Antioxidant Properties of Lippia alba Essential Oil: A Potential Treatment for Oxidative Stress-Related Conditions in Plants and Cancer Cells.

Lippia alba (Mill.) N.E.Br. ex Britton and P. Wilson is used in folk medicine of Central and South America for its biological activities: i.e., antifungal, antibacterial, antiviral, and anti-inflammatory. Based on ethnopharmacological information and the increasing interest in this species, this work aimed to test a possible wide use of its essential oil (EO) in pharmaceutical and horticultural applications. Therefore, we focused the attention on the antioxidant activity of the oil as a possible tool to overcome the oxidative stress in both applications. For this purpose, we have chosen three aggressive breast cancer cell lines and two horticultural species (Solanum lycopersicum L. and Phaseolus acutifolius L.) that are very sensitive to salt stress. We determined the antioxidant activity of L. alba EO through the quantification of phenols and flavonoids. Regarding tomato and bean plants under salt stress, L. alba EO was used for the first time as a seed priming agent to enhance plant salt tolerance. In this case, the seed treatment enhanced the content of phenolic compounds, reduced power and scavenger activity, and decreased membrane lipid peroxidation, thus mitigating the oxidative stress induced by salt. While in breast cancer cells the EO treatment showed different responses according to the cell lines, i.e., in SUM149 and MDA-MB-231 the EO decreased proliferation and increased antioxidant activity and lipid peroxidation, showing high cytotoxic effects associated with the release of lactate dehydrogenase, vice versa no effect was observed in MDA-MB-468. Such antioxidant activity opens a new perspective about this essential oil as a possible tool to counteract proliferation in some cancer cell lines and in horticulture as a seed priming agent to protect from oxidative damage in crops sensitive to salinity.

Hydroxytyrosol Counteracts Triple Negative Breast Cancer Cell Dissemination via Its Copper Complexing Properties.

Polyphenols have gained increasing attention for their therapeutic potential, particularly in conditions like cancer, due to their established antioxidant and anti-inflammatory properties. Recent research highlights their ability to bind to transition metals, such as copper. This is particularly noteworthy given the key role of copper both in the initiation and progression of cancer. Copper can modulate the activity of kinases required for the epithelial-mesenchymal transition (EMT), a process fundamental to tumor cell dissemination. We have previously demonstrated the copper-binding capacity of oleuropein, a secoiridoid found in Olea europaea. In the present study, we investigated the effect of hydroxytyrosol, the primary oleuropein metabolite, on the metastatic potential of three triple-negative breast cancer cell lines (MDA-MB-231, MDA-MB-468, and SUM159). We found that hydroxytyrosol modulated the intracellular copper levels, influencing both the epithelial and mesenchymal markers, by downregulating copper-dependent AKT phosphorylation, a member of the EMT signaling cascade, through Western blot, RT-qPCR, and immunofluorescence. Indeed, by optical spectra, EPR, and in silico approaches, we found that hydroxytyrosol formed a complex with copper, acting as a chelating agent, thus regulating its homeostasis and affecting the copper-dependent signaling cascades. While our results bring to light the copper-chelating properties of hydroxytyrosol capable of countering tumor progression, they also provide further confirmation of the key role of copper in promoting the aggressiveness of triple-negative breast cancer cells.

Phytoremediation of Pollutants: Applicability and Future Perspective.

Environmental pollution is a global issue since it is spreading worldwide, affecting entire ecosystems [...].

Role of Polyamines in the Response to Salt Stress of Tomato.

Plants irrigated with saline solutions undergo osmotic and oxidative stresses, which affect their growth, photosynthetic activity and yield. Therefore, the use of saline water for irrigation, in addition to the increasing soil salinity, is one of the major threats to crop productivity worldwide. Plant tolerance to stressful conditions can be improved using different strategies, i.e., seed priming and acclimation, which elicit morphological and biochemical responses to overcome stress. In this work, we evaluated the combined effect of priming and acclimation on salt stress response of a tomato cultivar (Solanum lycopersicum L.), very sensitive to salinity. Chemical priming of seeds was performed by treating seeds with polyamines (PAs): 2.5 mM putrescine (PUT), 2.5 mM spermine (SPM) and 2.5 mM spermidine (SPD). Germinated seeds of primed and non-primed (controls) were sown in non-saline soil. The acclimation consisted of irrigating the seedlings for 2 weeks with tap water, followed by irrigation with saline and non-saline water for 4 weeks. At the end of the growth period, morphological, physiological and biochemical parameters were determined. The positive effects of combined treatments were evident, when primed plants were compared to non-primed, grown under the same conditions. Priming with PAs improved tolerance to salt stress, reduced the negative effects of salinity on growth, improved membrane integrity, and increased photosynthetic pigments, proline and enzymatic and non-enzymatic antioxidant responses in all salt-exposed plants. These results may open new perspectives and strategies to increase tolerance to salt stress in sensitive species, such as tomato.

