Phenolic-rich extract of avocado Persea americana (var. Colinred) peel blunts paraquat/maneb-induced apoptosis through blocking phosphorylation of LRRK2 kinase in human nerve-like cells.

It is increasingly evident that LRRK2 kinase activity is involved in oxidative stress (OS)-induced apoptosis-a type of regulated cell death and neurodegeneration, suggesting LRRK2 inhibition as a potential therapeutic target. We report that a phenolic-rich extract of avocado Persea americana var. Colinred peel (CRE, 0.01 mg/ml) restricts environmental neurotoxins paraquat (1 mM)/maneb (0.05 mM)-induced apoptosis process through blocking reactive oxygen species (ROS) signaling and concomitant inhibition of phosphorylation of LRRK2 in nerve-like cells (NLCs). Indeed, PQ + MB at 6 h exposure significantly increased ROS (57 ± 5%), oxidation of protein DJ-1cys106SOH into DJ-1Cys106SO3 ([~3.7 f(old)-(i)ncrease]), augmented p-(S935)-LRRK2 kinase (~20-f(old) (i)ncrease), induced nuclei condensation/fragmentation (28 ± 6%), increased the expression of PUMA (~6.2-fi), and activated CASPASE-3 (CASP-3, ~4-fi) proteins; but significantly decreased mitochondrial membrane potential (ΔΨm, ~48 ± 4%), all markers indicative of apoptosis compared to untreated cells. Remarkably, CRE significantly diminished both OS-signals (i.e., DCF+ cells, DJ-1Cys106SO3) as well as apoptosis markers (e.g., PUMA, CASP-3, loss of ΔΨm, p-LRRK2 kinase) in NLCs exposed to PQ + MB. Furthermore, CRE dramatically reestablishes the transient intracellular Ca2+ flow (~300%) triggered by dopamine (DA) in neuronal cells exposed to PQ + MB. We conclude that PQ + MB-induced apoptosis in NLCs through OS-mechanism, involving DJ-1, PUMA, CASP-3, LRRK2 kinase, mitochondria damage, DNA fragmentation, and alteration of DA-receptors. Our findings imply that CRE protects NLCs directly via antioxidant mechanism and indirectly by blocking LRRK2 kinase against PQ + MB stress stimuli. These data suggest that CRE might be a potential natural antioxidant.

Neuroprotective Effects of Methanolic Extract of Avocado Persea americana (var. Colinred) Peel on Paraquat-Induced Locomotor Impairment, Lipid Peroxidation and Shortage of Life Span in Transgenic knockdown Parkin Drosophila melanogaster.

Parkinson's disease (PD) is a progressive neurodegenerative disorder associated with oxidative stress. Therefore, finding new antioxidant sources might be beneficial for its treatment. Avocado Persea americana is a fruit widely cultivated in tropical and subtropical climates worldwide. Although avocado by-products in the form of peel, seed coat and seeds are currently of no commercial use, they constitute a natural source of bioactive compounds. Methanolic (80%) extract obtained from lyophilized ground peels, seed coats, and seeds of the avocado Hass, Fuerte, Reed and Colinred varieties were analyzed for their total phenolic content (TPC) and their correlations with antioxidant capacity (AC) were assessed by ABTS, FRAP, and ORAC assays. For all varieties, the var. Colinred peel shows the highest TPC and AC. Further analysis showed that the var. Colinred peel presented major phenolic compounds B-type procyanidins and epicatechin according to HPLC-MS. The antioxidant effect of peel extract was evaluated upon in vivo oxidative stress (OS) model. We show for the first time that the peel extract can protect and/or prevent transgenic parkinDrosophila melanogaster fly against paraquat-induced OS, movement impairment and lipid peroxidation, as model of PD. Our findings offer an exceptional opportunity to test natural disease-modifying substances from avocado's by-products.

Vitamin E synthetic derivate-TPGS-selectively induces apoptosis in jurkat t cells via oxidative stress signaling pathways: implications for acute lymphoblastic leukemia.

