Anti-inflammatory and anticancer effects of flavonol glycosides from Diplotaxis harra through GSK3β regulation in intestinal cells

CONTEXT AND OBJECTIVE

Diplotaxis harra (Forssk.) Boiss. (Brassicaceae) is traditionally used as an antidiabetic, anti-inflammatory or anticancer agent. In these pathologies, the glycogen synthase kinase 3 β (GSK3β) is overactivated and represents an interesting therapeutic target. Several flavonoids can inhibit GSK3β and the purpose of this study was to search for the compounds in Diplotaxis harra which are able to modulate GSK3β.

MATERIALS AND METHODS

Methanol extracts from D. harra flowers were prepared and the bio-guided fractionation of their active compounds was performed using inflammatory [protease-activated receptor 2 (PAR₂)-stimulated IEC6 cells] and cancer (human Caco-2 cell line) intestinal cells. 50-100 μg/mL of fractions or compounds purified by HPLC were incubated with cells whose inhibited form of GSK3β (Pser9 GSK3β) and survival were analyzed by Western blot at 1 h and colorimetric assay at 24 h, respectively. LC-UV-MS profiles and MS-MS spectra were used for the characterization of extracts and flavonoids-enriched fractions, and the identification of pure flavonoids was achieved by MS and NMR analysis.

RESULTS

The methanol extract from D. harra flowers and its flavonoid-enriched fraction inhibit GSK3β in PAR₂-stimulated IEC6 cells. GSK3β inhibition by the flavonoid-enriched D. harra fraction was dependent on PKC activation. The flavonoid-enriched D. harra fraction and its purified compound isorhamnetin-3,7-di-O-glucoside induced a 20% decrease of PAR₂-stimulated IEC6 and Caco-2 cell survival. Importantly, normal cells (non-stimulated IEC6 cells) were spared by these treatments.

CONCLUSION

This work indicates that flavonoids from D. harra display cytotoxic activity against inflammatory and cancer intestinal cells which could depend on GSK3β inhibition.

PAR2-dependent activation of GSK3β regulates the survival of colon stem/progenitor cells

Protease-activated receptors PAR1 and PAR2 play an important role in the control of epithelial cell proliferation and migration. However, the survival of normal and tumor intestinal stem/progenitor cells promoted by proinflammatory mediators may be critical in oncogenesis. The glycogen synthase kinase-3β (GSK3β) pathway is overactivated in colon cancer cells and promotes their survival and drug resistance. We thus aimed to determine PAR1 and PAR2 effects on normal and tumor intestinal stem/progenitor cells and whether they involved GSK3β. First, PAR1 and PAR2 were identified in colon stem/progenitor cells by immunofluorescence. In three-dimensional cultures of murine crypt units or single tumor Caco-2 cells, PAR2 activation decreased numbers and size of normal or cancerous spheroids, and PAR2-deficient spheroids showed increased proliferation, indicating that PAR2 represses proliferation. PAR2-stimulated normal cells were more resistant to stress (serum starvation or spheroid passaging), suggesting prosurvival effects of PAR2 Accordingly, active caspase-3 was strongly increased in PAR2-deficient normal spheroids. PAR2 but not PAR1 triggered GSK3β activation through serine-9 dephosphorylation in normal and tumor cells. The PAR2-triggered GSK3β activation implicates an arrestin/PP2A/GSK3β complex that is dependent on the Rho kinase activity. Loss of PAR2 was associated with high levels of GSK3β nonactive form, strengthening the role of PAR2 in GSK3β activation. GSK3 pharmacological inhibition impaired the survival of PAR2-stimulated spheroids and serum-starved cells. Altogether our data identify PAR2/GSK3β as a novel pathway that plays a critical role in the regulation of stem/progenitor cell survival and proliferation in normal colon crypts and colon cancer.

A mineral and antioxidant-rich extract from the red marine Algae Alsidium corallinum exhibits cytoprotective effects against potassium bromate-induced erythrocyte oxidative damages in mice

The present study was carried out to investigate potassium bromate toxicity in mice and the corrective effects of marine algae Alsidium corallinum. The red algae demonstrated its rich composition in phenols, triterpenes, flavonoids, alkaloids, tropolones, sodium, potassium, calcium, magnesium, iron, copper, and zinc. To confirm its antioxidant potential, an in vivo study was performed on adult mice. The animals were divided into four groups: group I were used as controls, group II received potassium bromate (0.5 g/L) via drinking water, group III received potassium bromate (0.5 g/L) by the same route as group II and 7% of A. corallinum ethanolic extract via their diet, and group IV received only 7% of algae. The potassium bromate-treated group showed a significant decrease in erythrocyte, platelet, hemoglobin, and hematocrit values and a significant increase in total white blood cells, compared to those of controls. While, superoxide dismutase, catalase, glutathione, and vitamin C values were decreased by potassium bromate treatment, lipid peroxidation (as malondialdehyde) and erythrocyte osmotic fragility values were increased. Interestingly, potassium bromate treatment showed significant genotoxic effects, as demonstrated by DNA degradation. These changes were confirmed by blood smears histopathological observations which were marked by a necrosis and a decrease of erythrocytes number. A. corallinum extract appeared to be effective against hematotoxic and genotoxic changes induced by potassium bromate, as evidenced by the improvement of the parameters cited above.

Vitamin A deficiency among Moroccan women and children

BACKGROUND

Vitamin A deficiency (VAD), attributable to an inadequate food intake, constitutes a problem in developing countries. The determination of plasma vitamin A (VA) is a reliable method for assessing VA status of the population. In this context, high performance liquid chromatography (HPLC) has become the method of choice for VA analysis.

OBJECTIVES

We describe the VAD profile of Moroccan children and women, obtained by specific HPLC analysis of VA.

SUBJECTS AND METHODS

The study involved 2457 participants: 1453 children and 1004 women from different areas of Morocco. Vitamin A was assessed by HPLC. Validation was conducted by comparison of the analysis of VA achieved in two laboratories.

RESULTS

The prevalence of VAD in children (n = 1453) was 40.4% [37.8% - 43.0%] against 10.9 % [8.4% - 14.1%] of women in the Gharb (n = 494) and 6.3 % [4.4% - 8.8%] in women of Doukkala (n = 510). The VA distribution of the children was low compared to distributions among women. Children had significantly lower VA levels (0.773 +/- 0.252 micromol/l) than women of Gharb (1.17 +/- 0.43 micromol/l) and women of Doukkala (1.308 +/- 0.453 micromol/l). Analytical performance was good: the reproducibility and recovery rates were respectively 1.97 % and 98.7 +/- 3.1 %. The comparison of the mean VA and the cases of VAD obtained by the two laboratories showed no significant difference.

CONCLUSION

Vitamin A deficiency is severe among children and moderate among women. The absence of the stratum having comfortable averages in vitamin A (plasma VA>3.49 micromol/l) indicates likely inadequate alimentary habits for a suitable vitamin A intake. The use of HPLC analysis of vitamin A, on a large scale for the first time in Morocco, has demonstrated that vitamin A deficiency is a public health problem. The recycling of mobile phase has reduced the costs of HPLC. This analytical method is useful in the evaluation of intervention programs against vitamin A deficiency and in future epidemiological studies.