Relationship between Phenolic Compounds and Antioxidant Activity of Some Moroccan Date Palm Fruit Varieties (Phoenix dactylifera L.): A Two-Year Study.

In Morocco, the abundance of low-value varieties in the oases may provide an opportunity to capitalize on this richness to create new nutraceutical food products. In this context, the phenolic profile and antioxidant capacity of four Moroccan date varieties were analyzed. Our results indicate that the levels of total polyphenols, total flavonoids and total condensed tannins vary, respectively, from 91.86 to 364.35 mg GAE/100 g of dry weight (DW), 46.59 to 111.80 mg QE/100 g DW and 16.10 to 42.03 mg CE/100 g DW during the 2021 harvest season. Furthermore, during the 2022 harvest season, these contents vary, respectively, from 119.13 to 410.39 mg GAE/100 g DW, 59.30 to 110.85 mg QE/100 g DW and 21.93 to 53.95 mg CE/100 g DW. The results of the HPLC-UV-VIS analysis revealed that, in all four varieties, gallic acid was and remained one of the major compounds in the date extracts. In addition, a high antioxidant activity of date extracts was particularly observed in the three tests, namely ferric reducing power (FRAP), ferrous ion chelating capacity (FIC) and the phosphomolybdate test. This richness in phenolic compounds makes low-value dates a source of active ingredient that can replace the synthetic antioxidants used in the food and pharmaceutical industries.

The transcription factor, NFI/CTF plays a positive regulatory role in expression of the hSMUG1 gene.

SMUG1 is a recently discovered uracil-DNA glycosylase with the ability to remove uracil from single-stranded as well as double-stranded DNA. SMUG1 also has the capacity to excise oxidized pyrimidine bases such as 5-hydroxymethyluracil and 5-formyluracil from DNA. Very little is known about the regulation of this enzyme. Therefore, we undertook this study to begin to elucidate the mechanisms of hSMUG1 gene expression. Northern blot analysis performed on mRNAs derived from different cell lines reveals that the steady-state levels of hSMUG1 transcript are about 10-fold lower relative to UDG. In addition to the 1.6kb transcript known to encode a functional hSMUG1 protein, an alternate 0.7kb transcript was uncovered that contains an open reading frame. Interestingly, this alternate transcript is missing a carboxy-terminal domain which is necessary for catalytic activity. Utilizing a luciferase reporter assay system we show that significant promoter activity is associated with a 2000bp region, located immediately upstream of the first transcribed, non-translated exon. 5' deletion analysis of this 2000bp region reveals that there are both negative and positive regulatory elements that control expression of SMUG1. Using electrophoretic mobility shift analysis we show that a number of DNA-protein complexes are formed within the region (-705 to -604) of positive regulation. At least two of these complexes contain the transcription factor NFI/CTF as demonstrated by oligonucleotide competition studies with NFI/CTF consensus sequence containing both protein-binding half-sites. We further demonstrate that purified NFI-C protein will bind to this positive regulatory region within the hSMUG1 gene. DNase I footprint analysis reveals that the 3' half-site is protected when using crude nuclear extract as a protein source. However, the introduction of mutations into either or both of the half-sites indicates that the individual half-sites contribute to NFI/CTF binding. Overexpression of NFI-C in NIH-3T3 cells results in an increase in SMUG1 enzyme activity. Collectively, these data indicate that the NFI/CTF consensus site may function as a cis-element in the SMUG1 promoter and that this transcription factor contributes to the positive regulation of SMUG1 gene expression.

hSMUG1 can functionally compensate for Ung1 in the yeast Saccharomyces cerevisiae.

There are at least four distinct families of enzymes that recognize and remove uracil from DNA. Family-3 (SMUG1) enzymes have recently been identified and have a preference for uracil in single-stranded DNA when assayed in vitro. Here we investigate the in vivo function of SMUG1 using the yeast Saccharomyces cerevisiae as a model system. These organisms lack a SMUG1 homologue and use a single enzyme, Ung1 to carry out uracil-repair. When a wild-type strain is treated with antifolate agents to induce uracil misincorporation into DNA, S-phase arrest and cellular toxicity occurs. The arrest is characteristic of checkpoint activation due to single-strand breaks caused by continuous uracil removal and self-defeating DNA repair. When uracil-DNA glycosylase is deleted (deltaung1), cells continue through S-phase and arrest at G(2)/M, presumably due to the effects of stable uracil misincorporation in DNA. Pulsed field gel electrophoresis (PFGE) demonstrates that cells are able to complete DNA replication with uracil-substituted DNA and do not experience the extensive strand breakage attributed to uracil-DNA glycosylase-mediated repair. As a result, these cells experience early protection from antifolate-induced cytotoxicity. When either UNG1 or SMUG1 functions are reintroduced back into the null strain and then subjected to antifolate treatment, the cells revert back to the wild-type phenotype as shown by a restored sensitivity to drug and S-phase arrest. The arrest is accompanied by the accumulation of replication intermediates as determined by PFGE. Collectively, these data indicate that SMUG1 can act as a functional homolog of the family-1 uracil-DNA glycosylase enzymes.