ABSTRACT Leptocarpha rivularis is an autochthonous plant of the southern zone of Chile known as “Palo negro” that has been traditionally used by Mapuche people as anti-inflammatory and reliever of abdominal pain. More recently, aqueous infusion of this plant is being used in the treatment of cancer. The main phytochemical components of L. rivularis have been identified as a sesquiterpene lactones (SQL) being leptocarpine (LTC) the major component, which exhibits pro-apoptotic action against a variety of cancer cells lines. In this study we intend to compare the in vitro cytotoxicity against cancer cell lines of two different polarity extracts and LTC. To overcome the poor water-solubility of extracts they have been encapsulated in polymer micelles and its effect on activity has been assessed. The results indicate that both extracts reduce cell viability of all cancer cell lines. The IC50 values obtained for ethyl acetate are in the range of 11-16 μg/mL, and this activity is explained in terms of a synergic effect generated by SQL different to LTC. The IC50 values of extracts incorporated into polymer micelles formed by Pluronic F127 are 200 times lower than those measured for ethyl acetate extract applied in homogeneous solution. Finally, by assessing changes in cell and nuclear morphology it is suggested that the observed cytotoxicity of free and entrapped extracts is produced by apoptotic process. In conclusion, these results suggest that plant extracts may show an increased activity as result of synergic effect of minority components, and an important enhancement of cytotoxicity is induced by entrapment into polymer micelles.

ABSTRACT This study evaluates the content of polyphenols, flavonoids and anthraquinones from sequential extracts from four algae species from along the Chilean coastline: Desmarestia ligulata, Dictyota kunthii, Laurencia chilensis and Chondracanthus chamissoi. The antioxidant capacity of these extracts was evaluated through three complementary assays: the TRAP, FRAP, and DPPH assays. Additionally, the cytotoxic activity of these extracts was determined through sulforhodamine B assays on two cancer cell lines, one colon (HT-29) and one breast (MCF-7), and one non-tumor control group of epithelial colon cells (CoN). The greatest antioxidant activity was detected in the ethyl acetate and dichloromethane extracts from L. chilensis in its TRAP potential, ethyl acetate of D. kunthii in its FRAP potential, and finally D. ligulata in its DPPH radical scavenging activity. The activities of this D. ligulata and L. chilensis extracts were significantly correlated with their flavonoid contents. In addition, the dichloromethane extracts from D. kunthii and C. chamissoi showed strong cytotoxic activity against HT-29 and MCF-7; however, the activity was not selective. Future research is necessary to purify the bioactive compounds of interest and improve their selectivity for eventual therapeutic use.

Vanillin, o-vanillin, natural and synthetic benzaldehydes and benzyl alcohols were assessed for antiproliferative effects using different human cell lines. Benzyl alcohols were synthesized from benzaldehydes reduced with NaBH4 in methanol solution. A new method for deprotection of ether compounds with TiCl4 solution was achieved with better performance, than previously reported. Twenty four compounds were tested. The in vitro growth inhibition assay was based on sulphorhodamine dye to quantify cell viability. Catechol 9 derived from piperonal as well as compounds 4 and 12 showed higher cytotoxicity on breast and prostate cancer cell lines (MDA-MB-231 and PC-3 respectively). o-Vanillin 5 has the highest cytotoxicity for all cell lines. IC50 values of 35.40 ± 4.2 μM Breast MDA-MB231; 47.10 ± 3.8 μM Prostate PC-3; 72.50 + 5.4 μM Prostate DU-145; 85.10 + 6.5 μM and Colon HT-29, were obtained without toxicity towards dermal human fibroblast (DHF cells).

Natural geranylhydroquinone 1 and geranyl-p-methoxyphenol 2 were prepared by Electrophilic Aromatic Substitution (EAS) reactions between geraniol and 1,4-hydroquinone or p-methoxyphenol respectively, using BF3∙Et2O as a catalyst. Furthermore, natural geranylquinone 3, geranyl-1,4-dimethoxyquinone 4 and the new geranyl-4-methoxyphenyl acetate 5 were obtained by chemical transformations of 1 and 2. The compounds were evaluated for their in vitro cytotoxicity activities against cultured human cancer cells of PC-3 human prostate cancer, MCF-7 and MDA-MB-231 breast carcinoma, and Dermal Human Fibroblasts DHF. IC50 values were in the µM range.

Piridilaminonaftoquinonas foram preparadas a partir da reação de 2,3-dicloro-1,4-naftoquinona e aminopiridinas empregando irradiação de microondas. O uso de microondas diminuiu os tempos de reação e forneceu os melhores rendimentos em todos os casos. As substâncias preparadas foram avaliadas em células de câncer de mama (MCF-7).

The synthesis of pyridylaminonaphthoquinones by microwave-assisted reaction of 2,3-dichloro-1,4-naphthoquinone with aminopyridines is described. The use of microwave irradiation diminished the reaction times and improved the yields substantially in all these reactions. The compounds were tested for their cytotoxic activities against MCF-7 breast cancer cell line.