Unfolding the apoptotic mechanism of antioxidant enriched-leaves of Tabebuia pallida (lindl.) miers in EAC cells and mouse model.

ETHNOPHARMACOLOGICAL RELEVANCE: Tabebuia pallida (Lindl.) Miers (T. pallida) is a well-known native Caribbean medicinal plant. The leaves and barks of T. pallida are used as traditional medicine in the form of herbal or medicinal tea to manage cancer, fever, and pain. Moreover, extracts from the leaves of T. pallida showed anticancer activity. However, the chemical profile and mechanism of anticancer activity of T. pallida leaves (TPL), stem bark (TPSB), root bark (TPRB) and flowers (TPF) remain unexplored. AIM OF THE STUDY: The present study was designed to explore the regulation of apoptosis by T. pallida using Ehrlich Ascites Carcinoma (EAC) cultured cells and an EAC mouse model. LC-ESI-MS/MS was used for compositional analysis of T. pallida extracts. MATERIALS AND METHODS: Dried and powdered TPL, TPSB, TPRB and TPF were extracted with 80% methanol. Using cultured EAC cells and EAC-bearing mice with and without these extracts, anticancer activities were studied by assessing cytotoxicity and tumor cell growth inhibition, changes in life span of mice, and hematological and biochemical parameters. Apoptosis was analyzed by microscopy and expression of selected apoptosis-related genes (Bcl-2, Bcl-xL, NFκ-B, PARP-1, p53, Bax, caspase-3 and -8) using RT-PCR. LC-ESI-MS analysis was performed to identify the major compounds from active extracts. Computer aided analyses was undertaken to sort out the best-fit phytoconstituent of total ten isolated compounds of this plant for antioxidant and anticancer activity. RESULTS: In EAC mice compared with untreated controls, the TPL extract exhibited the highest cancer cell toxicity with significant tumor cell growth inhibition (p < 0.001), reduced ascites by body weight (p < 0.01), increased the life span (p < 0.001), normalized blood parameters (RBC/WBC counts), and increased the levels of superoxide dismutase and catalase. TPL-treated EAC cells showed increased apoptotic characteristics of membrane blebbing, chromatin condensation and nuclear fragmentation, and caspase-3 activation, compared with untreated EAC cells. Moreover, annexin V-FITC and propidium iodide signals were greatly enhanced in response to TPL treatment, indicating apoptosis induction. Pro- and anti-apoptotic signaling after TPL treatment demonstrated up-regulated p53, Bax and PARP-1, and down-regulated NFκ-B, Bcl-2 and Bcl-xL expression, suggesting that TPL shifts the balance of pro- and anti-apoptotic genes towards cell death. LC-ESI-MS data of TPL showed a mixture of glycosides, lapachol, and quercetin antioxidant and its derivatives that were significantly linked to cancer cell targets. The compound, pelargonidin-3-O-glucoside was found to be most effective in computer aided models. CONCLUSIONS: In conclusion, the TPL extract of T. pallida possesses significant anticancer activity. The tumor suppressive mechanism is due to apoptosis induced by activation of antioxidant enzymes and caspases and mediated by a change in the balance of pro- and anti-apoptotic genes that promotes cell death.

Chemical RNA Editing for Genetic Restoration: The Relationship between the Structure and Deamination Efficiency of Carboxyvinyldeoxyuridine Oligodeoxynucleotides.

Oligodeoxynucleotides containing 5-carboxyvinyl-2'-deoxyuridine ((CV) U-containing ODNs) for successful site-specific transition of cytosine to uridine by photo-cross-linking have three parts: the complementary sequence, hairpin loop and the 5'-terminal photoresponsive nucleobase (CV) U. Photo-cross-linking with (CV) U-containing ODNs was performed using UV (366 nm) irradiation, followed by heat treatment for deamination. The cross-linked nucleotide was cleaved by photosplitting (UV, 312 nm). The products were analyzed using restriction fragment length polymorphism and fluorescence measurements. In previous studies, we have successfully performed site-directed photochemical base substitution toward a synthetic single-stranded 100-mer ODN target (ss100-nt) and in vitro-synthesized full-length blue fluorescent protein mRNA as targets. Although the efficiency of C-to-U site-specific transition strongly depends on the sequence and structure of (CV) U-containing ODNs, the relationship between (CV) U-containing ODNs and the deamination efficiency of targeted editing remains unclear. Therefore, in this study, we attempted to identify the optimal sequence and primary structure of (CV) U-containing ODNs for site-directed specific transition. To evaluate the structure-deamination efficiency relationship, a series of eight (CV) U-containing ODNs were designed and studied. We showed that the optimal deamination efficiency was achieved with ODNs having a complementary sequence length slightly more than 14 nt and a hairpin length of 9 nt.

'Protected DNA Probes' capable of strong hybridization without removal of base protecting groups.

We propose a new strategy called the 'Protected DNA Probes (PDP) method' in which appropriately protected bases selectively bind to the complementary bases without the removal of their base protecting groups. Previously, we reported that 4-N-acetylcytosine oligonucleotides (ac(4)C) exhibited a higher hybridization affinity for ssDNA than the unmodified oligonucleotides. For the PDP strategy, we created a modified adenine base and synthesized an N-acylated deoxyadenosine mimic having 6-N-acetyl-8-aza-7-deazaadenine (ac(6)az(8)c(7)A). It was found that PDP containing ac(4)C and ac(6)az(8)c(7)A exhibited higher affinity for the complementary ssDNA than the corresponding unmodified DNA probes and showed similar base recognition ability. Moreover, it should be noted that this PDP strategy could guarantee highly efficient synthesis of DNA probes on controlled pore glass (CPG) with high purity and thereby could eliminate the time-consuming procedures for isolating DNA probes. This strategy could also avoid undesired base-mediated elimination of DNA probes from CPG under basic conditions such as concentrated ammonia solution prescribed for removal of base protecting groups in the previous standard approach. Here, several successful applications of this strategy to single nucleotide polymorphism detection are also described in detail using PDPs immobilized on glass plates and those prepared on CPG plates, suggesting its potential usefulness.