M. Cavia-Saiz

Antioxidant properties, radical scavenging activity and biomolecule protection capacity of flavonoid naringenin and its glycoside naringin: a comparative study

BACKGROUND This study was designed to evaluate and compare antioxidant capacity and radical scavenging activity of naringin and its aglycone by different in vitro assays. The effects of flavanones on lipid peroxidation, glutathione (GSH) oxidation and DNA cleavage were also assessed. RESULTS The results showed that naringenin exhibited higher antioxidant capacity and hydroxyl and superoxide radical scavenger efficiency than naringin. Our results evidenced that glycosylation attenuated the efficiency in inhibiting the enzyme xanthine oxidase and the aglycone could act like a more active chelator of metallic ions than the glycoside. Additionally, naringenin showed a greater effectiveness in the protection against oxidative damage to lipids in a dose-dependent manner. Both flavanones were equally effective in reducing DNA damage. However, they show no protective effect on oxidation of GSH. CONCLUSION The data obtained support the importance of characterizing the ratio naringin/naringenin in foods when they are evaluated for their health benefits.

TAp73 is one of the genes responsible for the lack of response to chemotherapy depending on B-Raf mutational status

BackgroundAlthough there have been many studies on the p73 gene, some of its functions still remain unclear. There is little research on the relationship between p73 gene transcription and its protein expression and the response to certain drugs such as oxaliplatin and cetuximab, which are drugs currently used in colorectal cancer.The purpose of this study was to evaluate the impact of TAp73 expression on oxaliplatin and cetuximab-based chemotherapy in colorectal cancer cell lines with different K-Ras and B-Raf mutational status.MethodsTAp73 was analyzed in three colorectal tumor cell lines HT-29, SW-480 and Caco-2. mRNA TAp73 was determined using Real time PCR; TAp73 protein by immunoblotting and cell viability was analyzed by the MTT method.ResultsWe found that mRNA and TAp73 protein were decreased in cells treated with oxaliplatin (in monotherapy or combined with cetuximab) when B-Raf is mutated. This was statistically significant and was also associated with higher cell viability after the treatment.ConclusionsHere, for the first time we report, that there is a signaling loop between B-Raf activation and p73 function.Low expression of TAp73 in colorectal cancer cell lines with mutated B-Raf may be involved in the lack of response to oxaliplatin in monotherapy or combined with cetuximab.

Enzymatic Debittering on Antioxidant Capacity of Grapefruit Juice

Conventional methods to reduce the bitterness in citrus juices involve not only the removal of the bitter compounds (naringin and limonin), but also bioactive components (organic acids, flavonoids, limonoids, etc.) from the juice. In this regard, biotechnological methods, either isolated enzymes or whole cells, have been suggested as an alternative way to remove bitterness, without affecting the nutritional and healthy properties of the processed juice. In this chapter, the current state of knowledge of the potential application of enzyme technology in the debittering of citrus juices, and their effects on the antioxidant properties of the juices, are reviewed and discussed. Furthermore, some specific results on the antioxidant capacity, superoxide and hydroxyl radical scavenger activity, and protective role against oxidative stress of grapefruit juice debittered with naringinase immobilized in poly(vinyl alcohol) cryogels are presented.

Revisiting the thiosemicarbazonecopper(II) reaction with glutathione. Activity against colorectal carcinoma cell lines

Thiosemicarbazones (TSCs), and their copper derivatives, have been extensively studied mainly due to the potential applications as antitumor compounds. A part of the biological activity of the TSC-CuII complexes rests on their reactivity against cell reductants, as glutathione (GSH). The present paper describes the structure of the [Cu(PTSC)(ONO2)]n compound (1) (HPTSC=pyridine-2-carbaldehyde thiosemicarbazone) and its spectroscopic and magnetic properties. ESI studies performed on the reaction of GSH with 1 and the analogous [{Cu(PTSC*)(ONO2)}2] derivative (2, HPTSC*=pyridine-2-carbaldehyde 4N-methylthiosemicarbazone) show the absence of peaks related with TSC-Cu-GSH species. However GSH-Cu ones are detected, in good agreement with the release of CuI ions after reduction in the experimental conditions. The reactivity of 1 and 2 with cytochrome c and myoglobin and their activities against HT-29 and SW-480 colon carcinoma cell lines are compared with those shown by the free HPTSC and HPTSC* ligands.