Use of Biostimulants as a New Approach for the Improvement of Phytoremediation Performance-A Review.

Environmental pollution is one of the most pressing global issues, and it requires priority attention. Environmental remediation techniques have been developed over the years and can be applied to polluted sites, but they can have limited effectiveness and high energy consumption and costs. Bioremediation techniques, on the other hand, represent a promising alternative. Among them, phytoremediation is attracting particular attention, a green methodology that relies on the use of plant species to remediate contaminated sites or prevent the dispersion of xenobiotics into the environment. In this review, after a brief introduction focused on pollution and phytoremediation, the use of plant biostimulants (PBs) in the improvement of the remediation effectiveness is proposed. PBs are substances widely used in agriculture to raise crop production and resistance to various types of stress. Recent studies have also documented their ability to counteract the deleterious effects of pollutants on plants, thus increasing the phytoremediation efficiency of some species. The works published to date, reviewed and discussed in the present work, reveal promising prospects in the remediation of polluted environments, especially for heavy metals, when PBs derived from humic substances, protein and amino acid hydrolysate, inorganic salts, microbes, seaweed, plant extracts, and fungi are employed.

Flavonoids: A Myth or a Reality for Cancer Therapy?

Nutraceuticals are biologically active molecules present in foods; they can have beneficial effects on health, but they are not available in large enough quantities to perform this function. Plant metabolites, such as polyphenols, are widely diffused in the plant kingdom, where they play fundamental roles in plant development and interactions with the environment. Among these, flavonoids are of particular interest as they have significant effects on human health. In vitro and/or in vivo studies described flavonoids as essential nutrients for preventing several diseases. They display broad and promising bioactivities to fight cancer, inflammation, bacterial infections, as well as to reduce the severity of neurodegenerative and cardiovascular diseases or diabetes. Therefore, it is not surprising that interest in flavonoids has sharply increased in recent years. More than 23,000 scientific publications on flavonoids have described the potential anticancer activity of these natural molecules in the last decade. Studies, in vitro and in vivo, show that flavonoids exhibit anticancer properties, and many epidemiological studies confirm that dietary intake of flavonoids leads to a reduced risk of cancer. This review provides a glimpse of the mechanisms of action of flavonoids on cancer cells.

Enhancement of Brassica napus Tolerance to High Saline Conditions by Seed Priming.

Plants grown in saline soils undergo osmotic and oxidative stresses, affecting growth and photosynthesis and, consequently, the yield. Therefore, the increase in soil salinity is a major threat to crop productivity worldwide. Plant's tolerance can be ameliorated by applying simple methods that induce them to adopt morphological and physiological adjustments to counteract stress. In this work, we evaluated the effects of seed priming on salt stress response in three cultivars of rapeseed (Brassica napus L.) that had different tolerance levels. Seed chemical priming was performed with 2.5 mM spermine (SPM), 5 mM spermidine (SPD), 40 mM NaCl and 2.5 mM Ca (NO3)2. Primed and not primed seeds were sown on saline and not saline (controls) media, and morphological and physiological parameters were determined. Since SPD treatment was effective in reducing salinity negative effects on growth, membrane integrity and photosynthetic pigments, we selected this priming to further investigate plant salt stress response. The positive effects of this seed treatment on growth and physiological responses were evident when primed plants were compared to not primed ones, grown under the same saline conditions. SPD priming ameliorated the tolerance towards saline stress, in a genotype-independent manner, by increasing photosynthetic pigments, proline amounts and antioxidant responses in all cultivars exposed to salt. These results may open new perspectives for crop productivity in the struggle against soil salinization.

