Evaluation of the genotoxic activity of ethanol extract and secondary metabolites isolated from Aiouea trinervis Meisn. (Lauraceae).

Aiouea trinervis Meisn. is a shrub that grows in the "Cerrado" (a savanna ecosystem) of Brazil. In this study, fractionation of ethanol extracts (EEs) from the leaves of A. trinervis led to the isolation of butanolides, namely isoobtusilactone A and obtusilactone A, as well as lignans, namely sesamin, methylpiperitol, and polyprenol-12. Their structures were determined by spectroscopic analyses. The genotoxic properties were evaluated for mutagenic and recombinogenic effects using the wing spot test (somatic mutation and recombination test, SMART) on Drosophila melanogaster. The standard and high bioactivation crosses were used. The latter cross is characterized by high sensitivity to promutagens and procarcinogens. EEs were evaluated at concentrations of 0.625, 1.25, and 2.5 mg/mL. Butanolides (isoobtusilactone A and obtusilactone A) were evaluated at concentrations of 0.1, 0.2, and 0.3 mg/mL. The results observed in both crosses were similar and indicated that EEs from the leaves of A. trinervis did not show genotoxicity at the doses that were used. However, the individuals resulting from standard and high bioactivation crosses that were treated with isoobtusilactone A and obtusilactone A showed statistically significant increases in mutant spots compared to those that were obtained in the negative control. Similar results were obtained between standard and high bioactivation crosses, indicating that butanolides had a genotoxic activity.

Assessment of the in vitro and in vivo genotoxicity of extracts and indole monoterpene alkaloid from the roots of Galianthe thalictroides (Rubiaceae).

Roots of Galianthe thalictroides K. Schum. (Rubiaceae) are used in folk medicine in the State of Mato Grosso do Sul, Brazil, for treating and preventing cancer. To gain information about the genotoxicity of extracts (aqueous and EtOH), the CHCl3 phase resulting from partition of the EtOH extract and the indole monoterpene alkaloid 1 obtained from this plant. The genotoxicity of 1 and extracts was evaluated in vivo through the Drosophila melanogaster wing Somatic Mutation and Recombination Test - SMART, while in vitro cytotoxic (MTT) and Comet assays were performed only with alkaloid 1. The results obtained with the SMART test indicated that the aqueous extract had no genotoxic activity. The EtOH extract was not genotoxic to ST descendants but genotoxic to HB ones. The CHCl3 phase was genotoxic and cytotoxic. Alkaloid 1 showed significant mutational events with SMART, in the cytotoxicity assay (MTT), it showed a high cytotoxicity for human hepatoma cells (HepG2), whereas for the Comet assay, not showing genotoxic activity. The ethanol extract was shown to be genotoxic to HB descendants in the SMART assay, while the results obtained in this test for the monoterpene indole alkaloid 1 isolated from this extract.

The effect of the dibenzylbutyrolactolic lignan (-)-cubebin on doxorubicin mutagenicity and recombinogenicity in wing somatic cells of Drosophila melanogaster.

The dibenzylbutyrolactolic lignan (-)-cubebin was isolated from dry seeds of Piper cubeba L. (Piperaceae). (-)-Cubebin possesses anti-inflammatory, analgesic and antimicrobial activities. Doxorubicin (DXR) is a topoisomerase-interactive agent that may induce single- and double-strand breaks, intercalate into the DNA and generate oxygen free radicals. Here, we examine the mutagenicity and recombinogenicity of different concentrations of (-)-cubebin alone or in combination with DXR using standard (ST) and high bioactivation (HB) crosses of the wing Somatic Mutation And Recombination Test in Drosophila melanogaster. The results from both crosses were rather similar. (-)-Cubebin alone did not induce mutation or recombination. At lower concentrations, (-)-cubebin statistically reduced the frequencies of DXR-induced mutant spots. At higher concentrations, however, (-)-cubebin was found to potentiate the effects of DXR, leading to either an increase in the production of mutant spots or a reduction, due to toxicity. These results suggest that depending on the concentration, (-)-cubebin may interact with the enzymatic system that catalyzes the metabolic detoxification of DXR, inhibiting the activity of mitochondrial complex I and thereby scavenging free radicals. Recombination was found to be the major effect of the treatments with DXR alone. The combined treatments reduced DXR mutagenicity but did not affect DXR recombinogenicity.

Cytotoxic and genotoxic butanolides and lignans from Aiouea trinervis.

The ethanolic extracts from the roots, the underground trunk and the leaves of Aiouea trinervis were active in the brine shrimp (Artemia salina) lethality assay (LD (50): 1.93, 0.92 and 262.1 microg/mL, respectively). Fractionation of the extracts led to the isolation of four butanolides, namely (-)-epilitsenolides C (2) and C (1) ( 1 and 2), isoobtusilactone A ( 3) and obtusilactone A ( 4), two of which ( 1 and 2) are reported for the first time as genuine natural products. The lignans (+)-sesamin ( 5) and (+)-methylpiperitol ( 6) and polyprenol-12 ( 7) were isolated as well. Their structures were determined with spectral methods (1D-, 2D-NMR and MS). Compounds 1, 2, 3, 5 and 6 were tested for their cytotoxic activities in Hep (2) human cancer cells. The butanolides 2 and 3 were the most active (IC (50): 5.96 microg/mL and 4.95 microg/mL, respectively) whereas the other compounds showed moderate IC (50) values ranging from 12.20 microg/mL to 25.64 microg/mL. The genotoxic properties of the crude ethanolic extracts and of compounds 3 and 5 were also evaluated in this study on CHO K1 and HTC mammalian cells with single-cell gel electrophoresis (comet assay). The crude extracts as well as the compounds tested induced DNA migration in this assay, which was indicative of DNA damage (genotoxic effect).