Unfolding the Apoptotic Mechanism of Antioxidant Enriched-Leaves of Tabebuia pallida in EAC Cells

Targeting apoptosis is a promising approach to inhibit the abnormal cell proliferation of cancer progression. Existing anti-apoptotic drugs, many derived from chemical substances, have often failed to combat cancer development and progression. Therefore, identification of apoptosis-inducing anticancer agents from plant-derived sources has become a key aim in cancer research. The present study was designed to explore the regulation of apoptosis by Tabebuia pallida (T. pallida) using an Ehrlich Ascites Carcinoma (EAC) mouse model and compositional analysis by LC-ESI-MS/MS. Dried and powdered T. pallida leaves (TPL), stem bark (TPSB), root bark (TPRB) and flowers (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 the most active extracts. In EAC mice compared with untreated controls, the TPL extract exhibited the highest cytotoxicity 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 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. 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.Graphical Abstract

Nutritional attributes of Hemiparasitic mistletoe Scurrula ferruginea in Brunei Darussalam

Three different associations of Scurrula ferruginea parasites on three different hosts, namely Tabebuia pallida, Acacia holosericea and Acacia auriculiformis were collected from the Brunei-Muara District, Brunei Darussalam. Moisture content and chemical analyses (ash content, total carbohydrate content, crude protein, proline and mineral content composition) were determined to explain the host-parasite physiological biochemistry. Scurrula ferruginea contained relatively higher moisture content (47 – 65%) and ash content (2.1-2.5%, dry basis) than the hosts (0.7-1.4%, dry basis). High nutrient and moisture contents in Scurrula ferruginea make it more preferred food source than its hosts for generalist herbivores in a given community. The mistletoe exhibited differential storage profile of total carbohydrate (1.9-6.4%, dry basis) and total nitrogen (1.2 – 3.0%, dry-basis) when compared to hosts (total carbohydrate 2.3 - 3.0 % dry basis; total nitrogen 1.6 - 2.1%). Meanwhile the proline content (24.9-56.0 mg/kg, dry basis) were found in Scurrula ferruginea. Among all the minerals analysed, potassium is the most abundant mineral present in all mistletoe-host associations. Data indicated that certain host desired solutes are preferentially absorbed and stored in mistletoe.

A study of the ecological history, vegetation and conservation management of Ile aux Aigrettes, Mauritius

ABSTRACTMuch of the unique native vegetation of Mauritius has been destroyed. Coastal ebony (Diospyros egrettarum I.B.K. Richardson) forest forms an extreme type of Mauritian lowland forest which no longer exists on mainland Mauritius and only survives on one offshore islet, Ile aux Aigrettes. Undisturbed D. egrettarum forest is resistant to invasion by exotic plants, which have now invaded most relict patches of native lowland vegetation in Mauritius. Human disturbance however, has allowed many exotics (particularly Flacourtia indica (Burm. fil.) Merrill) to invade and form new vegetation types. Much of the disturbance was caused by illegal woodcutting up to 1985, prompted by an acute fuelwood shortage in Mauritius. On the basis of 132 4 X 4 m quadrats, we recognize 10 types of natural, semi-natural and exotic vegeta-tion. The conservation of the remaining natural ebony woodland vegetation requires the total cessation of woodcutting and the eradication of Tabebuia pallida (Lindl.) Miers (potentially the most damaging exotic species).