Reduction of oxidative stress and ornithine decarboxylase expression in a human prostate cancer cell line PC-3 by a combined treatment with α-tocopherol and naringenin.

Differentiation of a human aggressive PC-3 cancer cell line was obtained, in a previous investigation, by the synergic effect of α-tocopherol (α-TOC) and naringenin (NG). This combined treatment induced apoptosis and subsequent reduction of the PC-3 cell proliferation and invasion, by a pro-differentiating action. Since one of the peculiar characteristics of NG and α-TOC is their strong antioxidant activity, this study aimed to investigate their potential effect on the activity of the main enzymes involved in the antioxidant mechanism in prostate cancer cells. NG and α-TOC administered singularly or combined in the PC-3 cell line, affected the activity of several enzymes biomarkers of the cellular antioxidant activity, as well as the concentration of total glutathione (GSH + GSSG) and thiobarbituric acid reactive substances (TBARS). The combined treatment increased the TBARS levels and superoxide dismutase (SOD) activity, while decreased the glutathione S-transferase (GST), glutathione reductase (GR), and glyoxalase I (GI) activities. The results obtained indicate that a combined treatment with these natural compounds mitigated the oxidative stress in the human PC-3 cell line. In addition, a significant reduction of both ornithine decarboxylase (ODC) expression and intracellular levels of polyamines, both well-known positive regulators of cell proliferation, accompanied the reduction of oxidative stress observed in the combined α-TOC and NG treatment. Considering the established role of polyamines in cell differentiation, the synergism with NG makes α-TOC a potential drug for further study on the differentiation therapy in prostate cancer patients.

Polyamine Oxidase Is Involved in Spermidine Reduction of Transglutaminase Type 2-Catalyzed ßH-Crystallins Polymerization in Calcium-Induced Experimental Cataract.

In an in vitro Ca2+-induced cataract model, the progression of opacification is paralleled by a rapid decrease of the endogenous levels of spermidine (SPD) and an increase of transglutaminase type 2 (TG2, EC 2.3.2.13)-catalyzed lens crystallins cross-linking by protein-bound N1-N8-bis(γ-glutamyl) SPD. This pattern was reversed adding exogenous SPD to the incubation resulting in a delayed loss of transparency of the rabbit lens. The present report shows evidence on the main incorporation of SPD by the catalytic activity of TG2, toward ßH-crystallins and in particular to the ßB2- and mostly in ßB3-crystallins. The increase of endogenous SPD in the cultured rabbit lens showed the activation of a flavin adenine dinucleotide (FAD)-dependent polyamine oxidases (PAO EC 1.5.3.11). As it is known that FAD-PAO degrades the N8-terminal reactive portion of N1-mono(γ-glutamyl) SPD, the protein-bound N8-mono(γ-glutamyl) SPD was found the mainly available derivative for the potential formation of ßB3-crystallins cross-links by protein-bound N1-N8-bis(γ-glutamyl)SPD. In conclusion, FAD-PAO degradation of the N8-terminal reactive residue of the crystallins bound N1-mono(γ-glutamyl)SPD together with the increased concentration of exogenous SPD, leading to saturation of glutamine residues on the substrate proteins, drastically reduces N1-N8-bis(γ-glutamyl)SPD crosslinks formation, preventing crystallins polymerization and avoiding rabbit lens opacification. The ability of SPD and MDL 72527 to modulate the activities of TG2 and FAD-PAO involved in the mechanism of lens opacification suggests a potential strategy for the prevention of senile cataract.

Evaluation of polyamines as marker of melanoma cell proliferation and differentiation by an improved high-performance liquid chromatographic method.