D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) is a water-soluble derivative of natural vitamin E commonly used as a drug delivery agent. Recently, TPGS alone has been reported to induce cell death in lung, breast and prostate cancer. However, the effect of TPGS on cancer cell viability remains unclear. Thus, this study was aimed to evaluate the cytotoxic effect of TPGS on human periphral blood lymphocytes (PBL) and on T cell acute lymphocytic leukemia (ALL) Jurkat clone E6-1 cells and its possible mechanism of action. PBL and Jurkat cells were treated with TPGS (10, 20, 40, 60, and 80 µM), and morphological changes in the cell nucleus, mitochondrial membrane potential (ΔΨm), and intracellular reactive oxygen species levels were determined by immune-fluorescence microscopy and flow cytometry. Cellular apoptosis markers were also evaluated by immunocytochemistry. In this study, TPGS induced apoptotic cell death in Jurkat cells, but not in PBL, in a dose-response manner with increasing nuclear DNA fragmentation, increasing cell cycle arrest, and decreasing ΔΨm. Additionally, TPGS increased dichlorofluorescein fluorescence intensity, indicative of H2O2 production, in a dose-independent fashion. TPGS increased DJ-1 Cys(106)-sulfonate, as a marker of intracellular stress and induced the activation of NF-κB, p53 and c-Jun transcription factors. Additionally, it increased the expression of apoptotic markers Bcl-2 related pro-apoptotic proteins Bax and PUMAand activated caspase-3. The antioxidant N-acetyl-L-cysteine and known pharmacological inhibitors protected the cells from the TPGS induced effects. In conclusion, TPGS selectively induces apoptosis in Jurkat cells through two independent but complementary H2O2-mediated signaling pathways. Our findings support the use of TPGS as a potential treatment for ALL.

Low doses of paraquat and polyphenols prolong life span and locomotor activity in knock-down parkin Drosophila melanogaster exposed to oxidative stress stimuli: implication in autosomal recessive juvenile parkinsonism.

Previous studies have shown that polyphenols might be potent neuroprotective agents in Drosophila melanogaster wild type Canton-S acutely or chronically treated with paraquat (PQ), a selective toxin for elimination of dopaminergic (DAergic) neurons by oxidative stress (OS), as model of Parkinson's disease (PD). This study reports for the first time that knock-down (K-D) parkin Drosophila melanogaster (TH-GAL4; UAS-RNAi-parkin) chronically exposed to PQ (0.1-0.25 mM), FeSO(4) (Fe, 0.1mM), deferoxamine (DFO, 0.01 mM) alone or (0.1mM) PQ in combination with polyphenols propyl gallate (PG, 0.1mM) and epigallocathecin gallate (EGCG, 0.1, 0.5mM) showed significantly higher life span and locomotor activity than untreated K-D flies or treated with (1, 5, 20mM) PQ alone. Whilst gallic acid (GA, 0.1, 0.5mM) alone or in the presence of PQ provoked no effect on K-D flies, epicathecin (EC, 0.5mM) only showed a positive effect on prolonging K-D flies' life span. It is shown that PG (and EGCG) protected protocerebral posterolateral 1 (PPL1) DAergic neurons against PQ. Interestingly, the protective effect of low PQ concentrations, DFO and iron might be explained by a phenomenon known as "hormesis." However, pre-fed K-D flies with (0.1mM) PQ for 7 days and then exposed to (0.25 mM) for additional 8 days affect neither survival nor climbing of K-D Drosophila compared to flies treated with (0.25 mM) PQ alone. Remarkably, K-D flies treated with 0.1mM PQ (7 days) and then with (0.25 mM) PQ plus PG (8 days) behaved almost as flies treated with (0.25 mM) PQ. Taken these data suggest that antioxidant supplements that synergistically act with low pro-oxidant stimuli to prolong and increase locomotor activity become inefficient once a threshold of OS has been reached in K-D flies. Our present findings support the notion that genetically altered Drosophila melanogaster as suitable model to study genetic and environmental factors as causal and/or modulators in the development of autosomal recessive juvenile Parkinsonism (AR-JD)/PD. Most importantly, we have shown for the first time that low amounts of stressors induce a health-promoting extending effect in K-D parkin flies. Altogether our present results open new avenues for the screening, testing and development of novel antioxidant drugs against OS stimuli in neurodegenerative disorders.