A New Flavanone from Chromolaena tacotana (Klatt) R. M. King and H. Rob, Promotes Apoptosis in Human Breast Cancer Cells by Downregulating Antiapoptotic Proteins.

Chromolaena tacotana is a source of flavonoids with antiproliferative properties in human breast cancer cells, the most common neoplasm diagnosed in patients worldwide. Until now, the mechanisms of cell death related to the antiproliferative activity of its flavonoids have not been elucidated. In this study, a novel flavanone (3',4'-dihydroxy-5,7-dimethoxy-flavanone) was isolated from the plant leaves and identified by nuclear magnetic resonance (NMR) and mass spectrometry (MS). This molecule selectively inhibited cell proliferation of triple-negative human breast cancer cell lines MDA-MB-231 and MCF-7 whit IC50 values of 25.3 µg/mL and 20.8 µg/mL, respectively, determined by MTT assays with a selectivity index greater than 3. Early and late pro-apoptotic characteristics were observed by annexin-V/7-AAD detection, accompanied by a high percentage of the Bcl-2 anti-apoptotic protein inactivated and the activation of effector Caspase-3 and/or 7 in breast cancer cells. It was verified the decreasing of XIAP more than Bcl-2 anti-apoptotic proteins expression, as well as the XIAP/Caspase-7 and Bcl-2/Bax complexes dissociation after flavanone treatment. Docking and molecular modeling analysis between the flavanone and the antiapoptotic protein XIAP suggests that the natural compound inhibits XIAP by binding to the BIR3 domain of XIAP. In this case, we demonstrate that the new flavanone isolated from leaves of Chomolaena tacotana has a promising and selective anti-breast cancer potential that includes the induction of intrinsic apoptosis by downregulation of the anti-apoptotic proteins XIAP and Bcl-2. New studies should deepen these findings to demonstrate its potential as an anticancer agent.

Phytoprostane and phenolic compounds from Chromolaena palmaris.

The chemical investigation of Chromolaena palmaris (Sch.Bip. ex Baker) R.M. King & H. Rob. expands the phytochemical composition knowledge of Chromolaena genus, since this is the first chemical investigation of this species. Twenty-five compounds were identified, including a phytoprostane, 17 flavonoids, 6 phenolic acids, and a caffeoyl-glucoside derivative obtained by classical chromatography and UHPLC-HRMS/MS analysis. Moreover, anti-Mycobacterium tuberculosis and antiproliferative activities of C. palmaris were evaluated. Dichloromethane fraction showed cytotoxicity towards human cancer cell lines, presenting TGI values on glioma (U251) of 27.8 µg mL-1. Furthermore, compounds 1 and 2 exhibited antimicrobial activity against Mycobacterium tuberculosis with MIC of 62.5 and 15.6 µg mL-1, respectively.

Chemical composition and antimicrobial activity of essential oils from Chromolaena laevigata during flowering and fruiting stages.

The chemical compositions and antimicrobial activities of essential oils from the leaves, stems, capitula, and cypselas of Chromolaena laevigata were evaluated at two different phenological stages, flowering and fruiting. Thirty-eight compounds were identified in the crude oils by GC/MS. The sesquiterpene laevigatin was the major constituent of the leaf, capitulum, and cypsela oils, while the sesquiterpene spathulenol was the main component in the stem oils. The antimicrobial activities of the oils were evaluated against Candida albicans, Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli. Stem oil obtained from Chromolaena laevigata during the fruiting stage generally showed the highest activity with minimum inhibitory concentration (MIC) values of 62.5 µg/ml against Candida albicans and S. aureus, and 500 µg/ml against P. aeruginosa and E. coli. Pure laevigatin exhibited MIC values of 500 and 125 µg/ml against C. albicans and S. aureus, respectively, indicating that this constituent could be responsible, at least in part, for the antimicrobial activities detected in the crude oils. More studies concerning the biological activities of isolated derivatives are required to improve our knowledge of the antimicrobial potential of volatile compounds present in native plants.

Supinidine viridiflorates from the roots of Chromolaena pulchella.

The alkaloid extract from the roots of Chromolaena pulchella provided two new pyrrolizidine alkaloids, elucidated as (-)-supinidine triviridiflorate (1) and (-)-supinidine diviridiflorate (2) based on their physical and spectroscopic properties. Their absolute configuration was determined by chemical correlation with (-)-supinidine (3) and (+)-viridifloric acid (4).

Chemical and biological activity of leaf extracts of Chromolaena leivensis.

The flavonoids 3,5-dihydroxy-7-methoxy-flavanone, 3,5-dihydroxy-7-methoxyflavone and 3,5,7-trihydroxy-6-methoxyflavone were isolated from the leaves of C. leivensis. Preliminary observations in K562 cells (human erythroleukemia) using the trypan blue test, showed a 90% viability at a concentration of 100 microg/mL; however, further testing of the flavonoids at concentrations of 25, 50 and 100 microg/mL showed toxicity affecting the morphology of human erythroleukemia cells (K562) and human melanoma cells (A375). Induction of apoptosis was produced by 3,5-dihydroxy-7-methoxyflavone at 72 hours after treatment with arrest in the G2 / M phase of the cell cycle. The A375 cells treated with 50 microg/mL of 3,5-dihydroxy-7-methoxy-flavanone for 24, 48 and 72 hours, display effects on the behavior of the cell cycle. The flavonoid 3,5-dihydroxy-7-methoxyflavone has activity on the mitochondrial membrane at concentrations of 25, 50 and 100 microg/mL, at time intervals of 8 to 12 hours. The flavonoids 3,5-dihydroxy-7-methoxy-flavanone and 3,5-dihydroxy-7-methoxyflavone at a concentration of 25 microg/mL increased the expression of costimulatory molecules corresponding to the phenotype presented by mature dendritic cells with differentiation markers CD40, CD83, CD86 and HLA-DR. The two flavonoids at concentrations between 0.39 and 100 microg/mL slightly increased the proliferation of peripheral blood mononuclear cells in the presence and in the absence of phytohemagglutinin. These flavonoids at concentrations of 50 and 100 microg/mL slightly increased the proliferation of fibroblasts.