The differentiation therapy is focused on the identification of new agents able to impair the proliferative and metastatic potential of cancer cells through the induction of differentiation. Although several markers of cell differentiation on tumor cells have been identified, their causal relationship with neoplastic competence has not been characterized in sufficient detail to propose their use as new pharmacological targets useful for the design of new differentiation agents. Polyamine level in cancer cells and in body fluids was proposed as potential marker of cell proliferation and differentiation. The main advantage of this marker is the possibility to evaluate the antineoplastic activity of new drugs able to induce cell differentiation and consequently to inhibit tumor growth and metastasis. The presented report shows a simply and highly reproducible reverse-phase high-performance liquid chromatographic (HPLC) method for the determination of ortho-phthalaldehyde (OPA) derivatives of polyamines: putrescine (PUT), cadaverine (CAD), spermidine (SPD) and spermine (SPM). The novelty of this method is the fluorescence response for OPA-derivate of SPM, generally low in other procedures, that has been significantly improved by the use of a fully endcapped packing material with minimal silanol interactions. The limits of detection for PUT, CAD, SPD and SPM were 0.6, 0.7, 0.8, and 0.4 pmol/mL, respectively. The analysis time was ≤ 20 min, and the relative recovery rate was of about 97%. To verify the usefulness of this method, it has been validated in a murine melanoma cell line (B16-F10) treated with two theophylline derivatives (namely 8-chlorotheophylline and 8-bromotheophylline). These two compounds increased the activity of tissue transglutaminase (TG2) and the synthesis of melanin, two recognized markers of melanoma cell differentiation, and significantly reduced the levels of intracellular polyamines.

Beneficial Role of Phytochemicals on Oxidative Stress and Age-Related Diseases.

Aging is related to a number of functional and morphological changes leading to progressive decline of the biological functions of an organism. Reactive Oxygen Species (ROS), released by several endogenous and exogenous processes, may cause important oxidative damage to DNA, proteins, and lipids, leading to important cellular dysfunctions. The imbalance between ROS production and antioxidant defenses brings to oxidative stress conditions and, related to accumulation of ROS, aging-associated diseases. The purpose of this review is to provide an overview of the most relevant data reported in literature on the natural compounds, mainly phytochemicals, with antioxidant activity and their potential protective effects on age-related diseases such as metabolic syndrome, diabetes, cardiovascular disease, cancer, neurodegenerative disease, and chronic inflammation, and possibly lower side effects, when compared to other drugs.

Extracts from Cell Suspension Cultures of Strawberry (Fragaria x ananassa Duch): Cytotoxic Effects on Human Cancer Cells.

Natural compounds are emerging as agents for the treatment of malignant diseases. We previously showed that extracts from in vitro cell suspension cultures of strawberry reduced murine melanoma cell proliferation, as shown for fruit extracts. In this work, chromatographic, mass spectrometric, and spectrophotometric analyses were carried out to identify the bioactive compound exerting the detected cytotoxic activity. Moreover, aiming to confirm the anti-proliferative activity of the extracts against both paediatric and adult human tumors, cytotoxic experiments were performed on neuroblastoma, colon, and cervix carcinoma cell lines. Extracts from in vitro cell suspension cultures of strawberry induced a statistically significant reduction of cell growth in all the tumor cell lines tested. Interestingly, human fibroblasts from healthy donors were not subjected to this cytotoxic effect, highlighting the importance of further preclinical investigations. The accurate mass measurement, fragmentation patterns, and characteristic mass spectra and mass losses, together with the differences in chromatographic retention times and absorbance spectra, led us to hypothesize that the compound acting as an anti-proliferative agent could be a novel acetal dihydrofurofuran derivative (C8H10O3, molecular mass 154.0630 amu).

Anthocyanic pigments from elicited in vitro grown shoot cultures of Vaccinium corymbosum L., cv. Brigitta Blue, as photosensitizer in natural dye-sensitized solar cells (NDSSC).

We investigated the effect on anthocyanins and total phenols content and antioxidant capacity of in vitro shoot cultures of Vaccinium corymbosum L., cv. Brigitta Blue, grown on an eliciting medium supplied with 10 µM naphthalene acetic acid, in combination with reduced content of salts and organics in respect to the basal medium. After 45 days, higher content of total phenols and anthocyanins was obtained from extracts of shoots grown on the elicitation medium. Anthocyanin molecules, absent in control shoots, were identified by HPLC-MS as delphinidine-glycoside, cyanidine-glycoside, delphinidine-arabinoside, cyanidine- arabinoside and cyanidine-acetylglycoside. Chlorogenic acid, present in control shoots, was nearly absent in elicited shoots. We exploited the anthocyanin - based raw extracts of "Brigitta Blue" shoots grown on the elicitation medium as a source of natural dye photosensitizers for Dye Sensitized Solar Cells, taking into account that such raw extracts showed antioxidant properties and photostability features. A purified dye was also prepared and the comparison of the latter with the raw one has been analysed by spectrophotometric, chromatographic and power conversion efficiency determination. The power conversion efficiencies from the raw and the purified dye were not different and they were comparable to the data obtained by other authors with anthocyanin-based dyes from in vivo grown plants.

