicate that the furanonaphthoquinones isolated from T. ochracea are potential antimalarial compounds.

In vitro cytotoxic activity of Brazilian Middle West plant extracts

“…In the Bignoniaceae family, naphthoquinones is the principal group of secondary metabolites. There are reports dealing with the following activities for these compounds: antimalarial (Pérez et al, 1997), antitumor (Ueda et al, 1994), anticancer (Abbott et al, 1967), antifungal (Guiraud et al, 1988), antibacterial and anti-inflammatory (Zani et al, 1991 …”

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

“…neochrysantha (Pérez et al, 1997) and T. avellanedae (Fujimoto et al, 1991) bark and have been shown to possess important activity against rodent and human malaria parasites Plasmodium berghei and P. falciparum (Pérez et al, 1997), respectively. Also, compound 1, extracted from dry T. avellanedae bark, is active in vitro against several types of malignant tumor cells and was patented in Japan in 1994 (Derwent, 2006).…”

Chemical composition and antioxidant activity of extracts from Erythroxylum suberosum A.St. Hil.leaves

“…It consists of exposing larvae to test sample in saline solution, and lethality is evaluated after 24h. Lethality assay has been used successfully to bioguide the isolation of cytotoxic (Siqueira, et al, 1998), antimalarial (Perez, et al, 1997), and insecticidal (Oberlies, et al, 1998) compounds from plant extracts. Also, this test has been used as a model to evaluate compounds for their ability to protect against superoxide-mediated toxicity (Matthews, 1995).For toxicity evaluation of plant extracts by brine shrimp bioassay, an LD 50 value lower than 1 mg/mL is considered active (Meyer, et al, 1982).Therefore, to verify the toxicity of crude extracts from aerial parts of E. Suberosum, the ability to induce Artemia salina death was evaluated.…”

“…It consists of exposing larvae to test sample in saline solution, and lethality is evaluated after 24h. Lethality assay has been used successfully to assess compounds presenting cytotoxic (Siqueira, et al, 1998), antimalarial (Perez, et al, 1997), and insecticidal (Oberlies, et al, 1998) activities from plant extracts. In the toxicity evaluation of plant extracts by brine shrimp bioassay, an LD 50 value lower than 1 mg/mL is considered active (Meyer, et al, 1982).…”

“…A control containing DMSO was included in each set of experiments. Potassium dichromate (LD 50 = 20 µg/mL) was used as reference (Perfeito, et al, 2005). Probit analysis calculated LC50 (after 24h).…”