Absolute configuration of labdanes and ent-clerodanes from Chromolaena pulchella by vibrational circular dichroism.

The aerial parts of Chromolaena pulchella biosynthesize two groups of diterpenes belonging to opposite enantiomeric series, specifically, the furanoid ent-clerodanes (5R,8R,9S,10R)-(-)-hardwikiic acid (1), methyl (5R,8R,9S,10R)-(-)-hardwikiate (2), (5S,8R,9S,10R)-(-)-hautriwaic acid lactone (3), methyl (5R,8R,9S,10R)-(-)-nidoresedate (4) and methyl (8R,9R)-(-)-strictate (5), as well as the labdanes (5S,8R,9R,10S)-(+)-(13E)-labd-13-ene-8,15-diol (6) and (5S,8R,9R,10S)-(+)-isoabienol (7). The absolute configuration of the two groups of diterpenes was unambiguously assigned by comparison of the vibrational circular dichroism spectra of 3 for ent-clerodanes, and of 7 for labdanes with their theoretical spectra obtained by density functional theory calculations. The results support a biogenetic proposal to diterpenes found in the studied botanical species.

Caracterización química de las fracciones volátiles y aceites esenciales de hojas y flores de Chromolaena barranquillensis encontrada en Sabanalarga (Atlántico, Colombia) / Chemical characterization of the volatile fractions and essential oils of leaves and flowers of Chromolaena barranquillensis from Sabanalarga (Atlántico, Colombia)

Volatile secondary metabolites obtained from the leaves and flowers (fresh and dried) of Chromolaena barranquillensis (native specie of the Departamento del Atlántico), and isolated by simultaneous-distillation extraction (SDE) and conventional hydrodistillation (HD), were characterized chemically by gas chromatography coupled with mass spectrometry (GC-MS). The main compounds identified in the volatile fractions were: (a). fresh flowers – beta - elemene (24.4 percent), a-pinene (19.6 percent), and limonene (15.7 percent); (b). dried flowers – beta-caryophyllene (21.4 percent), germacrene D (16.6 percent), and caryophyllene oxide (13.6 percent); (c). Fresh leaves – myrcene (39.0 percent), y-curcumene (17.8 percent), and limonene (10.2 percent); and, (d). Dried leaves – beta-caryophyllene (13.8 percent), -curcumene (9.8 percent), beta-elemene (7.7 percent), and caryophyllene oxide (6.4 percent). In the essential oils (EO) were recognized as major components: (e). Fresh flowers – beta-caryophyllene (22.9 percent), beta-elemene (14.3 percent), and germacrene D (14.0 percent); (f). Dried flowers – beta-caryophyllene (23.6 percent), -elemene (20.6 percent), and germacrene D (15.8 percent); (g). Fresh leaves – beta-caryophyllene (22.0 percent), limonene (11.8 percent), -cadinene (6.8 percent), and germacrene D (6.1 percent); and, (h). Dried leaves – beta-caryophyllene (29.1 percent), germacrene D (13.1 percent), and caryophyllene oxide (12.0 percent). The yields achieved in the isolation of EO were 0.2 percent/0.4 percent and 0.06 percent/0.1 percent for fresh/dried flowers and fresh/dried leaves, respectively.

Los metabolitos secundarios volátiles obtenidos de hojas y flores (frescas y secas) de Chromolaena barranquillensis (especie nativa del departamento del Atlántico), aislados por destilación-extracción simultánea con solvente (SDE) e hidrodestilación convencional (HD), se caracterizaron químicamente por cromatografía de gases acoplada a espectrometría de masas (GC-MS). Los compuestos mayoritarios que se identificaron en las fracciones volátiles fueron: (a). flores frescas – beta-elemeno (24.4 por ciento), a-pineno (19.6 por ciento) y limoneno (15.7 por ciento); (b). Flores secas – trans-beta-cariofileno (21.4 por ciento), germacreno D (16.6 por ciento) y óxido de cariofileno (13.6 por ciento); (c). Hojas frescas – beta-mirceno (39.0 por ciento), y-curcumeno (17.8 por ciento) y limoneno (10.2 por ciento); y, (d). Hojas secas – trans-beta-cariofileno (13.8 por ciento), y-curcumeno (9.8 por ciento), beta-elemeno (7.7 por ciento) y óxido de cariofileno (6.4 por ciento). En los aceites esenciales (AE) se reconocieron como componentes principales: (e). Flores frescas – trans-beta-cariofileno (22.9 por ciento), beta-elemeno (14.3 por ciento) y germacreno D (14.0 por ciento); (f). Flores secas – trans-beta-cariofileno (23.6 por ciento), beta-elemeno (20.6 por ciento) y germacreno D (15.8 por ciento); (g). Hojas frescas – trans-beta-cariofileno (22.0 por ciento), limoneno (11.8 por ciento), -cadineno (6.8 por ciento) y germacreno D (6.1 por ciento); y, (h). Hojas secas – trans-beta-cariofileno (29.1 por ciento), germacreno D (13.1 por ciento) y óxido de cariofileno (12.0 por ciento). Los rendimientos alcanzados en el aislamiento de los AE fueron 0.2 por ciento/0.4 por ciento y 0.06 por ciento/0.1 por ciento para las flores frescas/secas y hojas frescas/secas, respectivamente.