Background Flavonoids are compounds of interest in the search for new anti-cancer therapies. We have previously isolated the methoxyflavones 5,4′-dihydroxy-6,7,8,3′-tetramethoxyflavone (8-methoxycirsilineol), 5,4′-dihydroxy-6,7,8-trimethoxyflavone (xanthomicrol), and 5,4,'3′-trihydroxy-6,7,8-trimethoxyflavone (sideritoflavone) from Baccharis densiflora. Herein, we investigate the toxicity of these methoxyflavones in human breast-derived cell line. Our main aim was to focus on the cancer stem cell (CSC) sub-population of JIMT-1 breast cancer cells. Methods Initially, dose response experiments yielding inhibitory concentration 50 (IC50) values were performed using MCF-7, HCC1937, and JIMT-1 breast cancer, and the MCF-10A normal-like breast cell lines to get an understanding of toxic ranges. Due to a clear difference in the toxicity of the flavones, only sideritoflavone was selected for further studies using the JIMT-1 cell line. Effects on the CSC sub-population was investigated using flow cytometry-based methods. A wound healing assay and digital holographic microscopy were used to investigate effects on cell movement. A reporter assay was used to study effects on signal transduction pathways and Western blot for protein expression. Results The dose response data showed that 8-methoxycirsilineol was non-toxic at concentrations below 100 μM, that the IC50 of xanthomicrol was between 50 and 100 μM, while sideritoflavone was highly toxic with a single digit μM IC50 in all cell lines. Treatment of the JIMT-1 cells with 2 μM sideritoflavone did not selectively effect the CSC sub-population. Instead, sideritoflavone treatment inhibited the proliferation of both the non-CSC and the CSC sub-populations to the same extent. The inhibition of cell proliferation resulted in an accumulation of cells in the G2 phase of the cell cycle and the treated cells showed an increased level of γ-H2A histone family member X indicating DNA double strand breaks. Analysis of the effect of sideritoflavone treatment on signal transduction pathways showed activation of the Wnt, Myc/Max, and transforming growth factor-β pathways. The level of p65/nuclear factor kappa-light-chain-enhancer of activated Β cells was increased in sideritoflavone-treated cells. Cell movement was decreased by sideritoflavone treatment. Conclusions Altogether our data show that the methoxyflavone sideritoflavone has favourable anti-cancer effects that may be exploited for development to be used in combination with CSC specific compounds.

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Pseudognaphalium gaudichaudianum (DC.) Anderb., (Asteraceae) es una pequeña planta herbácea que crece en las alturas y en lugares montañosos, conocida con el nombre vernacular de “Wira Wira”. Tiene buena reputación en la medicina tradicional de las comunidades aimaras de las tierras altas de Bolivia para tratar enfermedades respiratorias como tos, resfriado común, bronquitis y neumonía. Por sus propiedades expectorantes, P. gaudichaudianum se ha propuesto como fitofármaco para prevenir la infección por COVID-19, en infusiones y vaporización. En este estudio, los terpenoides de su aceite esencial se caracterizaron por cromatografía de gases acoplada a espectrometría de masas (GC/MS). El análisis mostró la presencia de 1 monoterpenoide, 11 sesquiterpenoides, 2 diterpenoides y 4 compuestos menores no identificados. Los principales compuestos identificados fueron β-Eudesmene (16,35%), Rosifoliol (15,29%), Guaia 1(10), 11-dieno (15,20%), Guaia 6,9 dieno (14,46%), α-Pineno (11,32%). y α-Guaieno (6,16%).

El efecto que tiene la radiación solar sobre la morfología, biomasa y distintos compuestos químicos presentes en las plantas es de interés para la seguridad alimentaria frente al cambio climático. Este estudio tiene como objetivo contribuir al conocimiento del efecto de radiación infrarroja (IR) y ultravioleta (UV-A, UV-B) sobre la concentración de ácido oxálico, la biomasa y morfología en Oxalis triangularis (Oxalidaceae). Para esto, la especie fue expuesta a luz visible con radiación IR, UV-A o UV-B por separado y se estableció un grupo de control expuesto únicamente a luz visible. Cinco semanas después se contabilizó el número de hojas, se observaron los cambios morfológicos, se obtuvo el peso fresco y seco de las hojas y rizomas de cada espécimen, y la cuantificación de ácido oxálico se realizó por espectrofotometría UV/Visible. Los resultados mostraron que la biomasa, altura y número de hojas aumenta con la exposición a la radiación infrarroja, mientras que no se determinaron diferencias significativas en estos parámetros con la radiación UV-A. Con la radiación UV-B se observó despigmentación en los foliolos, un cierto brillo en los mismos por aumento probable de las ceras y una disminución en la altura del peciolo. Respecto a la concentración de ácido oxálico no se observaron diferencias significativas con los diferentes tratamientos, aunque se observa una tendencia a disminuir con IR y aumentar con UV-B. Estos hallazgos podrían tener implicaciones en plantas que contengan ácido oxálico por su valor nutricional, por esta razón se debe continuar con más estudios.

The essential oils from the leaves of five species of the genus Baccharis, namely Baccharis boliviensis, B. densiflora, B. latifolia, B. papilllosa and B. tola collected in three counties, Cota-Cota, Mecapaca and Carpani at La Paz, Bolivia, were extracted using hydrodistillation procedures and subsequently analyzed by GC/MS. Four of the species were collected in two places of the La Paz valley, in order to establish the changes in composition in function of the place of origin. B. densiflora was collected only in one place because of the scarcely availability of the plant material in the other collecting sites. The essential oils obtained from the five species are composed mainly by monoterpenes, and a less percentage of sesquiterpenes, in addition, few non terpenic components were detected. The only exception was B. latifolia that showed almost the same amount of sesquiterpenes and monoterpenes. The samples of a same species collected at two different sites showed, as a rule, similar GC/MS profiles with the exception of B. tola that showed higher amounts of hydrocarbon sesquiterpenes and lower quantities of cyclic monoterpenes from Carpani to Cota Cota. The analysis of the identified compounds showed that some of them were present in good quantities in all the samples of essential oils examined, like for instance, β-myrcene, D-limonene, αthujene, D-α-pinene, sabinene, L-β-pinene and α-muurolene.