A simple and efficient microwave-assisted extraction process has been developed in order to extract plumieride from Allamanda cathartica flowers. The extracts have been obtained through microwave-assisted extraction (MAE) process with ethanol and ethyl acetate at different time, power and temperatures. Static maceration at room temperature with ethanol and ethyl acetate was obtained in order to compare the efficiency of extraction. HPLC method was validated to quantify plumieride in the extracts. The analyzed parameters: linearity (R2 = 0.999), precision (CV 3.3%), recovery (98%), specificity (97%), limit of detection (1 µg mL-1), and limit of quantification (2 µg mL-1) were satisfactory. The yield of plumieride reached 43% in the extracts under the optimal MAE conditions (10 min, 300W). Plumieride recoveries by conventional extraction method were 12% with ethanol and 22% with ethyl acetate. Time and power parameters on plumieride extraction yield was determined by applying a factorial design and surface plots. Ethanol was the best extractor solvent and it was possible to obtain high contents (52 mg g-1 of dry flowers) at optimized conditions. It can be concluded that MAE process has actual advantages over the conventional extraction method in terms of shorter time and higher efficiency to recover plumieride from A. cathartica flowers.

The aim of this research was to evaluate the fractions obtained from the leaf, stem and roots of Allamanda schottii Pohl, Apocynaceae, responsible for the cytotoxicity, using several cell lines. Cytotoxicity was correlated with the season the part of the plant, and the major compounds were assessed. The ethanol extracts of leaves, stems and roots obtained at different seasons were evaluated in the human erythromyeloblastoid leukemia cell line (K562). Subsequently the ethanol extracts and dichloromethane fractions collected in winter were evaluated in mouse fibroblast cell line (Mus musculus) (L929), cervix adenocarcinoma (HeLa), human pre-B leukemia (Nalm6), as well as K562 cell line. The compounds plumericin, plumieride and ursolic acid isolated from ethanol extracts of the stems were evaluated in the same cell lines, as well as on breast adenocarcinoma cell line (MCF-7), and Mus musculus skin melanoma cell line (B16F10). The chromatographic profiles of the dichloromethane fractions were obtained by high performance liquid chromatography. The results revealed that the season during which A. schottii was collected, and the part of the plant analyzed, influence the cytotoxicity on the K562 cells tested. On the other hand the dichloromethane fractions, mainly from the stems and roots, are responsible for the cytoxicity on the cells tested. These results may be associated with the seasonal variation of plumericin in these parts of the plant. This information is in accordance with the HPLC analysis. The results clearly show the potential for the phytotherapeutic use of this species, and suggest that the cytotoxic activity observed may be due to the presence of plumericin, or to minor compounds not yet identified. The seasonal influence on the production of secondary metabolites was verified.