Antioxidant and selective anticancer activities of two Euphorbia species in human acute myeloid leukemia.

In this study, two Euphorbia species (i.e. terracina and paralias) were investigated for their cytotoxic and antioxidant activities. Cytotoxicity of plant methanol and chloroform fractions was examined towards human acute myeloid leukemia (THP1) and human colon epithelial (Caco2) cancer cell lines, as well as CD 14 and IEC-6 normal cells by targeting various modulators of apoptosis or inflammation. Moreover, secondary metabolite pools (phenolic classes, alkaloids, terpenes, saponins) and antioxidant activities (DPPH, ABTS and O2- scavenging, as well as FRAP tests) were assessed in plant extracts. Both Euphorbia species appeared to be rich in phenolic compounds and terpenoids, Moreover, E. terracina polar and apolar fractions and E. paralias polar fraction were highly active against THP1 cells, with IC50 values of 2.08, 14.43 and 54.58µg/mL, respectively. However, no cytotoxicity was found against normal cells (CD14+ monocytes). The results indicate that the three fractions induce apoptosis in THP1 cell line after 6h of exposure. Furthermore, apoptosis caused by apolar fraction was related to a caspase-dependent process, whereas other death pathways seemed to be involved with the polar fractions. An enhanced production of reactive oxygen species was detected upon cell treatment with plant extracts. Interestingly, they have no effect on cytokine TNF-α secretion in THP1 and normal cells compared to untreated cells, indicating that the three fractions caused no inflammation. Euphorbia terracina and E. paralias polar fractions showed strong antioxidant activity with potent scavenging capacity against DPPH, ABTS and superoxide radicals. Moreover, these fractions displayed a very high ferric reducing power. These findings confirm the strong antioxidant capacity of Euphorbia plants and suggest a targeted anti-cancer effect with a potent anti-proliferative property of E. terracina and E. paralias extracts, which induce programmed cell death in leukemia cell lines but not in normal monocytes cells.

Inoculation of Phaseolus vulgaris with the nodule-endophyte Agrobacterium sp. 10C2 affects richness and structure of rhizosphere bacterial communities and enhances nodulation and growth.

Agrobacterium sp. 10C2 is a nonpathogenic and non-symbiotic nodule-endophyte strain isolated from root nodules of Phaseolus vulgaris. The effect of this strain on nodulation, plant growth and rhizosphere bacterial communities of P. vulgaris is investigated under seminatural conditions. Inoculation with strain 10C2 induced an increase in nodule number (+54 %) and plant biomass (+16 %). Grains also showed a significant increase in phosphorus (+53 %), polyphenols (+217 %), flavonoids (+62 %) and total antioxidant capacity (+82 %). The effect of strain 10C2 on bacterial communities was monitored using terminal restriction fragment length polymorphism of PCR-amplified 16S rRNA genes. When the initial soil was inoculated with strain 10C2 and left 15 days, the Agrobacterium strain did not affect TRF richness but changed structure. When common bean was sown in these soils and cultivated during 75 days, both TRF richness and structure were affected by strain 10C2. TRF richness increased in the rhizosphere soil, while it decreased in the bulk soil (root free). The taxonomic assignation of TRFs induced by strain 10C2 in the bean rhizosphere revealed the presence of four phyla (Firmicutes, Actinobacteria, Bacteroidetes and Proteobacteria) with a relative preponderance of Firmicutes, represented mainly by Bacillus species. Some of these taxa (i.e., Bacillus licheniformis, Bacillus pumilus, Bacillus senegalensis, Bacillus subtilis, Bacillus firmus and Paenibacillus koreensis) are particularly known for their plant growth-promoting potentialities. These results suggest that the beneficial effects of strain 10C2 observed on plant growth and grain quality are explained at least in part by the indirect effect through the promotion of beneficial microorganisms.

Optimization of ultrasound-assisted extraction of antioxidant compounds from Tunisian Zizyphus lotus fruits using response surface methodology.

The optimization of antioxidant extraction conditions from a ripe edible fruits of Zizyphus lotus (L.) with an ultrasound-assisted system was achieved by response surface methodology. The central composite rotatable design was employed for optimization of extraction parameters in terms of total phenolic content and antioxidant activities using 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity and phosphomolybdenum assay. The optimum operating conditions for extraction were as follows: ethanol concentration, 50%; extraction time, 25 min; extraction temperature, 63°C and ratio of solvent to solid, 67 mL/g. Under these conditions, the obtained extract exhibited a high content of phenolic compounds (40.782 mg gallic acid equivalents/g dry matter) with significant antioxidant properties (the total antioxidant activity was 75.981 mg gallic acid equivalents/g dry matter and the 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity was 0.289 mg/mL).