The effect of five Taraxacum species on in vitro and in vivo antioxidant and antiproliferative activity

Differences between antioxidant and cytotoxic activities have been found among five Taraxacum species.

Cytotoxic activity of hirsutanone, a diarylheptanoid isolated from Alnus glutinosa leaves

BACKGROUND

The low efficacy of cancer therapy for the treatment of patients with advanced disease makes the development of new anticancer agents necessary. Because natural products are a significant source of anticancer drugs, it is important to explore cytotoxic activity of novel compounds from natural origin.

PURPOSE

The aim of this work is to evaluate the cytotoxic capacity of hirsutanone, a diarylheptanoid isolated from Alnus glutinosa leaves. Hirsutanone cytotoxic way of action was also studied.

MATERIAL AND METHODS

The cytotoxic ability of Alnus glutinosa leaves ethyl acetate extract was studied over HeLa and PC-3 cell lines, with the MTT colorimetric assay. Hirsutanone was isolated from this extract using chromatographic methods, and its structure elucidated by spectroscopic analysis. HT-29 cell viability after hirsutanone treatment was determined using SRB assay. In order to understand hirsutanone way of action, cytotoxicity was evaluated adding the diarylheptanoid and antioxidants. DNA topoisomerase II (topo II) poison activity, was also evaluated using purified topo II and a supercoiled form of DNA that bears specific topo II recognition and binding region; topo II poisons stabilize normally transient DNA-topo II cleavage complexes, and lead an increased yield of linear form as a consequence of a lack of double-strand breaks rejoining.

RESULTS

The diarylheptanoid hirsutanone was isolated from Alnus glutinosa (L.) Gaertn. (Betulaceae) leaves extract that showed cytotoxic activity against PC-3 and HeLa cell lines. Hirsutanone showed cytotoxic activity against HT-29 human colon carcinoma cells. Pre-treatment with the antioxidants NAC (N-acetylcysteine) and MnTMPyP (Mn(III)tetrakis-(1-methyl-4-pyridyl)porthyrin) reduced this activity, suggesting that reactive oxygen species (ROS) participate in hirsutanone-induced cancer cell death. Using human topo II and a DNA supercoiled form, hirsutanone was found to stabilize topo II-DNA cleavage complexes, acting as a topo II poison.

CONCLUSION

Our data suggest that, like curcumin, an induction of oxidative stress and topo II-mediated DNA damage may play a role in hirsutanone-induced cancer cell death. Since both compounds share similar structure and cytotoxic profile, and curcumin is in clinical trials for the treatment of cancer, our results warrant further studies to evaluate the anticancer potential of hirsutanone.

Biological activity of extracts from Catalpa bignonioides Walt. (Bignoniaceae)

Catalpa bignonioides Walt. (Bignoniaceae) is a species that belongs to a tropical family but has been introduced in many countries as ornamental. Although this plant is consumed by indigenous cultures of South America for medical uses, experimental studies of the biological properties of Catalpa bignonioides are lacking. The aim of this work was to study the biological activity of crude extracts from either pods, seeds or leaves of Catalpa bignonioides which were collected in Spain. Ethyl ether, butanolic and aqueous fractions of the pod extract were also prepared and studied. We have examined the antimicrobial activity against five bacteria and one yeast, the cytotoxic activity against HepG2 cells and the anti-inflammatory and antinociceptive effects in rodents. A preliminary phytochemical analysis of the extracts and fractions was also conducted. Results showed no antimicrobial or antitumoral effects, but prominent anti-inflammatory and antinociceptive actions of the extracts. These last activities may be a result of the presence of either of saponins, sterols or phenols, mainly found in the leaves and pods of the plants.

Effect of heavy metals on soil denitrification and CO2 production after short term incubation

The toxicity of three heavy metals, Cd, Zn and Cu, has been tested in a Mediterranean soil. The soil was incubated (108h) with mixed solutions of those metals before evaluating denitrification and CO2 production, both by gas chromatography. These activities were used as biological indicators of heavy metal toxicity, and compared to non-treated control soil samples. Statistical analyses showed no significant differences in CO2 production between treated and non-treated control soils. The lowest levels of respiration were observed in soils treated with the largest amounts of Zn and Cd. Denitrification increased significantly in soils treated with solutions containing 100 micrograms/ml of Cu and 1000 micrograms/ml of Cd or Zn.