Disposable electrochemical sensor to evaluate the phytoremediation of the aquatic plant Lemna minor L. toward Pb(2+) and/or Cd(2+).

In this work a miniaturized and disposable electrochemical sensor was developed to evaluate the cadmium and lead ion phytoremediation potential by the floating aquatic macrophyte Lemna minor L. The sensor is based on a screen-printed electrode modified "in-situ" with bismuth film, which is more environmentally friendly than the mercury-based sensor usually adopted for lead and cadmium ion detection. The sensor was coupled with a portable potentiostat for the simultaneous measurement of cadmium and lead ions by stripping analysis. The optimized analytical system allows the simultaneous detection of both heavy metals at the ppb level (LOD equal to 0.3 and 2 ppb for lead and cadmium ions, respectively) with the advantage of using a miniaturized and cost-effective system. The sensor was then applied for the evaluation of Pb(2+) or/and Cd(2+) uptake by measuring the amount of the heavy metals both in growth medium and in plant tissues during 1 week experiments. In this way, the use of Lemna minor coupled with a portable electrochemical sensor allows the set up of a model system able both to remove the heavy metals and to measure "in-situ" the magnitude of heavy metal removal.

Antineoplastic activity of strawberry (Fragaria×ananassa Duch.) crude extracts on B16-F10 melanoma cells.

The antiproliferative and differentiation potential of anthocyanin-rich strawberry fruit crude extracts (SE) were investigated on B16-F10 murine melanoma cells. Treatment of melanoma cells with SE produced a remarkable reduction of cell proliferation, paralleled with both the lowering of the intracellular levels of polyamine, and the enhancement of tissue transglutaminase (TG2, EC 2.3.2.13) activity (used as a differentiation marker). To gain further insight into profiling altered protein expression as a potential biomarker of the SE action on melanoma cells, analysis of the proteomic profile was performed on the treated B16-F10 cells, compared to the control. Following SE treatment, 30 proteins resulted up-regulated, and 87 proteins were down-regulated. In particular proteins overexpressed in cancer cells, involved in tumor progression and metabolism, were down-regulated. The possibility that SE may affect the Warburg effect in B16-F10 melanoma cells is discussed.

Polyamine concentration, transglutaminase activity and changes in protein synthesis during cryopreservation of shoot tips of apple variety Annurca.

Changes in metabolism and protein expression were analysed during cryopreservation of the ancient apple variety Annurca. Our experiments concerned transglutaminase activity, polyamine levels and protein expression associated with shoot tip dehydration. Cryopreserved shoot tips displayed 72% regrowth after treatment in liquid medium with 0.75 M sucrose for 1 day followed by dehydration to 19% moisture content (fresh weight basis). After dehydration, the concentration of polyamines putrescine and spermidine decreased compared with untreated controls, while spermine concentration remained unaffected. Transglutaminase activity was slightly reduced in treated samples, while post-thaw regrowth enzyme activity approached control values. We also detected significant changes in protein expression profiles and identified six proteins related with stress response or involved in the slowing down of the cell cycle. The relationship between biochemical parameters, protein synthesis and cryotolerance is discussed.

Sulphadimethoxine and Azolla filiculoides Lam.: a model for drug remediation.

Plants can be an interesting tool for in situ remediation of drug contaminated waters. In a laboratory model Azolla filiculoides Lam., an aquatic fern known to absorb pollutants, has been exposed to an environmental persistent antibiotic commonly used in intensive farming, sulphadimethoxine (S), to test its bioremediation capability. In a 5 week experiment, plants were cultivated outdoor at four drug concentrations (50, 150, 300 and 450 mg l(-1)) in N-free mineral medium. Drug affects growth rate (as biomass yield per week), N2-fixation, heterocyst frequency, but plants are able to survive. Notwithstanding, at all concentrations tested drug was actively removed from the medium and the accumulation in the biomass is in order of magnitude up to mg g(-1) plant dry weight (1000 ppm). Drug uptake and degradation rates increase with S concentrations in the culture medium. The efficacy of the model was very high. These results demonstrated that Azolla can be taken into consideration as a tool for sulphonamides environmental monitoring and decontamination.